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Charcoal recognition, taphonomy and uses in palaeoenvironmental analysis

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Abstract

Charcoal, predominantly the product of wildfires, is abundant in many sedimentary rocks deposited in a wide range of environments, from terrestrial to marine. It also occurs in some volcanic rocks. This paper outlines aspects of charcoal formation (both natural and experimental) and briefly considers the taphonomic processes leading to a final assemblage. This is done using examples from recent fires and through experimentation. The ways in which charcoal assemblages are recognized in the field and extraction in the laboratory are also considered. Methods of charcoal identification are presented. The range of charcoalified plant organs that can be found is discussed and a wide range of study methods outlined (including light microscopy, dark field light microscopy, reflectance microscopy, scanning electron microscopy and synchrotron radiation X-ray tomographic microscopy). Emphasis in this paper is on the study of macro- and meso-charcoal (above180 µm). Finally there is a consideration of the broad use of charcoal from plant evolution studies, fire history studies, vegetation studies, anatomical studies, climate and atmospheric studies and the wider importance of charcoal for the Earth and Biological Sciences. Charcoal is information rich but yet is an under-utilized resource.

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... Additionally, fire plays a significant role in the evolution of different biomes (Preston and Schmidt, 2006;Bowman et al., 2009;Flannigan et al., 2009;Belcher et al., 2010a;Bond and Scott, 2010;Jasper et al., 2013). In Earth's history, evidence for palaeowildfire occur frequently in deposits of many periods ever since the Silurian (Scott and Stea, 2002;Uhl and Kerp, 2003;Glasspool et al., 2004;Scott and Glasspool, 2007;Uhl et al., 2004Uhl et al., , 2008Scott, 2010;Uhl et al., 2010;Jasper et al., 2021). Macro-and microscopic fossil charcoal fragments in clastic sediments are considered as the most robust and reliable proxy to reconstruct palaeowildfire events, together with pyrogenic PAHs and pyrogenic inertinites in coals (Glasspool et al., 2004;Scott and Glasspool, 2006). ...
... The charcoal fragments present in the analyzed samples exhibit a large size range from 5 to 12 mm to 2.0-15 mm, and all are highly compressed with sharp, angular, unabraded edges (Fig. 9). These fragments exhibit the typical characters of macro-charcoal; i.e., black colour and streak on touch, as well as a silky luster (Jones and Chaloner, 1991;Scott, 2000Scott, , 2010. Homogenized cell walls, another character typical for charcoal (e.g., Scott, 2000) of tracheids are clearly visible under SEM (Fig. 10d). ...
... The abundance of opaque phytoclasts indicates oxic conditions and is seen as a result of the prolonged oxidation/transportation of translucent phytoclasts, and/or through raised temperatures (Tyson, 1989(Tyson, , 1995Cincotta et al., 2015). The high incidences of opaque phytoclasts are also related to charcoalification (natural pyrolysis) due to palaeowildfires (Scott, 2000(Scott, , 2010Mahesh et al., 2017). The opaque phytoclasts are mainly lath-shaped suggesting that the deposition took place in distal settings (delta fronts, oxic swamp etc.) by a fluvio-deltaic source (Tyson, 1995;Ercegovac and Kostic, 2006). ...
... Valentim et al., 2016;Wang et al., 2020) there seems to be a broad agreement, at least amongst palaeobotanists, that fossil charcoal (including most of the inertinite group of coal macerals) can be regarded as the product of palaeo-wildfires (e.g. Scott, 2000Scott, , 2010Scott et al., 2014;Moroeng et al., 2018a, b;Wang et al., 2019). ...
... For this overview we compiled a list of published evidence for palaeo-wildfire in form of charcoal from clastic sediments, as well as inertinites (assuming that this equals pyrogenic inertinites; cf. Scott, 2000Scott, , 2010Scott & Glasspool, 2007, from the Silurian up to the Cretaceous (Fig. 2). This compilation is based on previous studies that summarized charcoal records from diverse intervals (e.g. ...
... Due to several studies dealing with such inertinites in greater details in the last two decades a huge amount of evidence has accumulated that such inertinites are mostly of pyrogenic origin (e.g. Scott, 2000Scott, , 2010Scott & Glasspool, 2007. ...
Article
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Journal of Palaeosciences (previously: The Palaeobotanist) 70(2021): 159–171 Fire is a major driver for the evolution of biodiversity throughout the Phanerozoic and occurs in continental palaeoenvironments since the advent of the first land plants in the Silurian. The detection of palaeo–wildfire events can be based on different proxies, and charcoal is widely accepted as the most reliable evidence for such events in sedimentary layers. Although the identification of sedimentary charcoal as the product of incomplete combustion was the subject of controversial scientific discussions, palaeobotanical data can be used to confirm the pyrogenic origin of such material. In an overview on Palaeozoic and Mesozoic charcoal remains, differences in the number of published records can be detected for individual periods; including phases with both, lower (Silurian, Triassic, Jurassic) and higher (Devonian, Carboniferous, Permian, Cretaceous) numbers of published evidences for palaeo–wildfires. With the aim to discuss selected advances in palaeo–wildfire studies since the beginning of the 21st Century, we present an overview on the published occurrences of charcoal for an interval from the Silurian up to the Cretaceous. It was possible to confirm that a lack of detailed palaeobotanical data on the subject is detected in some intervals and regions, despite the high potential of occurrences detected in form of pyrogenic inertinites by coal petrographic studies. Although such temporal and regional gaps can be explained by taphonomic and palaeoenvironmental biases, it also indicates the scientific potential of future studies in diverse palaeogeographical and temporal settings.
... Charcoal preserves in strata and is an important indicator when studying wildfires largely due to its steady structure and stronger inoxidizability (Scott and Jones, 1991). Charcoal can be sub-divided by size; macro-charcoal is greater than 180 µm and micro-charcoal is less than 180 µm (Clark et al., 1998;Scott, 2010). These divisions help to simplify the analysis of plant evolution and the reconstruction of the wildfire history (Haytham et al., 2019). ...
... Burning temperature plays a large role in the combustion intensity of a wildfire, and can be predicted through fusinite reflectance (Scott, 2010;Wang et al., 2019). According to the classification of wildfire burning intensity, wildfires can be divided into three types: 1) ground fires mainly burning of organic materials such as leaves and weeds at about 400℃; 2) surface fires mainly burning of shrubby and herbaceous plants at around 600℃; 3) crown fires mainly burning of larger shrubs and the tree canopy at around 800℃ (Scott, 2010). ...
... Burning temperature plays a large role in the combustion intensity of a wildfire, and can be predicted through fusinite reflectance (Scott, 2010;Wang et al., 2019). According to the classification of wildfire burning intensity, wildfires can be divided into three types: 1) ground fires mainly burning of organic materials such as leaves and weeds at about 400℃; 2) surface fires mainly burning of shrubby and herbaceous plants at around 600℃; 3) crown fires mainly burning of larger shrubs and the tree canopy at around 800℃ (Scott, 2010). Based on the relationship between the charcoal burning temperatures and inertinite reflectance, several expressions have been proposed by former researchers (Jones, 1997;Scott and Glasspool, 2005). ...
Article
The coal‐bearing strata in the southern Junggar Basin in north‐western China have recently attracted the attention of coal geologists. Its abundance of coal resources is of great interest as there is a potential of unlocking details about the palaeoclimatic information. Coal deposits have the capacity to record wildfire events, even those with inefficient combustions. To characterize wildfire events and palaeoclimatic history of the Middle Jurassic Xishanyao Formation (Aalenian and Bajocian ages), 22 coal samples from MM‐2 drilling cores and coal mines in were collected and their macerals were analyzed. The results indicated that fusinite and semi‐fusinite were the dominant components of inertinite with proportions of 35.27% and 54.67%, respectively. The presence of inertinite is an indicator that ancient wildfires occurred at the time of deposition, and the widespread occurrence suggests large scale wildfires during the Middle Jurassic. This study proposes a new parameter for the evaluation of wildfire features by combining burning frequency and burning temperature. The comprehensive evaluation index (CEI) was influenced by the lacustrine basin level and ancient plant types from a sequence framework. During the Aalenian and Bajocian ages, most wildfires were low level surface firesand high level ground fire withs. High oxygen levels were identified in the lower, middle, and upper sections of the Xishanyao Formation with corresponding to 26.78%, 24.55%, and 23.55%, respectively. The high oxygen levels in the Aalenian and Bajocian ages would be the primary cause of repeated wildfires in the Middle Jurassic. These results will help establish ancient plant and palaeoclimatic transitions in the Middle Jurassic.
... On the other hand, the charcoals and fine charcoal were exceptionally abundant, especially in the depths of 160-165 cm and 63-68 cm. Such accumulations may indicate an increase in the frequency of fire events in the region (Scott, 2010;Scott and Glasspool, 2007). The low presence of macroscopic charcoal also indicates the site's distance from the source of the fire (Whitlock and Larsen, 2002;Scott, 2010). ...
... Such accumulations may indicate an increase in the frequency of fire events in the region (Scott, 2010;Scott and Glasspool, 2007). The low presence of macroscopic charcoal also indicates the site's distance from the source of the fire (Whitlock and Larsen, 2002;Scott, 2010). In addition, the small size range of the charcoal fragments in the STPII profile means that the material has been sorted, probably during its movement with water (Scott, 2010), i.e., slope wash processes. ...
... The low presence of macroscopic charcoal also indicates the site's distance from the source of the fire (Whitlock and Larsen, 2002;Scott, 2010). In addition, the small size range of the charcoal fragments in the STPII profile means that the material has been sorted, probably during its movement with water (Scott, 2010), i.e., slope wash processes. Among the larger charcoal fragments, the remains of trees such as Alnus sp., Picea abies, and Pinus sylvestris were determined, with Pinus sylvestris being the dominant species. ...
Article
In the rich of archaeological sites dated from the late Palaeolithic to the Modern Period region of the Serteyka River, deposits of an extensive accumulative fan were studied in detail. In the lower sector of the present-day Serteyka River valley, the strict chronology and depositional conditions of an extensive accumulative fan deposits were studied in detail. An important part of the project has been also: a checking of usefulness of luminescence, radiocarbon and lead methods of dating in determination of the age of inorganic deposits accumulation The ¹⁴C, optically stimulated luminescence (OSL), and ²¹⁰Pb dating methods were used to determine the fan's deposition age. Then, we discussed the depositional conditions of the accumulative fan by the textural, geochemical, and palaeoecological analysis. The use of ¹⁴C and ²¹⁰Pb methods of dating allows for elaboration of a reliable model of the evolution of slope processes occurring from the 2nd half of 17th c. AD to 2nd half of 19th c. AD (i.e. during the younger part of the Little Ice Age). It was a period of human induced deforestation, as confirmed by the first results of palaeobotanical analyses. In addition, four OSL dates have been obtained, but the acquired age significantly exceeded previous expectations. Three dates indicate the Neolithic period, and a chronological inversion of OSL dates can be seen. This may be due to incomplete bleaching of the sand grains during transport, which indicates that the material being transported had a relatively large volume. The lower deluvium of the accumulation fan is formed by the drainage of hydrated sediment (mudflows). Summarizing, slope sediments can be extremely difficult material for absolute dating. This may be due to the redeposition of the material, the hiatuses in deposition and incomplete bleaching of quartz grains. In the case of ¹⁴C (AMS) dating, the dependence is on the presence of plant macroremains within the studied material. In the case of slope deposits, there is a very high probability of the redeposition of organic material. Lead dating, on the other hand, has a small chronological range. Moreover, the dating of inorganic sediments with this method poses many problems, including of a methodological nature. In the tested accumulative fan, as a result of insufficient grain whitening and the short chronological range of the ²¹⁰Pb method, the ¹⁴C method was the main analysis determining the age of inorganic sediments.
... Charcoal, produced from the incomplete combustion of vegetation, has paleoecological and paleoenvironmental characteristics, being considered a (paleo) indicator, preserving the source material anatomy, its chemical and biological structure (SCOTT, 2010). Thus, the study of charcoal provides us with information on the interactions between climate, fire ecology, and vegetation, interpreting such interactions under the climatic changes that occurred in the past (JASPER et al., 2011). ...
... An important factor in the usefulness of charcoal, a paleoecological indicator, is the ability to preserve the anatomy of plants in environments where the material decays, having their botanical affinities visualized in a scanning electron microscope (CRAWFORD; BELCHER, 2014;SCOTT, 2000;2010). In Figures 4 to 7 we can observe the samples of charred wood in an atmosphere in the percentages of 21% and 30% of O2 in transversal, radial and tangential cuts in order to illustrate the differences and similarities that occur in pyrolysis. ...
... However, the temperatures influence the decrease in mass, between 380 to 500ºC there is a reduction in gas emissions released, with the production of acetic acid, methanol, tar and various condensable gaseous substances. The mass loss is of the order of 70% in relation to the origi nal mass Addressing that atmospheric oxygen levels had risen to 30% in the atmosphere, the highest in Earth's history, triggering higher incidences of forest fires (BELCHER, 2013;SCOTT, 2010;SCOOT et al., 2017). The work links some observed anatomical characteristics of Araucarioides to other gymnosperms. ...
... In the literature fossil charcoal is also known as fusain, or as coal macerals of the inertinite group, i.e., fusinite, semifusinite and inertodetrinite (e.g., Scott, 2000;Scott and Glasspool, 2007). Due to its chemical inertness it can easily be preserved in the fossil record as it is largely resistant against chemical and biological decay (Scott 2000(Scott , 2009(Scott , 2010Friis et al., 2006;Glasspool et al., 2006). The occurrence of charcoal in sediments indicates the occurrence of past wildfires and, as fire regimes are coupled to certain climatic parameters, it is also useful in understanding some of the effects of climate change on past ecosystems (Power et al., 2008). ...
