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Influence of sediment source on the shapes and surface textures of glacial quartz sand grains
Abstract
A study of the shapes and surface textures of glacial quartz sand grains that were largely derived from sediment sources of different rock types was conducted in order to evaluate the influence of the sediment source on these textures. The results show that the roundness and surface textures of glacial quartz sand grains are largely dictated by their sources and that surface textures may not always be reliable indicators of ancient glacial deposits.
... Furthermore, the presence of grains recycled from pre-existing sediments and sedimentary rocks can create a strong provenance-related overtone in the texture tallies in studies of glacial environments (cf. Mazullo & Ritter, 1991). To avoid this problem, observations on the various layers of textures that overprint each other are also made on the entire grain surface with the aim to separate textures produced during the multiple cycles of surface exposure, erosion, sediment transport and deposition (cf. ...
... One challenge with the environmental interpretation of raw frequencies of quartz grain microtextures ( Figure 5) is the strong provenance signal in the texture distributions in grains from glacial environments (Mazullo & Ritter, 1991;Moss & Green, 1975). In Cenozoic tills deposited in valleys in the uplands of the Transantarctic Mountains, conchoidal and sublinear fractures are abundant, and v-shaped impact pits are also present (Mahaney et al., 1996). ...
... In Cenozoic tills deposited in valleys in the uplands of the Transantarctic Mountains, conchoidal and sublinear fractures are abundant, and v-shaped impact pits are also present (Mahaney et al., 1996). In samples of AND-2A diamictites the high frequencies of fractured plates, breakage blocks, in addition to v-shaped impact pits ( Figure 5) points to glacial erosion and transport of quartz derived from crystalline and/or immature sedimentary rocks (Mazullo & Ritter, 1991). Rounding of grains and an increase in v-shaped impact pits on glacially sourced grains have been observed elsewhere after only ca 80 km of subaqueous transport (Sweet & Brannan, 2016). ...
On high‐latitude continental margins sediment is supplied from land to the deep sea through a variety of processes, including iceberg and sea‐ice rafting, and bottom current transport. The accurate reconstruction of sediment fluxes from these sources through time is important in palaeoclimate reconstructions. The goal of this study was to assess a shift in the intensity of glacial processes, iceberg and sea‐ice rafting during the Pliocene through an investigation of coarse sediment deposited at the AND‐2A site in the Ross Sea and at International Ocean Discovery Program Site U1359 on the Antarctic continental rise. Terrigenous particle‐size distributions and suites of quartz grain microtextures in the sand fraction of the deep‐sea sediments were compared to those from Antarctic glaciomarine diamictites as a baseline for proximal glacial sediment in its source area. Using images acquired through Scanning Electron Microscopy, and following a quantitative approach, fewer immature and potentially glacially transported grains were found in Pliocene deep‐sea sand fractions than in ice‐contact sediments. Specifically, in the lower Pliocene interval silt and fine sand percentages are elevated, and microtextures in at least half of the sand fraction are inconsistent with a primary glacial origin. Larger numbers of chemically altered and abraded grains in the deep‐sea sand fraction, along with microtextures that are diagnostic of periglacial environments, suggest a role for eolian sediment transport. These results highlight the anomalous nature of high‐latitude sediment fluxes during prolonged periods of ice‐retreat. Furthermore, the identification of a significant offshore sediment flux during Antarctic deglaciation has implications for estimated nutrient supply to the Southern Ocean and the potential for high‐latitude climate feedbacks under warmer climate states.
... Microscopic textures on the surface of minerals resistant to chemical and physical weathering can record the transport history of clastic sediments (Mazzullo and Ritter 1991, Krinsley and Doornkamp 1973, Margolis and Krinsley 1971. Surface texture analysis of quartz grains has been used to infer depositional settings and sedimentary transport processes in a variety of environments (Krinsley and Doornkamp 1973), including ice sheets and glaciers (Mazzullo and Ritter 1991), Arctic fluvial settings (Helland and Holmes 1997), and beach dunes (Vos et al. 2014). ...
... Microscopic textures on the surface of minerals resistant to chemical and physical weathering can record the transport history of clastic sediments (Mazzullo and Ritter 1991, Krinsley and Doornkamp 1973, Margolis and Krinsley 1971. Surface texture analysis of quartz grains has been used to infer depositional settings and sedimentary transport processes in a variety of environments (Krinsley and Doornkamp 1973), including ice sheets and glaciers (Mazzullo and Ritter 1991), Arctic fluvial settings (Helland and Holmes 1997), and beach dunes (Vos et al. 2014). An important consideration in analysing quartz surface textures is also the influence of the source rock on the shape of grains (Mazzullo and Ritter 1991). ...
... Surface texture analysis of quartz grains has been used to infer depositional settings and sedimentary transport processes in a variety of environments (Krinsley and Doornkamp 1973), including ice sheets and glaciers (Mazzullo and Ritter 1991), Arctic fluvial settings (Helland and Holmes 1997), and beach dunes (Vos et al. 2014). An important consideration in analysing quartz surface textures is also the influence of the source rock on the shape of grains (Mazzullo and Ritter 1991). ...
This study tested and assessed several methods for identifying and describing physical and chemical characteristics of nearshore sediments in East Antarctica. The study emphasised non-destructive techniques that can be used with small volumes of sample. There were three key aims:
1. Provide information about analytical techniques that are non-destructive and can be used on small-volume samples,
2. Apply these techniques to a set of samples where sufficient material is available and compare the results with the outcomes of traditional geochemical techniques, and,
3. Gain additional information on sedimentary processes in the nearshore environment in East Antarctica.
Sediment samples from the Antarctic region are especially difficult to collect because of large logistical requirements and are thus highly valuable. Sediment traps are an example of samples with typically small volumes. Such samples provide valuable information about the nature and quantity of marine sediment in the water column and are highly sought after by researchers. By testing characterisation methods on larger samples, this scoping study provides recommendations for analysing small-volume samples, using non-destructive techniques and techniques that can provide additional information to traditional analysis.
... Crescenting and conchoidal fractures and crystalline nodes are three main features of micro-textures on quartz grains ( Fig. 3c and d). Crescenting and conchoidal micro-textures are spoon-shaped fractures that are entirely surficial and do not pass through grains (Mazzullo and Ritter, 1991). These features reported from typical glacial stages are mainly produced by the release from parent rocks or percussion impact in falling off cliffs (Whalley and Krinsley, 1974). ...
... These features reported from typical glacial stages are mainly produced by the release from parent rocks or percussion impact in falling off cliffs (Whalley and Krinsley, 1974). Crystalline nodes, as stated by Mazzullo and Ritter (1991), are grain protuberance with either flat or slightly curved faces that form by the interface of the growth of a quartz crystal by previously crystallised minerals. Crystalline nodes are 5-20 mm blocks (or cleavage flakes) composed of very small (<5 mm) quartz particles that adhere to grain surface (Mazzullo and Ritter, 1991). ...
... Crystalline nodes, as stated by Mazzullo and Ritter (1991), are grain protuberance with either flat or slightly curved faces that form by the interface of the growth of a quartz crystal by previously crystallised minerals. Crystalline nodes are 5-20 mm blocks (or cleavage flakes) composed of very small (<5 mm) quartz particles that adhere to grain surface (Mazzullo and Ritter, 1991). These microblocks are series of concentric stepped arcs on conchoidal breakage faces. ...
... Crescenting and conchoidal fractures and crystalline nodes are three main features of micro-textures on quartz grains ( Fig. 3c and d). Crescenting and conchoidal micro-textures are spoon-shaped fractures that are entirely surficial and do not pass through grains (Mazzullo and Ritter, 1991). These features reported from typical glacial stages are mainly produced by the release from parent rocks or percussion impact in falling off cliffs (Whalley and Krinsley, 1974). ...
... These features reported from typical glacial stages are mainly produced by the release from parent rocks or percussion impact in falling off cliffs (Whalley and Krinsley, 1974). Crystalline nodes, as stated by Mazzullo and Ritter (1991), are grain protuberance with either flat or slightly curved faces that form by the interface of the growth of a quartz crystal by previously crystallised minerals. Crystalline nodes are 5-20 mm blocks (or cleavage flakes) composed of very small (<5 mm) quartz particles that adhere to grain surface (Mazzullo and Ritter, 1991). ...
