Article

Palynofacies as useful tool to study origins and transfers of particulate organic matter in recent terrestrial environments: Synopsis and prospects

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Abstract

Palynofacies analysis is based on transmitted light microscope study of organic constituents isolated and concentrated by acid and basic digestions. Published results of studies of present-day terrestrial environments show that two complementary approaches successfully characterize particulate organic matter (OM) from palynofacies analyses. The first method is based on the identification and the quantification of some typical particles (optical markers) according to their origin (i.e. aquatic or terrestrial), their nature (i.e. biogenic, anthropogenic, fossil), and/or their formation (i.e. biodegradation, combustion, oxidation). The second approach is based on the use of binary or ternary diagrams in order to define petrographical signatures from the relative proportions of significant organic constituents. This approach can be used for tracking i) changes in OM composition during humification in soil profiles, ii) transport of reworked terrestrial particles, iii) diagenesis of peaty deposits, or iv) weathering of geological substratum. The more advanced approach is based on the use of some predefined optical markers and their optical signatures to establish the relation between the OM compositions (palynofacies) and their depositional environments. In addition, this kind of study aims to define a modern frame of reference that can be applied in paleoenvironmental reconstructions . This paper combines a bibliographic review with previously unpublished data from palynofacies analyses. The aim is to present some applied examples illustrating (1) the main approaches developed for characterization of the particulate OM in surficial deposits, and (2) the study of OM transfers in terrestrial geosystems.

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... The GP group has recently been proposed in several research studies (Sebag et al., 2006;Graz et al., 2010;Ţabără et al., 2015). These studies focused more attention on the environmental and climate in formation of the deposits, whereas few studies have focused on the organic origin of these common phytoclasts. ...
... The paleoenvironments control the organic matter composition. The quantitative assemblages of particulate organic matter exhibit an excellent capacity to record environmental evolution under different climatic and sedimentary settings (de Araujo Carvalho et al., 2006;Sebag et al., 2006). Thus, the palynofacies analysis was applied as one of the traditional parameters for paleoenvironmental interpretation (Buchardt and Nielsen, 1991). ...
... Thus, the palynofacies analysis was applied as one of the traditional parameters for paleoenvironmental interpretation (Buchardt and Nielsen, 1991). According to the principle that the relative abundances of different organic matter groups primarily reflect oxygenation conditions, it is similarly suitable for considering the lake level changes and estimated distances from the lakeshore (Sebag et al., 2006). ...
... In the present study tubes and filaments and gelified particles are very scarce but very easy to identify because of their distinct morphological and optical features. Gelified particles have recently been introduced in numerous research studies (Sebag et al. 2006;Graz et al. 2010;Tabara et al. 2015). These particles are mainly derived from the leaf organs of the plants. ...
... The primary composition of sedimentary organic matter is represented by the palynofacies after long process of sedimentation and the organic matter composition represents the palaeoenvironment. The quantitative palynofacies assemblages reveal remarkable capability to represent the environmental evolution under diverse climatic and sedimentary settings (Sebag et al. 2006). As a result, palynofacies analysis Text Figure 2: Classifications of palynofacies produced by cluster analysis in TILIA. ...
... has been widely used as an important parameter for palaeoenvironment reconstruction (Buchardt and Nielsen 1991). Different types of organic matter association reflects the oxic-anoxic conditions, which estimates the lake level changes and approximate distance from the lakeshore (Sebag et al. 2006). ...
Article
Palynofacies analysis has been carried out in borecore VEM-1 from Vemanpalli area of Chinnur Coalfield of Godavari sub-basin, south India. Palynofacies analysis indicates that the sediments are rich in amorphous organic matter and charcoal. On the basis of the quantitative composition of the sedimentary organic matter, four distinct palynofacies association (A-D) have been identified. Palynofacies-A is marked by the dominance of amorphous organic matter and the sub-dominance of charcoal. Palynofacies-B has been recognized by the dominance of amorphous organic matter along with good percentage of degraded terrestrial and charcoal. Palynofacies-C is acknowledged by the dominance of charcoal along with very less percentage of amorphous organic matter. Palynofacies-D is distinguished by the dominance of structured terrestrial along with good percentage of charcoal. Palynofacies A-D, reflect the depositional settings in a distal dysoxic-anoxic deep basin, dysoxic conditions in proximal settings, suboxic conditions in proximal settings and shallowest oxidizing continental shelf respectively.
... The SP category in other continental environments similar to our study site, includes plant-related remains (spores and pollen), other photosynthetic biota (green algae, and rarely, cyanobacteria or dinoflagellates), zoomorphs (e.g. exoskeletal parts of arthropods) and fungi (hyphae, spores and sclerotia) (Courtinat et al. 2003;Sebag et al. 2006b;Traverse 2007b). Each identified remain from these taxonomic groups can be further classified according to degradation state (coalification, oxidation, gelification, amorphization, physical disaggregation). ...
... Furthermore, the average particle size was 100-150 lm, considerably larger than the 15-25 lm obtained using P1, P2 and P3. Some debris acquired a reddish color and displayed dull outlines, an artifact typically described in the literature as ''amorphization'' or ''gelification'' (Sebag et al. 2006b). ...
... The organic matter composition of the samples from this study differed markedly from samples found in other riparian sub-environments. Opaque Particles (OP), typically reported for riparian environments (Tyson 1995;Batten 1996;Di-Giovanni et al. 1999Sebag et al. 2006b, Zocatelli et al. 2012), were only found in the OL sample. Enrichment of OP in this sample could be related to enhanced coalification, a process common in swamp environments (Teichmüller and Teichmüller 1967). ...
Article
We conducted a palynofacies analysis on late Holocene fluvio-palustrine sediments from a succession that outcrops as a terrace proximal to the Cauca River, Colombia, in northern South America. The succession is composed of laminated clay, organic-rich laminae, sand beds and buried soils. These buried soils range in thickness from 2 to 16 cm and are composed of silty clay with varying degrees of root bioturbation and have a gray-green-bluish color. They could classify as Entisols and in this article we refer to them as paleosols. Samples from each of these sediment types (except sand), and samples from two modern-analog environments, also on the proximal part of the Cauca River, i.e. sediment from a seasonally flooded pond and the upper-most layer of a modern soil, were analyzed for organic matter content. Prior to selection of an organic matter extraction method, four protocols were tested on the modern pond sediment sample. A modified protocol involving flotation with ZnCl2 proved to be the best method for these sediment types. We produced an atlas of the main taxa and their relative proportions found in this study and propose this method as an excellent approach to environmental reconstruction of fluvial environments. Very little work has been done on fluvio-palustrine palynofacies in the Neotropics.
... A pollen standard (Cupressus sp.) was added to the solution before the preparation of thin sections. Organic compounds were then quantified and classified according to their color (transparent yellowish to dark brown reddish), their shape (amorphous vs. figured), and their texture (gelified, granular or flocky) (e.g., Sifeddine et al., 1996;Di Giovanni et al., 1998, 2000Sebag et al., 2006a;Simonneau et al., 2013Simonneau et al., , 2014. ...
... The semi-quantitative signal from XRF coupled to LA-ICP-MS analyses allows the quantification of an elemental terrigenous tracer: titanium (Ti expressed in %). On the other hand, quantitative organic petrography allows the quantification of organic terrigenous particles such as red Amorphous Particles (rAP expressed in mg·g −1 ) (e.g., Sebag et al., 2006a;Simonneau et al., 2013Simonneau et al., , 2014. Both results were transformed into fluxes expressed in mg·cm −2 ·yr −1 using the dry bulk density (g·cm −3 ) and the sedimentation rate (cm·yr −1 ). ...
... Among them, amorphous organic particles (AOM) display a yellow to grey color with an amorphous irregular shape and a granular to flocky texture. They have only been identified in lake sediments and are therefore, attributed to the primary productivity in the water column (Sebag et al., 2006a;Simonneau et al., 2013Simonneau et al., , 2014. Red amorphous particles (rAP) display a dark reddish color and a gelified texture without internal structure. ...
Article
A 14-m long sedimentary sequence (core PAV12) was collected in the deepest part of Lake Pavin, a maar lake located in the French Massif Central. The PAV12 sedimentary sequence documents the lake's environmental evolution since its formation 7000 years ago. The relationships between the catchment's vegetation cover, erosion processes and changes in trophic status were shown using a multi-proxy characterization of mineral and organic fractions supported by palynological data. The record shows a succession of lithological units starting at the base, with volcanoclastic material corresponding to the early stage of Lake Pavin. The deposition of organic-rich and diatomaceous sedimentary units above volcanoclastic material indicates an evolution toward a pristine lacustrine state. The Late Holocene environmental history of this lake is marked by two tipping points reflecting major environmental disturbances at ca. 4000 cal BP and after the deposition of erosive mass-wasting deposits (MWDs) at 1350 cal BP (AD 600) and 650 cal BP (AD 1300). The upper unit of core PAV12, which corresponds to the past 700 years, indicates that one of these MWDs was likely the driving force behind a major limnological change marked by a shift in redox-sensitive elements (i.e., current meromictic lacustrine state). The palynological diagram indicates a forested catchment where woodland clearances and agro-pastoral activities have remained limited except over the last 700 years. These findings suggest restricted human impact within the watershed compared to other regional archives. The reconstruction of the Lake Pavin erosion record determined from titanium and red amorphous particle fluxes highlights phases of enhanced erosion at ca. 6.5–5.5, 4.1–3.8, 3.5, 2.8–2.6, 1.6–1.4 cal kyr BP and during the Little Ice Age (LIA). A comparison between this erosion record, palaeoenvironmental archives from Western Europe and palaeoclimatic data supports an Atlantic signal driving precipitation patterns over Lake Pavin at centennial to millennial timescales. The influence of local human activities, even on a small scale, cannot be completely discounted as their impact on erosional processes may be amplified in a steep catchment such as that found in Lake Pavin.
... According to Batten (1996), most cuticles identified in palynological slides are derived from leaves, and are generally associated with fluvial-deltaic environments of low energy, from where they can be transported over long distances prior to destruction or deposition. However, the cuticles identified in this core are well preserved, suggesting that their deposition most likely occurred near the source Un-biostructured phytoclasts, identified in some studies (Sebag et al., 2006a(Sebag et al., , 2006bBoussafir et al., 2012;Zocatelli et al., 2012) as gellified particles, have their origin related to plant tissue degradation in aquatic environments, such as lakes, or under anaerobic conditions, such as in hydromorphic (excess water) soils (Sebag et al., 2006a). Biostructured phytoclasts are described as originating from local vegetation (Tyson, 1995), but they can also be deposited in river channels during flooding (Batten, 1996). ...
... According to Sebag et al. (2006b), all constituents of the particulate 5. a δ 13 C vs. C/N values (weight/weight) of Lake Canto Grande organic matter. Interpretation was based according to data presented by Meyers (1997) and Ogrinc et al. (2005). ...
... organic matter are present in marshes but have different relative abundances. In aquatic environments, autochthonous elements (AOM and algae) are predominant, while allochthonous fractions (phytoclasts) are moderately preserved (Sebag et al., 2006b). Sedimentary samples with TOC values lower than 2-3% are usually associated with assemblages dominated by phytoclasts where these values are determined by variations in the abundance of vegetal particles. ...