... The fossil record of charcoal can be traced back to the Late Silurian . Evidence of palaeo-wildfires, is known in the form of macroscopic and microscopic charcoal in clastic sediments, pyrogenic inertinites in coals and lignites, as well as pyrogenic polyarmomatic hydrocarbons, which are produced during the combustion of organic matter (e.g., Scott 2000Scott , 2010Scott and Glasspool, 2007;Scott et al., 2014). Especially macro-charcoal, which often exhibits excellently preserved anatomical details, can provide information about the botanical affinities of the plant which were affected by wildfires (e.g., Scott, 2000;Friis et al., 2006). ...
... The plant remains exhibit a black colour, silky lustre and a black streak on touch, which are considered as characteristics for charcoal (e.g. Scott, 2000Scott, , 2010. The fragments were isolated with help of dissecting knives and needles, then mounted on stubs with double sided adhesive carbon tape, coated with gold palladium (model JEC 3000PC) and subsequently investigated under Field Emission Electron Microscope (model JEOL 7610F) at the Birbal Sahni Institute of Palaeosciences, Lucknow, India. ...
Article
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Macroscopic fossil charcoal fragments have been recovered from the borehole AK-19 (at a depth of 120.00 m) drilled at the Astona-Kothurna coal block, Wardha valley coalfield. In general, the occurrence of charcoal in sediments is accepted as a direct indicator for palaeo-wildfires. The charcoal fragments exhibits well preserved homogenized cell walls as well as anatomical details such as uniseriate and biseriate pitting patterns on tracheid walls under Field Emission Scanning Electronic Microscope (FESEM), suggesting a gymnospermous wood affinity of the studied material. The excellent preservation, their large size and almost unabraded edges of charcoal fragments suggest a par-autochthonous origin. These findings add further evidence for the widespread occurrence of such wildfires during the Early Permian not only in India, but on the entire Gondwana continent.
... Fires are an important part of the Earth System today (Bowman et al., 2009) and as has been previously demonstrated, they represent an important element of the Carboniferous Earth System (Beerling et al., 1998;Scott and Glasspool, 2006;Scott, 2010Scott, , 2018Glasspool et al., 2015).Yet today it is well appreciated that there are a range of fire environments and that some types of vegetation are more flammable than others (Hudspith et al., 2018;Scott, 2020). There is also an increasing understanding of the relationship between fire and climate change (Scott, 2020). ...
... This exothermic reaction creates a chain reaction allowing the fire front to spread (see Scott, 2020 for a description of the charcoalification process). The fire may initially spread as a surface fire, but may not only consume surface vegetation but also char litter through the exposure to heat (Scott, 2010). Fire may spread through ladder fuels into the crowns of shrubs and trees but in such cases much of the smaller plant material may be completely consumed by the fire (Scott, 2010). ...
... The fire may initially spread as a surface fire, but may not only consume surface vegetation but also char litter through the exposure to heat (Scott, 2010). Fire may spread through ladder fuels into the crowns of shrubs and trees but in such cases much of the smaller plant material may be completely consumed by the fire (Scott, 2010). In modern wildfires much of the charred material preserved comes from charred litter that will include all plant organs and even insects Scott, 2010). ...
Article
New data on some fossil charcoal deposits from the British Isles is integrated into previous studies to provide an indication of our current understanding of the role of fire on land in the Pennsylvanian and also provide strategies for obtaining new information in the future. The nature and occurrence of fossil charcoal (often called fusain) in sediments and coals (often described as inertinite/fusinite/semi-fusinite) is the main way that the history of Carboniferous fire has been studied. Fires have been shown to have been common in many Carboniferous ecosystems around the world, yet we still have little understanding of the details of what these fires were, where and how they occurred, or their effects upon both on the local ecosystem and the Earth System as a whole. Research has demonstrated that detailed scanning electron microscope studies of charcoal residues can provide data on the plants that have been charred by wildfires. Information on the amount of charcoal in coal globally appears to relate to atmospheric oxygen composition and this shows that throughout the Carboniferous oxygen levels were as high or higher than those of the present day, suggesting that wildfires were more frequent. Interpreting the frequency of fires in different ecosystems remains fraught with difficulty and calculations within peat (coal) systems are at an early stage. The impact of fire on vegetational change as well as the relationship between fire and climate in the Carboniferous remains little studied. A study of the inertinite (charcoal) distribution within the Low Barnsley Seam in Yorkshire, England indicates that levels remained high throughout much of the 1.8m thick coal seam. A previous palynological study of the seam has demonstrated three repeated successions of vegetational development interpreted as repeated phases of wet to dry mire development (rheotrophic swamp to ombrotrophic bog). Inertinite peaks above 20% background have indicated a minimum of 18 significant large fire events and an analysis of depositional rates suggests a fire return interval of these large fires to be 500 years or less. A study of charcoalified vegetation from fine-grained clastic sediments from Swillington Brickworks, Yorkshire recovered from bulk maceration of the sediment, that was not evident from bedding surface examination, has demonstrated that some levels contain abundant leaf charcoal, mainly from pteridosperms, in addition to wood charcoal derived from a range of gymnosperms. The charcoalified plants are interpreted as wildfire residues mainly from surface fires that have been transported and deposited on low-lying floodplains.
... These fragments are threedimensionally preserved, exhibit a black streak on touch as well as a silky lustre (Plate I,2). Under SEM homogenised cell walls (Plate II) and excellently preserved anatomical details (Plates II-III) can be observed, and together these features are considered as characteristic for charcoal (e.g., Scott, 2000Scott, , 2010. Thus, this material represents direct evidence for the occurrence of palaeo-wildfire(s) during deposition of the late Eocene lignite of the Bubenheim Formation. ...
... The relatively large size spectrum of the specimens, as well as the absence of abraded edges of the individual charcoal specimens, indicates that this material has probably not been transported over large distances as no clear evidence of sorting into different size classes can be seen (e.g., Vaughan and Nichols, 1995;Nichols et al., 2000;Scott, 2010). Thus, it is assumed that this material has an (par-)autochthonous origin, representing the remnants of wildfire(s) that occurred probably within the peat-forming vegetation. ...
... The material is black and exhibits a silky lustre. Under SEM homogenised cell walls (Plate IV,4) and excellently preserved (Plate IV,(3)(4), though mostly rather heavily compressed anatomical details (Plate IV,2) can be observed, and together these features are considered as characteristic for charcoal (e.g., Scott, 2000Scott, , 2010. Thus this material represents direct evidence for the occurrence of palaeo-wildfire(s) during deposition of the early Oligocene clay of the Maifeld Formation. ...
Article
Macro-charcoal from late Eocene–late Oligocene deposits of the Neuwied Basin in W-Germany provides evidence for the occurrence of palaeo-wildfires in three different time-slices in this region. (Par-)Autochthonous macro-charcoal from lignites of the late Eocene Bubenheim Formation of the locality Koblenz-Metternich can best be compared to the genus Doliostroboxylon Dolezych, the wood of the extinct conifer genus Doliostrobus Marion. Small, unidentifiable charcoal fragments from the early Oligocene Maifeld Formation of the locality Kärlich have been discovered in limnic/brackish deposits. Due to the small size of the fragments, as well as their general bad preservation it is not possible to provide any meaningful interpretation of the source vegetation. Macro-charcoal from a lignitic lens within the late Oligocene Kärlich Formation of the locality Koblenz-Schmidtenhöhe can be assigned to taxodioid? Cupressaceae. Like other late Oligocene charcoals assigned to this plant group from the nearby Westerwald region, these remains exhibit marked growth rings, pointing to some kind of seasonality. These findings, together with previous records of charcoal from adjacent areas, demonstrate that wildfires, an important source of disturbance in terrestrial ecosystems since the late Silurian, were part of late Eocene to late Oligocene ecosystems in the Neuwied Basin and/or its direct vicinity.
... Wildfires have played an important role in Earth system changes since the Silurian period when land plants first appeared on Earth and profoundly influenced global ecosystem patterns and processes (Glasspool et al., 2004;Glasspool et al., 2015;Lu et al., 2021). Charcoal, as the byproduct of wildfires, is recorded from the late Silurian (~420 Ma) to the present (Scott and Glasspool, 2006) and provides evidence for wildfire events in the rock fossil record Scott and Glasspool, 2007;Scott, 2010;Shao et al., 2012;Wang et al., 2019a;Wang et al., 2021a). Fusinite and semifusinite, the most frequent members of the inertinite maceral group, are believed to be the product of incomplete combustion from wildfires and were regarded as fossil charcoal in previous studies (e.g., Bustin and Guo, 1999;Scott, 2002). ...
... Abundant charcoal particles from several microns to several centimeters were observed in hand specimens, in transmitted and reflected light microscopy and under the SEM (Figs. 4, 5, 6 and 7). These macroscopic and microscopic features are consistent with the characteristics of charcoal described by Scott (2010). In the study area, relative inertinite contents (8.3-42.5 vol.%) ( Table 1) are very similar to relative inertinite values (mostly 10-45 vol.%) in coals from the Lower Cretaceous Erlian, Hailar, and Sanjiang basins in northeastern China (Wang et al., 2019b). ...
... 10). According to Jones (1996) and Scott (2010), the cell walls of inertinite become homogenized above a temperature of 300-325 • C. In Unit C, the inertinite observed under SEM shows homogenized cell walls (Fig. 7), indicating that the burning temperature of wildfire was higher than 300-325 • C. In Unit D, the proportion of inertinite with reflectance values less than 1.8%Ro increases to 81%, while inertinite with reflectance values between 1.8 and 3.5%Ro accounts for 19% of the inertinite population of Unit D. These results indicate a decrease in burning temperatures through time in Unit D. ...
Article
Full-text available
Wildfires are an important source of disturbances in the Earth's system and are of great significance for understanding the interactions between environmental, atmospheric and vegetation changes over deep time. The early Cretaceous was a “high-fire” interval with frequent and widespread wildfires globally, but the timing and global significance of these wildfire events during this time remain uncertain. We undertook a multi-proxy study evaluating kerogen macerals, inertinite reflectance, and polycyclic aromatic hydrocarbons (PAHs) from mudstones to characterize wildfire activity in the Albian coal-forming Fuxin lacustrine Basin, and correlate these with (i) environmental and floral changes on land, and (ii) well-dated marine events including the early Albian Oceanic Anoxic Event 1b (OAE 1b), to consider their environmental and climatic significance. The presence of high inertinite contents demonstrate that multiple, widespread wildfire events occurred during the early Albian, which are correlated stratigraphically to the Kilian, Paquier and Leenhardt sub-events of the early Albian OAE 1b. Inertinite reflectance values ranging from 0.6% to 3.8%Ro show that wildfires in the early Albian were dominated by ground fires, with a smaller proportion of surface fires and almost no crown fires. Atmospheric oxygen concentration (pO2) levels, estimated from inertinite contents, attained ~25% during the early Albian, which exceeded the present atmospheric oxygen level of 21% and was able to support sustained combustion. Climatic conditions and frequent wildfire activity in the early Albian might have acted as an important control on vegetation distribution and diversification, which possibly further promoted the evolution of early angiosperms during the early Cretaceous. Wildfire activity resulted in the burning and destruction of both vegetation and soil structure, enhancing the post-fire erosion associated with intensified continental weathering under warmer and more humid conditions during the early Albian OAE 1b interval. These episodes of high wildfire activity correlate with high nutrients and organic matter levels in lakes and thereby contributed to eutrophication and anoxia in lacustrine and in contemporaneous oceanic systems.
... Additionally, fire plays a significant role in the evolution of different biomes (Preston and Schmidt, 2006;Bowman et al., 2009;Flannigan et al., 2009;Belcher et al., 2010a;Bond and Scott, 2010;Jasper et al., 2013). In Earth's history, evidence for palaeowildfire occur frequently in deposits of many periods ever since the Silurian (Scott and Stea, 2002;Uhl and Kerp, 2003;Glasspool et al., 2004;Scott and Glasspool, 2007;Uhl et al., 2004Uhl et al., , 2008Scott, 2010;Uhl et al., 2010;Jasper et al., 2021). Macro-and microscopic fossil charcoal fragments in clastic sediments are considered as the most robust and reliable proxy to reconstruct palaeowildfire events, together with pyrogenic PAHs and pyrogenic inertinites in coals (Glasspool et al., 2004;Scott and Glasspool, 2006). ...
... The charcoal fragments present in the analyzed samples exhibit a large size range from 5 to 12 mm to 2.0-15 mm, and all are highly compressed with sharp, angular, unabraded edges (Fig. 9). These fragments exhibit the typical characters of macro-charcoal; i.e., black colour and streak on touch, as well as a silky luster (Jones and Chaloner, 1991;Scott, 2000Scott, , 2010. Homogenized cell walls, another character typical for charcoal (e.g., Scott, 2000) of tracheids are clearly visible under SEM (Fig. 10d). ...
... The abundance of opaque phytoclasts indicates oxic conditions and is seen as a result of the prolonged oxidation/transportation of translucent phytoclasts, and/or through raised temperatures (Tyson, 1989(Tyson, , 1995Cincotta et al., 2015). The high incidences of opaque phytoclasts are also related to charcoalification (natural pyrolysis) due to palaeowildfires (Scott, 2000(Scott, , 2010Mahesh et al., 2017). The opaque phytoclasts are mainly lath-shaped suggesting that the deposition took place in distal settings (delta fronts, oxic swamp etc.) by a fluvio-deltaic source (Tyson, 1995;Ercegovac and Kostic, 2006). ...