... Crystalline nodes, as stated by Mazzullo and Ritter (1991), are grain protuberance with either flat or slightly curved faces that form by the interface of the growth of a quartz crystal by previously crystallised minerals. Crystalline nodes are 5-20 mm blocks (or cleavage flakes) composed of very small (<5 mm) quartz particles that adhere to grain surface (Mazzullo and Ritter, 1991). These microblocks are series of concentric stepped arcs on conchoidal breakage faces. ...
... Also note that the decrease in early Pliocene 5D samples (4.4-5.1 Ma), interpreted as decreased glacial influence, is coeval with an early Pliocene warm event from 4.02 to 5.03 Ma (Smellie et al. 2006). Crystalline rock samples exhibited greater mean harmonic 19 amplitudes compared to sedimentary rock samples (Haines and Mazzullo 1988;Mazzullo and Ritter 1991). A plot of mean harmonic 2 amplitudes and mean harmonic 19 amplitudes shows a clear break between JRB/SI and JP samples at about 0.0036 for harmonic 19 (Fig. 6). ...
... Provenance, not environmental (glacial) conditions, is responsible for the greater roughness seen in JRB and SI Eocene samples. Mazzullo and Ritter (1991) compared proglacial and glacial sediments sourced from crystalline and sedimentary sources. Regardless of glacial setting (e.g., proglacial vs. englacial), glacial sediment sourced from crystalline rock exhibited greater angularity than glacial sediments sourced from sedimentary source rock. ...
... Although provenance controls first-order changes in grain roughness, other factors such as depositional processes, including glacial activity, may control second-order changes in grain roughness. However, any climatic or environmental interpretation based on grain roughness must be done keeping in mind the strong influence of sediment provenance on grain shape (Mazzullo and Ritter 1991). For example, an observed change in grain roughness may be caused by a shift in provenance rather than by a change in regional climate and, hence, glacial activity. ...
Grain shape is useful as a depositional, environmental, diagenetic, and provenance proxy. Here we conduct the first study of down-core grain-shape variation in Antarctica. This study further examines the utility of grain shape as a depositional proxy, namely of glacial influence, in the James Ross Basin and Joinville Plateau of the Antarctic Peninsula from the Eocene to the present. Fourier grain-shape analysis was used to quantify the grain shape of 31 samples spanning the glacial history of the Antarctic Peninsula Ice Sheet. A total of 6,442 quartz grain peripheries were digitized and described through the twenty-first Fourier harmonic. Sediment provenance has a greater influence on grain roughness than glacial activity in the study area. However, provided a similar sedimentary source, secondary changes in roughness correlate with changes in the extent of the Antarctic Peninsula Ice Sheet since the late Oligocene. Grain roughness increased with increased glacial influence during the middle Miocene, after an early Pliocene warm period, and just above a Pliocene regional glacial unconformity. Conversely, grain roughness decreased with less glacial influence during the late Oligocene and during an early Pliocene warm period. This study further illustrates the usefulness of grain shape in distinguishing sediment provenance and environmental conditions in Antarctic settings.
... Such microfractures are susceptible to failure in rigorous Ž . surface environments Mazzullo and Ritter, 1991 . Conchoidal fractures are spoon-shaped fractures that are entirely surficial and not pass through grains Ž . ...
... Crystalline Ž . nodes, as stated by Mazzullo and Ritter 1991 , are grain protuberance with either flat or slightly curved faces that form by the interface of the growth of a quartz crystal by previously crystallized minerals. ...
... y water during warmer period from older bed rock after deposition of first generation loess. Scale bar is 250 mm. Abrasion textures are manifested by worn, dull and rounded edges with low-relief microtopography. Weathering textures consist of flatter or hummocky sheets and caps of amorphous silica that smooth the Ž surfaces and edges of the grains Mazzullo and . Ritter, 1991 . Finally, some grains of the Gharatikan loess show 'carapace' of comminuted debris cemented by sili-Ž . con between the very small -20 mm flakes and Ž . the quartz grain surface Fig. 4c . Carapace was Ž . defined Whalley and Krinsley, 1974 as an adhering Ž mixture of fragments usually comminution debris of . various kinds which form a ve ...
Loess and loess-like deposits cover large areas of north and central parts of Iran. Studies of shapes, inclusions, and surface textures of sand grains plus mineralogical composition and trace elements of these loesses in the Gharatikan watershed basin, located in northeast Iran, show that they had been derived from crystalline rocks (mostly granitic or granitoidic). They had been modified in glacial environment during the last glacial stage, transported in eolian suspension mode and deposited during glacial periods, when the area was a cool, arid, and poorly vegetated steppe. The loess was evidently derived from the Qaraqum desert to the north because (1) the beds become thicker and coarser-grained in that direction, (2) the deposits mostly cover northward facing hills and plains. The major and trace elements distribution patterns of the Gharatikan loesses are similar to that of Uzbekistan and Tajikistan loesses. Therefore, Gharatikan loess is the extension of the Uzbekistan and Tajikistan loesses. Changes in the petrographical characteristics of loess deposits of the Gharatikan watershed allow the reconstruction of the paleoenvironments during the periods of their formation and the detection of the trends of Pleistocene climate changes.
... Almost 30 years ago, Mazzullo and Ritter (1991) cautioned that micro-scale fractures and striations in scanning electron microscope (SEM) analyses does not necessarily imply a glacial origin, as these characteristics can be inherited from metamorphic or igneous rock crystals. This must be confronted by studies that present evidence for glacial processes at the SEM scale, hence the burden of proof is now greater (Woronko, 2016). ...
... Collectively, the thin section scale assemblage, in particular the presence of micro-shears and edge-edge crushing along which striations and arc-shaped steps would be expected to form, reinforces the view that the SEM-scale phenomena are mechanically produced, either at the ice-bed interface or within the upper few millimetres of the deforming bed. Thus, whilst the misidentification of metamorphic and igneous "striations" on quartz grains remains a valid assumption to test in every ancient glacial deposit (Mazzullo and Ritter, 1991), we argue that in the case of the African SSSS these structures originate through glacial abrasion at the microscale. At the macroscale, the rotation of clasts in shearing mass flows can produce striated clast faces (Kennedy and Eyles, 2020). ...
The expansion of ice sheets over soft, sandy substrates was widespread in the Early Palaeozoic, during the Late Ordovician glaciation of North Africa and Arabia. Similarly, large parts of southern Africa were glaciated by soft bedded ice sheets in the Late Palaeozoic Ice Age. An unanswered question is the extent to which subglacial deformation involved the passive recycling of unconsolidated materials, or the active production of new sediment through erosion and shearing. Here, we compile thin section data dovetailed with scanning electron microscope imagery from sandy subglacial substrates from South Africa, Algeria and Libya. Six samples were collected from soft-sediment striated pavements, i.e., surfaces that were sheared and deformed subglacially in an unconsolidated state. The samples show a considerable variation in deformation style but a unifying trait is the occurrence of striated and facetted quartz sand grains. These textural features testify to grain-grain attrition, and the potential production of sediment in the subglacial environment.
... Sedimentary grains can be largely free of microfractures because they have been recycled, causing polycrystalline or deformed quartz grains to be broken down to smaller sizes (Haldorsen, 1981;Wright, 1995;Langroudi and others, 2014). Metamorphic reactions can result in an overprinting of fresh microfractures (Slatt and Eyles, 1981) and the development of polycrystalline quartz (Gomez et al., 1988;Mazzullo and Ritter, 1991). Alternatively, annealing can lead to a reduction in planar defects and dislocation density during metamorphism. ...
... Smalley, 1966a) are broken down to smaller sizes with a larger standard deviation than metasedimentary quartz grains, which may have had a lower microfracture density prior to metamorphism (e.g. Gomez et al., 1988;Mazzullo and Ritter, 1991;Wright, 1995). ...