Article
The aim of this paper is to reconstruct an 11,000-year history of depositional environmental change in southeastern Brazil, based upon the integration of particulate organic matter and stable isotope (C and N) data from a 136-cm sediment core from Lake Canto Grande. These proxies are used to explore the evolution of terrestrial and marine influence on the lake. Isotopic (δ¹³C: −27.87‰ to −31.9‰; δ¹⁵N: −0.07‰–4.9‰) and elemental (total organic carbon - TOC: 0.58%–37.19%; total nitrogen - TN: 0.08%–1.73%; C/N: 0.3 to 54.7) values recorded in Lake Canto Grande suggest that the sedimentary organic matter was derived from mostly C3 land plants and freshwater phytoplankton. Particulate organic matter and cluster analyses distinguished four associations characterized by the predominance of amorphous organic matter, followed by phytoclasts and palynomorphs. These results indicate two different phases of lake evolution. The first phase (136 - 65 cm; ∼10,943 cal yr. B.P. to ∼8529 cal yr. B.P.) is recorded by sand layers interbedded with mud, which contain amorphous organic matter (AOM, 45–59%) and phytoclasts (opaques - OP: 6–18%; non-opaques – NOP: 17–23%) which indicate a floodplain area. The second phase (65–0 cm; ∼8529 cal yr. B.P. to ∼662 cal yr. B.P.) comprises mud, AOM (68–86%) and palynomorphs (PAL, 8–16%) related to lake establishment comparable to modern conditions. Thus, characterizing particulate organic matter, in combination with stable isotopes, proved to be invaluable proxies for lacustrine paleoenvironmental change through the Holocene.
... The TOC concentrations in the sediment are regulated by the most abundant group (Tyson, 1995), in this case, the phytoclasts. The main organic fraction, comprised of terrestrial plant-derived elements, is typical for peatland systems according to Sebag et al. (2006b). ...
... However, the significant presence of POL suggests that such elements might have been transported by the river or might be a result of the charring processes of surrounding terrestrial vegetation. Sebag et al. (2006b) confirmed the importance of opaque phytoclasts as tools for tracking allochthonous inputs. Nevertheless, it was observed, by the same author, that the opaque particles include heterogeneous constituents that can have various origins, such as combustion residues. ...
... Interval 4 (Figs. 10 and 11) corresponds to Association IV (70cm depth), which is marked by a POE peak, a particle related to the Palynofacies C. The significant percentage of POE suggests that such allochthonous particles may have been loaded into the system due to the overflow of the Uruguay River, which becomes more influential on the depositional system from this interval. The studies of Sebag et al. (2006b) also have demonstrated fluvial influence in the Holocene alluvial deposits of the lower Seine Valley (France) from the gradual increasing frequency of opaque particles. The reappearance of algae, even if not significant, can also be attributed to increased moisture subsidized by fluvial influences. ...
Article
The main goal of this study was to quantitatively and qualitatively characterize the sedimentary organic matter (OM) and demonstrate the usefulness of geochemistry and palynofacies analysis for obtaining paleoenvironmental data for the Holocene in southernmost Brazil. The results indicate that during the time interval from 10586 cal yr BP to the present, the study area housed a wetland characterized by different hydrologic regimes. The basal peaty deposits correspond to a phase influenced mainly by the groundwater table, whereas the upper deposits composed of silty organic mud indicate fluvial influence related to river overflow events. In a similar manner, the TOC (total organic carbon) and TS (total sulfur) contents are higher in the basal portion of the profile, decreasing toward the top. These findings could be related to granulometry alterations that are linked to hydrologic regimes or anthropogenic interference in the landscape dynamics. Anomalous TS content observed in one of the samples might be due to an external source and perhaps related to the presence of thermal springs in the region. These types of areas have potential as a modern reference that can be applied in the reconstruction of past analogous environments such as coal deposits associated with fluvial paleoenvironments.
... van der Zwan 1990, Tyson 1995, Batten 1996, Gastaldo et al. 1998, Cirilli et al. 2015, Hochuli et al. 2015, García Muro et al. 2016, Kumar et al. 2016, Okeke & Umeji 2016, Koch et al. 2017) and has recently been tested in characterization of Holocene alluvial and palustrine deposits (e.g. Gastaldo & Huc 1992, Laggoun-Défarge et al. 1995, Cohen et al. 1999, Di Giovanni et al. 1999, Bourdon et al. 2000, Sebag et al. 2006a, b, Serna et al. 2015 through the identification and quantification of organic matter (OM) phytoclasts according to their origin, nature, formation or preservation in sedimentary processes. In palaeoenvironmental reconstruction studies, palynofacies analysis offers a useful tool in examining geological deposits with poorly preserved or absent fossil material, such as in non-marine, continental and high-energy depositional environments (Traverse 2007). ...
... The sediment samples from Santa Giusta (SG1, SG2, SG4, SG5) and Santa Gilla Lagoon (LSG6), included in Cluster 1 (Fig. 4), show the highest AOM concentrations, indicating terrestrial conditions with high input of organic matter and bacterial action under reducing conditions in proximity to an aqueous environment (Noël et al. 2001, Sebag et al. 2006a). Palynological analysis reveals a landscape dominated by herbaceous plants, mainly Chenopodiaceae and Poaceae developed on an alluvial plain with wetlands, as shown by the presence of Juncaceae and Cyperaceae pollen grains. ...
... Degradation of a higher amount of plant debris such as Cyperaceae/Juncaceae could have produced a high percentage of AOM. According to Sebag et al. (2006a), AOM content increases from terrestrial environments to fluvial deposits and reflects an abundance of aquatic production. Data from Site 1 (Santa Giusta) indicate that agriculture was not practised at the site during the Neolithic, as shown by the absence of mycorrhizal and coprophilous fungi and the low percentage (< 1%) of "Cerealia-type" and anthropic-indicator pollen grains. ...
Article
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A study method based on characterization of palynofacies (organic matter, palynomorphs) preserved in sediments was applied to obtain information about past environments of Sardinian sites. Organic matter (OM) was classified in ten categories according to its biological source, ecological characteristics, morphology and preservation state. These categories included woody and non-woody particles (cuticles, amorphous organic matter), phytoclasts, spores and pollen grains, gelified particles, and altered phytoclasts that ranged from transparent to opaque fragments. Cluster analysis classified the samples into associations. Each cluster includes stations with a similar spatial distribution pattern. The characterization of the different types of OM was coupled with palyno-logical analyses to produce suggested hypotheses about past vegetation, human activity and land use in Sardinia.
... No entanto, as cutículas identificadas neste testemunho apresentam-se bem preservadas, refletindo que sua deposição deva ter ocorrido próxima a área fonte . Os fitoclastos não-opacos não-bioestruturados, identificados em alguns trabalhos (SEBAG et al., 2006a;2006b;BOUSSAFIR et al., 2012;ZOCATELLI et al., 2012) como partículas gelificadas, são partículas sem estruturas e de cor marrom, tendo sua origem relacionada a degradação de tecidos de plantas em ambientes aquáticos, tais como lagos, ou em condições anaeróbicas como em solos hidromórficos (SEBAG et al., 2006a). Além dos não-bioestruturados, os fitoclastos não-opacos bioestruturados listrados foram registrados como elementos subordinados nas palinofácies 1 e 2, que caracterizam a fase 1 na evolução da Lagoa Canto Grande. ...
... Os sedimentos são transportados como sedimentos de fundo ou suspensos durante períodos de cheia, e as mudanças no fluxo de água e no transporte dos sedimentos são responsáveis pelo controle da erosão e da deposição nas planícies de inundação(BRIDGE, 2006). SegundoSebag et al. (2006b), todos os constituintes da matéria orgânica particulada estão presentes em ambientes flúvio-palustres, mas possuem abundância relativa diferente.Em ambientes aquáticos, elementos autóctones (e.g. MOA e algas) são predominantes, enquanto que a fração alóctone (e.g. ...
... MOA e algas) são predominantes, enquanto que a fração alóctone (e.g. fitoclastos) é moderadamente preservada(SEBAG et al., 2006b). Amostras sedimentares com valores de COT menores que 2% e 3% são geralmente associadas com assembléias dominadas por fitoclastos, onde o conteúdo de COT é determinado pelas variações na abundância das partículas vegetais, enquanto que amostras sedimentares com valores de COT acima de 3% são dominadas pela matéria orgânica amorfa(MENDONÇA-FILHO et al., 2010). ...
... The particles considered autochthonous or allochthonous may vary according to the depositional environment. The autochthonous organic matter can include not only phytoplankton but also particles of aquatic plants, while the allochthonous organic matter (terrestrial) comprises particles weathered from the watershed (Sebag et al. 2006). ...
... In the group of phytoclasts, there are two categories: (1) preserved fragments (cuticle and lignocellulosic translucent), which have initial biogenic structures and (2) fragments processed (gelled material, lignocellulosic opaque, and charcoal), which have characteristics resulting from their degradation or thermal maturation (Sebag et al. 2006). The plant fragments are observed in various degradation stages: cuticle and translucent lignocellulosic correspond to the better preservation stage. ...
... The plant fragments are observed in various degradation stages: cuticle and translucent lignocellulosic correspond to the better preservation stage. The gelled material corresponds to the phytoclasts degradation in reducing environment, and lignocellulosic opaque and oxidized charcoal match phytoclasts in reducing environment, the second being formed only at high temperatures (Sebag et al. 2006). The cuticles are extra-resistant cell layers covering the epidermis of higher plants and are characterized by the cellular structure unchanged and the presence of stomata and palisade parenchyma, with a structure more or less visible (Ercegovac 2006). ...
Article
Full-text available
Guanabara Bay is an estuarine environment of great socio-economic importance, where around 12 million people live in its drainage basin. We aim to characterize the sedimentary matter of Guanabara Bay, two mangrove systems therein (Suruí and Piedade mangroves), and the rivers, São João do Merití, Iguaçu, Sarapui, Suruí, and Guapimirim, by performing sedimentological, mineralogical, elemental/isotopic organic matter composition (total organic carbon and total nitrogen, 13C and 15 N) and organic matter petrography. Samples from the entrance of the bay present high values of quartz, low values of C/N ratio, and high percentages of diffuse amorphous organic matter indicating marine influence, whereas samples from rivers mouths present high percentages of translucent lignocellulosic, opaque lignocellulosic, gelified organic matter, and high C/N ratio probably due to the influence of terrestrial organic matter that comes from the drainage basin and the mangroves areas. Stations of the central sector of the bay were characterized by high percentages of TOC, intermediated values of δ13C, low C/N ratio, and also high diffuse amorphous organic matter indicating a predominant influence of organic matter from algae origin. High values of δ15N indicate large assimilation of nitrate or a high denitrification process in the highest productivity areas. In the river mouth regions, it is mainly influenced by terrestrial organic matter; however, in the northwestern and western sectors, organic matter is influenced both by terrestrial and domestic sewage influences which promote anaerobic decomposition of organic matter.
... Palynofacies analysis, phytoliths, and isotopic techniques are widely applied in studies of palaeoenvironmental reconstruction (vegetation and climate) and also to the understanding of soil genesis (Souza et al., 2007;Horak et al., 2011Horak et al., , 2014Calegari et al., 2013a). The study of palynofacies includes qualitative and quantitative analyses of the different components of particulate organic matter (Tyson, 1995;Sebag et al., 2006aSebag et al., , 2006bGraz et al., 2010). This approach aims to identify the organic components and determine their state of preservation. ...
... After following the steps to prepare the material, the obtained fraction was concentrated in glycerin for the assembly of slides. The palynofacies analysis involved the quantitative (counting 400 particles) and qualitative (identification of particles) examination of groups and subgroups of particulate organic matter components, according to Tyson (1995), Sebag et al. (2006a), and Graz et al. (2010). Based on the quantitative analysis of the components of the particulate organic matter, the data were statistically treated and recalculated to obtain the percentage values before conducting the multivariate statistical analyses (cluster analysis), among organic components groups and subgroups (R-Mode) and for the similarities observation between samples (Q-Mode). ...