Article
We report studies of petrography, palynofacies, charcoal and adpressed plant fossils for the coal-bearing Jagannath section in the Talcher Coalfield, Mahanadi Basin, India, to improve understanding of the age, palaeoecology and depositional setting of this palaeo-mire. Palynology is indicative of the Scheuringipollenites barakarensis assemblage, suggesting an Early Permian (Artinskian) age for the studied section. The age of the studied section is inferred based on correlation with coeval assemblages across Gondwana. Palynoassemblages have more similarity with those of Africa than South America. Petrographic indices suggest that peat-forming vegetation accumulated mainly in telmatic settings under ombrotrophic-mesotrophic (intermittent fluctuating) hydrological conditions. Palynofacies suggest that the deposition of organic matter (by high energy fluvio-deltaic agents) took place in an oxic to occasionally dysoxic setting. Megaflora comprise a low diversity assemblage dominated by Equisetales (Schizoneura and Paracalamites), with less common Glossopteridales (Glossopteris, Gangamopteris) and Filicales (Dichotomopteris) indicative of dense arborescent vegetation. Numerous fossil macrocharcoal fragments indicate the repeated occurrence of wildfires in the catchment area. The high abundance of pyrogenic inertinites in Permian coals of Gondwana may indicate a high-fire phase of Earth history linked to elevated atmosphere oxygen level, and our current study further substantiates this idea demonstrating the occurrence of fire, not only in seasonally dry ecosystems but also in peat forming ecosystems under humid conditions. Our multiproxy study is significant for understanding Permian peat-forming ecosystems and environments and provides a robust age assessment based on inter and intra-basinal correlations of coeval sequences across the Gondwana.
... When assessing deep-time paleowildfires, dispersed fossil charcoal ('fusinite' and 'semi-fusinite') is typically considered the most diagnostic form of evidence (Scott and Glasspool 2007;Scott 2010). Fossil soot can be derived from the combustion of hydrocarbons rather than vegetation (Kaiho et al. 2016), while combustion-related PAHs can have various sources (Whiteside and Grice 2016;Kaiho et al. 2021). ...
... Following Scott (2010), fossil charcoal was identified by its black color, silky luster, very high reflectivity, general lath-shaped form, and splintery texture. These grains commonly have well-preserved cellular structure with homogenized walls, and a tendency to fracture longitudinally owing to contraction of cell walls away from the middle lamella (Jones and Chaloner 1991). ...
... Furthermore, the inert nature of charcoal (Jones and Chaloner 1991) makes it resistant to chemical breakdown, enhancing its longevity in the sedimentary cycle. The detection of reworked micro-charcoal is confounded by its tendency to splinter into lath-shaped fragments (Scott 2010) rather than become rounded like many other common sedimentary particles. The sparse vegetation in the immediate aftermath of the EPE led to a paucity of autochthonous plant remains ; hence, reworked pre-EPE charcoal could be over-represented in this interval. ...
Article
Wildfire has been implicated as a potential driver of deforestation and continental biodiversity loss during the end-Permian extinction event (EPE;~252 Ma). However, it cannot be established whether wildfire activity was anomalous during the EPE without valid pre-and post-EPE baselines. Here, we assess the changes in wildfire activity in the high-latitude lowlands of eastern Gondwana by presenting new long-term, quantitative late Permian (Lopingian) to Early Triassic records of dispersed fossil charcoal and inertinite from sediments of the Sydney Basin, eastern Australia. We also document little-transported fossil charcoal occurrences in middle to late Permian (Guadalupian to Lopingian) permineralized peats of the Lambert Graben, East Antarctica, and Sydney and Bowen basins, eastern Australia, indicating that even vegetation of consistently moist high-latitude settings was prone to regular fire events. Our records show that wildfires were consistently prevalent through the Lopingian, but the EPE demonstrates a clear spike in activity. The relatively low charcoal and inertinite baseline for the Early Triassic is likely due in part to the lower vegetation density, which would have limited fire spread. We review the evidence for middle Permian to Lower Triassic charcoal in the geosphere, and the impacts of wildfires on sedimentation processes and the evolution of landscapes. Moreover, we assess the evidence of continental extinction drivers during the EPE within eastern Australia, and critically evaluate the role of wildfires as a cause and consequence of ecosystem collapse. The initial intensification of the fire regime during the EPE likely played a role in the initial loss of wetland carbon sinks, and contributed to increased greenhouse gas emissions and land and freshwater ecosystem changes. However, we conclude that elevated wildfire frequency was a short-lived phenomenon; recurrent wildfire events were unlikely to be the direct cause of the subsequent long-term absence of peat-forming wetland vegetation, and the associated 'coal gap' of the Early Triassic.
... The lower observed limit of charcoalification has been previously reported at~250°C (Jones et al., 1991), consistent with reported limits of hemi-/ cellulose decomposition (Graham et al., 1984;Mohan et al., 2006). This is contrasted in recent studies reporting cellulose decomposition initiation closer to 280-290°C (Braadbaart et al., 2009;Scott, 2010). Chemical changes in organic matter during charcoalification may begin at lower temperatures, however the wood-charcoal transition has been observed between 310 and 370°C (Braadbaart and Poole, 2008), with full charcoalification occurring at 400°C (Vaughan and Nichols, 1995;Scott, 2010), accompanied by full aromatization (Braadbaart et al., 2009). ...
... This is contrasted in recent studies reporting cellulose decomposition initiation closer to 280-290°C (Braadbaart et al., 2009;Scott, 2010). Chemical changes in organic matter during charcoalification may begin at lower temperatures, however the wood-charcoal transition has been observed between 310 and 370°C (Braadbaart and Poole, 2008), with full charcoalification occurring at 400°C (Vaughan and Nichols, 1995;Scott, 2010), accompanied by full aromatization (Braadbaart et al., 2009). This is, however, dependent on the characterization of "full charcoalification", as changes in mass, carbon content, biochemistry, structure, and reflectance continue up to, and exceed, 1200°C (Braadbaart and Poole, 2008;Braadbaart et al., 2009). ...
... This is, however, dependent on the characterization of "full charcoalification", as changes in mass, carbon content, biochemistry, structure, and reflectance continue up to, and exceed, 1200°C (Braadbaart and Poole, 2008;Braadbaart et al., 2009). More specifically, the generation of true charcoal may be associated with the occurrence of cell wall homogenization within the cellular structure of plant material, the temperatures associated with this process varying widely between 280 and 350°C McParland et al., 2007;Scott, 2010;Osterkamp et al., 2018). It is below this threshold of~300°C that presents significant variability in reflectance, particularly between species (Scott, 1989), indicating a key difficulty for the application of reflectance geothermometry during early charcoalification (McParland et al., 2007). ...
Article
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Charcoal geothermometry continues to offer considerable potential in the study of palaeowildfires over decadal, centennial, millennial, and deep time scales—with substantial implications for the understanding of modern wildfire intensification. Recent developments in the application of Raman spectroscopy to carbonaceous organic material have indicated its capability to potentially reconstruct the palaeocharcoal formation temperature, and equivalent palaeowildfire pyrolysis intensity. Charcoal reflectance geothermometry (which also relies upon microstructural change with thermal maturation) has also been the subject of extensive modern evaluation, with multiple studies highlighting the key influence of energy flux on the resultant charcoal microstructure. The ability to accurately quantify modern wildfire temperatures based upon novel Raman-charcoal analyses has not yet been attempted. Using Raman band width-ratios (i.e., FWHMRa) and accompanying geothermometric trends to natural wildfire charcoals, our results identify differences between microstructurally-derived fire temperatures compared to those recorded during the fire event itself. Subsequent assessments of wildfire energy flux over time indicate no dominant influence for the observed differences, due to the inherent complexity of natural fire systems. Further analysis within this study, regarding the influence of reference pyrolysis methodology on microstructural change, also highlights the difficulty of creating accurate post-fire temperature reconstructions. The application of Raman spectroscopy, however, to the quantification of relative changes in fire temperature continues to prove effective and insightful.
... Moreover, the block-and-crack preservation contradicts structures related to charring. Because wildfires impact woods only superficially, blocky disintegration due to fire would be limited to the periphery (Scott, 2010). By contrast, many block-and-crack-preserved stems from Winnweiler provide evidence of pervasive fracturing (Plate III, 3, 5). ...
... By contrast, many block-and-crack-preserved stems from Winnweiler provide evidence of pervasive fracturing (Plate III, 3, 5). The entire fracturing and charring process of stems likely required long-term thermal overprinting at high temperatures present in hot pyroclastic flows and their resulting deposits (Scott, 2010). However, as the recent excavations also unveiled (Trümper et al., 2021), such depositional scenarios do not apply to the Winnweiler fossil woods. ...
... Bright lines indicate former rays. Scale: 100 μm. and experimental studies in plant taphonomy may be the youngest part of this science reflecting a broad spectrum of terrestrial environments (Scheihing and Pfefferkorn, 1984;Ferguson, 1985;Fritz, 1986;Burnham and Spicer, 1986;Gastaldo, 1988;Spicer, 1989;Rich, 1989;Phillips and DiMichele, 1990;Tegelaar et al., 1991;McLoughlin, 1993;Gastaldo, 1995;Behrensmeyer et al., 2000;Falcon-Lang and Bashforth, 2005;Kelber, 2007;Opluštil et al., 2009;Scott, 2010;Wang et al., 2012;Capretz and Rohn, 2013;Dietrich et al., 2013;Falcon-Lang, 2015;Mustoe, 2017;Trümper et al., 2020a;Liesegang and Gee, 2020;Ricardi-Branco et al., 2020;Rößler, 2021). ...
Article
Silicified wood is one of the most frequent and insightful records of ancient life since the Devonian. Although cellular anatomy is often preserved in great detail, alterations of organic matter occur during fossilization modifying tissue properties. Due to taphonomic pathways, plant tissues experience multiple changes, which may cause a tissue-volume reduction, including desiccation, microbial decay, charcoalification, coalification and mineralization. Case studies from different geological ages, fossilization backgrounds and paleogeographical positions provide evidence of widely distributed but still underestimated shrinkage phenomena in fossil woods. Samples from seven Paleozoic to Cenozoic localities representing several geologic settings are analyzed to understand putative shrinkage reasons. Volume reduction is more widespread in fossilized wood than commonly thought. Accordingly, quantitative data on cellular anatomy may be misleading, and cell size and shape modifications affect morphometric purposes, like the interpretation and identification of fossil species. Differences in preservation demonstrate the profound effects of microbial degradation, such as lacking tracheid secondary walls and decayed tissue constituents. Differential shrinkage of silicified wood and their encrustation by stromatolites help quantify volume loss during fossilization. They provide graphically measurable, one- and two-dimensional parameters to assess percental volume loss. Our approach reveals essential shrinkage-related alterations independent of paleoenvironment, plant material and host rock. Tissue contraction varies considerably: Unexpectedly, variability even occurs in wood from the same fossil site, the same strata and reflecting the same taphonomy. The results demonstrate that shrinkage needs to be taken into account in comparisons of morphometric data obtained from fossil and modern woods, irrespective of their particular provenance.
... Macroscopic charcoal has been identified based on the following criteria (Scott, 2000(Scott, , 2010: black color and streak on touch, silky luster ( Fig. 7), excellent three-dimensional preservation (Figs. 8-10) and homogenized cell walls (e.g., Figs. ...
... The size of the inertinite particles varies from less than 10 μm to more than 200 μm in the polished bulk lignite samples (Fig. 4), suggesting that both local and regional wildfire activity occurred in the peatforming environment and its surroundings (Innes and Simmons, 2000;Nichols et al., 2000;Scott and Glasspool, 2007;Scott, 2010;. The inertinite group consists of a considerable proportion of inertodetrinite in the whole lignite seam , whereas bigger inertinite particles are more common in pale layers (Figs. ...
... This can be explained by the different depositional environments between the two kinds of layers, as pale layers were formed under relatively dry conditions, whereas dark ones were deposited under more wet and humid conditions (Liu et al., , 2020. The dominance of inertodetrinite suggests regional crown fires as a potential source of this micro-charcoal throughout the entire lignite seam (Clark et al., 1998;Scott, 2010) since inertodetrinite is usually considered to be predominantly windblown (Scott, 2010). However, meso-charcoal (180 μm-1 mm, sensu Scott, 2010, semifusinite with low reflectance, Fig. 4e) in pale layers indicates that locally lowtemperature surface fires also occurred occasionally. ...
Article
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Charcoal remains and bulk lignites collected from the late Pliocene Jinsuo Basin in Yunnan, southwestern China, have been studied to reveal changes in the wildfire regime related to changes of the palaeoenvironment, palaeoclimate, and paleobotany. Different types of wildfire occurred in this paleomire with a predominance of low-temperature surface fires, as indicated by mean inertinite reflectance (Ro) values ranging from 1% to 2% in most samples. High-temperature fires are less recorded and occurred more frequently in dark layers compared with pale layers and charcoal layers, as deduced from the elevated proportion of high Ro values (>3%) produced by crown fires or high-temperature surface fires. Wildfire distribution in pale and dark layers was probably influenced by, changes of both plant community and of the depositional environment during their formation. Charcoal layers represent in situ surface and ground fires, whereas pale and dark layers probably record both in situ and remote fire events inside and/or around the basin. PAH were detected in all samples throughout the whole lignite seam, indicating that burning temperatures were low (<400 °C) in most cases in the peatland. Evidence of pre-charring decay observed in some macro-charcoal fragments and pyrogenic inertinite, along with the relatively high content of perylene, shows that decaying wood materials could be a part of the source fuel for the combustion during ground or surface fires. The occurrence and spread of wildfires in the basin during the formation of pale layers probably owe to the drought conditions driven by climate, whereas seasonality of precipitation and temperature was probably the major factor for the occurrence of wildfires recorded from dark layers. The distribution of wildfires within the profile may be relate to climate changes during the mid-Piacenzian.