Glacial erosion produces vast quantities of fine-grained sediment that has a far-reaching impact on Earth surface processes. To gain a better understanding of the production of glacial silt and clay, we use automated mineralogy to quantify the microstructure and mineralogy of rock and sediment samples from 20 basins in the St. Elias Mountains, Yukon, Canada. Sediments were collected from proglacial streams, while rock samples were collected from ice marginal outcrops and fragmented using electrical pulse disaggregation. For both rock fragments and sediments, we observe a log-normal distribution of grain sizes and a sub-micrometer terminal grain size. We find that the abrasion of silt and clay results in both rounding and the exploitation of through-going fractures. The abundance of inter- versus intragranular fractures depends on mineralogy and size. Unlike the relatively larger grains, where crushing and abrasion are thought to exploit and produce discrete populations of grain sizes, the comminution of fines leads to a grain size, composition and rounding that is continuously distributed across size, and highly dependent on source-rock properties.
... These parameters are widely used in geotechnical and geoengineering analyses (Cox and Budhu, 2008;Tsomokos and Georgiannou, 2010;Altuhafi and Baudet, 2011;Altuhafi and Coop, 2011;Khayat et al., 2012;Altuhafi et al., 2013), as well as in geological (Clark, 1981;Rong et al., 2013;Altuhafi et al., 2016) and pedological studies (e.g., Feda, 2002;Miur Wood, 2008;Cavarretta et al., 2010;Polakowski et al., 2014;Liu et al., 2015;Chang et al., 2018;Zheng et al., 2019). In addition, grain shape provides useful information on sedimentary environments and transport conditions (including the extent), as well as on sediment origin (Mazzullo and Ritter, 1991;Selly, 2000;Cho et al., 2006;Sokołowski et al., 2013;Woronko et al., 2017;Sandeep et al., 2018). ...
The quartz-grain shape is an important sedimentological attribute typically used to reconstruct depositional settings and sediment transport conditions and predict the duration of grain transport. A common assumption is that the extent and duration of eolian and fluvial transport are reflected in the increased sphericity and roundness of sand grains, and this study aims to verify this relationship. Automatic particle-shape image analysis was performed on quartz grains (0.8–1.0 mm) from three sedimentary environments: weathered with angular fresh grains (GNU), eolian with well-rounded grains (GRM), and fluvial with well-rounded grains (GEL). This enabled us to obtain four associated shape-description parameters: highly sensitive circularity (circularity HS), convexity, solidity, and aspect ratio. Subsequent principal component analysis and discriminant analysis of the parameters indicated that circularity HS (associated with the degree of roundness) best distinguished the shape of GNU, GRM, and GEL grains. However, the aspect ratio was more useful for analyzing the degree of grain sphericity. GRM and GEL grains, those with a high degree of roundness, had either low or high sphericity, which should be considered a characteristic of long-term reworking by eolian and fluvial processes. The presence of grains with low sphericity and high degree of roundness, such as those found in environments where transport prevails, should be considered a shape inheritance. Using both sphericity and roundness parameters facilitates an accurate interpretation of transport environments in terms of transport duration and sediment maturity. However, neglecting grain sphericity when analyzing these sorts of sedimentary settings may result in the misinterpretation of their true sedimentary settings.
... These textures are partially overprinted by fluvial abrasion. V-shaped patterns are indicating high energy grain collision (Fig. 5) usually produced due to the grain saltation during aquatic transport (Krinsley and Donahue, 1968;Mahaney et al., 2001;Mazzullo and Ritter, 1991). ...
The Pleistocene loess and Holocene alluvial sediments are dominant lithological members of Eastern Croatia. Impressive loess-palaeosol successions up to 30 m thick are exposed in Croatian part of Baranja (Zmajevac) and along the steep cliffs of the Danube River (Erdut and Šarengrad). The Croatian loess record provides an excellent high-resolution archive of climate and environmental change, providing evidence for the interaction between accumulation and erosion of aeolian and fluvial sediments during the Middle and Late Pleistocene. Sedimentological and pedological investigations were carried out on 110 samples collected from the loess sections at Zmajevac, Erdut and Šarengrad. Analyses include grain size analyses, microscopic analyses of light and heavy mineral fraction, chemical analyses of major and trace elements and REE, determination of carbonate content, pH, TOC and dating by infrared optically stimulated luminescence (IRSL) Presence of erosional discontinuities and infilling of crotovinas with soil material that is not present in overlaying sediments indicate that some of palaeosols are eroded and so represent an incomplete record. Presence of soil sediments indicate that within the loess sediment a hiatus can be detected consisting of eroded palaeosol(s), which is not documented by the presence of Cc-horizon. Assuming that intensive pedogenesis is required for forming Cc -horizon that is extremely resistant to erosion, one can infer that several Cc -horizons without interbedded palaeosols indicate that their palaeosols were eroded. Thus, the possibility is ruled out of marking palaeosols by “ counting from surface” and of using correlation method conversing similar outcrop sections in the region. The synthesis of investigated profiles would probably result with at least eight profiles. A-horizons are eroded from all palaeosols. The loess successions are intercalated by at least four palaeosols or pedocomplexes. Alluvial sediments are intercalated in the loess deposits, indicating periods of fluvial activity. Therefore, a higher sampling resolution is needed in the future for the quantitative reconstructing of accumulation and erosion rates as well as a more reliable regional and interregional correlation correlation combining luminescence dating with magnetic and malacological investigations.
... Due to its complexity and the lack of a commonly accepted definition, this parameter is usually omitted when defining the shape of grains. There were high hopes for this novel method of analysing the microtextures based on Fourier harmonic analysis, albeit relatively complex in the technological terms, which hitherto only resulted in its incidental use in geological studies (Mazzullo et al., 1984;Mazzullo and Ritter, 1991;Mazzullo and Magenheimer, 1987;Pye, 2007). ...
Well-rounded grains extracted from aeolian and subaqueous environments were analysed to determine a quantitative parameter describing the microtopographic surface properties of sand-sized quartz grains, expressed as a degree of smoothness or as an inverse roughness. To this end, the spectral method was used to calculate their fractal dimension values. Fractal characteristics and spectral fractal dimension (DS) were determined for a scanning electron microscope (SEM) image (560 × 560 pixels) obtained for each study grain. This parameter, (DS), describes the complexity of objects, which means that the higher its value, the more complicated the analysed grains are in terms of exterior roughness and surface microirregularities. The obtained results indicate that values of the parameter (DS) were higher for all aeolian grains compared to grains from either low- or high-energy subaqueous environments. This difference in results is attributed to the presence of microirregularities on the surface of aeolian grains, microtextures forms such as mechanically upturned. This parameter value increases as the energy of the aeolian environment increases. Values of (DS) for subaqueous environments grains correlated with the frequency of microtextures that resulted from high-energy grain-to-grain collisions (e.g., V-shaped percussion cracks), or from the chemical etching of the grain surface (e.g., solution pits, solution crevasses)—the higher the frequency of either collision or chemical-etching microtextures, the higher the value of the fractal dimension (DS). Thus, it has been demonstrated that fractal analysis can serve as a useful tool to discriminate between the analysed sedimentary environments, to assess a depositional system’s kinetic energy, and to compare the intensity of chemical weathering.
... Resulting polygenetic microtextures include conchoidal fractures, mechanically upturned plates, step fracturing, and lineations (Table 1). A wide range of environments impart polygenetic microtextures onto grain surfaces, including burial or tectonic stress (Mazzullo and Ritter 1991), glacial stress (Mahaney and Kalm 2000;Mahaney 2002), mass-flow, matrix shearing (Mahaney 2002), bed-load grain contact during eolian and aqueous saltation (Mahaney andAndres 1991, 1996;Helland and Diffendal 1993;Mahaney and Kalm 2000;Sweet and Soreghan 2010;Mahaney and Dohm 2011), comet impacts (Mahaney 2002), and shrink-swelling of soil (Mahaney et al. 2001b(Mahaney et al. , 2001cSweet and Soreghan 2008). Thus, SEM Helland and Diffendal 1993;Mahaney andKalm 1995, 2000;Mahaney 2002 (1) Descriptions from Mahaney (2002). ...