... Ternary diagrams were used from the relative proportions of significant organic constituents to obtain the optical signature and composition of significant organic matter (Sebag et al., 2006a). This approach provides the spatial separation, which is useful for grouping samples into empirically defined associations or assemblies (Tyson, 1995). ...
... According to the classification criteria of palynofacies of Li and Batten (2005) and Sebag et al. (2006), the organic debris of the Yanchang Formation was divided into three classes with distinct characteristics and biological sources: amorphous organic matter (AOM), phytoclasts, and palynomorphs (Tyson, 1995;Li and Batten, 2005;Sebag et al., 2006;Suarez-Ruiz et al., 2012). AOM can be further divided into granular AOM and gelified AOM based on morphological characteristics. ...
... According to the classification criteria of palynofacies of Li and Batten (2005) and Sebag et al. (2006), the organic debris of the Yanchang Formation was divided into three classes with distinct characteristics and biological sources: amorphous organic matter (AOM), phytoclasts, and palynomorphs (Tyson, 1995;Li and Batten, 2005;Sebag et al., 2006;Suarez-Ruiz et al., 2012). AOM can be further divided into granular AOM and gelified AOM based on morphological characteristics. ...
... There are also obvious residual biological structures inside the gelified AOM which may have come from the terrestrial plant tissue that was degraded by bacteria (Pacton et al., 2011;Ţ abȃrȃ et al., 2015). Phytoclasts include cuticle, translucent lignocellulosic fragments (TLF), gelified particles (GP), and opaque particles (OP) (Sebag et al., 2006;Graz et al., 2010;Mueller et al., 2014). Cuticle is formed by the oxidation and degradation of fragments of epidermal plant tissue during transportation and deposition. ...
Article
To reveal the effects of lacustrine hydrothermal activities on the organic matter input of source rocks and the formation of excellent source rocks in the Ordos Basin during the Middle and Late Triassic Yanchang period, samples of the Yanchang Formation in the YK1 well in the southern Ordos Basin were selected; source rock evaluations, element geochemical analysis, and palynofacies studies were systematically conducted. The results show that excellent source rocks are developed in the Chang 7-3 interval. The intensity indicators of hydrothermal activity (IIHAs), namely Al/(Al + Fe + Mn) (IIHA1) and (Fe + Mn)/Ti (IIHA2) show that the lake underwent three episodes of obvious thermal fluid activity during the depositional period of the Chang 7-Chang 6 members of which the Chang 7-3 period was the peak of hydrothermal activity. The main hydrocarbon-generating components in the source rocks of the Yanchang Formation were granular amorphous organic matter (AOM) and algae and gelified particles were the secondary hydrocarbon-generating components. Three palynofacies assemblages have been identified in the source rocks. Assemblage A is distributed in the Chang 8-Chang 9 members and Chang 6-2 + 3 interval. The organic matter present in this assemblage mainly consists of type III and transparent lignocellulosic fragments and gelified particles comprise the dominant organic debris. Assemblage B is distributed in the Chang 7-3 interval which consists mainly of Type I and Type II organic matter and is characterized by high abundances of algae and AOM. Assemblage C is distributed in the Chang 7-1 + 2 interval and consists mainly of Type II organic matter which is characterized by the simultaneous development of AOM and phytoclasts. The correlations between the contents of AOM and algae in the source rocks and the IIHAs indicate that hydrothermal activity may have led to the development of algae and source rock formation. The distribution of AOM and algae show consistently high contents over the entire Chang 7-3 interval which are not only coupled with the peak of total organic carbon content, liquid hydrocarbon potential, hydrogen index, and peak of hydrothermal activity but also shows different degrees of correlation with the IIHAs. Their relationships indicate that the peak of the lake’s hydrothermal activity may have induced algae and plankton blooms, which may have been one of the important controlling factors for the formation of excellent source rocks. The close relationship between the IIHA and sulfur content indicates that hydrothermal fluids may have further deprived the lake bottom of oxygen and formed a reducing environment which was helpful for the preservation of organic matter and deposition of excellent source rocks.
... Los demás componentes de la materia orgánica palinológica están caracterizados por el predominio casi exclusivo de fitoclastos translúcidos. En las áreas de bosques, la abundancia de fitoclastos translúcidos podría estar en relación con una alta productividad de la cubierta vegetal local (Sebag et al., 2006). ...
... Esto indica la proximidad del área de aporte continental al ambiente marino, con distancias y/o tiempos de transporte relativamente cortos. Sebag et al. (2006) sugieren que las variaciones en la materia orgánica particulada estarían vinculadas a fluctuaciones del nivel del agua y/o a los influjos sedimentarios terrestres. La presencia de pirita indicaría condiciones reductoras, probablemente asociadas a ambientes marino-marginales. ...
... Palynofacies corresponds to the study under the optical microscope in transmitted light of all the particulate organic constituents of a sediment (Combaz, 1964). It is widely used to assess the origin and preservation state of organic matter in recent and ancient deposits (Tyson, 1995), from continental to marine environments (e.g., Batten, 1982;Garel et al., 2013;Gorin and Steffen, 1991;McArthur et al., 2016a;Sebag et al., 2006;Schnyder et al., 2009aSchnyder et al., , 2009bTyson, 1995). ...
... Terrestrial AOM, if derived from degraded translucent phytoclast tissues such as cuticles, or degraded lignocellulosic tissues, may exhibit flakes with sub-rectangular shapes and is often poorly fluorescent. Such amorphous particles are formed through biologically mediated amorphization and gelification processes in peat and aquatic marsh environments on the continent (Laggoun-Défarge et al., 1999;Sebag et al., 2006) or in soils (Graz et al., 2010). This origin is in some cases well evidenced in the same set of samples and sometimes even in the same palynofacies slide by transitional forms from phytoclasts, gelified phytoclasts, and gelified AOM with rectangular shape corresponding to various stages of biodegradation (Garel et al., 2013;Storme et al., 2012). ...
Article
The Congo deep-sea fan is directly connected to the Congo River by a unique submarine canyon. The Congo River delivers up to 2×10¹²gPOC/yr, a part of which is funnelled by the submarine canyon and feeds the deep-sea environments. The more distal part of the Congo deep-sea fan, the terminal lobe area, has a surface of 2500 km² and is situated up to 800 km offshore at depths of 4750 to 5000 m. It is a remarkable place to study the fate and distribution of the organic matter transferred from the continent to the deep ocean via turbidity currents. Forty-two samples were analyzed from the terminal lobes, including sites from the active channel, one of its levees and an abandoned distal channel. Samples were collected using multitube cores and push-cores using a Victor 6000 ROV, which surveyed the dense chemosynthetic habitats that locally characterize the terminal lobes. Palynofacies reveal a remarkably well-preserved, dominantly terrestrial particulate organic matter assemblage, that has been transferred from the continent into the deep-sea by turbidity currents. Delicate plant structures, cuticle fragments and plant cellular material is often preserved, highlighting the efficiency of turbidity currents to transfer terrestrial organic matter to the sea-floor, where it is preserved. Moreover, the palynofacies data reveal a general sorting by density or buoyancy of the organic particles, as the turbulent currents escaped the active channel, feeding the levees and the more distal, abandoned channel area. Finally, in addition to aforementioned hydrodynamic factors controlling the organic matter accumulation, a secondary influence of chemosynthetic habitats on organic matter preservation is also apparent. Palynofacies is therefore a useful tool to record the distribution of organic matter in recent and ancient deep-sea fan environments, an important topic for both academic and petroleum studies.
... Los demás componentes de la materia orgánica palinológica están caracterizados por el predominio casi exclusivo de fitoclastos translúcidos. En las áreas de bosques, la abundancia de fitoclastos translúcidos podría estar en relación con una alta productividad de la cubierta vegetal local (Sebag et al., 2006). ...
... Esto indica la proximidad del área de aporte continental al ambiente marino, con distancias y/o tiempos de transporte relativamente cortos. Sebag et al. (2006) sugieren que las variaciones en la materia orgánica particulada estarían vinculadas a fluctuaciones del nivel del agua y/o a los influjos sedimentarios terrestres. La presencia de pirita indicaría condiciones reductoras, probablemente asociadas a ambientes marino-marginales. ...
Article
The Aserradero Lapataia 1 and 2 sites present clayey silty sediments including mollusk shell; Mulinia edulis, Mytilus chilensis, Aulacomya atra and Yoldia sp. Besides, dinoflagelate cysts, covers of benthonic foraminifera and copepod eggs are dominant. The microflora is represented by sporomorphs and fresh to salty water microplancton. Radiocarbon dates on Mulinia edulis shells yielded ages of 8094 ± 43 (AA74047) and 8167 ± 43 (AA74048) yr B.P. At Arroyo Baliza, clayey silts were found including Venus antiqua, Aulacomya atra, Mytilus chilensis, among others, accompanied by acritarchs and remnants of copepods. This association suggests marginal marine environments, with low to moderate salinity, and high nutrient concentration in the surface waters. Radiocarbon dating on Venus antiqua shells yielded 2844 ± 34 yr B.P. (AA74046). Marine deposits of the Aserradero Lapataia sites confirm the oldest ages known for the estuarine phase of the Holocene transgression in the Beagle Channel. Arroyo Baliza provide new evidence for the Late Holocene regressive phase in the Beagle Channel.
... while quartz is relatively inert (Van Olphen, 1977;Wu et al., 2012;Yuan et al., 2013). OM can be categorized into amorphous OM, palynomorphs and structured OM based on its microstructures (Tyson, 1995;Sebag et al., 2006), soluble OM and insoluble OM based on its solubilities (Durand, 1980;Tissot and Welte, 1984). Meanwhile, based on chemical properties, OM can be divided into proteins, carbohydrates, lipids, lignins, and tannins, among other substances, which vary greatly with regard to chemical activity (Tissot and Welte, 1984). ...
... OM in mudrocks is derived from organisms, which includes dead organic bodies, debris and decomposed products (e.g., proteins, carbohydrates, lipids, and lignins). They can be deposited via mechanical action (Tyson, 1995;Sebag et al., 2006), chemical flocculation (Turner, 2002(Turner, , 2015, and mineral surface adsorption (Kennedy et al., 2002;Keil and Mayer, 2014), and subsequently formed as sedimentary OM. Thus, AOM, palynomorphs and STOM can be identified following the destruction of minerals. ...
Article
Mudrocks buried at different depths in a single well exhibiting different sedimentary environments and lithologies were collected from the Dongying Sag of the Jiyang Depression of eastern China to investigate the heterogeneities of organic matter (OM) and its occurrence forms. In this study, both bulk rocks and their organo-clay composites (i.e., <2 μm clay-sized fractions) were subjected to palynofacies analysis. The results demonstrate that palynological OM abundance and total organic carbon (TOC) content for bulk rocks are positively correlated with those in organo-clay composites respectively, suggesting that the palynological OM in organo-clay composites is intimately related to that in bulk rocks. However, other numerous variations between them exist: a) OM in the organo-clay composites is aquatic and prone to type I, while it is both terrestrial and aquatic and has multiple types of OM in bulk rocks; b) the palynological organic components in the organo-clay composites, which are mostly amorphous OM (AOM) with an average abundance exceeding 90%, are substantially different from those in bulk rocks, which possess both AOM and terrestrial OM (palynomorphs and structured OM); and c) at different depths, sedimentary environments and lithologies, the percentages of individual palynological organic components are relatively stable in organo-clay composites, whereas they vary over a wide range in bulk rocks. As many previous studies have indicated that OM occurrence is dominantly in the form of organo-clay composites, our results reveal that OM in mudrocks is heterogeneous with respect to its components and occurrence forms, namely, free OM and organo-clay composites, within which OM is greatly varied in association with minerals and its palynofacies. Free OM is physically coexisted with minerals and has different palynological organic components, while OM in organo-clay composites is combined with minerals and is dominantly composed of AOM. Our work demonstrates that OM occurrence in mudrocks has two distinct forms and their palynological organic components are greatly varied, which should be concerned in studies of source rock for further understanding the source material of petroleum.