... Sedimentary microcharcoal analysis was used in this study to assess the history of fire activity in southern Africa. Charred particles are produced through incomplete combustion of organic matter (Scott 2010). These are transported away from points of combustion by wind or water and collect in sedimentary basins. ...
... Charcoal quantities are typically reported as a range of metrics, including influx, concentration, charcoal/pollen ratios, gravimetrics, image analysis, size classification etc. Previous charcoal syntheses (Power et al. 2008;2010) reveal that values from individual sedimentary-based charcoal sample range over 13 orders of magnitude. A protocol has been established for transforming and standardizing individual charcoal records. ...
Article
Globally, fire is a primary agent for modifying environments through the long-term coupling of human and natural systems. In southern Africa, control of fire by humans has been documented since the late Middle Pleistocene, though it is unclear when or if anthropogenic burning led to fundamental shifts in the region's fire regimes. To identify potential periods of broad-scale anthropogenic burning, we analyze aggregated Holocene charcoal sequences across southern Africa, which we compare to paleoclimate records and archaeological data. We show climate-concordant variability in mid-Holocene fire across much of the subcontinent. However, increased regional fire activity during the late Holocene (∼2000 BP) coincides with archaeological change, especially the introduction and intensification of food production across the region. This increase in fire is not readily explained by climate changes, but rather reflects a novel way of using fire as a tool to manage past landscapes, with outcomes conditioned by regional ecosystem characteristics.
... Charcoal is an inorganic carbon compound resulting from the incomplete combustion of plant tissues, which typically occurs at temperatures of 280-500 • C (Rein, 2014). Charcoal particles vary in size and form, but they can preserve morphological characteristics such as edge aspects, surface features, cleavage, luster, or anatomical details (tracheids with border pits, leaf veins, cuticles, etc.) that can be used to determine the potential fuel source, a crucial factor in determining fire type (MacDonald et al., 1991;Scott, 2010;Enache and Cumming, 2006;Jensen et al., 2007;Feurdean, 2021). Several recent studies have attributed fossil charred particles to certain fuel and fire types (Walsh et al., 2010a, Courtney-Mustaphi andPisaric, 2014;Feurdean et al., 2017;Unkelbach et al., 2018;Vasiliev et al., 2020;Dussol et al., 2021). ...
... Sedimentary charcoal has high preservation potential, and it is the most common proxy to determine relative changes in biomass burning (Whitlock and Larsen, 2001;Scott, 2010). Several studies have shown Fig. 6. ...
Article
Charcoal particles vary in size and form, but they can preserve morphological characteristics used to infer the type of vegetation being burnt. To deduce potential fuel and fire type, we reconstructed local fire activity analyzing macrocharcoal morphologies and pollen data of the sediment core CHA08-V from Lake Chalco from the sub-stage MIS 5a to MIS 3, with CHAR data and Z-Score analysis. We identified the following fuel types: i) wood, characterized by blocky and quadrilateral morphologies with solid, foliated or striated surface textures; ii) grass, represented by rectangular-porous and rectangular-latticed morphologies; and iii) herbs, characterized by long-thin filaments and polygonal porous particles. Arboreal pollen components were associated to wood morphotypes whereas non-arboreal pollen related to herbs and grass morphotypes, indicating that variation in vegetation composition was important regulating factor determining fire types in the Basin of Mexico. This study provides the first long-term record of charcoal morphotypes for Mexico region to emphasize the importance of charcoal morphotypes analyses to complement paleoenvironmental interpretation of past fire regimes.
... Charcoal is a black, inert biological fossil formed during the incomplete combustion of wood, and is widely preserved in geological deposits and archaeological sites [1][2][3] . Charcoal contains not only anatomical and hence species information but also physical and chemical attributes representative of the environment at the time of its formation. ...
... Fresh wood tissue was transformed to charcoal and eventually ash as the temperature and time under limited-oxygen conditions increased. The macroscopic criteria for identifying charcoal proposed by Scott [1] were used here, including black color and streaks; conchoidal fracturing; fragility; and bright silky luster. Both Qinghai spruce and Chinese pine samples showed identical color changes with heating. ...
Article
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Charcoal is commonly preserved in both natural and artificial sediments, and is intensively used in paleontological, paleoenvironmental, and archaeological studies due to the abundant bio-information it contains. The biochemical properties of charcoal are also used for paleoclimatic reconstruction; however, the reliability of this approach has been challenged due to a lack of clarity on how physicochemical properties change during the charring process, as well as the temperatures required for charcoalification. To address this lack, in this study, Qinghai spruce and Chinese pine wood samples from the northeastern Tibetan Plateau were heated at different temperatures and for different lengths of time under restricted oxygen conditions. The reflectance; carbon, nitrogen, and oxygen content; and tracheid morphology were quantified before and after heating to assess changes related to the charring process. Archaeological charcoal remains were then evaluated to determine the charcoalification temperatures by comparing with the experimental results. The minimum temperature required for wood charcoalification was ∼300℃, while temperatures of 400–500℃ were recorded for archaeological charcoal. During the charring experiments, the tracheid cell walls gradually homogenized, and tracheid cell wall thickness and lumen area decreased by ∼20%. On average, 50% mass losses were observed; the carbon and oxygen content (% wt.) approximately changed from 47% to 60% and 48% to 35% respectively, while the nitrogen content (% wt.) fluctuated around 0.2%. The reflectance increased slightly from 0% to 0.5%. We propose that the charcoalification of wood tissue refers to charring (in restricted air) and carbonization (in the almost absence of air) when the wood is exposed to a heat source, which then finally transforms into a black, inert solid. This quantitative study provided valuable data and a thorough assessment of the process of wood charcoalification, as well as accurately estimated the feasibility of using charcoal physicochemical properties in paleoclimatic research.
... The material was collected along with other fossils that have been recently described (Kellner et al. 2019;Pinheiro et al. 2020;Piovesan et al. 2021) by the PALEOANTAR team, during the fieldwork of the XXXIV Brazilian Antarctic Operation (austral summer 2015/16). Four fragments showing macroscopic features of charcoal (≥2.0 mm, black colour and streak, silky luster [sensu Jones & Chaloner 1991;Scott 2000Scott , 2010) were mechanically extracted from the sedimentary levels for evaluation in the laboratory. ...
... Under SEM, well-preserved anatomical details, including homogenized cell walls, can be observed (Fig. 3a-c). Charcoal is a direct evidence for palaeo-wildfires (Scott 2010), and the presence of homogenized cell walls confirms that the material we studied was charred. In longitudinal section, tracheids show rare uniseriate (Fig. 3d-e) or biseriate alternate pitting (Fig. 3f) consisting of uniseriate pits (Fig. 3e). ...
Article
The Cretaceous “high-fire” period was a global event that reached almost all continental masses during that period in Earth’s history. The extensive wildfires directly affected plant communities. Significant palaeobotanical records in the Antarctic Peninsula have been studied from the James Ross Sub-Basin, especially from the Santa Marta Formation. However, there is no described evidence for palaeo-wildfires in the area so far. Here, we present the first occurrence of fossilized macro-charcoal coming from James Ross Island, confirming that palaeo-wildfires occurred in the Campanian vegetation preserved in the Santa Marta Formation. The new charcoal material has a gymnospermous taxonomic affinity, more specifically with the Araucariaceae, which is in accordance with previous palaeobotanical records from James Ross Island. This occurrence adds new information to the construction of the palaeo-wildfire scenario for Gondwana.
... Charcoal anatomy analysis or Anthracology is a tool of recognised importance in the framework of archaeological or palaeoenvironmental studies (e.g. Scott 2010;Wright et al. 2015;Scheel-Ybert 2016;Höhn and Neumann 2018;Osterkamp et al. 2018). It has also been adopted quite recently, especially in Brazil, as a charcoal identification forensic tool (e.g. ...
Article
Protected areas in the Brazilian Amazon suffer from conflicting activities, such as the production of charcoal from illegal logging. Charcoal anatomy is an important tool that can be useful for forensic charcoal identification and to help the conservation of these areas. To assist in combating deforestation in protected areas, this study describes the charcoal anatomy of 14 tree species that occur in the Tapirapé–Aquiri National Forest, Pará, Brazil, and provides macrographs of transverse surfaces and scanning electron microscope (SEM) images to aid government agencies during surveillance. We adopted a carbonisation method that simulated real conditions. Anatomical features were well preserved in the charcoal. The axial parenchyma and vessel frequency are easily observed in both macrographs and SEM images, so they are important diagnostic features for initial screening of families and for checking the load according to the ‘document of forestry origin’ (DOF) by the surveillance agents. Uncommon and highly diagnostic features for distinguishing genera or even species, such as rays exclusively uniseriate, sheath cells, tile cells and storied structure, were observed only in SEM images. Our findings are suitable to provide a database on charcoal anatomy of native tree species of the Amazon, with practical application in government inspection activities in protected areas in Brazil and other countries with similar issues.
... Both size fractions of charcoals were identified according to the following criteria: opaque and black in colour, reflective of light, lustrous shine, often an elongated lath-like shape that shows sharp edges, original anatomy preserved, and fracture is brittle with splintery fragmentation 99 (Fig. 5). ...
Article
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Fire regimes are changing due to both anthropogenic climatic drivers and vegetation management challenges, making it difficult to determine how climate alone might influence wildfire activity. Earth has been subject to natural-background climate variability throughout its past due to variations in Earth's orbital parameters (Milkankovitch cycles), which provides an opportunity to assess climate-only driven variations in wildfire. Here we present a 350,000 yr long record of fossil charcoal from mid-latitude (~35°N) Jurassic sedimentary rocks. These results are coupled to estimates of variations in the hydrological cycle using clay mineral, palynofacies and elemental analyses, and lithological and biogeochemical signatures. We show that fire activity strongly increased during extreme seasonal contrast (monsoonal climate), which has been linked to maximal precessional forcing (boreal summer in perihelion) (21,000 yr cycles), and we hypothesize that long eccentricity modulation further enhances precession-forced fire activity.
... Charcoal is mainly classified as a fusinite maceral within the inertinite group; however, some semifusinite and inertodetrinite macerals may also be associated with wildfires [24]. On a global scale, the formation of charcoal is affected by the atmospheric oxygen concentrations, with paleoclimate conditions also playing a role in fire occurrence [29,30]. The concentration of O 2 has been varied throughout geological time, and almost the entire Jurassic is considered to have been a period of low oxygen concentration (approximately 13.5-16%; [31] and, consequently, less prone to fire occurrence, e.g., [32,33]). ...
Article
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Organic petrology is an important tool used to characterize dispersed organic matter (DOM) in sediments and sedimentary rocks, and to assess its thermal maturity. This study was carried out on 33 cutting samples (Middle-Upper Jurassic) from the Ramalhal-1 well to characterize the particulate organic matter and to evaluate its thermal maturity. The samples were submitted to optical petrography analysis (reflected white and blue incident lights) and the mean random reflectance was measured. Microscopic observations revealed a low DOM content, characterized by the predominance of macerals of the inertinite group (including charcoal), followed by solid bitumen. Huminite/vitrinite is usually small in size and quantity. Liptinite macerals were also present, represented by sporinite, cutinite, liptodetrinite and rare bituminite. A type III-IV kerogen was defined for the Ramalhal-1 sequence. Huminite/vitrinite mean random reflectance varied between 0.38% and 0.75%, pointing to an immature-to-mature stage of the organic matter. Multi-populations of solid bitumen occurred in almost all the samples, filling voids and fractures in the inorganic materials (mainly carbonates). The bitumen populations were quite heterogeneous, concerning both the optical characteristics and distribution, displaying different thermal maturities. No relationship between vitrinite and bitumen reflectance was established, indicating that these bitumens were not generated in situ.
... However, high temperatures also affect properties of compounds that are not directly involved in the process of combustion, and these they may carry signal about the occurrence of this phenomenon. Direct indicators of fire include, most importantly, carbonized plant remains, which are summarily referred to as 'charcoal' (Scott, 2010). However, they also include a diverse array of organic compounds, of which one very often utilized group of indicators comprises the monosaccharide anhydrides levoglucosan, galactosan and monosan (Kirchgeorg et al., 2014;Zennaro et al., 2014). ...
Thesis
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The present thesis attempts to provide a comprehensive overview of the fire dynamics in Central Europe over the course of the last 12,000 years. Based on extensive analyses of charcoal particles deposited in terrestrial and lacustrine sedimentary sequences and carbonized plant tissues deposited in soils, I was able to track past fire dynamics across a range of spatial scales – from the forest stand scale to the landscape scale.
... The samples from BI and MI were rinsed and picked, but not bleached or counted. Charcoal was identified in these samples using non-destructive characteristics (Scott, 2010). For each sample at FLB, 4 g of sediment was soaked in 5% sodium metaphosphate solution for a minimum of 72 h to deflocculate the sample, decanting excess solution. ...