Certain micrometer-scale fractures, or microtextures, on grain surfaces are the result of specific transport processes. Accordingly, these transport-induced microtextures are used to infer depositional setting in ancient deposits. Multiple transport histories complicate the microtextural record because modification of grain
surfaces can reduce or eliminate the signal of earlier transport episodes. This study utilizes scanning electron
microscopy to analyze surface microtextures to assess the role of fluvial overprint on glacially derived grains along ~ 188 km of the proglacial Chitina River, SE Alaska. Results indicate that occurrence frequency of glacially induced microtextures (i.e., straight and curved grooves, deep troughs, and crescentic gouges) negatively correlates to distance downstream, yet these microtextures persist in every sample. Conversely, occurrence frequency of fluvially induced microtextures (i.e., v-shaped cracks and edge rounding) positively correlate to distance downstream. At least in the Chitina River watershed, the ratio of fluvially to glacially induced microtextures (F/G ratio) generally records physiographic variation, including increase in fluvial signal after a major tributary confluence, and decrease downstream from the intersection of valley glaciers. These results suggest that analysis of quartz grain microtextures in ancient fluvial deposits can be used to infer glacial influence when other diagnostic sedimentologic indicators of glaciation are lacking. Other potential uses for the proxy may exist, but need to be assessed after other modern proglacial systems are studied, including: 1) estimates of distance to paleo–ice margins using the respective downstream trends of glacially or fluvially induced microtextures, and 2) paleogeography of ancient glacio-fluvial systems through F/G ratio analysis.
... categories: 0 = case absent, 1 = isolated case, 2 = frequent case, and 3 = very abundant case. The microtextures considered are defined in Krinsley and Doornkamp (2011) and Mazzullo and Ritter (1991), completed with those of Mahaney and Kalm (2000), Curry et al., (2009), Mahaney and Hancock (2015). ...
The present paper provides new information on Pleistocene glacial activity in a mountainous area of the Iberian Central System. A sediment analysis associated with Pleistocene modelling was carried out using: (1) granulometric and morphometric procedures, (2) quartz grain microtexture techniques (SEM) to discriminate between glacial and no glacial origins of sediments, (3) clay X-ray diffraction study to determine intra-Pleistocene climate variability, and (4) optically stimulated luminescence (OSL) absolute dating. The results show that the sediments were formed in two different phases associated with glacial dynamics, one of them was 35–30 ky BP and another was 25–20 ky BP, separated by a short intermediate warm-wet period. Identification of glacial phenomena is new for the northern slopes of the Guadarrama Mountains (facing the north Meseta, Duero basin), although they are not unusual within the general context of the Iberian Central System. From the data provided, we deduce that glaciation in these mountains was much more intense and widespread than had previously been thought because, on the northern slopes, glaciers occupied large areas reaching the base of the mountains. The evidence favours new interpretations of Pleistocene morphology in the centre of the Iberian Peninsula and, by extension, on the southwestern edge of Europe; it also highlights the sensitivity of mountainous areas with regard to Quaternary climate changes.
... Some workers have cited examples of similar SEM microtextures on freshly weathered granitic bedrock fragments and tills (Brown 1973), which gave rise to the principle of equifinality; that is, that different geologic processes might produce similar microfeatures on sand-size clasts. Still other workers have emphasized operator variance (Culver et al. 1983) stressing that different operators may produce different interpretations from observed microfeatures, or that bedrock source is more important than process and depositional environment (Mazzulo & Ritter 1991). ...
Samples of Middle Devonian (Eifelian age; 387-380 Ma) indurated and non-cemented sandstone were compared with Pleistocene basal tills in Estonia and Latvia to test a hypothesis that glacial SEM (scanning electron microscopy) microtextures are distinctly different from those produced in a fluvial depositional environment. The deposits of Middle Devonian Arukula Stage were emplaced in a continental water basin close to sea level and well away from any glacial source. Therefore, the SEM microtextures on quartz grains from the Arukula Stage should show mainly the effect of stream transport. The basal tills are of Late Weichselian age deposited as ground moraine directly over the sandstone. Additional glaciofluvial and glaciolacustrine samples were included with the tills to determine whether glacial and fluvial-lacustrine transport could be differentiated by the SEM microtextures. Samples of oriented blocks of till from a limited number of sites were studied without pretreatment to determine whether sand clast orientation could provide a method for determining glacial flow vectors. While there are some microtextural similarities between grains from glacial and glaciofluvial-lacustrine depositional environments, the vast majority of grains from till deposits (50%-60%) are faceted, sharp edged, angular to subangular, and comprised of numerous and distinct microfeatures including abraded surfaces over microfractures, deep linear and curved troughs (striations), step features, and a preponderance of conchoidal and linear microfractures. Glaciofluvial and lacustrine grains contain abundant abrasion features and v-shaped percussion cracks that make them very distinct from glacial grains. Fluvial transport produces primarily rounded grains, well abraded, with v-shaped percussion scars dominating. Thus, it is possible to use microtextural differences between the three sample suites to identify particular depositional environments. Oriented till blocks provide information on sand clast orientation. Although carbonate coatings often obscure sand clasts in untreated blocks, it is possible to determine some microfabric information that can be useful in determining flow direction of the ice.
... These textures are partially overprinted by fluvial abrasion. V-shaped patterns are indicating high energy grain collision (Fig. 5) usually produced due to the grain saltation during aquatic transport (Krinsley and Donahue, 1968;Mahaney et al., 2001;Mazzullo and Ritter, 1991). ...
In the Eastern Croatia impressive loess-paleosol successions up to 30. m thick are exposed. In the Zmajevac I section three paleosols are intercalated in loess while in the Zmajevac, Erdut and Šarengrad sections there are four paleosols are intercalated in loess. IRSL age estimates of 17.8 ± 1.9 and 217 ± 22 ka. In all investigated sections, alluvial sediments are intercalated in the loess deposits, indicating periods of fluvial activity. Strongly abraded typical aeolian spherical grains characterized by pitted well-rounded surface that was developed during transportation have original crystal surface almost destroyed. Surface of quartz grains preserves micro textures characteristic for all transport medias that it has been exposed to. However, muscovite grain surface enable successful distinguishing if the last transport was by wind or by aquatic media. Characteristic of all horizons with muscovite as a dominant mineral is recent settling of organisms. Beside the Danube, Drava and Sava River flood plains, part of the analyzed sediments also originates from regional Tertiary sediments which are rich in granite (as a muscovite-bearing rock), indicating the local influence. Enrichment of pyroxenes in the Šarengrad section points to the Dinaride Ophiolite Zone as its source of origin eroded by the Sava River southern tributaries. Šarengrad section is the southernmost among the analyzed sections and the southern edge of the Carpathian Basin. Thus, beside the Alpine region, the mineral composition is influenced by minerals from the Dinaride Ophiolite Zone in Bosnia. Warming periods are not represented just by paleosols, but also with laminated alluvial sediments.
... The largest sand grain analyzed for shape was 1 mm, the smallest silt grain was 7 mm. The second harmonic is a proxy for vertical elongation of grains and is correlated to Rittenhouse sphericity values (Rittenhouse, 1943;Mazzullo and Ritter, 1991). Higher harmonics are correlated with the angularity of the grains and the roughness of the surface (Krumbein and Pettijohn, 1938;Lees, 1964). ...
... These microtextures are analogous to those formed on quartz grains in modern glacial systems (e.g., Mahaney and Kalm 2000;Mahaney 2002) and contrast with the prevalence of etch pits and dissolution features documented in first-cycle quartz derived from upland granitic terranes in modern temperate/humid (upland Mediterranean) climates (Scarciglia et al. 2005). In another study of first-cycle quartz from plutonic and metamorphic source terranes, Mazzullo and Ritter (1991) observed various types of fractures, but all of polygenetic origin and none indicative of high-stress or percussion origin, such as occur on grains transported from glacial and proglacial systems (Mahaney 2002; Sweet and Soreghan 2010a). Facies sam- pled consist of fluvial and near-shore marine deposits, and the studied quartz grains also exhibit features consistent with percussion grain-to-grain contact, such as V-shaped cracks and edge rounding (Sweet and Soreghan 2010a). ...