... Palynofacies has been defined as a set of distinctive assemblages of various types of sedimentary organic matter (SOM) derived from sediments after the dissolution of carbonate and silicates (Combaz, 1964;Powell et al., 1990;Traverse, 1994;Tyson, 1995). The study of the palynofacies gained importance with an approach to define palaeoenvironmental reconstructions in the field of palynology to establish depositional settings (Pocknall and Beggs, 1990;Roncaglia, 2004;Sebag et al., 2006). Palynofacies has now been identified as a robust proxy for multi-dimensional studies like climate change, hydrodynamic conditions, oxic-anoxic environments, runoff related processes, proximal-distal trends, palaeoenvironments and archaeological studies, both in continental and marine records (Tyson and Follows, 2000;Hoaen, 2000;Closas et al., 2005;Zobaa et al., 2011;Carvalho et al., 2013;Mueller et al., 2014;Aggarwal et al., 2017). ...
... Initially the palynofacies approach was developed for pre-Quaternary studies due to their importance to petroleum exploration (Traverse, 1994;Tyson, 1995) for kerogen characterization. However, in recent few decades the application of palynofacies has broadened and now it has become a major proxy for Quaternary depositional environments (Roncaglia, 2004;Sebag et al., 2006;Thakur et al., 2019). ...
... Mangroves are a linkage between terrestrial and marine environments, and sea-level changes play an important role in the development and dynamics of this ecosystem (Behling et al., 2001;Vedel et al., 2006;Cohen et al., 2012). The unbiostructured non-opaque phytoclasts identified in some studies (Jacob et al., 2004;Sebag et al., 2006) as gelified cells are typical of root tissues. They were described by Lallier-Verges et al. (1998) in zones with high concentrations of Rhizophora and Laguncularia as a result of the aerial systems of these plants. ...
... Therefore, isotopic data and significant relative abundances of non-opaque phytoclasts indicate that terrestrial plants were the major source of organic matter during this interval. In wetlands, constituents derived from vascular plants represent the main organic fraction (Sebag et al., 2006). ...
... However, because mudrock is composed of OM and minerals, employing EGME adsorption to measure MSA within mudrocks needs caution (Bu et al., 2019a(Bu et al., , 2019bDerkowski and Bristow, 2012). Mudrock generally contains different types of OM, such as amorphous OM and structural (or morphological) OM (Sebag et al., 2006;Tyson, 1995;Zhu et al., 2014), soluble OM and insoluble OM (Durand, 1980;Tissot and Welte, 1984), all of which may interact with minerals and can occur in various ways, e.g., free OM, adsorbed on mineral surface, intercalated in interlayer spacing of clay minerals, encapsulated in carbonates (Cai et al., 2007;Fan et al., 2011aFan et al., , 2011bIngalls et al., 2004;Kennedy et al., 2002;Mayer, 1994;Zhu et al., 2014). These different types of OM can occupy the adsorption sites of mineral surfaces, T excluding the free OM. ...
... These different types of OM can occupy the adsorption sites of mineral surfaces, T excluding the free OM. Moreover, previous findings showed that the different forms of OM are varied in micro surface morphology, have a certain geometrical morphology, and presents as porous materials (Loucks et al., 2012;Modica and Lapierre, 2012;Sebag et al., 2006;Zhu et al., 2014), suggesting that the OM has a potential to contribute the quantity of absorbed EGME molecules (Derkowski and Bristow, 2012). In addition, OM cannot be completely removed without mineral destruction to recover the in situ mineral surface, even in a strong oxidant treatment (Meier and Menegatti, 1997;Mikutta and Kaiser, 2011;Mikutta et al., 2005). ...
... assemblage and its relative abundance associated to sedimentological data allow distinguish organic matter source. Although palynofacies is largely applied in petroleum geology studies, it is also useful in all sorts of research concerned to particulate transfers and POM catchments, in order to reconstruct depositional environments and their hidrodynamics (Sebag et al., 2006). Other data provided by palynofacies proxy are: contrasting biological inputs in estuaries; distinguishing between aquatic and terrestrial POM origin, if it occurs (Tyson, 1995); variance on sedimentary organic matter, always linked to fluctuations in water level or terrestrial sedimentary fluxes (Sebag et al., 2006); and determining if the POM is allochthonous or not based on particles composition (Di Giovanni, 1994; Tyson, 1995). ...
... Although palynofacies is largely applied in petroleum geology studies, it is also useful in all sorts of research concerned to particulate transfers and POM catchments, in order to reconstruct depositional environments and their hidrodynamics (Sebag et al., 2006). Other data provided by palynofacies proxy are: contrasting biological inputs in estuaries; distinguishing between aquatic and terrestrial POM origin, if it occurs (Tyson, 1995); variance on sedimentary organic matter, always linked to fluctuations in water level or terrestrial sedimentary fluxes (Sebag et al., 2006); and determining if the POM is allochthonous or not based on particles composition (Di Giovanni, 1994; Tyson, 1995). Palynofacies is sensitive proxy to perceive environmental changes caused by either climatic or human influence. ...
Article
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The Araguari estuarine dynamics is singular among traditional models of estuaries under tidal regime due to influence of macrotidal and tidal bore. In order to establish estuarine zones in Araguari according foraminifera, thecamoebians, paliynomorphs and physical-chemistry parameters, sixteen sample stations were established along the estuary. Turbidity and temperature were the environmental parameters which allowed determination of the estuarine gradient. Eighteen species of foraminifera, ten of thecamoebians and fourteen of particulate organic matter types were identified. Cluster analysis in R-mode showed three microorganism assemblages and four palynomorph ones. The CCA analyze shows turbidity and total organic matter with the most influence over foraminiferal and thecamoebians distribution at Araguari. Clustering analysis in Q-mode using all data formed four groups suggesting three estuarine zones in Araguari: Zone I composed of thecamoebian species and continental palynomorphs; Zone II -composed by mangrove foraminifera, thecamoebians and all palynomorph assemblages; and Zone III – composed by mangrove and estuarine foraminifera and all palynomorph assemblages.
... A counting of 500 points is required to statistically reflect the abundance of each class of palynofacies. The classification and the characterization of the origin of organic constituents were derived from the work of Tyson (1995), revisited by Sebag et al. (2006c). In this study, phytoclasts consist of (i) ligno-cellulosic (LC) debris showing variable degradation states (from translucent to degraded LC, named TLC and DLC), (ii) opaque particles (OP) obtained either from the incomplete combustion or severe oxidation of LC particles, (iii) gelified particles (GP) originating from an earlier gelification process of OM inside the higher plant cells under aquatic conditions. ...
... Main organic particles observed in BB2 and TK1 cores. Palynofacies classification derives from the review ofSebag et al. (2006c). ...
... El registro de los pedocomponentes durante los conteos se hizo considerando aspectos clave de su morfología, y otros caracteres específicos según criterios formulados por varios autores (PIPERNO, 1988;TRAVERSE, 1994;TYSON, 1995;FLÓREZ, 2000;PARRA & FLÓREZ, 2001;MADELLA et al., 2005;PARRA, 2005;ERCEGOBAC & KOSTIC, 2006;FLÓREZ et al., 2006;SEBAG et al., 2006). Dicho registro consideró solamente los pedocomponentes de origen biológico tal como se muestra en la clasificación de la Figura 3, debido a que, en este caso, eran los que ofrecían mayor potencial de registro de procesos y eventos de interés arqueológico. ...
... El cociente D:P ha arrojado valores de 2,0 y 2,3 que son altos y sugieren la presencia mayoritaria de plantas dicotiledóneas, tal como se observa con las formas esféricas, polihédricas y amorfas pero de contorno regular y definido que constituyen la reserva fitolítica de estas plantas según varios autores (PIPERNO, 1988;BOZARTH, 1992;ALEXANDRE et al., 1997a;ALEXANDRE et al., 1997b;PREBBLE et al., 2002;BREMOND et al., 2005;ALBERT, 2006;TSARTSIDOU, 2007). El ambiente arbóreo que se advierte por el registro de fitolitos es confirmado por la gran cantidad de tejidos lignificados o maderas pertenecientes a especies de bosque (Figura 9) (BOULDER, 1994;GASTALDO, 1994;TYSON, 1995;ERCEGOBAC & KOSTIC, 2006;SEBAG et al., 2006). Diagrama de pedocomponentes fitolitos. ...
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This article presents the results of a microscopic analysis of soil components in an archaeological context, in order to obtain several lines of evidence for understanding of the relationships between human populations and their natural environment. After the paleoecological reconstruction, it was concluded that in these contexts there are multiple indicators of vegetation, climate and human activity conditions, different from the traditional palynological markers, including ligninolitic tissues, fungi and phytoliths. All these results were consistent with the conversion process of forest in the area. They also present new horizons for research in plant ecology and ethnobotany.
... The fresh-water peatlands are inland swamps having no connection to sea, including upper delta and alluvial plain swamps, marshes and bogs. Contributions on depositional systems have also been made by Amijaya and Littke (2005), Marques (2002), Sebag et al. (2006a), and Silva et al. (2008). Coal petrography based models can help in reconstruction of the depositional environments of the paleomire. ...
Article
The results of the petrological investigations carried out on coal samples from the Oligocene deposits of Northeastern India (Assam, Arunachal Pradesh and Nagaland) have been discussed. These deposits occur in the Tikak Parbat Formation (Barail Group) and were probably deposited in the foreland basin. Petrographically, these coals are enriched in vitrinite macerals (65.8-96.6 vol %, mean 87.2 vol %) with variable concentrations of liptinite macerals (2.7-35.4 vol %, mean 11.9 vol %). They contain low concentration of inertinite (nil-3.3 vol %, mean 0.9 vol %) macerals. The microlithotype is dominated by vitrite (61.5-100 vol %, mean 90.8 vol %). An elevated volatile matter (44.15 - 60.20 wt %, mean 52.90 wt %, d.a.f. basis) and reflectance values (VRr 0.39-0.61%) put their rank as sub-bituminous type 'C' to high volatile bituminous type 'C'. The GI and TPI values favour telmatic conditions of origin with high tree density and prolonged wet conditions. This is in agreement with the paleoenvironment interpreted from the vitrinite and liptinite-rich microlithotypes, which suggested a forest and reed facies. However, the presence of inertinite in some coal seams indicates tectonic upheavals / regression of the sea resulting to periodic and short span dryness of the basin.
... Los métodos de palinofacies son bien conocidos y aplicados por geólogos petroleros, sedimentólogos y científicos del Cuaternario, que estudian paleoambientes y cambios climáticos (Sebag et al. 2006). En el presente trabajo, cada palinofacies identificada, es caracterizada en base a los siguientes criterios: proporción relativa de constituyentes orgánicos (palinomorfos, fitoclastos y materia orgánica amorfa, sensu Tyson, 1995), especies diagnósticas desde el punto de vista ecológico (esporas de hongos, algas, Bryophyta), tipo de deterioro predominante (corrosión, degradación y daño mecánico) y fluorescencia del material. ...