Article
Arctic warming is expected to accelerate northward migration of the boreal zone, altering the boreal wildfire regime, with changes in fire frequency, intensity, size, and fire season length. The closest analogue to these future high latitude climate conditions occurred during the Pliocene Epoch (2.58–5.33 Ma). Palaeoenvironmental reconstructions at four Pliocene-aged sites across the Canadian Arctic Archipelago reveal that boreal forest occurred at the southern-most site on Banks Island (74.30◦N), while open forest or tundra-forest ecosystems existed further north, characterized by species tolerant of low to moderate fire intensity. The climate that supported these ecosystems was much warmer and wetter than the current climate of the Canadian Arctic Archipelago. Charcoal was discovered in samples across all sites, suggesting that wildfire was ubiquitous within these ecosystems and climate regimes. The reflectance of the charcoal is consistent with crowning fire or a mixed fire regime on Banks Island and a surface fire regime on Meighen and Ellesmere islands. Boreal forest in southern Ontario, Canada, and open taiga are potential analogues for southern and northern Pliocene Arctic ecosystems, respectively.
... The fusinite maceral is common in carbonaceous mudrocks and coals, belonging to the inertinite group, interpreted as charcoal (Arzadún et al., 2017, Fig. 12 a-c and d; Table 2). Permian charcoals have been documented in the sedimentary record of southern Gondwana Basins, attributed to peat fires (Scott and Jones, 1994;Scott, 2000Scott, , 2010Mendonça Filho et al., 2013;Jasper et al., 2008Jasper et al., , 2011Jasper et al., , 2012Jasper et al., , 2013Degani-Schmidt et al., 2015;Kauffmann et al., 2016;Arzadún et al., 2017;Benício et al., 2019). The presence of inertinite in low quantities in coal samples from basal horizons (Fig. 11), and more predominant in samples from the upper section (Fig. 11), reflects drier and more oxidizing environmental conditions (Taylor et al., 1989;Scott, 2000Scott, , 2002 toward the top of the succession. ...
Article
Coal-bearing deposits of the Tunas Formation suggest the existence of potential gas-prone source rocks in the Claromecó Basin, south of Buenos Aires province, Argentina. Two wells, PANG 0001 and PANG 0003, containing Permian rocks assigned to the Tunas Formation were studied through core observation, X-Ray diffraction, petrographic description, geochemical analysis, and organic petrography to investigate the hydrocarbon potential of the Claromecó Basin and define horizons with source rock potential. The analyzed sedimentary successions are composed of medium- to fine-grained sandstones interbedded with tuffs, mudrocks, carbonaceous mudrocks, and coal. Two main horizons with potential source rocks were determined: an upper horizon, at the top of the succession (300–400 m) and a lower one, at the base (740–850 m). These layers are mainly composed of mudrocks, carbonaceous mudrocks, and coal beds up to 4.50 m in cumulative thickness. Total organic carbon (TOC%) content is high, with most samples ranging from 0.5 to 2% in organic-rich mudrocks, and from 26 to 53.9% in carbonaceous mudrocks and coals, characterizing the coal-bearing layers as good-quality source rocks. The organic matter is of terrigenous origin as indicated by the abundance of woody plant debris. Predominant organic matter constituents belong to vitrinite group (type III kerogen), with a low abundance of the inertinite group macerals. Vitrinite reflectance (Ro) values in carbonaceous mudrocks and coals ranged from 1.3 to 1.6% for the upper horizon to 1.9–2.4% at the lower one, reflecting a catagenesis to late catagenesis stage within the wet to dry gas window. The organic matter quantity, type, and maturity in Tunas Formation coal-bearing deposits suggest that this unit has a good potential as gas-prone source rocks.
... The physical properties shown by the pinna compressions such as black color, lustrous sheen and checkered fractures in rachises and pinnulae (Fig. 2D) led to preliminary identification of potential macrocharcoal fragments as per Scott (2000Scott ( , 2010, a preservation type frequently reported for Weichselia remains (e.g., Abu Hamad et al., 2016;Alvin, 1974;Blanco-Moreno et al., 2019;Harris, 1981). However, organic petrography analysis on the material showed low reflectance (Ro = 0.40%), withdrawing the affinity with charcoal and consequently the occurrence of fire events. ...
Article
The presence of the fern Weichselia in a restricted sedimentary interval of a drilling core in the Parnaíba Basin (Brazil) was used as a lead for paleoenvironmental interpretation integrating paleobotanical, palynofacies, palynological, organic petrography and clay mineralogy analyses. The fern paleobiogeography was amplified and its association with terrestrial bryophyte gametophytes (Muscites) indicated depositional conditions corresponding to marginal areas of freshwater bodies subjected to frequent flooding under the general fluvial-deltaic conditions so far accepted for the intermediary portion of the Codó Formation. The high dominance of non-opaque phytoclasts and very scarce autochthonous non-marine palynomorphs pointed to a shallow water body linked to marginal areas of fluvial systems in the river outlets, channel margins in estuarine systems, and/or shallow floodplain lakes connected/open to fluvial canals. The very scarce marine palynomorphs (dinoflagellate cysts) suggest a limited influence from unstable environments on coastal margins or estuarine canals. The terrestrial vegetation surrounding the depositional setting, deciphered by palynological analysis, reflected distinct environmental conditions prevailing simultaneously in 1) humid areas dominated by fern communities, and 2) dry-xerophytic areas dominated mainly by Araucariaceae and Cheirolepidiaceae gymnosperms, both as components of a wider Aptian paleoenvironment within the periequatorial latitudes in South America. The results were supported by clay mineralogy that showed abundance of detrital kaolinite over montmorillonite and suggest the dominance of a climatic humidification process and a less expressive semiarid climate in a regional context.
... Natural wildfires, considered integral part for certain biomes and biochemical cycles [1][2][3][4], are among the crucial processes of the earth systems during the last 400 000 millenniums [5]. Previous studies have reported corroborations of forest fire ecosystem services in the maintenance of the endemic vegetative communities [6]. ...
Article
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The main objective of this study is to push forward a rapid and cost-free method for forest fire proneness assessment within the wildland urban interface (WUI) for developing metropolitan areas. It compares between the forest surfaces within two capital regions from the Western Balkans (WB), namely Sarajevo and Tirana. This study follows a multi-criteria approach and integrates a variety of wildfire ignition or spreading causes relying on an-thropogenic, hydro-meteorological, geophysical, and fuel properties of the study area. The indexing method utilizes specific techniques of data clustering and criteria weighting. The relative degree of implication that each criterion has with wildfire ignition and spreading behaviour is weighted via a hierarchical pairwise comparison (AHP) among criteria. The workflow is automated via graphical modeller in QGIS, making the method easily reproducible to other metropolitan areas in the developing regions. Relying on the map of wildfire spreading capacity index (WSCI), the study demonstrates a vulnerability analysis focusing on the exposed buildings. According to the results, Sarajevo has four times more exposed buildings than Tirana. However, the exposed buildings in Tirana record higher risk values than in Sarajevo. The sensitivity of the proposed indexing model is tested via Receiver Operating Characteristic (ROC) curve method, utilizing historical data on wildfire occurrences relying on the EFFIS database. The results of ROC analysis suggest that the relative weighted factors per each criteria are context-dependent, and must be calculated referring to local occurrences of wildfire. This study suggests that the urbanization and transportation network planning have a direct impact on the wildfire risk for the vegetated wildland urban interface (WUI). This study recommends the identification of wildfire-prone areas of metropolitan forest surfaces to be considered by policy-making bodies which are responsible for the disaster risk reduction at metropolitan level.
... In Żyglin, the highest concentration of charcoal was found in the period from 1740 BCE to 135 CE. The charcoal fragments have different sizes, which may indicate that their transport was minimal (Scott, 2010). With the increase of charcoal accumulation in the sediment (ca. ...
Article
The analyses of human-environment interactions in prehistoric and medieval mining and metallurgical centres in Europe result in various assessments of the environmental impact of early metal ore mining and metallurgy. In some mining and metallurgical sites or areas, such as the prehistoric basin on the Greek island of Kythnos or the later Morvan and Mont Lozère areas in France as well as Tjursbosjön in Sweden, the impact was significant and lasting. In others, such as: Cors Fochno in Wales, the Falkenstein region in Austria, or the Northern Vosges Mountains in France, the environmental changes were limited and reversible. The results of palaeobotanical research (pollen analysis and analysis of plant macroremains) in peat cores from southern Poland enabled the Holocene vegetation transformations in one of the oldest mining regions in Central Europe to be reconstructed. They also provided new data, used to assess the impact of settlements as well as the development of metallurgy on the environment in the region and changes in bog ecosystems. The first changes in vegetation caused by human activity were observed at the boundary between the Neolithic and Bronze Ages. They are documented by pollen indicating shepherding activity and single grains of cereal pollen. The greatest intensity of change, reflected in sediment as a maximum concentration of charcoal, was recorded at the end of the Bronze Age and attributed to the Lusatian culture. The changes in the vegetation under the impact of human activity until the early Middle Ages were reversible and had a local scope. The intensification of slash-and-burn agriculture was indicated as the most probable and important cause.
... Éste es un producto sólido, frágil y poroso, con un alto contenido de carbono (del orden del 80%). Se produce por un proceso de calentamiento en materiales orgánicos como madera y otros residuos vegetales en ausencia de aire (hasta temperaturas de 400 a 700°C) llamado pirólisis o carbonización (Scott, 2010). ...
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Forest fires, defined as the free spread of fire, release carbonized material into the atmosphere resulting from the burning of vegetation. The differentiation of primary / secondary signals in the carbon particles deposited in the lake sediments, allows the reconstruction of the fire regimes of local (near the lake), extra-local (limits of the basin) and regional (originated in another basin) origin. The Basin of Mexico, particularly Lake Chalco, has witnessed significant environmental changes during the late Pleistocene and Holocene. The periods of glaciations and interglacials, together with the intense volcanic activity, have been the forces that have shaped the vegetation, and have determined the fire regime in the area. The goal of this study is to analyze charcoal particles in lake sediments from Lake Chalco, before and after four volcanic eruption under different climatic contexts in the framework of the last 30 thousand years. These are: the Teuhtli tephra or also named Great Basalt Ash (~28,500 years old, possible origin of the Teuhtli volcano); the tephra 9.12 m (~ 27,000 years, with possible origin of the Chichinautzin monogenetic field); the Pómez Tutti Frutti or also known as Andesine Pumice (~17,600 years, from the Popocatépetl volcano) with its associated Gray Pumice (possible early phase of the eruption of the Popocatépetl or Dos Cerros volcanic activity) and the Upper Toluca Pumice (~12,000 years , from the Nevado de Toluca volcano) with an associated previous ash layer. It is analyzed whether the fires are related to the plant composition at the time of the volcanic event, the climatic context, the particular dynamics of each eruption or the interaction of all these factors. Charcoal concentration in the samples were estimated and the carbon flux value (CHAR) was calculated. From the area data in each particle, it was made the differentiation between primary signal (nearby fires) and the secondary signal (possible regional contribution and subsequent deposit to the lake). CHAR data were compared with spring insolation data for 20 ° N, δ18O values from the Greenland NGRIP, and paleovegetation data and percentage of titanium from the sediments of Lake Chalco.
... To perform the macrocharcoal study, the material was sent to the Laboratório de Paleobotânica e Evolução de Biomas of the Museu de Ciências at the Universidade do Vale do Taquari -Univates, Brazil, where it is stored under the acronym PbUMCN (1296-1299). Fragments with diagnostic features of charcoal (black colour and streak, as well as a silky lustre 1,4,21 ) were observed under a stereomicroscope (Zeiss SteREO Discovery, V12) and mechanically extracted from the sediment with the aid of preparation needles and tweezers. Next they were mounted on standard stubs with LeitConducting glue (Plano GmbH, Wetzlar, Germany; www.plano-em.de) ...
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The record of Cretaceous palaeo-wildfires is rather scarce for peninsular India. We aim to report a detailed macro-charcoal analysis as evidence for palaeo wildfires of Early Cretaceous deposits from India. The macro-charcoal was studied using SEM and classified into three morphotypes based on anatomical characteristics. All morphotypes are probably associated with gymnosperms. These findings constitute a record of macro-charcoal and consequently of palaeo-wildfires for the Lower Cretaceous strata of the Saurashtra Basin, Northwest India.
... Another interesting insight from Pian di Lago is provided by microcharcoal counts, which can be correlated with the intensity of human burning activities on the landscape (Guido et al., 2020). In turn, it can serve as an indirect indicator of the overall intensity of human occupation in the past (Scott, 2009(Scott, , 2010. At Pian di Lago, microcharcoal counts in LPAZ PdL-1a average ca. ...
Article
Constrained by the Maritime Alps and a steep coastal shelf, Liguria served as a biogeographic corridor linking mainland Western Europe to peninsular Italy throughout the Late Pleistocene. It may also have served as a biogeographic refugium for Neanderthals, since sites in the region have yielded some of the latest Mousterian dates in Western Europe and, paradoxically, some of the earliest dates for Protoaurignacian occupations. This paper presents an overview of the Neanderthal presence in Liguria between Marine Isotope Stage (MIS) 5 and MIS 3, with a particular focus on the record from the Balzi Rossi site complex. This permits a critical evaluation of diachronic shifts in the Neanderthal occupation of Liguria. This is followed by an analysis of new data from ‘semi‐sterile Mousterian’ Level MS at Riparo Bombrini that show it was occupied very ephemerally by the end of the Mousterian, highlighting major late Neanderthal behavioral shifts. We conclude by proposing that this behavioral pattern is best explained by the last Neanderthals of the Balzi Rossi having occupied the region as an ecologically stable, taxon‐specific in situ micro‐refugium. This has implications for our understanding of Paleolithic refugia more broadly and of the social and ecological conditions in place during the terminal Mousterian period in western Liguria.