The late Paleozoic archives a prolonged icehouse, long recognized by means of Gondwanan continental glaciation. In contrast, the paleotropics have long been considered warm. Here we present the hypothesis of upland glaciation in the Ancestral Rocky Mountains (ARM) of western equatorial Pangaea, a region located within 11° of the paleoequator. The data to support this hypothesis include (a) a Permo-Pennsylvanian valley with glacial attributes and diamictite exhibiting rare striated clasts; (b) coarse-grained lacustrine strata onlapping the valley and preserving lonestones in Gilbert-type deltaic deposits proximally, along with (c) coarse-grained fluvial siliciclastic strata with microstriae and evidence for widespread flood deposition; (d) polygonally cracked paleosurfaces inferred to reflect frozen ground; and (e) voluminous paleoloess. Tropical glaciation occurs today at altitudes >4500 m and descended to 2100–3000 m at the last glacial maximum (LGM). However, ARM depositional systems terminating at sea level and emanating from inferred ice-contact facies indicate that ice-terminus elevations were lower (
... The largest sand grain analyzed for shape was 1 mm, the smallest silt grain was 7 mm. The second harmonic is a proxy for vertical elongation of grains and is correlated to Rittenhouse sphericity values (Rittenhouse, 1943;Mazzullo and Ritter, 1991). Higher harmonics are correlated with the angularity of the grains and the roughness of the surface (Krumbein and Pettijohn, 1938;Lees, 1964). ...
Modern Pine Island and Thwaites Glaciers, which both drain into Pine Island Bay, are among the fastest changing portions of the cryosphere and the least stable ice streams in Antarctica. Here we show that the uppermost sediment unit in Pine Island Bay was deposited from a meltwater plume, a plumite, during the late stages of ice sheet retreat ∼7–8.6 k cal yr BP and argue that this deposit records episodes of meltwater intensive sedimentation.
The plumite is a hydraulically sorted, glacially sourced, draping deposit that overlies proximal glacimarine sediments and thickens towards the modern grounding line. The uppermost sediment unit is interpreted as a product of non-steady-state processes in which low background sedimentation in large bedrock-carved basins alternates with episodic purging of sediment-laden water from these basins. The inner part of Pine Island Bay contains several basins that are linked by channels with a storage capacity on the order of 70 km3 of stagnant water and significant sediment storage capacity. Purging of these basins is caused by changes in hydraulic potential and glacial reorganization. The sediment mobilized by these processes is found here to total 120 km3.
This study demonstrates that episodes of meltwater-intensive sedimentation in Pine Island Bay occurred at least three times in the Holocene. The most recent episode coincides with rapid retreat of the grounding line in historical time and has an order of magnitude greater flux relative to the entire unit. We note that the final phase of ice stream retreat in Marguerite Bay was marked by a similar sedimentary event and suggest that the modern Thwaites Glacier is poised for an analogous meltwater-intensive phase of retreat.
... Somewhat in contrast, grain shape has been viewed as an important and often used descriptor in qualitative and quantitative sedimentology (e.g. Barrett, 1980;Boggs, 1967;Blott and Pye, 2008;Dobkins and Folk, 1970;Folk, 1955;Howard, 1992;Krumbein, 1941;Powers, 1953;Mazzullo and Ritter, 1991;Smith and Cheung, 2005;Wadell, 1936). In this study we show the potential advantages of quantifying PSD, particle shape, and mineralogy for a better understanding of deformation processes. ...
Granular material from a fault and a clastic dike in granodiorite at the NW contact of the Hornelen basin has been compared by a new digital image analysis tool to extract size and shape characteristics for individual phases.Particle size distributions measured in both samples are consistent with shear fracturing (D∼3.0–3.2). However, the shape characteristics of the samples are distinct. Granular material from the dike shows no clear shape–size relationship. In contrast, granular material from the fault shows a systematic shape–size relationship (smaller grains being circular and smoother) suggesting a shift in deformation mechanism from intragranular fracturing to abrasion with decreasing grain size. Similarly, field observations, petrography, and the shape and texture of epidote indicate repeated faulting events. Field and textural observations combined with grain size and shape characteristics indicate that the dike sample has a mixed origin. Granulation in fractures connecting to the dike indicates mechanical deformation, while flow structures, texture, grain shape, and high content of epidote in the dike itself suggest that basinal fluids were present.We show that combined size, shape and phase recognition analyses can reveal quantifiable differences in the granular material associated with a fault and a clastic dike, hence allowing us to interpret the distinct origin of these materials.
... Quantitative analysis of digitized grain outlines can be carried out more easily on larger numbers of grains (typically 50 to 500 in published studies) using digital image capture and form analysis techniques such as Fourier and fractal analysis (e.g., Schwartz and Shane 1969;Porter et al. 1979;Mazzullo and Ritter 1991;Pye and Mazzullo 1994;Evangelista et al. 1994;Lee and Osborne 1995;Krinsley et al. 1998). However, such analysis is usually performed on two-dimensional projected grain outlines, which inevitably involve a superimposition of surface textural features which acts to subdue the actual nature of fine surface textural detail and in extreme cases may produce major distortions of the true grain shape. ...
Abstract: Shape and surface texture are fundamental characteristics of sand grains, which have long been used by sedimentologists to provide information about grain provenance, transport pathways, and post-depositional weathering. Hitherto, most work on the gross aspects of grain shape (sphericity, roundness, or angularity) has been undertaken on two-dimensional digitized grain images analyzed by Fourier or fractional methods, or simple shape-factor measurements, and studies of grain surface textures have mainly involved qualitative or semi-quantitative recordings of the relative abundance of a number of discrete surface textural features. Here we describe a new nitrogen gas adsorption technique that can be used to provide information on three dimensional shape and surface texture with very high precision, and to test hypotheses about sediment sources and post-depositional alteration. The method has been tested on a range of sandy sediments from around the world and found to provide a useful quantitative measure of the shape and surface texture of different sediments, provided that strict protocols are observed in sample preparation.
... The CI was calculated as a percentage of well rounded, rounded, and subrounded grains that bear evidence of fresh fractures. Statistical errors related to the grain size (Krinsley and Doornkamp, 1973) and lithology (Szabo and Angle, 1983;Mazzullo and Ritter, 1991) were minimized by using exclusively dark limestones in the 2-4 mm range. ...
Elisebreen, a retreating valley glacier in NW Svalbard, experienced a surge in the past, possibly during the Little Ice Age when ice was thicker and the bed warmer. The surge produced an assemblage of subglacial landforms and sediments now appearing in front of the downwasting ice margin. We have analysed an array of sedimentary properties of basal till from glacial flutings, ploughing marks, an interflute ground moraine, and meandering ridges in order to infer processes of till formation and deformation during the unrecorded surge. Till in flutings and ploughing marks reveals higher mechanical abrasion than in other landforms, but grain size distribution and mineralogy are largely the same everywhere. Micromorphological characteristics are also very similar and comprise ductile and brittle deformation structures, indicating fluctuating porewater pressures. Frequent micrograin fracturing suggests stress concentration along grain bridges during the surge. Till was formed by a combination of lodgement and deformation, caused mainly by clast ploughing. Meandering ridges containing till with water escape structures indicate that surge termination was facilitated by rapid water evacuation from the ice-bed interface through R-type channels. Micromorphological similarity of till found in flutings, ploughing marks, and interflute areas suggests that the resolution of the micromorphological signature is insufficient to constrain the different processes that led to the formation of those landforms.
... Previous workers have invoked specific depositional environments based on sand-grain surface textures (Krinsley and Doornkamp 1973;Mahaney 2002;Chakroun et al. 2009), with most studies focusing on the characteristics of glacial grains (Mahaney and Kalm 1995;Mahaney et al. 1996;Helland and Holmes 1997). However, using surface textures to determine depositional environments is problematic because microtextures may develop during erosion of the source rock (Krinsley and Doornkamp 1973;Mazzullo and Ritter 1991) and during multiple episodes of recycling. Sea glass represents excellent material with which to study the textural and chemical features of single-cycle, silica-rich beach sediment. ...