Article
PALYNOFACIES ANALYSIS OF LATE CENOZOIC SEDIMENTS FROM THE UNDULATING PAMPA (ARGENTINA): FIRST RESULTS. A palynofacies analysis of a loessial profile (Late Cenozoic) in the surroundings of Castelar (Buenos Aires, Argentina) was carried out. Integrated analysis of sedimentology, palynofacies, pH and TOC, allowed detection of palaeoenvironmental and palaeoclimatic fluctuations during the period under analysis. Middle Pleistocene (<780 ka): palynofacies type A (loess), palaeoenvironments moderately oxidizing, evidenced by a predominance of finely divided organic matter (not fluorescent), abundance of opaque phytoclasts and a small amount and diversity of palynomorphs. Palynofacies type B (laminar calcrete), locally moist and regionally semiarid palaeoenvironments associated with the development of the herbaceous psammophytic steppe. The evidence of biological and chemical oxidation, both in phytoclast and amorphous organic matter, suggest an alternation of anaerobic and aerobic environments. Late Pleistocene (24,098 cal yr BP): palynofacies type C (loess and lightly edaphized loess), oxidizing palaeoenvironments represented by darkened amorphous organic matter and abundant opaque phytoclasts. The considerable proportion of Myrtaceae was correlated with the input of sediments from the NE of the country. Late Holocene (2,582 cal yr BP): palynofacies type D (modern soil) locally moist and regionally sub-moist palaeoenvironments associated with the presence of the psammophytic herbaceous steppe, with high proportions of water plants pollen, Bryophyta, fungi and algae spores. The predominance of partially gellified and darkened translucent phytoclasts is in accordance with the pedogenic process.
... However, the study of Sebag et al. (2006) provides evidence that the palynofacies method offers a valuable contribution for connecting particulate OM to the depositional environments in Holocene deposits; this work also includes a review of the main approaches performed for the POM characterization from Quaternary deposits in recent terrestrial environments and is based on applied examples in surface deposits, soil profiles, wetlands, lacustrine ecosystems and within catchments. ...
Article
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This paper presents the quantitative and qualitative results obtained from palynofacies and geochemistry analyses carried out on a core covering approximately 8000 years of sedimentation of a pond of altitude located at the mining district of Ametista do Sul, southernmost Brazil. The main objective of this paper is to consider the paleoclimatic and paleoenvironmental significance of these analyses. The hydrological isolation renders this pond climatically sensitive to variations in pluviometric regime and this enabled infer rainfall events during the early Holocene, which was responsible for the beginning of the processes of water accumulation in the gossan and the sedimentation of the pond. Changes in the pattern of moisture over the time become the drier environment, resulting in the intermittent pattern of water depth that currently exists at the site. The fluctuations in water depth are inferred from the frequency of Botryococcus and other algae, which tend to decrease progressively toward the top where the autochthonous elements are replaced by parautochthonous and allochthonous elements. Pseudoschizaea, in turn, appears to act as a biological marker of these transitional intervals. The present results are of great importance for understanding the extent of climate change and its environmental impacts at regional and global levels.
... Further, the TOC of sediments (or sedimentary rocks) represents only the content of total organic matter. The sedimentary organic matter in the natural environment can be divided into different organic components, e.g., soluble organic matter and insoluble organic matter (Durand, 1980;Tissot and Welte, 1984), and amorphous organic matter, palynomorphs, structured organic matter (Li and Batten, 2005;Mendoncça Filho et al., 2012;Sebag et al., 2006;Thakur and Dogra, 2011;Tyson, 1995). These components combine or co-exist with minerals as the states of particle, surface adsorption and clay mineral interlayers combination, and so on (Cai et al., 2007;Fan et al., 2011;Lu et al., 2011;Ransom et al., 1997Ransom et al., , 1998. ...
... The fresh-water peatlands are inland swamps having no connection to sea, including upper delta and alluvial plain swamps, marshes and bogs. Contributions on depositional systems have also been made by Amijaya and Littke (2005), Marques (2002), Sebag et al. (2006a), and Silva et al. (2008). Coal petrography based models can help in reconstruction of the depositional environments of the paleomire. ...
... QOP developed by Graz et al. (2010) is based on the optical identification and quantification of the organic frac- tion after elimination of carbonate and silicate phases by hy- drochloric and hydrofluoric attacks. Components are charac- terized by their optical properties (colour and reflectance), their forms (amorphous or figurative) and their origins (al- gal, phytoclastic or fossil) (Combaz, 1964;Tyson, 1995;Di Giovanni et al., 2000;Sebag et al., 2006;Simonneau et al., 2013). Excluding the standard, which was deliberately added into preparations, three main types of organic particles have been used in this study: red or grey amorphous particles (rAP and gAP, respectively) and lignocellulosic fragments (LCF), whose significations are given from analysis results (see Sect. 4.3 below). ...
... Characterization of soil organic matter by Rock-Eval pyrolysis Rock-Eval pyrolysis (Rock-Eval 6 Turbo; Vinci Technologies, France) is used to identify the type and maturity of organic matter (Béhar et al. 2001;Disnar et al. 2003;Sebag et al. 2006). This technique can be applied to soils (Di Giovanni et al. 1998). ...
Article
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The efficiency of aided phytostabilization using organic amendments such as ramial chipped wood (RCW) and composted sewage sludge (CSS) was studied on contaminated techno-soils, on nine experimental plots. The objective was to characterize the role of fulvic (FA) and humic acids (HA) on the mobilization of trace elements, specifically As, Cu, Mo, Pb and Zn. Results showed that the addition of CSS increased the total organic carbon and nitrogen content more than with RCW and as a result, the C/N ratio in the CSS soil was higher than in the RCW and non-amended (NE) soil, reflecting the high decomposition of soil organic matter in the CSS soil compared with the other soils. The RCW and CSS amendments increased the hydrogen index (HI) values and the oxygen index (OI) values compared with the NE soil, especially for the soil treated with CSS which contained more aliphatic than aromatic compounds. The addition of CSS to the techno-soil significantly increased the percentage of C org associated with the HA fractions compared with the RCW and NE soils. The soil amended with CSS showed the highest E 4/E 6 ratio and the lowest E 2/E 3 ratio of FA. Zn and As were more abundant in the FA fraction than in the HA fraction, whereas Pb, Cu and Mo were more associated to HA than to FA in the treated and untreated soils, which may explain the difference in their mobility and availability.
... Note that dark green background is imposed by Elvacite. UV-light (after Combaz, 1980;Venkatachala, 1981;Batten, 1983Batten, , 1996Highton et al., 1991;Tyson, 1995;Ercegovac and Kostić, 2006;Sebag et al., 2006, Stephenson et al., 2008. Table 2: Observed sporomorph genera and related palaeoecological groups, modified after Stephenson et al. (2008), Davies and McLean (1996). ...
Article
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Carboniferous mudstones in central and northern England are shale gas prospects but the controls on the amount and composition of organic matter are not well understood, even though these parameters define the volumes of gas generated in fine-grained sediments. Organic matter in samples from basinal late Mississippian (Arnsbergian) mudstones in the Widmerpool Gulf was characterised by using semi-quantitative (n = 58) and quantitative palynofacies (n = 16) analyses, sporomorph counts and bulk rock geochemistry (total organic carbon, δ13C of bulk organic matter, Rock-Eval Pyrolysis).
... The fresh-water peatlands are inland swamps having no connection to sea, including upper delta and alluvial plain swamps, marshes and bogs. Contributions on depositional systems have also been made by Amijaya and Littke (2005), Marques (2002), Sebag et al. (2006a), and Silva et al. (2008). Coal petrography based models can help in reconstruction of the depositional environments of the paleomire. ...
Article
Full-text available
The results of the petrological investigations carried out on coal samples from the Oligocene deposits of Northeastern India (Assam, Arunachal Pradesh and Nagaland) have been discussed. These deposits occur in the Tikak Parbat Formation (Barail Group) and were probably deposited in the foreland basin. Petrographically, these coals are enriched in vitrinite macerals (65.8-96.6 vol %, mean 87.2 vol %) with variable concentrations of liptinite macerals (2.7-35.4 vol %, mean 11.9 vol %). They contain low concentration of inertinite (nil-3.3 vol %, mean 0.9 vol %) macerals. The microlithotype is dominated by vitrite (61.5-100 vol %, mean 90.8 vol %). An elevated volatile matter (44.15-60.20 wt %, mean 52.90 wt %, d.a.f. basis) and reflectance values (VRr 0.39-0.61%) put their rank as sub-bituminous type 'C' to high volatile bituminous type 'C'. The GI and TPI values favour telmatic conditions of origin with high tree density and prolonged wet conditions. This is in agreement with the paleoenvironment interpreted from the vitrinite and liptinite-rich microlithotypes, which suggested a forest and reed facies. However, the presence of inertinite in some coal seams indicates tectonic upheavals / regression of the sea resulting to periodic and short span dryness of the basin.
... The high percentage of fungi in the first samples of this phase indicates the beginning of soil development, since the abundance of fungal fragments is indicative of aerobic biodegradation of plant remains (Sebag et al. 2006). Dominance of pollen of herbs and spores of bryophytes (Sphagnum and Phaeoceros) indicates the beginning of vegetation colonization. ...
Article
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This paper presents a paleoenvironmental reconstruction from palynological analyses of a sedimentary core of Holocene age, drilled at municipality of Garopaba (Santa Catarina), Southern Brazil. A total of 46 samples was collected for palynological analyses in the 450 cm-long core PCSC-3, as also three samples for radiocarbon dating and granulometric analyses. The palynological content includes 84 taxa related to pollen grains of angiosperms (38) and gimnosperm (3), spores of pteridophyta (16) and bryophyta (2), spores of fungi (8), algae (3), acritarchs (3), dinoflagellate cysts (2) and microforaminiferal linings (1). Three specimens of acritarchs are described and illustrated in detail. Three palynological phases were defined based on changes in assemblages: Phase I, Phase II and Phase III. The Phase I is characterized as a lagoonal paleoenvironment with marine influence from the beginning of the sedimentation (5390 cal yr BP), based on occurrences of acritarchs, dinoflagellate cysts and microforaminiferal linings. The Phase II (3032 yr BP until 858 cal yr BP) also is characterized by a lagoonal paleoenvironment, however, presented decrease in percentage of marine elements and increase in freshwater algae record, suggesting less marine influence in the lagoonal body. In Phase III (last 856 years), underwater sedimentation prevailed, under swamp-like conditions.
... OM occurrences have been broadly investigated for a variety of reasons (e.g., carbon sequestration, carbon cycle and carbon distribution) in soils, marine sediments and shales (Arndt et al., 2013;Kennedy and Wagner, 2011;Mikutta et al., 2006;Solomon et al., 2012;Torn et al., 1997). As sedimentary OM and minerals are heterogeneous materials, OM occurs in many different forms in sediments and sedimentary rocks (Durand, 1980;Sebag et al., 2006;Tissot and Welte, 1984;Tyson, 1995;Zhu et al., 2014), which can be divided into free and mineral-combined states. The free OM constitutes no more than 10% of the total organic carbon content (TOC) (Ertel and Hedges, 1985;Fan et al., 2011a;Keil et al., 1994aKeil et al., , 1994bMayer, 1994), is not bounded to the minerals (Cai et al., 2007;Fan et al., 2011b;Ransom et al., 1997Ransom et al., , 1998, and occurs in the pores and is vulnerable to decomposition by bacteria and through oxidation (Baldock and Skjemstad, 2000;Six et al., 2002). ...