... Over the past several decades, macroscopic charcoal analysis (MCA) has emerged as the most widely used method for reconstructing long-term, local (i.e., approximately watershed-scale) fire histories (Clark and Patterson 1997;Clark et al. 1998;Whitlock and Anderson 2003;Gavin et al. 2007;Lafon et al. 2017). Charcoal particles, which are the by-product of the incomplete combustion of biomass during a wildfire, accumulate horizontally in lake, wetland, and other perennially wet sediments (Patterson, Edwards, and Maguire 1987;Scott 2010). Macroscopic charcoal particles >100 microns (µm) are separated from vertically extracted sediment cores using the wet-sieve technique, and are easily identifiable under low-power stereomicroscopes (Whitlock and Bartlein 2003;Conedera et al. 2009). ...
... Thus, we consider that the inertinite in the study area has not been reworked. Fusinite is considered to be the product of incomplete combustion (Guo and Bustin, 1998;Bustin and Guo, 1999), and it has been suggested that inertinite debris is common in the remains of peat following wildfires (e.g., Goodarzi, 1985;Glasspool and Scott, 2010;Scott, 2010). We consider that fusinite is a reliable proxy for wildfire in the study area during the time of deposition. ...
Article
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The Permian-Triassic Mass Extinction (PTME) is the greatest biodiversity crisis in Earth history and while the marine crisis is increasingly well constrained, the timing and cause(s) of terrestrial losses remain poorly understood. There have been suggestions that the End- Permian Terrestrial Collapse (EPTC) pre-dated, was synchronous with or post-dated the marine crisis, or even occurred asynchronously in different regions. We address these conflicting interpretations through a detailed geochemical study of a terrestrial sequence in the Liujiang Coalfield on the North China Plate (NCP) in which we apply zircon UPb dating of tuffaceous claystone, kerogen identification, and analysis of organic carbon isotopic composition (δ¹³Corg), total organic carbon (TOC), continental weathering (via the chemical index of alteration; CIA) and Ni concentrations. Our study constrains the Permian-Triassic boundary (PTB) near the base of bed 20 in our sequence at approximately 251.9 ± 1.1 Ma, immediately above a Ni anomaly also known from other terrestrial sequences and the marine PTME. Organic carbon isotope chemostratigraphy together with evidence for algal blooms and the presence of mudstone clasts suggests that the onset of the EPTC in the NCP was synchronous with the crisis in low latitudes (e.g., South China), but was about 310 kyr later than the EPTC in higher southerly latitudes (e.g., Australia). The EPTC predates the marine PTME. Kerogen macerals suggest that a phase of increased wildfire was sustained from the onset of the EPTC in the NCP until the marine PTME interval, implicating wildfire as a major driver of the EPTC (at least in low latitudes) that, in turn, had devastating consequences for the marine realm.
... The three samples analysed here can be identified as charcoal based on the following criteria (cf. Scott, 2000Scott, , 2010: black colour and streak on touch, as well as silky lustre (Figure 2a), and homogenised cell-walls and well-preserved anatomical details (as seen under SEM; Figure 2b to d). Individual charcoal fragments are up to approx. ...
Article
Fossil evidence for wildfires, in form of fossil charcoal, is known from a large number of Cretaceous localities worldwide and it has repeatedly been argued that wildfires were connected to the evolution and radiation of angiosperms during this period. The present study provides new evidence (in form of macro-charcoal) for the occurrence of wildfires during deposition of the Lower Cretaceous (pre-Aptian) Malha Formation at Wadi Budra of the Sinai Peninsula, Egypt. Despite growing evidence for the worldwide occurrence of wildfires during the Cretaceous, the available database for pre-Aptian wildfires is still rather scarce for large regions when seen on a global scale, hampering causal interpretations concerning the interactions between fire ecology and the evolution of ecosystems during these stages.
... Some quantity of charcoal is transported long distances by wind (Clark 1988, Adolf et al. 2018, Vachula and Richter 2018, Vachula 2021 and has been directly observed in temperate forest fires (Pisaric 2002, Tinner et al. 2006. Charcoal preserves well in depositional environments, such as lake and wetland sediments, because it is abundant and relatively inert (Scott 2010, Scott and Damblon 2010, Hawthorne et al. 2018. Charcoal analysed from the sediments of depositional environments are a useful proxy for past fire activity over geologic time and utilised to analyse ecological changes Larsen 2001, Whitlock et al. 2010), human-environment interactions (Taylor et al. 2005, Bowman et al. 2011, Archibald et al. 2012, Petek 2018, Shipton et al. 2018) and rangeland management (Marchant 2021, Dabengwa et al. 2022. ...
Article
Whirlwinds and visible dust devils occur over semi-arid ecosystems and entrain particles from the ground surface. Fires produce abundant charcoal across savannahs and the resulting blackened surfaces create a large albedo contrast. Whirlwinds have been observed associated with active fires; yet, there are few published observations on post-fire landscapes. Spatiotemporal patterns of whirlwinds have been documented for a limited number of regions and have not been made for the ecosystems of eastern Africa. From field-based sightings in the Serengeti National Park, Tanzania, we report on whirlwinds over burned savannah patches that entrained large quantities of charcoal to produce black coloured charcoal devils that lofted charcoal into the atmosphere. Two occurrences of charcoal devils were sighted and photographed, one each in the Western Corridor (Bunda District) and Lamai (Serengeti District), Mara Region. The observations were compared with regional scale meteorological data and remote sensing satellite imagery and albedo estimates of the land cover conditions. Although direct meteorological or particulate matter measurements were not made, the observations show that both charcoal devils differed in colour, funnel shape, height, and savannah land cover types (different woody to grass fuel canopies), and thus different charcoal morphologies. Charcoal laden whirlwinds require further study and characterization to analyse the contribution to local-scale redistribution of matter and regional-to-global fluxes of terrestrially derived atmospheric particulates. Future research focusing on the spatiotemporal patterns of whirlwinds over burned patches of savannah, the formation, duration and dissipation mechanisms, and characterisation of the entrained material would contribute to our understanding of the phenomena. The redistribution of organic and clastic material would contribute to understanding of detrital fluxes to depositional environments, such as lakes, wetlands, and snow.
... Although samples in this study represent only whole seam thickness, the slight decrease in total inertinite upwards is also noted across a stratigraphic section that is inferred to be the same in three additional locations in the geographically nearby study conducted by Gómez Neita and López Carrasquilla (2017). The presence of inertinite can indicate occurrence of fire(s) (Brown et al., 2012;Scott, 2010). Thus, the decrease in inertinite noted both in this and other studies by Gomez Neita and Lopez Carraquilla (2017) and may suggest a general decrease in fire incidence, perhaps as a result of a 'wetter' environment or a climate less conducive to fire. ...
Article
Petrographic, geochemical and carbon isotopic determinations were conducted on five samples from four seams within the Late Cretaceous-Paleocene of the Guaduas Formation in Colombia. The individual coal seams are thin, ranging from 0.59 to 1.2 m, and occur over a 157 m interval. The average weighted ash yield is 13.7% (dry basis), although one sample presented values >35%. Vitrinite reflectance increases from 1.33% in the stratigraphically uppermost seam (La Cuarta) to 1.44% in the lower most coal seam (Cisquera), indicating their rank to be medium volatile bituminous. The studied sequence of the Guaduas Formation represents a peat environment influenced by shifting depositional settings, particularly in relation to the proximity of marine/brackish water environments as indicated by Sr/Ba values, sulfur, pyrite, δ¹³C and the proportion of telinite. A decrease in inertinite indicates that the peat mires were becoming relatively ‘wetter’ stratigraphically upwards. This trend, unlike that of Sr/Ba and telinite, may be driven by climatic shifts rather than only changes in depositional environment. Both trace and rare earth elements, plus yttrium (REY) are related to the inorganic fraction of the coal. All rare earth elements are depleted relative to average worldwide hard coals (for trace elements) and average upper continental crust (for REY) with the notable exception of Li and Sb for the high ash yield sample (the La Cuarta lower coal seam). The abundance of some REY elements (i.e. Eu, Gd, Tb, Dy, Y, Ho, Er, Tm, Yb and Lu) may be more influenced by the presence of illite rather than just the quantity of total ash yield. Based on the relationship between SiO2 and Nb/Y, the provenance of the inorganics changed from a rhyolitic source at the lowest seam (Cisquera) to a dacite source in the middle layer (El Tesoro) to an andesite source in the stratigraphically uppermost seams (La Gemela and La Cuarta).
... The increase in OI is dominated by volcanic eruption-induced wildfires, which causes leaves to drop and trees to burn (Cui et al., 1997). A large amount of land plant fragments is transported by air or rivers to oceans, which increases the content of terrestrial organic matter in an ocean (Scott, 2010) ( Figure 8C). This causes a sharp reduction in the biodiversity of an ocean (Hints et al., 2003;Perrier et al., 2012) and when organisms die, many corrosive animals first migrate into this area (Walker et al., 2013). ...
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Volcanic ash improves the amount of nutritive elements in the lake and ocean, but it is not fully understood how volcanic ash influences the total organic matter content (TOC) and bio-precursor, and the scope. A volcanic layer, measuring 5 cm in thickness, was examined using electron microscopy scanning, TOC/TS, rock pyrolytic, and inorganic geochemical analyses. The study shows that the TOC content in the overlying shales increases by 18 wt.% on average, and the vertical scope of influence on shales is twice as thick as the volcanic layer. Organic matter enrichment is attributed to the fact that the volcanic layer provides nutritive elements and meanwhile changes the oxidation-reduction condition. Large variations of hydrogen index (HI) and oxygen index (OI) in the lower and upper parts of the volcanic layer is related to terrestrial organic matter vanishing, due to volcanic eruption and subsequently more terrigenous organic matter migrating into the ocean. Little change of the bio-precursor in the overlying and underlying shales may be related to the fast restoration within the ocean and land ecosystems after a volcanic eruption. The decrease in terrigenous sediments indicated by Rb/Sr, Zr/Y, and ∑REE after a volcanic eruption indirectly reflects fast restoration of terrestrial vegetation boom. This study could decipher the influence of volcanic ash on the qualities of the source rock, which can provide a better understanding on discovering more economically petroleum reservoirs in igneous rocks.
... Charcoal, as a product of incomplete wood combustion [1], is an effective indicator revealing fire activity during prehistorical and historical periods [2][3][4][5]. Relatively large pieces of charcoal retain structural features [6,7], allowing identification of taxa with the help of modern reference collections and identification manuals/databases. To obtain a better understanding of charcoal assemblages in strata, Chabal (1997) has proposed that the number and percentage of charcoal fragments of different taxa could be used to estimate the occurrence in primeval vegetation [8]. ...
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The objective of this paper is to examine the representativeness of charcoal taxa at archeological sites in northern China. We carried out standardized laboratory compression tests on 168 samples representing 21 taxa charred at four different temperatures to characterize the mechanical properties of common taxa in temperate China. The results indicate that significant fragmentation differences occur between taxa. Ring-porous/semi-ring-porous taxa with a moderate density (>0.55 g/cm ³ ) are overrepresented, while those with a very low to low density (<0.55 g/cm ³ ) are moderately represented. Diffuse-porous taxa with slightly dense uniseriate rays, rare multiseriate rays and distinct helical thickenings are underrepresented, and those with slightly dense multiseriate rays are overrepresented, while those with rare to moderate multiseriate rays and helical thickening absence are moderately represented. Gymnosperm trees are generally well represented. Among the ubiquitous taxa at the archeological sites across northern China, Quercus and Ulmus may be overrepresented, and Pinus , Salix , Populus , and Acer may be underrepresented, while Betula may be moderately represented.
... Third, the presence of direct residues of fire-ash and charcoal-is easily altered or removed by natural processes such as fungal degradation, water flow, and wind (Scott 2010;Théry-Parisot et al. 2010;Vidal-Matutano et al. 2017). Finally, the reverse can occur where environmental charcoal is introduced into a site, especially at open-air sites, or organic deposits in cave sites can catch fire, leaving evidence of burning there. ...
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The primary focus of this paper is to examine the extent to which the pattern of Neandertal fire use in southwest France occurred at other times and places during the European Late Pleistocene. In previous studies, both direct and indirect data showed a pattern of limited fire use in layers associated with colder intervals in MIS 4 and 3 and more frequent evidence of fire use in those from warmer periods in MIS 5. One possible explanation for this pattern is that Neandertals were harvesting fire from naturally occurring fires. To test the uniformity of this pattern in other geographic regions and climatic conditions, we expanded our analysis to a wider range of paleoenvironmental contexts beyond those found in southwest France, which included new data from five Middle Paleolithic sites and one Upper Paleolithic site. The subsequent analyses of burned flints suggested that Neandertal use of fire was not frequent when climate regimes were colder, and was more variable and frequent during warmer periods. In fact, the study sites did not show abundant evidence for fire use, especially during colder climatic intervals. Such a result provides strong support for the argument of Dibble et al. about the contextuality of the pattern of fire use during Late Pleistocene Europe. We suggest that environmental variables, such as local climate and geographic contexts, influenced the pattern of fire use during the European Late Pleistocene regardless of the marine isotope stages represented at these sites.
... . Particulate charcoal is produced by the incomplete combustion of organic matter and therefore provides direct evidence of burning (MacDonald et al., 1991;Scott, 2010). Charcoal particles within the sediment record may have a local (within the watershed), regional, or even global origin (Conedera et al., 2009) because -depending on size -they can be transported distances as short as several meters up to hundreds of kilometers. ...