Chemical and mechanical weathering textures on siliciclastic grains have provided important information concerning depositional processes and environments, yet understanding is limited by the multicycle origin of most sedimentary deposits. Sea glass grains sampled from a beach in Port Allen, Kauai, Hawaii, were analyzed for mechanical and chemical weathering features using scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis, and X-ray photoelectron spectroscopy (X PS). As a result of a proximal dumping-ground source, the sea glass offers a unique opportunity to study first-cycle grain weathering processes in a moderate- to high-energy shoreline environment. Grain-size analysis indicates that the largest grains are located behind natural barriers, such as outcrops and boulders. The best-sorted samples are from the lower to middle foreshore environment, whereas moderately sorted deposits are located closer to the backshore where storm waves predominate. Although there is no preferred distribution of different-colored sea glass grains on the beach, non-frosted grains predominate over frosted varieties, suggesting constant input of fresh material. Grain surface textures can be divided into mechanically dominated and chemically dominated weathering groups. Evidence of mechanical weathering is provided by conchoidal fractures, crescentic gouges, and straight grooves, whereas chemical weathering is indicated by c-shaped cracks, halite (salt) and silica precipitation, and solution pits. Combinations of these features demonstrate that both weathering processes work together to degrade the grains. XPS depth profiling of individual grains indicates that chemical weathering occurs at different grain depths, with leaching of sodium from the glass surfaces. This study provides a rare opportunity to relate grain compositions and textures with depositional and weathering processes, due to the first-cycle origin of the sea glass. The results show that using XPS and SEM techniques is a broadly applicable approach toward unraveling chemical and mechanical breakdown of sediment in beach environments.
... There are limited data published on the analysis of microfeatures and characteristics of striated clasts thought to have a glacial origin (Agassiz 1840; Wentworth 1928; Judson and Barks 1961; Bjørlykke 1974; Hicock and Dreimanis 1989; Helland and Diffendal 1993). The majority of previous research concerning microtextures associated with tills has primarily focused on individual quartz grains (Brown 1973; Krinsley and Doornkamp 1973; Folk 1975; Mahaney et al. 1988 Mahaney et al. , 1991 Mahaney et al. , 2004 Mazzullo and Ritter 1991; Campbell and Thompson 1991; Kalm 1995, 2000; Mahaney 1995; 2002; Strand et al. 2003). Surface textures of quartz grains have been used to determine local ice transport vectors (albeit problematic), ice thickness, and depositional environment. ...
Preliminary research on striated clasts from a variety of depositional environments suggests that scanning electron microscopy (SEM) of striated clasts of varying lithology in diamictons may prove useful in interpreting a glacial origin. Evaluating whether SEM analysis of clasts from diamictons is an applicable technique to define a glacial origin requires a better understanding of the microfeatures occurring on glacial and nonglacial clasts. We describe microtextures and surface characteristics for samples of quartzite, granite, limestone, basalt, chert, pillow basalt, and quartz pebbles collected from a variety of depositional environments. Our study suggests that it is possible to differentiate between glacial and nonglacial deposits based on frequency and morphology of diagnostic surface microfeatures observed on entrained clasts. These microfeatures are best preserved and identified on competent and monomineralic samples (e.g., quartzite, chert, limestone) and poorly preserved on less resistant and polymineralic samples (e.g., basalt and granite).
... Some workers have cited examples of similar SEM microtextures on freshly weathered granitic bedrock fragments and tills (Brown 1973), which gave rise to the principle of equifinality; that is, that different geologic processes might produce similar microfeatures on sand-size clasts. Still other workers have emphasized operator variance (Culver et al. 1983) stressing that different operators may produce different interpretations from observed microfeatures, or that bedrock source is more important than process and depositional environment (Mazzulo & Ritter 1991). SEM microtexture analyses are not limited to the Quaternary Period. ...
Samples of Middle Devonian (Eifelian age; 387–380 Ma) indurated and non-cemented sandstone were compared with Pleistocene basal tills in Estonia and Latvia to test a hypothesis that glacial SEM (scanning electron microscopy) microtextures are distinctly different from those produced in a fluvial depositional environment. The deposits of Middle Devonian Aruküla Stage were emplaced in a continental water basin close to sea level and well away from any glacial source. Therefore, the SEM microtextures on quartz grains from the Aruküla Stage should show mainly the effect of stream transport. The basal tills are of Late Weichselian age deposited as ground moraine directly over the sandstone. Additional glaciofluvial and glaciolacustrine samples were included with the tills to determine whether glacial and fluvial-lacustrine transport could be differentiated by the SEM microtextures. Samples of oriented blocks of till from a limited number of sites were studied without pretreatment to determine whether sand clast orientation could provide a method for determining glacial flow vectors. While there are some microtextural similarities between grains from glacial and glaciofluvial-lacustrine depositional environments, the vast majority of grains from till deposits (50%–60%) are faceted, sharp edged, angular to subangular, and comprised of numerous and distinct microfeatures including abraded surfaces over microfractures, deep linear and curved troughs (striations), step features, and a preponderance of conchoidal and linear microfractures. Glaciofluvial and lacustrine grains contain abundant abrasion features and v-shaped percussion cracks that make them very distinct from glacial grains. Fluvial transport produces primarily rounded grains, well abraded, with v-shaped percussion scars dominating. Thus, it is possible to use microtextural differences between the three sample suites to identify particular depositional environments. Oriented till blocks provide information on sand clast orientation. Although carbonate coatings often obscure sand clasts in untreated blocks, it is possible to determine some microfabric information that can be useful in determining flow direction of the ice.
... The CI index is calculated as the percentage of subrounded, rounded and wellrounded grains with fresh physical breakage zones and sharp edges. Statistical errors related to different granulometry (Krinsley & Doornkamp, 1973) and lithology (Szabo & Angle, 1983; Mazzullo & Ritter, 1991) were minimized by restricting the analysis to quartz grains in the 2–4 mm size range. Crushed grains are found in various environments and they cannot alone be used as an indicator of a specific depositional environment. ...
A multi-proxy approach involving a study of sediment architecture, grain size, grain roundness and crushing index, petrographic and clay mineral composition, till fabric and till micromorphology was applied to infer processes of till formation and deformation under a Weichselian ice sheet at Kurzetnik, Poland. The succession consists of three superposed till units overlying outwash sediments deformed at the top. The textural characteristics of tills vary little throughout the till thickness, whereas structural appearance is diversified including massive and bedded regions. Indicators of intergranular bed deformation include overturned, attenuated folds, boudinage structures, a sediment-mixing zone, grain crushing, microstructural lineations, grain stacking and high fabric strength. Lodgement proxies are grooved intra-till surfaces, ploughing marks and consistently striated clast surfaces. Basal decoupling by pressurized meltwater is indicated by undisturbed sand stringers, sand-filled meltwater scours under pebbles and partly armoured till pellets. It is suggested that the till experienced multiple transitions between lodgement, deformation and basal decoupling. Cumulative strain was high, but the depth of (time-transgressive) deformation much lower (centimetre range) than the entire till thickness (ca 2 m) at any point in time, consistent with the deforming bed mosaic model. Throughout most of ice overriding, porewater pressure was high, in the vicinity of glacier floatation pressure indicating that the substratum, consisting of 11 m thick sand, was unable to drain subglacial meltwater sufficiently.
... Quartz-grain surface-texture relief, scratches, silica overgrowths, V-shaped impact pits, grain angularity and shape were the most diagnostic features (Figs. 4 and 5). Conchoidal fractures (Fig. 5c) were abundant but their significance for depositional interpretation was diminished due to the link with source rock processes detailed by Mazzullo and Ritter (1991). None of the grains examined exhibited the exceptional roundness, surface-frosting and dish-shaped concavities characteristic of aeolian transport. ...
Sediment mineralogy, quartz-grain surface-textures, grain-size analysis, bore-hole logging and ground penetrating radar are combined to develop a three dimensional stratigraphic model of a back-barrier sand island in southeast Queensland, Australia. The island consists of an unconsolidated sedimentary pile above an erosional bounding surface at the top of the underlying bedrock. The stratigraphy is complex, recording the shift in depositional environments from fluvio-deltaic to strandplain, via estuarine stages of evolution. The back-barrier island deposits are correlated with the stratigraphy of the adjacent coastal plain to the west and the barrier island to the east. Extrapolation of optically stimulated luminescence dates obtained from the barrier island combined with direct dating of the back-barrier island sediments is used to constrain the depositional age and chronology of the back-barrier island stratigraphy. The modern depositional environment evolved from a chenier plain into a barrier island system by the flooding of an interdune swale and development of a shore-parallel back-barrier tidal lagoon. The lithological heterogeneity of the back-barrier island succession was controlled by the presence of a bedrock incised palaeovalley and changes in relative sea-level.