... These particles partly derive from terrestrial wood fragments and/or from lignified parts of aqueous plants that are heavily degraded, gelified and amorphized in an aqueous environment. Similar amorphization and gelification processes due to bio-degradation of terrestrial or aquatic plant tissues have been reported in peat and aquatic marshes environments Sebag et al., 2006;Storme et al., 2012). The vertical evolution of the relative percentage of these classes is represented on Fig. 8. ...
Article
The Late Jurassic was a period of major global carbon cycle perturbations with episodes of anoxia leading to regional accumulation of organic matter in sediments worldwide. The Tubiegatan section (SW Gissar Mountains, Uzbekistan) located in the Northern Tethys, shows atypical organic-rich limestone and marl deposits (up to 6% of total organic carbon) marked by pronounced negative excursions of δ13Ccarb (amplitude of ca. 12‰) and δ13Corg (amplitude of ca. 4‰) recorded during the Middle Oxfordian (Transversarium Zone). A transdisciplinary approach including sedimentology, palynofacies characterization, mineralogy, organic and inorganic geochemistry was carried out to elucidate the origin of these organic-rich deposits. Highest TOC are measured in nodular limestones, and lowest δ13Ccarb values in thinly laminated facies consisting in alternances of infra-millimeter-thick organic and carbonate laminae. In the latter, the presence of organic-carbonate peloids and of possible remnants of exopolymeric substances associated with clay indicate that these structures are probably mineralized laminated benthic microbial mats (i.e., stromatolites). Rock-Eval pyrolysis coupled to palynofacies analyses point to a dominant altered marine organic matter of probable algal/microbial origin, with subordinate continental phytoclasts inputs in the upper part of the organic-rich interval. Trace elements (U/Th, V/Cr and Mo/Al ratios) indicate two anoxic episodes coinciding with the highest TOC, punctuated by dysoxic periods. Such O2-depleted conditions have allowed the preservation and probably the development of anaerobic microbial communities in the microbial mats. In these latter, sulfate reduction probably had a significant contribution to the production of carbonates, which would explain the precipitation of pyrite and the relatively low δ13Ccarb values. The progressive decrease then disappearance of kaolinite from the base of the organic-rich interval, is interpreted as a progressive aridification of the Amu Darya Basin during the Transversarium Zone, culminating with the progradation of a large-scale gypsum sabkha overlying the organic deposits. Overall, the organic-rich deposits could record the onset of the disconnection of the Amu Darya Basin from the open sea to the south, induced by compression and subsequent uplifts in the Afghan and Central Iranian blocks. The elevated evaporation, coupled with the presence of hydrological barriers (such as coral reefs) could have led to the formation of local to regional anoxic conditions in the Amu Darya Basin. Similar microbial organic accumulations are recently known throughout the Tethys (e.g., Arabian Plate, Western Europe) and from other oceans (e.g., Central Atlantic, Pacific) during the Late Jurassic, suggesting common controlling factors. The increase of organic matter storage worldwide coupled with potential methane release could have in turn induced major perturbations of the carbon cycle during the Oxfordian-Kimmeridgian interval. The relatively shallow anoxia model proposed in this study contrasts with the well-known organic carbon-rich pelagic models proposed for the Jurassic anoxia (e.g., Toarcian, Kimmeridgian) and Cretaceous OAEs.
... Palynofacies analysis is based on transmitted light microscopy of organic components isolated and concentrated by acid and basic digestions (Combaz 1964). It allows quantification of various organic components, including palynomorphs, palynodebris, and amorphous organic matter (Tyson 1995), and is used for reconstruction of depositional environments (Batten 1996;Sebag et al. 2006). Palynomorphs and palynodebris behave in the same way as clastic particles of the same size and specific gravity affected by densitybased hydrodynamic sorting (hydrodynamic equivalence effects) (Traverse 1988;Tyson 1995). ...
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A palynological analysis was carried out for the first time on sediments from Hupo Basin, East Sea, offshore Korea, to locate the Pliocene–Pleistocene boundary and thus determine the depositional age of this stratigraphic unit. Core 19ESDP-101, taken from Hupo Basin, yielded diverse, abundant to common pollen and dinocysts. Age-diagnostic palynomorphs were present in certain core intervals (Zone I, depths 120–63.96 mbsf). However, those age indicators were dark brown, heavily broken representatives that appeared together with poorly sorted, opaque, dark phytoclasts in the lower part of Zone II (63.96–38.76 mbsf), and they were considered to have been recycled from reworked late Pliocene strata due to contour currents during the transgression. Biostratigraphically meaningful taxa were the pollen Carya, Liquidambar, and Fagus and the dinocysts Filisphaera filifera subsp. pilosa and Spiniferites pachyderma. The latest stratigraphic occurrence of these pollen taxa in northeast Asia is the Late Pliocene, and that of the dinocysts is the Late Pliocene across a wide range of aquatic areas, especially in the Pacific. The last appearance datum of the age indicators in this study suggested 63.96 mbsf (top boundary of Zone I) as the Pliocene–Pleistocene boundary in core 19ESDP-101.
... The slides were then scanned under Olympus BH-2 microscope and photographs taken with DP-25 camera ( Supplementary Fig. 1). The maceration process and literature consulted for the palynofacies J o u r n a l P r e -p r o o f Journal Pre-proof analysis follows Traverse, 1994;Pocknall and Beggs, 1990;Batten, 1996;Roncaglia, 2004, andSebag et al., 2006. ...
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The dung of the Indian wild ass was analyzed using biotic and abiotic proxies to determine its dietary habits in relation to the plant diversity and ecology in the arid region of western India. The presence of both micro and macrobotanical remains of Poaceae, Chenopodiaceae, and Fabaceae indicates they are the primary food plants of the wild ass. The continuous recovery of arboreal pollen taxa chiefly, Prosopis, Acacia, and Ephedra is indicative of dry thorny forest under semi-arid to arid conditions which display the existing vegetation and climate in the region. The recovery of marshy pollen taxa like Cyperaceae and Onagraceae along with Arcella indicates utilization of water-logged environments in the habitat. Spores of coprophilous fungi, Sporormiella, Sordaria, and Podospora are also present in the dung samples. The low value of stellate trichomes in winter dung samples reflects the seasonal migration of wild ass. Average δ¹³C values ranging between − 15.8‰ and–26.3‰ are indicative of a mixed diet of both C3 and C4 plants. The generated multiproxy data from dung samples can provide a reliable counterpart to modern data for the interpretation of the palaeoecology in relation to the palaeoherbivory and palaeodietary analysis in the region. This study also provides a basis to distinguish between wild and domesticated herbivores by analyzing coprolites and cultural sediments in archeological sites.
... The composition and preservation of PM are not only directly controlled by their parent source but also influenced by the sedimentary environment and its diagenesis. The variation in PM components can reflect the depositional distance, oxygenation conditions, and lake-level fluctuation during the deposition of source rocks (Sebag et al., 2006;Gonzalez et al., 2020). A large amount of AOM in marine and nonmarine environments indicates dysoxic-anoxic conditions and a high preservation rate. ...
Article
The Lower Cretaceous Chijinbao Formation is one of the primary source rocks in the Jiuxi Basin in Northwest China. However, it is poorly studied due to the lack of a complete stratigraphic sequence exposed by drilling. In this research, an integrated analysis of palynofacies, organic geochemistry, and element geochemistry was systematically conducted on samples with longitudinal continuity collected from the Chijinbao Formation in the Hanxia Section of the Jiuxi Basin to determine the distribution of source rocks and the source and type of organic matter and to reconstruct the depositional paleoenvironment of the Chijinbao Formation. The lower part of the sequence, which is governed by poor source rocks with Type III organic matter, is characterized by palynofacies A (woody tissue–charcoal assemblage) grown in a proximal alluvial fan–shallow lacustrine environment. The excellent source rocks with mostly Type II1 organic matter are considerable in the middle part of the sequence, which is marked by palynofacies B (amorphous organic matter assemblage), and occur in a distal semi-deep lacustrine–deep lacustrine environment. The upper part of the sequence is largely composed of poor and fair source rocks, represented by palynofacies C (amorphous organic matter–woody tissue assemblage), and a small amount of sporadically distributed good and excellent source rocks (approximately 1/3), which may be deposited in a proximal fan delta and a local semi-deep lacustrine–deep lacustrine environment. A semiarid–semi-humid climate and a freshwater–brackish water environment prevailed during the deposition of the Chijinbao Formation. The lower part of the sequence is characterized by the highest terrestrial detritus influx, strong weathering, humid paleoclimate, oxic water column conditions, and the lowest paleoproductivity. The middle part of the sequence has the lowest terrestrial detritus influx, relatively weak weathering, relatively arid paleoclimate, predominantly anoxic water environment, and the highest paleoproductivity. The climate became humid again during the deposition of the upper part, which is typified by an intermediate terrestrial detritus influx, strong weathering, fluctuations of oxic–anoxic bottom-water conditions, and moderate paleoproductivity. The correlation analysis of element proxies suggests that the increase in salinity during the deposition of the middle part is associated with an arid climate. Amorphous organic matter, which is derived mostly from aquatic organisms and degraded terrestrial higher plants, is the major hydrocarbon generation component in the source rocks of the Chijinbao Formation. It increases in abundance with an improvement in water reducibility and productivity, favoring the formation and preservation of excellent source rocks.
... During the pedogenetic process of the forest environments, it is common to record fragments of plant tissues and amorphous particles; however, the preservation of non-opaque phytoclasts may be abundant due to the high productivity of the local vegetation. In addition, the abundance of fungi (spores, hyphae and filaments) suggests the aerobic degradation of plant tissues (Sebag et al., 2006). Isotopic data corroborate the palynological and palynofacies interpretations. ...
Article
The coastal plain of southern Brazil documents several environmental changes mainly related to sea-level fluctuation and climatic variations during the Quaternary. Comprehensive studies have been carried out, of local and regional scope, in order to improve the knowledge about the geological evolution of this portion of the South American. In this paper we present the results of stable isotope, palynological and palynofaciological analysis of the PSC-03 core (7744 cal yr BP – Modern) was performed to provide the sedimentary evolution of the Santa Catarina coastal plain. Palynological and palynofacies analyses revealed abundant and diversified palynological associations, including terrestrial palynomorphs (spores, pollen grains, fungi, and freshwater algae), marine elements (dinoflagellate cysts and foraminiferal linings), besides abundant phytoclasts and amorphous organic matter. Based on the combined analysis of δ¹³C isotopes (−20.7 ‰ to −29.6 ‰) and the C/N ratio (15.5–68) of the selected samples, we deduce that the organic matter is derived from marine phytoplankton and terrestrial C3 plants. The integrated approach of palynofacies and stable isotopes (δ¹³C and C/N) analyses revealed three distinct intervals, which characterize the environmental evolution of this portion of the coastal plain. The Interval I (7744 to 2844 cal yr BP) is related to a marginal marine environment, followed by the Interval II (2857 to 2276 cal yr BP), which indicates shallow water conditions, with wetland or soggy soils, while the Interval III (2124 cal yr BP to Modern) shows a subaerial scenario, strongly influenced by arboreal forms of the Atlantic Forest. Comparisons with other sites in southeastern South America were carried out, especially from Uruguay and Argentina, showing similarities in the palynological succession, as response to broader climatic conditions.