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Long-term paleofire perspectives provide key information on natural and human-derived land cover changes. The last few millennia are crucial to understanding the future of wildfire threats, since the increasing global temperatures are expected to have an impact on regions previously assumed to not be endangered. In this study we investigate the interplay between changing climatic conditions, land cover transformation, fires, and human activity based on the first 1750-year-long macrocharcoal record derived from varved sediments of Lake Jaczno, located in northeast Poland. The study is supported by macrocharcoal morphotype analysis, pollen and historical data, and statistical analysis, which revealed that in the vicinity of the lake both low- and high-intensity fires may have occurred. Most of them were set by humans, but in some periods biomass burning was favored by droughts or even derived by natural causes (i.e. lightning). Human-induced fires are especially evident between AD 1081 and 1283. This period corresponds to the peak activity of the Jatvings tribe in the region and the related deforestation for agrarian purposes. Fire combined with human activity and deforestation in the area impacted the limnological processes increasing primary productivity and shifts in water mixing regime.
... The mid-Cretaceous (Albian-Turonian; 112-90 Ma) was exceptionally warm, with some of the highest temperatures in Phanerozoic geological history 40,41 and a relatively shallow temperature gradient between the poles and the tropics 42 . Elevated atmospheric oxygen levels in the Cretaceous (23-29% compared with 21% at present [43][44][45][46] ) and abundance of charred plant fossil remains in the rock record [47][48][49][50][51] suggest that fires were frequent during this period 14,[52][53][54][55][56][57][58] . Some hypotheses of angiosperm diversification highlight that Cretaceous fire regimes may have opened land up for the first flowering plants, whose rapid colonization of regeneration gaps may have provided an advantage over the then-dominant gymnosperms that are intrinsically slower growing 13,14,59 . ...
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The rapid Cretaceous diversification of flowering plants remains Darwin’s ‘abominable mystery’ despite numerous fossil flowers discovered in recent years. Wildfires were frequent in the Cretaceous and many such early flower fossils are represented by charcoalified fragments, lacking complete delicate structures and surface textures, making their similarity to living forms difficult to discern. Furthermore, scarcity of information about the ecology of early angiosperms makes it difficult to test hypotheses about the drivers of their diversification, including the role of fire in shaping flowering plant evolution. We report the discovery of two exquisitely preserved fossil flower species, one identical to the inflorescences of the extant crown-eudicot genus Phylica and the other recovered as a sister group to Phylica, both preserved as inclusions together with burned plant remains in Cretaceous amber from northern Myanmar (~99 million years ago). These specialized flower species, named Phylica piloburmensis sp. nov. and Eophylica priscastellata gen. et sp. nov., exhibit traits identical to those of modern taxa in fire-prone ecosystems such as the fynbos of South Africa, and provide evidence of fire adaptation in angiosperms.
... The potential pyrolysis temperature could be lower than 500 °C (Wolf et al., 2013). Ordinary temperatures in biomass burning were approximately 400 °C, whereas canopy fires can be much hotter (Scott, 2010). The special fuel load may have contributed to the high concentration of BC and low fire temperature, such as wet fuel or smoldering (Marlon et al., 2013;Han et al., 2020). ...
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A series of biotic crises and turnovers have been recorded at the Norian/Rhaetian boundary (NRB), together with a putative perturbation to the global carbon cycle in the form of one or more negative carbon-isotope shifts. Despite this evidence, the full validation of Norian/Rhaetian climate changes has not been possible. In particular, no clear record of Norian/Rhaetian environmental change has yet been recovered from a terrestrial setting. The eruption of the Angayucham Large Igneous Province has been considered as a possible cause for the putative NRB negative carbon-isotope shifts. Hg as a volcanism proxy has been well-studied in many ancient marine and terrestrial sediments, but to date no Hg record has been obtained across the NRB. In this study, we focus on a terrestrial Norian-Rhaetian section (Xujiahe section) located north of Guangyuan in the northwestern Sichuan Basin, which has been correlated to the NRB using cyclostratigraphy and magnetostratigraphy. A long-lived negative trend in δ¹³Corg, superimposed with four negative shifts, is recognized across the NRB interval. This can be correlated to the uppermost part of the third negative δ¹³Corg shift (named S3) recognized in profiles from marine sites in Europe. Contemporaneous Hg concentration, Hg/Al and Hg/TOC anomalies in the Xujiahe section were possibly caused by large-scale volcanic activity. The large amplitude changes in δ¹³Corg (ca. −5.2‰) that we observe are suggested to be associated with local wildfire and enhanced coarse sediment input, indicating a significant environmental change during the NRB interval. Similar paleoclimatic perturbations have been noted across other extinction events (e.g., end-Permian mass extinction event) as a result of the emplacement of large igneous provinces, or because of felsic volcanism.
... The palynoassemblage is showing the dominance (in number) of Scheuringipollenites and sub-dominance Anatomical characteristics of charcoal Jones and Chaloner (1991) and Scott (2000Scott ( , 2010 (Tiwari and Tripathi, 1992). ...
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The present endeavour documents the evidence of Artinskian wildfire from the Indian geological record by means of analysing macroscopic fossil charcoal fragments embedded in the coal bearing succession of Bharatpur Coalmine in Talcher Coalfield, Mahanadi Basin, India. The palynological and SEM analyses record palaeobotanical evidence of this wildfire. The Scheuringipollenites barakarensis palynoassemblage of the present contribution assigns an Early Permian (Artinskian) age to the studied section and it also shows the dominance of glossopteridales, sub dominance of coniferales followed by cordaitales and filicales plant groups. The SEM study of macroscopic charcoal fragments exhibits anatomical features like homogenized cell walls, uniseriate simple, biseriate simple as well as alternate pitting patterns present on tracheid walls and also rays of varying heights signifying gymnospermous wood affinities. The good preservation and large size as well as almost unabraded edges of the charcoal fragments are indicative of a parautochthonous origin.
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The Late Devonian witnessed landscape evolution, increased atmospheric O2 level, intense organic and volcanic activities and initial expansion of earliest wildfires. This paper is focused on petrographic and geochemical studies of Famennian inertinite-bearing marine shale facies in northern Kerman (central Iran), a Late Devonian key area in north of Gondwana. Our studies point to a wildfire activity. During the Famennian, the wildfire activity occurred in lowland vegetation (covered by lycopods) under warm and humid conditions. The moderately hot burning temperature (446.7 °C to 487.9 °C) of the fire and the type of the land vegetation suggest prevalence of a surface wildfire. Following the burning of the land plants, the ground became exposed to weathering that could result in erosion of the soil. Inputs of terrestrial organic matter, nutrients (particularly phosphate) and detrital materials into a nearshore marine environment were mainly controlled by proximity of the depositional environment to the terrestrial source, intense continental weathering of rocks and the soil in the land, wildfire and continental runoff during rainfall. Generally, preservation and enrichment of organic matter and formation of macerals were controlled by wildfire activity, transportation, oxidation, bacterial/fungal degradation and detrital input.
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This study investigated the effects a dilute solution of bleach (4% sodium hypochlorite), has on charcoal. We were particularly interested in considering if charcoal formed under different conditions of pyrolysis was differentially affected by this treatment, which is commonly used for the quantification of charcoal in sediments. We first produced a series of charcoal samples, under laboratory conditions (at temperatures between 250°C and 800°C and under oxygen limited conditions) and then measured total surface area of charcoal before and after treatment in a solution of 4% bleach. We found that charcoal formed ⩽400°C showed nearly complete bleaching after 24 h, while high temperature charcoal (>400°C) was much more resistant. These results indicate this treatment bleaches charcoal formed at lower temperatures: this means particles charred at low temperature may not be quantified in common optical counting or image analysis methods. This could have serious ramifications for sediment-based paleofire research as low intensity fire may be lost from a record, and the resulting fire history biased towards high intensity (high temperature) fires. Our findings suggest the need for a new, non-destructive method for extracting charcoal from sediment.
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Fires are an integral part of modern and ancient ecosystems, serving as friends for renewal or foes for complete destruction and extinction. Indicators of palaeowildfire were so far absent from the Lower Triassic. Lack of plants in the Early Triassic due to the end-Permian mass extinction event and low atmospheric oxygen levels were proposed as the major reasons for the scarcity of wildfires. We present macroscopic charcoals from the Olenekian (Lower Triassic) in northwestern China, indicating probable ground/smoldering fires occurred on landscapes in mid-latitudes of northeastern Pangaea. Atmospheric oxygen concentration during the Olenekian would have been above 18.5%. These findings demonstrate that wildfires continued to be a source of disturbance of terrestrial ecosystems in Bogda Mountains after the end-Permian marine biotic crisis. There were adequate supplies of fuels and oxygen during this critical time period in the Earth history.
Article
The main objective of this study was to develop a methodology to evaluate, by physical and chemical methods, artificially charred logs from three species of Araucariaceae, and compare them fossil charcoal collected in the Faxinal and Belvedere outcrops for possible paleoenvironmental inferences. The species studied were Araucaria angustifolia, Araucaria bidwillii and Araucaria columnaris. For fossil charcoal analyses we used samples from the Mina do Faxinal and samples from the Curva do Belvedere Outcrop. The carbonization process from species of Araucariaceae were Thermogravimetric Analysis (TGA) associated to the techniques of Fourier Transform Infrared Spectroscopy (FTIR) and multivariate analysis. The Principal Component Analysis (PCA) showed that it is possible to describe 90,9% of the data, grouping the samples into two main clusters. Both samples of fossil charcoal from Belvedere and Faxinal showed charring characteristics above 400ºC. Results showed that technical associations, such as TGA, FTIR and multivariate analysis may help to characterize the natural carbonization process and contribute to important paleoenvironmental and archaeological information and inferences.
Article
Measuring and estimating dispersion coefficients for ash particles released in watercourses is required for a broad understanding of their transport and behaviour in aquatic ecosystems. Calibration of a high-frequency acoustic backscattering system and estimates of its sensitivity to particulates of known size distribution and concentration are presented. Laboratory experiments were conducted to derive the relationship between suspended sediment concentration (SSC) of biomass ashes and the signal-to-noise ratio (SNR) measured by a 10 MHz ADV. Small portions of ashes were added in steps (0.006–20 gl⁻¹) into a stirred water tank while ADV was recording changes in SNR, with various combinations of ADV settings, which included power (LOW, LOW+), transmit length (TL = 0.3 mm, 0.6 mm) and frequencies of data acquisition (25 Hz, 100 Hz). Samples were collected for gravimetric and particle size distribution (PSD) analysis. As expected, the salinity and pH of the collected samples increased with SSC. Different backscatter responses were detected depending on the ADV settings and SSC. To maximize the calibration range, the ADV settings power LOW+, TL = 0.3 mm and sample frequency 25 Hz were combined, resulting in a calibrated SSC range of 10–500 mgl⁻¹, where a linear relationship was obtained. The results suggest that it may be possible to apply a single-frequency acoustic technique to the detection of suspended ashes. The particle type and size distribution changed with a concentration above 0.5 gl⁻¹, which may lead to errors in the acoustic estimates of SSC in ash-laden flows.
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Our present knowledge of Permian and Triassic occurrences of fossil charcoal, as direct evidence of palaeo-wildfire, is summarized. These data show that contrary to previous assumptions at least for the Permian a more or les continuous fossil record of charcoal exists. Permian gaps in the fossil record of charcoal are very likely to be explained by taphonomic biases and can not be linked to changes in atmospheric oxygen concentrations. In contrast the record of Triassic charcoal seems to be extremely scarce and this scarcity may be linked, at least to some extent, to rather low oxygen levels. However, parallel to the delayed recovery of terrestrial vegetation after the mass extinction at the Permian-Triassic boundary the fossil record of charcoal improves from the Ladinian up to the Rhaetian, contrary to a drop in atmospheric oxygen concentrations reconstructed by geochemical modeling. Probably a simple correlation between atmospheric oxygen concentrations and the frequency and intensity of naturally occurring wildfires may not be as easily linked to the abundance of fossil charcoal as proposed earlier. Additional factors like taphonomical filters should be taken into account whenever it is attempted to use the frequency and abundance of fossil charcoal as evidence for changes in atmospheric oxygen concentrations.
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Diverse anatomically preserved plant assemblages occur abundantly in Lower Carboniferous volcanic sequences in the Midland Valley Basin, Scotland. They are preserved as calcareous permineralizations and as fusain (fossil charcoal). The plants occur in basaltic ashes, lavas, peats, and limestones. Many of the assemblages occur in deposits that are interpreted as products of phreatomagmatic activity. Numerous genera and species occur specifically in volcanic rocks. The volcanic activity may have stimulated the diversification of early ferns and pteridosperms in particular, as well as causing ecological disturbance and vegetational change.
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This review highlights the ubiquity of black carbon (BC) produced by incomplete combustion of plant material and fossil fuels in peats, soils, and lacustrine and marine sediments. We examine various definitions and analytical approaches and seek to provide a common language. BC represents a continuum from partly charred material to graphite and soot particles, with no general agreement on clear-cut boundaries. Formation of BC can occur in two fundamentally different ways. Volatiles recondense to highly graphitized soot-BC, whereas the solid residues form char-BC. Both forms of BC are relatively inert and are distributed globally by water and wind via fluvial and atmospheric transport. We summarize, chronologically, the ubiquity of BC in soils and sediments since Devonian times, differentiating between BC from vegetation fires and from fossil fuel combustion. BC has important implications for various biological, geochemical and environmental processes. As examples, BC may represent a significant sink in the global carbon cycle, affect the Earth's radiative heat balance, be a useful tracer for Earth's fire history, build up a significant fraction of carbon buried in soils and sediments, and carry organic pollutants. On land, BC seems to be abundant in dark-colored soils, affected by frequent vegetation burning and fossil fuel combustion, thus probably contributing to the highly stable aromatic components of soil organic matter. We discuss challenges for future research. Despite the great importance of BC, only limited progress has been made in calibrating analytical techniques. Progress in the quantification of BC is likely to come from systematic intercomparison using BCs from different sources and in different natural matrices. BC identification could benefit from isotopic and spectroscopic techniques applied at the bulk and molecular levels. The key to estimating BC stocks in soils and sediments is an understanding of the processes involved in BC degradation on a molecular level. A promising approach would be the combination of short-term laboratory experiments and long-term field trials.