... Striations appear to be strongly indicative of glacial processing (Krinsley and Doornkamp, 1973;Bull, 1986). Adhering particles, present in these samples on greater than 50% of the grains, is also characteristic for glacially influenced grains (Krinsley and Doornkamp, 1973;Whalley and Krinsley, 1974;Mazzullo and Ritter, 1991). There is sufficient similarity (1) among the five samples and (2) with reported glacially associated morphology and textures, to infer that all are IRD, transported to the Irminger Basin by glacial ice. ...
Shipboard analysis of the 1183-m sedimentary section recovered at Site 918 in the Irminger Basin during Ocean Drilling Program Leg 152 revealed material of glacial origin (diamictons, ice-rafted debris (IRD) and dropstones) as deep as 543 m below sea floor (bsf). The sediment containing the deepest dropstone was biostratigraphically dated shipboard as approximately 7 Ma, pushing back the date for the onset of glaciation on southern Greenland by 5 Ma. Thin layers of fine sand were found as much as 60 m deeper in the core, raising the possibility of an even earlier date for glaciation. To determine the sedimentary history of these deeper sand layers, the surface textures on quartz grains from eleven cores bracketing the interval of interest were analyzed by scanning electron microscope. The results suggest that the grains in the 60-m interval below the deepest dropstone have a glacial history. At that level, an 11-Ma Sr-isotope date was obtained from planktonic foraminifers. This late Miocene timing is supported biostratigraphically by both nannofossil and foraminifer assemblages, indicating a new minimum age for the onset of glaciation on southern Greenland and in the North Atlantic.
Quartz is regarded as one of the minerals most resistant to chemical weathering. Nevertheless, quartz does weather under certain conditions. Several geographic phenomena, including downstream sorting of fluvial sediments, the distribution of loess, and the absence of silica in tropical soils, may be directly or indirectly related to quartz weathering. Weathering may impact the use of quartz in geographic applications of geochronology and paleoenvironmental analysis. This paper defines the molecular-scale mechanisms of chemical weathering in quartz, and presents the first examination of quartz weathering in the terrestrial environment using high resolution transmission electron microscopy (HRTEM). HRTEM images illustrate crystalline disintegration, or amorphization, of exterior surfaces and internal fractures of quartz sand grains collected from tills of the Eastern Sierra Nevada, California. Of several alternative mechanisms, in situ hydration of the crystalline matrix is the most plausible for quartz amorphization. Scale and mineral structure appear to be prominent factors in quartz amorphization; microenvironment and weathering rates may also be significant, but data are insufficient to make more precise generalizations.
The Himalayan-Tibetan orogen has a great influence on regional and global atmospheric circulation and, hence, it is important for understanding the dynamics of global environmental change. The Kashmir valley, located in the northwestern Himalaya, provides a unique sequence of continuous sedimentary records of unconsolidated sediments of more than a km thickness, dated back to 4 Ma. There are number of studies which suggest episodic and widespread cold conditions, including glaciations, within the Kashmir valley during the Plio-Pleistocene. In order to test the hypothesis of the glacial input into the Kashmir basin, scanning electron microscopy (SEM) was applied to analyze quartz grains of the Karewa deposits stratigraphically for the evidence of their sedimentary history. The microtextures indicate the dominant presence of sustained high stress fractures on the quartz grains with little effect of weathering and dissolution from 4 to 2.1 Ma and from 1.6 to 0.4 Ma. The quartz grains are also angular and of high relief. All these features suggest that these sediments are primarily transported by glaciers and melt water streams. However, the samples ranging in age from 2.1 to 1.7 show a mixed signal (glacial and fluvial) with a dominance of fluvial signal. This transition is attributed to the source area change from the Himalayan range (NE) to the Pir Panjal range (SW) because of the uplift along the Main Boundary Thrust (MBT). Furthermore, we report the first occurrence of a till deposit within the lower part (Dubjan Member 4–3.5 Ma) of the Karewa Group of the Kashmir basin which points to ice advancement in the northwestern Himalaya during the mid-Pliocene. Since, the till occurs in the upper part of the Dubjan Member, therefore, the timing of this glaciation can be restricted to be between 3.7 and 3.5 Ma. Hence, matches well with the mid-Pliocene glaciation that occurred in the Tibetan Plateau (~3.6 Ma) and other parts of the Northern Hemisphere (3.5 Ma).
This represents one of several sections of "A Bibliography Related to Crime Scene Interpretation with Emphases in Geotaphonomic and Forensic Archaeological Field Techniques, Nineteenth Edition" (The complete bibliography is also included at ResearchGate.net.). This is the most recent edition of a bibliography containing resources for multiple areas of crime scene, and particularly outdoor crime scene, investigations. It replaces the prior edition and contains approximately 10,000 additional citations. As an ongoing project, additional references, as encountered, will be added to future editions.
Geological and pedological processes of formation affect the ante-, peri-, and post-deposition of artifacts or evidence. Areas of geotaphonomy such as Stratification, Bioturbation, Compression/Depression, and Sedimentation are fundamentals of geology. An understanding of geological, pedological and hydrological processes must extend beyond the immediate crime scene feature to the surrounding environment. For example, information that a victim’s body was buried near a river ten years ago, is greatly supplemented with an understanding of the effects of soil formation, erosion, and hydraulics in a flood plain environment. The compiler encountered one such scene along the Mississippi River. After a man fishing discovered a skull and other human skeletal elements scattered across an embankment along the river, he reported the find to the local Sheriff. The systematic recovery, and three dimensional documentation of same, illustrated a pattern of distribution in which the remains were carried down the embankment in the direction of of waves that slapped against the shore. As the shore eroded over the years, it exposed and disrupted a historic burial along the river cove. Archaeologically, the distribution of cut iron nails further supported the interpretation of the scene as an eroded historical grave.
Remote sensing and photogrammetric data of topographic, geological, and botanical conditions can be used to reconstruct a history of the search or crime scene environs (See Geophysical/ Remote Sensing Technology and Applications.) Although every site will be unique, there are basic principles of stratification, superposition, and contemporaneous deposition, which have served as tenets of geology and archaeology since the seventeenth century. The impact of burrowing animals, and even earthworms, (Bioturbation), on buried objects is well documented. An awareness of the terrestrial and subterranean fauna inhabiting crime scene environs may be essential in understanding the formation and or disruption of soils containing primary, associated, and trace evidence. For this reason, the reader is directed to “Reconnaissance, Surveys, and Mapping Techniques” for general guides to the types of fauna which might inhabit a particular crime scene area. Likewise, the subsection of "Scavenging" within the section on "Taphonomy" contains references to subterranean animals which directly impact buried evidence and the subterranean feature in which they are contained.
This subsection contains references directly and indirectly addressing soil sciences including the recognition and interpretation of soils in archaeological contexts - geoarchaeology. Of interest, from the standpoint of trace evidence, are those references to cases in which geoarchaeology has been utilized not only to understanding soil formation/alteration related to buried evidence, but in identifying once buried items via trace soil evidence (ie. Adovasio, et al. [1991]). It has been the experience of the compiler that forensic scientists are generally unfamiliar with work accomplished on, and toward the interpretation of, traditional archaeological sites. Most forensic references in forensic geology concentrate on laboratory techniques and analyses, rather than formal archaeological collection of geological and pedological samples/evidence. Therefore, this section occasionally references archaeological site reports, or journal articles, citing specific site interpretations and the techniques used in those interpretations. The reader is also refered to sections such as Stable Isotope Analyses and Shoe, Foot, and Tire Impression Evidence. in as much as soil sampling is necessary for control and comparitive purposes. (2262 citations)
Analyses of microtextures on quartz particles by scanning electron microscope from tills in Antarctica, Germany, southern Ontario, western Wyoming, Tibet, the Austrian Alps, and Mount Kenya show that glacial fracture and abrasion microfeatures may be used to infer the thickness, transport history and ice dynamics of Pleistocene and Holocene glaciers. Relative differences in ice thicknesses, distances of transport, and/or ice dynamics have determined the frequency of occurrence and type of microtextures occurring on sand-size particles. Subparallel fracture microfeatures tend to increase in frequency over a greater proportion of particle surfaces with increasing ice thickness and distance of transport. Conchoidal fractures abound on fragments emplaced by continental ice. Other fracture and fragmentation mechanisms, involve low velocity impacts induced by stick-slip mechanisms, under variable cryostatic stresses, producing fracturing and abrasion across particle surfaces. Implies high local contact stresses associated with high strain rates. -from Author
The scanning electron microscope (SEM) study of microtextures in quartz grains in India is still in infancy and restricted mostly to the placer or beach sediments. SEM study of micromorphology of quartz grains from Late Pleistocene-Holocene sediments in Uttarkashi district, Uttarakhand, has been taken up for understanding the depositional environment. In the Netal section the quartz grain micromorphological studies indicate basal part of a valley glacier environment or remnant glacial lake, as the quartz grains are angular with high silica deposition besides other imprints of glacial origin. In the Shiror section the sediment appears to be part of the glacial till. The present study provides a new approach to the much needed palaeoenvironmental evaluation of the Himalayan Quaternary sediments on a nanoscale.