... Interpretación paleoambiental Palinofacies tipo I. Los fitoclastos traslúcidos no bioestructurados semiopacos y los fi toclastos opacos (Tabla 3), probablemente deriven de leños próximos a la fuente de origen, los que habrían sido oxidados, ya sea por exposición subaérea durante el transporte o bien dentro del mismo ambiente de depósito (Sebag et al., 2006), e incluso algunos habrían sufrido maduración térmica a causa de incendios (charcoal, sensu Scott, 2010). El predominio de fi toclastos opacos equidimensionales (angulares, subredondeadosangulares) denota escaso transporte y alta energía del medio. ...
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PALYNOFACIES ANALYSIS OF PLAYA DEL ZORRO ALLOFORMATION (LATE MIOCENE/PLIOCENE) CAJON VALLEY, CATAMARCA, ARGENTINA. This paper presents the palynofacies analysis results from La Cascadita locality of Playa del Zorro Alloformation (late Miocene-Pliocene), being the fi rst palynological study of the Neogene outcrops of the Cajon Valley, northwestern Argentina. Eleven palynological and organic matter samples were analyzed, only three of them containing palynomorphs (spores of Glomus sp. and Lycoperdon sp., Chlorophyta algae colonies, spores Zygnemataceae and few angiosperm pollen grains). Four types of organic matter were identifi ed: phytoclasts (translucent and opaque), palynomorphs, amorphous organic matter and zooclasts. Given the overall frequency of these types and relative frequencies of the particles that constitute them, two palynofacies can be distinguished. The Palynofacies Type I is characterized by the relatively high frequency semi-opaque and equidimensional opaque phytoclasts, reduced organic amorphous matter and low representativeness of palynomorphs; suggesting oxidizing environments, poor transport and high-energy environment. The Palynofacies Type II is characterized by high relative frequency of palynomorphs and amorphous organic, and have the lower values of phytoclasts, which suggests an environment with more reducing conditions than those of the Palynofacies I, temporarily anoxic and shallow. The climate regime would have been warm, semi-arid with a marked dry seasonality.
... Solid bitumen (SB) is the dominant kind of organic matter in very mature source rocks (Gonçalves et al., 2014;Hackley and Cardott, 2016;Yang et al., 2020). Complex relationships between OM and minerals lead to multiple kinds of mineral associations with OM in shale (Sebag et al., 2006;Wu et al., 2012;Kennedy, 2014;Zhu et al., 2016;Rahman et al., 2017Rahman et al., , 2018. For example, OM-clay mineral complexes that contain nanopores associated with illite plates and a small amount of OM-heavy mineral complexes have been identified in the Lower Silurian Longmaxi Formation in the Upper Yangtze Platform, South China (Ji et al., 2019). ...
Article
The occurrence and enrichment of organic matter (OM) are influenced by the deposition of minerals in shale reservoirs. However, inadequate research has been published on the origin, spatial relationships, and significance of organic matter–mineral associations (OMMA) for predicting “sweet spots” in shale gas reservoirs. We describe OMMA in the Wufeng Formation and the Longmaxi Formation in the Sichuan Basin, which is the largest commercial shale gas accumulation outside of North America. We characterize the presence of solid bitumen (SB) and graptolite fragments (the most important kinds of OM in these reservoirs) with four important minerals: i.e., quartz, clay minerals, carbonates, and pyrite. The occurrence of OMMA is influenced by the physical (e.g., morphology, texture, and density) and chemical properties of the associated minerals, which influences the accumulation of OM and the development of porosity. By carefully studying the type and relative amount of OM, we have determined how the surface porosity, pore diameters, and amount of porosity in each kind of OMMA influence the quality of shale gas reservoirs: e.g., diagenetic quartz or clay minerals encased in SB is the most favorable kind of OMMA. The quality of OM–carbonate associations is lower because they contain a relatively low amount of OM. Similarly, the relatively low abundance and dispersed distribution of OM–pyrite associations do not improve the quality of shale gas reservoirs. We identified four important lithofacies using the color, composition, and sedimentary structures of samples. The heterogeneous distribution of OMMA has important implications for shale gas reservoirs by influencing hydrocarbon generation and gas storage conditions in each lithofacies: i.e., siliceous shale > argillaceous siliceous shale > calcareous shale > silty shale.
... The POM was then observed under light microscopy (Leica DMR XP) in transmitted light (objective x50) using a grid (10 μm mesh) where 200 elementary surfaces were considered to obtain a percentage of error lower than 5% 44 . The origin and the state of degradation are defined on the basis of morphological, textural and colorimetric criteria 45 . Since this method is surface-based, the quantitative palynofacies that allows access to the amount of POM (in mg/g) of the different classes defined by counting has been used 46 . ...
Article
Tritium of artificial origin was initially introduced to the environment from the global atmospheric fallout after nuclear weapons tests. Its level was increased in rainwaters by a factor 1000 during peak emissions in 1963 within the whole northern hemisphere. Here we demonstrate that tritium from global atmospheric fallout stored in sedimentary reservoir for decades as organically bound forms in recalcitrant organic matter while tritium released by nuclear industries in rivers escape from such storages. Additionally, we highlight that organically bound tritium concentrations in riverine sediments culminate several years after peaking emission in the atmosphere due to the transit time of organic matter from soils to river systems. These results were acquired by measuring both free and bound forms of tritium in a 70 year old sedimentary archive cored in the Loire river basin (France). Such tritium storages, assumed to be formed at the global scale, as well as the decadal time lag of tritium contamination levels between atmosphere and river systems have never been demonstrated until now. Our results bring new lights on tritium persistence and dynamics within the environment and demonstrate that sedimentary reservoir constitute both tritium sinks and potential delayed sources of mobile and bioavailable tritium for freshwaters and living organisms decades after atmospheric contamination.
... The POM was then observed under light microscopy (Leica DMR XP) in transmitted light (objective x50) using a grid (10 μm mesh) where 200 elementary surfaces were considered to obtain a percentage of error lower than 5% 44 . The origin and the state of degradation are defined on the basis of morphological, textural and colorimetric criteria 45 . Since this method is surface-based, the quantitative palynofacies that allows access to the amount of POM (in mg/g) of the different classes defined by counting has been used 46 . ...
Article
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Tritium of artificial origin was initially introduced to the environment from the global atmospheric fallout after nuclear weapons tests. Its level was increased in rainwaters by a factor 1000 during peak emissions in 1963 within the whole northern hemisphere. Here we demonstrate that tritium from global atmospheric fallout stored in sedimentary reservoir for decades as organically bound forms in recalcitrant organic matter while tritium released by nuclear industries in rivers escape from such storages. Additionally, we highlight that organically bound tritium concentrations in riverine sediments culminate several years after peaking emission in the atmosphere due to the transit time of organic matter from soils to river systems. These results were acquired by measuring both free and bound forms of tritium in a 70 year old sedimentary archive cored in the Loire river basin (France). Such tritium storages, assumed to be formed at the global scale, as well as the decadal time lag of tritium contamination levels between atmosphere and river systems have never been demonstrated until now. Our results bring new lights on tritium persistence and dynamics within the environment and demonstrate that sedimentary reservoir constitute both tritium sinks and potential delayed sources of mobile and bioavailable tritium for freshwaters and living organisms decades after atmospheric contamination.
... Samples with significant proportions of terrestrial OM are also characterized by dAOM relative concentrations > 3%. This type of organic particle traces, when associated with strong terrestrial OM concentration, a source from soil layers (Sebag et al., 2006), thus indicative of detrital inputs in the environment (Tyson, 1995). On the other hand, degraded fAOM was only observed in Lally, Muse and Surmoulin beds. ...
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The Autunian (Late Gzhelian-Sakmarian, ∼295 Ma) of the Autun Basin (Saône-et-Loire, France) is well known for its lacustrine oil-shales and boghead that were exploited during the 19th and 20th centuries. A study of the kerogen geochemistry, palynofacies, hydrocarbon (HC) distribution of pyrolysates and kinetics on these organic-rich sediments gave indications on the control of lacustrine primary fluid characteristics by palaeoenvironmental settings. Palynofacies results have shown a Botryococcus algae dominance in the boghead, whereas the oil-shales were dominated either by a mixing of terrestrial particles and lacustrine phytoplanktonic/bacterial organic matter (OM), or by a lacustrine OM that suffered biodegradation within the water column. During the Autunian, an increasing trend of degraded lacustrine OM concentration is observed in the successive oil-shales. Geochemical and kinetics analyses showed that, except for the boghead, hydrogen index values were
... Various studies have focused on OM classification in source rocks according to the OM occurrence (Kennedy et al., 2002;Zhu et al., 2016), and the physicochemical interactions between OM and clay minerals Keil and Maye, 2014;Lützow et al., 2006;Zhu et al., 2020). Soluble and insoluble OM (Durand, 1980;Tissot and Welte, 1984), OM combined with minerals and not combined with minerals (Keil and Mayer, 2014), and structured and amorphous OM (Sebag et al., 2006;Tyson, 1995) demonstrate the diversity of OM. The OM combined with minerals have various bonding mechanisms with mineral surfaces, such as ligand exchange (Kaiser et al., 2007;Kleber et al., 2007), ion exchange (Mikutta et al., , 2009, cation bridging (Li et al., 2015;Lützow et al., 2006), etc. Soluble OM is generally in a free state or physically adsorbed in source rocks (Tissot and Welte, 1984). ...
... Peat may form in forest swamps from various plant associations, or in marshes with herbaceous vegetation (sedges and grasses) or in open swamps with predominantly submerged and floating plants or in raised bog with mosses or shrubs or trees. Several coal geologists made significant contributions towards the depositional system, mention may be the name of Amijaya and Littke (2005), Marques (2002), Sebag et al. (2006), and Silva et al. (2008). For retrieving the type of Karharbari coal facies, petrography based model proposed by Hacquebard and Donaldson (1969), Diessel (1986), Mukhopadhyay (1986, Singh and Singh (1996) and Singh et al. (2013) have been used. ...
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In the present study an attempt has been made to carry out the detailed petrographic characterization of the Karharbari coals of Talcher coalfield and to reconstruct the paleoenvironment conditions of coal formation using macerals and microlithtotypes as a tool. For these purposes a large number of samples were collected following the pillar sampling method and were subjected to detailed petrographic study. The petrographic observation shows that these coals are vitrinite rich followed by the liptinite and inertinite group of macerals. On microlithotype scale, these coals shows the dominance of the vitrite followed by clarite, vitrinertite and inertite. The concentration of liptite, clarodurite, duroclarite and vitrinertoliptite are insignificant. The vitrinite reflectance ranks the Karharbari coal as high volatile bituminous ‘C’ to high volatile ‘B’ bituminous. Coal petrography based depositional models suggest peat accumulation in forested telmatic swamp. Moreover, during the time of their evolution, there were alternate phases of oxic and anoxic moor conditions with good tissue preservation.