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We present a new model of biogeochemical cycling over Phanerozoic time. This work couples a feedback-based model of atmospheric O2 and ocean nutrients (Lenton and Watson, 2000a, 2000b) with a geochemical carbon cycle model (Berner, 1991, 1994), a simple sulfur cycle, and additional components. The resulting COPSE model (Carbon-Oxygen-Phosphorus-Sulfur-Evolution) represents the co-evolution of biotic and abiotic components of the Earth system, in that it couples interactive and evolving terrestrial and marine biota to geochemical and tectonic processes. The model is forced with geological and evolutionary forcings and time-dependent solar insolation. The baseline model succeeds in giving simultaneous predictions of atmospheric O2, CO2, global temperature, ocean composition, δ13C and δ34S that are in reasonable agreement with available data and suggested constraints. The behavior of the coupled model is qualitatively different to single cycle models. While atmospheric pCO2 (CO2 partial pressure) predictions are mostly determined by the model forcings and the response of silicate weathering rate to pCO2 and temperature, multiple negative feedback processes and coupling of the C, O, P and S cycles are necessary for regulating pO2 while allowing δ13C changes of sufficient amplitude to match the record. The results support a pO2 dependency of oxidative weathering of reduced carbon and sulfur, which raises early Paleozoic pO2 above the estimated requirement of Cambrian fauna and prevents unrealistically large δ34S variation. They do not support a strong anoxia dependency of the C:P burial ratio of marine organic matter (Van Cappellen and Ingall, 1994, 1996) because this dependency raises early Paleozoic δ13C and organic carbon burial rates too high. The dependency of terrestrial primary productivity on pO2 also contributes to oxygen regulation. An intermediate strength oxygen fire feedback on terrestrial biomass, which gives a pO2 upper limit of ∼1.6PAL (present atmospheric level) or 30 volume percent, provides the best combined pO2 and δ13C predictions. Sulfur cycle coupling contributes critically to lowering the Permo-Carboniferous pCO2 and temperature minimum. The results support an inverse dependency of pyrite sulfur burial on pO2 (for example, Berner and Canfield, 1989 , which contributes to the shuttling of oxygen back and forth between carbonate carbon and gypsum sulfur. A pO2 dependency of photosynthetic carbon isotope fractionation (Berner and others, 2000; Beerling and others, 2002) is important for producing sufficient magnitude of δ13C variation. However, our results do not support an oxygen dependency of sulfur isotope fractionation in pyrite formation (Berner and others, 2000) because it generates unrealistically small variations in δ34S. In the Early Paleozoic, COPSE predicts pO2=0.2-0.6PAL and pCO2>10PAL, with high oceanic [PO3-4] and low [SO=4]. Land plant evolution caused a 'phase change' in the Earth system by increasing weathering rates and shifting some organic burial to land. This change resulted in a major drop in pCO2 to 3 to 4PAL and a rise in pO2 to ∼1.5PAL in the Permo-Carboniferous, with temperatures below present, ocean variables nearer present concentrations, and PO4:NO3 regulated closer to Redfield ratio. A second O2 peak of similar or slightly greater magnitude appears in the mid-Cretaceous, before a descent towards PAL. Mesozoic CO2 is in the range 3 to 7PAL, descending toward PAL in the Cretaceous and Cenozoic.
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This paper presents carbon isotope data measured in three soil profiles from the Salitre area, Central Brazil. The study forms part of a research project on tropical and subtropical soils in Brazil, in which the main objective is to use carbon isotopes to provide information about vegetation changes that have occurred in relation to climate changes during the Holocene. 14C data from charcoal samples and soil organic matter (SOM) indicate that the organic matter in the soils studied is of Holocene age at least. Furthermore, the presence of a significant amount of charcoal in the soils suggests that forest fire was a significant ocurrence during the Holocene and probably had an important role in determining the dynamics of forest vegetation in the study area. Correspondingly, 13C data indicate that C3 plants provided the dominant vegetation of the study area, even during the dry periods when savanna vegetation is supposed to have replaced the forest communities. This study contributes to our better understanding of the relation between climatic changes and vegetation in the subtropical region of Brazil.
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The relationship between mean random reflectance (Rr) and temperature of modern charcoal formation has been established as a reference for the examination of fusain and the probable temperature ranges of charcoal formation in palaeowildfires. Reflectance measurements were made on three suites of laboratory produced wood charcoals. Three wood species - Pinus sylvestris (Scots Pine), Picea abies (Spruce) and Betula pendula (Silver Birch) - were charcoalified using different experimental parameters. The relationship between temperature and reflectance is seen to be non-linear and there is a rapid rise in reflectance around the 500°C level. The length of "soak' at the heat treatment temperature (H.T.T.) is seen to be significant for a given temperature and the reflectance increases with time. Other factors such as depth of burial, time to reach H.T.T. and the character of the wood also appear to affect the reflectance readings. -from Authors
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Fire may not only be seen as a destructive force but also as a preservational mechanism. Charcoal, a fire residue, preserves anatomy allowing for the identification of plants, is inert, and may survive transport, burial and diagenesis. Evidence of fires in deep time, before man, comes predominantly from macroscopic charcoal deposits. Our earliest records of wildfire come from the late Silurian and early Devonian (420 to 400 million years ago) but evidence of fire through the Devonian (400 to 350 my) is rare, possibly because of low atmospheric oxygen. Atmospheric oxygen levels are thought to have risen rapidly through the Carboniferous and Permian (350 to 250 my) and this coincides with the spread of fire into a range of environments from lowland tropical mires to floodplains and in to upland regions. Sedimentological evidence suggests that post-fire erosion-depositional systems are more widespread in the fossil record than has been previously thought. Studies of charcoalified plants not only provide data on the evolution of plants but also of fire-prone vegetation. Fire has played an important role in the Earth system processes for over 400 million years impacting on the atmosphere, climate and the evolution of terrestrial ecosystems. It is in this context that we should see the Earth as a ‘fire planet’ (S.J. Pyne).
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The application of bio-char (charcoal or biomass-derived black carbon (C)) to soil is proposed as a novel approach to establish a significant, long-term, sink for atmospheric carbon dioxide in terrestrial ecosystems. Apart from positive effects in both reducing emissions and increasing the sequestration of greenhouse gases, the production of bio-char and its application to soil will deliver immediate benefits through improved soil fertility and increased crop production. Conversion of biomass C to bio-char C leads to sequestration of about 50% of the initial C compared to the low amounts retained after burning (3%) and biological decomposition (< 10–20% after 5–10 years), therefore yielding more stable soil C than burning or direct land application of biomass. This efficiency of C conversion of biomass to bio-char is highly dependent on the type of feedstock, but is not significantly affected by the pyrolysis temperature (within 350–500 ∘C common for pyrolysis). Existing slash-and-burn systems cause significant degradation of soil and release of greenhouse gases and opportunies may exist to enhance this system by conversion to slash-and-char systems. Our global analysis revealed that up to 12% of the total anthropogenic C emissions by land use change (0.21 Pg C) can be off-set annually in soil, if slash-and-burn is replaced by slash-and-char. Agricultural and forestry wastes such as forest residues, mill residues, field crop residues, or urban wastes add a conservatively estimated 0.16 Pg C yr−1. Biofuel production using modern biomass can produce a bio-char by-product through pyrolysis which results in 30.6 kg C sequestration for each GJ of energy produced. Using published projections of the use of renewable fuels in the year 2100, bio-char sequestration could amount to 5.5–9.5 Pg C yr−1 if this demand for energy was met through pyrolysis, which would exceed current emissions from fossil fuels (5.4 Pg C yr−1). Bio-char soil management systems can deliver tradable C emissions reduction, and C sequestered is easily accountable, and verifiable.
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The effects of formation temperature, particle size, water salinity, and composition of suspended clay and substrate on the sedimentation of charcoal under agitated conditions in a wave tank were studied in a series of experiments. The temperature of formation of charcoal has a strong effect on the rate at which charcoal becomes waterlogged. Examination of the microstructure of the chars formed at different temperatures shows that the formation of fractures within the wood affects the permeability and hence the rate of water penetration. Heating up to 300 degrees C results in fusion of the cell walls, which inhibits water penetration and shows the rate of settling. At higher temperatures the cell walls progressively fracture, increasing the permeability, and the chars waterlog and settle faster. The settling rates and hence the distribution of charcoal in sedimentary deposits are therefore controlled by the temperatures reached in the fire that generated the material. This sorting related to temperature of charcoal formation has implications for the determination of the size of a paleowildfire from the volume of fusain in a sedimentary deposit. Salinity variations and the presence of a clay substrate were also shown to have a small effect on charcoal sedimentation rates.
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Stratigraphic charcoal data are used to interpret combustion at a range of spatial and temporal scales. Interpretation is based on assumptions regarding how charred particles are transported to and deposited in sedimentary basins and how the variance structure of stratigraphie profiles is affected by transport. Here we examine evidence for “background” and “local” signals in stratigraphie data based on total abundances of particles and on distributions of particle sizes. Distributions of particle sizes in sediments and in the atmosphere show remarkable consistency, with a ~ 2% decrease in frequency for a 1% increase in particle diameter. Relatively large differences in source distance are required to produce differences in particle size distributions. Thus, stratigraphie samples with disproportionate representation of large particles are likely to represent a nearby source. Simple transport models suggest particles 100 to 101 μm have substantially longer atmospheric residence times than do particles > 102 μm. Several factors can produce a “dichotomy” (background vs local) in total abundances of charred particles. Transport during a single experimental burn shows abrupt decline in accumulation at a burn edge and relatively constant values out to 102 m. Saltation and redistribution of particles in surface runoff following fire are expected to focus accumulation within a catchment (local scale). The amount of transport that occurs by these modes is unstudied. The stratigraphie record appears to support a distinction between local, catchment sources vs. fires burning at greater distance. Charcoal profiles often show distinct peaks when fires burn within a lake catchment but are unaffected by fires that occur at greater distance. Broad subcontinental scale patterns in particle accumulation indicate shifts in regional importance of fire. The low frequency variance can be extracted from charcoal profiles and used to differentiate local from background changes in burning. Although the empirical data are still far too few to permit good characterization of particle transport, the evidence suggests utility in the concepts of background and local signals in profiles.
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Charcoal is produced by pyrolysis of plant material and its occurrence in the fossil record can be broadly equated with the incidence of palaeowildfire. The past record of such naturally occurring fire, and tha availability of the biomass which represents its fuel, put two constraints on oxygen levels. For combustion of plant material to occur at all requires that the atmospheric oxygen did not drop below a threshold of 13%. Increasing inflammability of plant material at higher oxygen levels suggests that 35% would be a ceiling above which plant biomass would ignite and burn so readily as to be incompatible with sustained forest growth. As we have more or less continuous fossil evidence of forest trees from the Late Devonian onwards, and a similarly sustained record of fossil charcoal from that time to the present (Cope, 1984), this constraints oxygen levels between 13% and 35% over that period (Rabash and Langford, 1968; Watson et al., 1978). However, further experimental work is required to establish the validity of these oxygen values under appropriate conditions and also to sharpen the certainty by which we can discriminate between fusain produced by pyrolysis, and inert wood degradation products produced by other (? biogenic) means. We discuss experiments directed at attempting to establish the validity of physical parameters by which pyrolytically produced fusain can be characterized. The most convincing evidence of pyrolysis hitherto recognised is the apparent homogenization of xylem cell walls, as seen under SEM. Work on charcoal from both wildfires and laboratory wood charring under controlled conditions confirms the homogenization as seen under both SEM and TEM. Controlled temperature experiments show that a further rise in temperature causes the cell walls, initially homogenized, to crack and separate along the site of the middle lamella, giving the charcoal a characteristic fibrous texture. Both of these distinctive phases of response to pyrolysis can be observed in fossil charcoals.
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Lacustrine and coastal marine sediments often contain polycyclic aromatic hydrocarbons (PAH) of combustion origin. Many higher molecular weight PAH, like charcoal, are hydrophobic and resistant to biodegradation. Recent studies are presented here which indicate that the stratification of PAH in bottom sediments can provide a useful historical record of combustion activity, ranging back millions of years. The distribution of individual PAH in environmental samples often has been used to infer their source. However, this PAH “fingerprint” is affected not only by the combustion conditions and fuel, but also by transport and transformation processes that affect PAH as they runoff from land or move through the atmosphere and water to the sediments. Recent studies, though sparse, suggest that non-linear, higher-molecular-weight PAH sorbed on aerosol black carbon are most resistant to alteration during long-range environmental transport. During the past century there has been a large increase in sedimentary PAH derived from fossil fuel combustion. The latter qualitatively produces PAH distributions similar to biomass burning. The use of new techniques, such as compound-specific isotope analysis (CSIA), which allow for the isotopic determinations of individual compounds, has shown great promise for apportioning PAH sources, e.g. fossil fuel or biomass burning.