Article
Phytostabilization have been proposed as promising tools for long‐term management of polluted sites. Optimization of the process efficiency involves choosing suitable amendments to allow both efficient plant growth and the immobilization of contaminants. The objectives of this study were to evaluate the effect of amendments on (i) the physicochemical properties of technosol and (ii) the mobility and phyto‐availability of metal(loid)s. A dwarf bean growth test was conducted on technosols amended with compost, garden soil, slag and biochar. The physicochemical properties of soil pore water (SPW) were determined as well as the phyto‐available concentrations of metal(loid)s by simple extraction tests. All amendments used were able to increase SPW pH and electrical conductivity, allowing a decrease in the lead concentration in SPW by 90% and the lead phytoavailable part by 93%. However, for all amendments, SPW As concentration increased. Lastly, the amendments improved bean growth and tended to decrease the metal(oid) concentrations in aerial organs. As concentration in roots did not decrease whereas Pb concentration decreased. Metal(loid) concentrations of Pb accumulated in the aerial parts of beans and their extractable concentrations showed a significant positive correlation with the extraction procedures. In contrast, the phytoavailable As showed a weak correlation with As concentrations in the aerial parts. The 1‐M NH4NO3 extraction procedure was the most appropriate and provided the most useful indications of the phyto‐availability for the studied elements.
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Samples of Albian Tégulines Clay outcropping near Brienne-le-Château in the eastern part of the Paris Basin were subjected to a geochemical characterization of organic matter (OM), combining OM bulk Rock-Eval analysis (RE), organic petrography and molecular analysis. In this study, the objective was to investigate the oxidation of natural organic matter in critical zone developed in early reduced marine clay formation. For that purpose, core samples from three boreholes crosscutting the Tégulines Clay formation down to the Greensands were selected. Several meters of Brienne marls preserved Tégulines Clay from atmosphere and therefore from high weathering and high oxidation in AUB240 borehole, whereas Tégulines Clay were weathered in their upper part in AUB1010 and in AUB230 boreholes as a result to their vicinity to the surface. The results showed that the Total Organic Carbon (TOC) contents in all clays are very low, ranging between 0.3 and 0.7 wt%. The RE bulk data and Tmax parameter of OM in preserved Tégulines Clay indicate that the OM is immature. The organic petrography shows a predominance of gel-like amorphous OM preserved by natural sulphurisation in anoxic environments. Organic matter in Tégulines Clay from the AUB230 and AUB1010 boreholes show similar characteristics. The OM at the top of Tégulines Clay contains large amounts of oxidized lignocellulosic debris and has high RE Oxygen-Index values. In the first upper 10 m of the clays, the RE bulk, organic petrography and molecular data revealed oxidative events (high OI and high oxidized debris contents). Below 10 m, the OM is almost preserved. The OM in the reduced marine Tégulines Clay formation is very little functionalized and seems to be slightly reactive but not negligibly with the inorganic fractions in presence of oxygen.
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A quantitative assessment of historical sediment yields (SY) was performed using sediment budgets from lacustrine records located in the Mont Dore and Cezallier volcanic provinces (French Massif Central). A source-to-sink approach combining hydro-acoustic images, organic geochemistry (Rock-Eval and quantitative organic petrography) and radiocarbon dating of sediment cores has been adopted on three lake-catchment systems, namely Pavin, Chauvet and Montcineyre. SY was estimated from the quantification of red Amorphous Particles (rAP), a terrigenous organic tracer identified in both soils and sediments. Historical SY range between 3 and 320 t km⁻².yr⁻¹, which is comparable to the magnitude reached in other European lake-based SY records in similar geographical and climatic settings. Comparison of recent SY with predicted values of soil erosion rates from the RUSLE2015 model highlights large differences linked to scale differences between the model at plot scale and lake-based SY reflecting erosion export from the catchment to the lake. In this sense, the role of peatlands as sediment traps within two studied catchments must be considered to explain the large differences between modelled soil erosion rates and reconstructed SY data. SY differences between sites can be firstly attributed to morphology, size and lithology of the catchments as well as to vegetation cover whereas fluctuations reconstructed for each record seem to be mainly related to human-induced land use management. Historical SY from Chauvet and Montcineyre synchronously recorded two events in 850 CE and 1450 CE, respectively. The first marked the rise of SY to their maxima following land-use changes in the catchments. Nearby palaeoenvironmental records from Lake Aydat, Chambedaze peatland, and Espinasse marsh suggest this rise was consecutive to intensification of agro-pastoral activities recorded at regional scale. The second event followed a land-use shift characterized by a ten to fifteen-fold decrease in SY values. The driver remains unclear but could be possibly related to historical events causing a demographic decline (i.e., the Black Plague and/or the Hundred Years War) and/or cultural adaption in response to the onset of the Little Ice Age. Overall, both records suggest erosion in the area has been historically more susceptible to human-induced land use change rather than to precipitation and temperature changes induced by climate variability of the past millennium.
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Organic matter (OM) is preserved as different occurrences in mudstones, which can affect the hydrocarbon generation process. However, little research has focused on hydrocarbon generation as a function of different occurrences of OM. This study collected a suite of mudstones in the Dongying Sag, Bohai Bay Basin, and conducted Rock-Eval VI pyrolysis after Soxhlet extraction and Na2S2O8 oxidation, aiming to quantify the OM with different occurrences and Fig. out the contributions of each occurrence of OM to the hydrocarbon generation. There are three types of occurrences of OM: soluble organic matter (SOM), mineral-bound organic matter (MOM), and particulate organic matter (POM). MOM is the most abundant among the three occurrence types of OM. SOM and MOM are the main hydrocarbon precursors, and their hydrocarbon contributions alternate with different kerogen types and layers. Additionally, MOM-contributed hydrocarbons are numerous at shallow depths; SOM-contributed hydrocarbons mainly occur at deep depths; and POM-contributed hydrocarbons change little with depth. These results demonstrate that MOM should be the main hydrocarbon precursor in shallow formations and that SOM is the main hydrocarbon contributor at deep depths.
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Lacustrine mudrocks are important hydrocarbon source rocks due to their high contents of organic matter (OM). An accurate determination of the origins of OM in the rocks can contribute greatly to the identification of the sedimentary environment and the evaluation of the hydrocarbon generation capacity of the mudrocks. In this study, the lacustrine mudrocks of the Eocene Shahejie Formation in the Dongying Sag of China were sampled for further discussion of the types and origins of OM and the hydrocarbon generation capacity of the mudrocks. On that basis, the classical palynofacies classification scheme was improved, and five palynofacies types (PF1 to PF5) were classified to accurately reflect different lacustrine environments. Among them, PF1 to PF3 are rich in various amorphous organic matter (AOM), including benthic microbial mats, organic aggregates and algal aggregates, which are part of the lake environment in which aquatic organisms bloom. The hydrocarbon generation abilities of the three palynofacies are different but generally strong. PF5 and PF4 have abundant terrestrial plant fragments and macrophyte fragments, respectively, indicating a shallow, near-provenance lake environment and a shallow, macrophyte-flourishing lake environment. These two types of palynofacies have weaker hydrocarbon generation capacities than the former three. Due to the enrichment of different types of palynofacies, each formation of the Dongying Sag shows distinct hydrocarbon generation potentials. Therefore, it is important to pay special attention to the origin of OM and its influences on the hydrocarbon generation capacity of lacustrine mudrocks for a better understanding of the deposition and hydrocarbon generation potential of source rocks.
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This study aimed to identify differences in organic matter (OM) composition and origin in the main depositional subenvironments within the floodplain of a meandering river in a temperate climate zone. The study analysed organic-rich sediments found within different facies (side bars, natural levees, crevasse splays, palaeochannels, flood basins, and alluvial fans). Quantitative macrofossil analysis of the OM present in proximal floodplain sediments pointed to a dominance of amorphous OM (AOM), the average proportion of which comprised up to 60% of the total OM. During floods, the most significant phenomenon is the deposition of wood and leaf debris; however, these debris are subject to rapid decomposition in sandy layers and, as a result, do not contribute much to the total OM composition. Root and epidermis remain accumulated in situ and, with an average share of more than 10% of the total OM, are an important part of the more fine-grained alluvial layers. The other components were no more than bioindicators. The proximal floodplain is characterised by sponge spicules in the alluvia and mycelia in the epipedons. In addition, diatom remains are often recorded in the flood layers. The average AOM content in the OM found within the distal floodplain was approximately 40%, although a significantly higher proportion of this component was recorded in flood basin sediments. The accumulation of rhizodermis, epidermis, wood, and periderm (with shares ranging from 5% to 22% of the total OM) plays an important role. Less common components that are of indicative value within the distal zone include the remains of mosses, Cladocera, and sporomorphs. OM within the distal floodplain has high preservation potential, and the sediments in this zone are crucial for carbon sequestration processes in river valleys.
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A lithological study of the clay-with-flints of the Western Paris Basin shows that they can be divided into a several spatial types. Granulometric, mineralogical and chemical comparisons between chalks and clay-with-flints reveal that these formations are not solely the product of decalcification of the chalk. Allochthonous inputs to their matrix are significant and vary both vertically and spatially. Mapping and lithological comparisons between the clay-with-flints and remnants of overlying Cenozoic deposits indicate that the latter are the sources of allochthonous inputs and thus they contribute to the genesis and spatial variations in the clay-with-flints. Cenozoic deposits have also influenced the age and duration of weathering of the clay-with-flints.
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The petroleum quality (IH) of the humic organic matter of the Mahakam delta is very variable at given total organic carbon and maturation index. The HI is not only correlated to the organic composition, but also to the mutual spatial relations of the organic and mineral constituents. A characteristic organo-mineral microtexture has been identified in each depositional environment of this delta. There is an abridged English version. -English summary
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The petrographical study of the sedimentary organic matter contained in recent sediments from "Le Petit Lac d'Annecy" allows to obtain a palaeoenvironmental signal based on the autochthonous/allochthonous organic matter ratio of the past 1000 years. The new limnological regime, linked with the anthropisation of the watershed, makes possible to read directly this signal in terms of lacustrine phytoplanktonic production since ca AD 1000. This signal also points out various erosion events seen by specific organic deliveries from the watershed, evidencing periods of increased running-off or intensive land-uses.
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A sedimentological study of a 755 cm length core sampled in the marshy depression surrounded by a cloud forest in the central Andes reveals that this site has recorded important environmental variations during the last 50 000 years. For the most part (625 cm) the core is composed of detrital rich sediments deposited during the Upper Pleistocene. The highest amount of detrital influx underlines the Last Glacial Maximum which ranges from ca 29 000 14C yr B.P. to ca 16 000 14C yr B.P. (ca 18 500 cal yr B.P.), between two relatively humid phases. The sedimentation of the present Interglacial, starting at ca 12 500 14C yr B.P. (14 500 cal yr B.P.), is mainly organic, as a consequence of the great development of soils and the forest vegetal cover all over the catchment area. The maximum extension of this vegetal cover ranging from 12 500 to ca 10 500 14C yr B.P. (14 500 and 12 400 cal yr B.P.) is followed from 10 500 to 8000 14C yr B.P. (12 400 and 8800 cal yr B.P.) by a drier period as revealed by the occurrence of micro-charcoals in the sediment. Between ca 8000 and 4000 14C yr B.P. (8800 and 4500 cal yr B.P.), the sharp increase of micro-charcoals content, likely related to palaeofires, underlines an intensification of this dry trend.
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Petrographic (palynofacies) and geochemical (Rock Eval pyrolysis) studies of sedimentary organic matter of a core from a crater lake in Madagascar show a peaty sedimentation before 36 ky and between ca 28 and 15 ky, and between 6 and 0 ky. Between 36 and 28 ky, the organic sedimentation is characterized by alternate phytoplanktonic sedimentation and migrations of vegetation from the basin slope to the lake itself. Contributions of oxidized allochthonous organic matter also prove the presence of vegetation on the surrounding basin and soil leaching. The variation of the ecosystems and their development reveal the climatic changes during the last 36 kyrs, in terms of arid and humid periods. -English summary