The Kamouraska Formation is a quartz-arenitic unit of latest Cambrian – earliest Ordovician age in the Quebec Appalachians that was deposited by hyperconcentrated to concentrated density flows in a meandering submarine canyon on the continental slope bordering the Iapetus Ocean, as outlined in a companion paper. Detailed petrographic study of the quartz arenites of the Kamouraska Formation combined with scanning electron microscopy of grain surface textures suggests that the quartz sands are of eolian origin having been derived from an inland desert or, less likely, a barrier beach dune system. Transport of the mature quartz-arenitic sand onto the shelf and deposition into the deep sea was not accompanied by substantial mixing with material from other sources thus preserving the inherited eolian characteristics. A modern analogue for the eolian interpretation of the deep-sea quartz-arenite beds is as follows: thick, Late Pleistocene eolian sand beds on a modern abyssal plain in the East Atlantic referred to as eolian-sand turbidites that were deposited in the deep sea during glacial sea level lowstands when eolian sand transport to canyon heads was enabled by an exposed and shortened shelf. Similarly, an established sea level lowstand at the Cambro–Ordovician boundary would have facilitated the introduction of eolian sand of the Kamouraska Foundation into canyon heads on the upper slope from where turbidity currents and related density flows were triggered. Correlation of the Kamouraska Formation with the quartz arenites of the Cairnside Formation of Quebec (Keeseville Formation in northern New York State, Nepean Formation in southern Ontario) links the deep-sea deposits with remnants of an inland dune system.
This article is concerned with the changes that erosion and transport have on the properties of sediment as it moves through a dispersal system, which point to the processes responsible for its dispersal, and the ways in which the characteristics imparted to sediment in the source area by parent lithology and climate can be used to indicate its spatial origin (provenance). Examples are provided of the changes to particle size and shape that have been observed to occur during transport by water, wind and ice, and of the different approaches used to ascribe provenance that rely on conservative physical and chemical properties. These include mineral, stable and radioactive isotope, major and trace element compositions and environmental magnetism. The different uses to which such data have been put and the range of scales at which provenance studies have been conducted are illustrated using examples drawn from investigations conducted in marine, fluvial and lacustrine settings.
While most research on quartz weathering has focused primarily on surface textures and morphologies, very little is known about the internal weathering of quartz. This study demonstrates that internal weathering is ubiquitous in quartz. Internal weathering is measured in terms of porosity, which represents mass loss from the quartz grain, hence silica lost through dissolution. Mass loss calculated from porosity suggests higher-than-expected rates of quartz dissolution in the terrestrial environment. Internal weathering occurs through various grain defects, and is classified into several forms (in decreasing order of frequency): fractures, enlarged grain boundaries, holes, and networks. These features may be distinguished from occasional artifact voids left by laboratory procedures. The most intensely weathered grains exhibit large fractures and extensive networks, and occasionally contain secondary weathering products within the void areas. The presence of internal weathering in quartz supports field and laboratory observations of particle comminution in sediment transport systems, and can account for at least part of the production of silt- and clay-sized quartz. Given the potentially large surface area afforded by these internal defects, internal weathering plays an important role in the generation of quartz particles and dissolved silica, and presents a new avenue of study for the generation of secondary porosity in detrital sediments. [Key words: geomorphology, quartz, silica, weathering.]
Geomorphological and sedimentological analysis of aeolian deposits, combined with scanning electron microscopy (SEM) of quartz-grain surface characteristics, suggest six dune-building episodes during late Quaternary time in the southern Mojave Desert, California. The aeolian units accumulated largely in response to the lowering of water levels in lake basins and a consequent increase in fine sediment availability, and to stronger and more persistent winds, associated with rapidly changing environmental conditions. Peak dune deposition is believed to have taken place during the middle Holocene Altithermal between around 7.5 and 5 ka, a period characterized by greater aridity than the present. SEM analysis of the quartz surface textures indicates that mechanical and especially chemical weathering processes play a significant role in the post-depositional modification of aeolian sediments. Such evidence permits paleoenvironmental reconstruction during and since deposition, and a basis for the relative dating of aeolian sequences. Discriminant analysis using grain-size parameters, combined with principal components analysis of the SEM data from quartz-grain surfaces, is an effective analytical tool for distinguishing between spatially and temporally distributed aeolian deposits. [Key words: aeolian geomorphology, granulometry, quartz grain surface microfeatures, scanning electron microscopy, multivariate statistical analysis.]
Mineralogical, textural, geochemical, and weathering characteristics of loess deposits in Golestan province of Iran suggest that they are mostly derived from felsic igneous rocks and are related to Quaternary palaeoclimate. Whole-rock analyses indicate heavy minerals such as zircon, tourmaline and phyllosillicate minerals (e.g. muscovite, chlorite, illite) exert a significant control on the chemical composition. The loess samples display uniform chemical composition, indicative of similar alteration history. Chemical index of alteration suggests a weak to moderate degree of weathering in a felsic source area. Scanning electron micrographs of quartz grains reveal abundant silt-sized quartz particles, a result of glacial grinding during the Late Pleistocene in Central Asia. Subsequently, these silt particles were transported from Central Asia to their depositional site by wind and paraglacial processes. Local topography of northeast Iran (Alborz Mountains) acted as a major barrier, entrapping the airborne particles on the plains of Golestan province. Copyright © 2012 John Wiley & Sons, Ltd.
Scanning electron microscopic imagery is often used to identify and discriminate among environments of sedimentation with the main aim of identifying individual microfeatures, or suites of microtextures, that are considered indicative of a particular depositional environment or geologic process. Because few microtextures are considered to represent a single geologic process it is necessary to analyze a large number of quartz sands and other mineralic grains with the objective of determining the frequency of occurrence of a range of microtextures within a distinct sample suite. Using percent frequency of occurrence of different microtextures from suites of fluvial, glaciofluvial and glacial sands from sites in Estonia and Latvia, we invoked statistical comparison of different sample suites using Euclidean distances. These provide a quantitative means of measuring the differences among different sediments and processes that formed them and also a quantification tool useful
Samples of sediments from beneath Ice Stream B (at camp UpB), West Antarctica, provide the first opportunity to study the relationship between sediment properties and physical conditions in a sub-ice-stream environment. Piston coring in holes bored by hot-water drilling yielded five 1-3 m long, undisturbed subglacial sediment cores. We analyzed granulometry, composition, and particle morphology in these cores. The UpB cores are composed of a clay-rich, unsorted diamicton containing rare marine diatoms. Sedimentary particles in these cores bear no evidence of the recent crushing or abrasion that is common in other subglacial sedimentary environments. The presence of reworked diatoms and their state of preservation, as well as the relative spatial homogeneity of this diamicton, suggest that the UpB cores sampled a several-meter-thick till layer and not in situ glacimarine sediments. The till does incorporate material recycled from the subjacent poorly indurated Tertiary glacimarine sediments of the Ross Sea sedimentary basin, which extends beneath this part of the West Antarctic Ice Sheet. We propose that the lack of significant comminution in the UpB till is ultimately due to its setting over these easily erodible, clayrich source sediments. The resulting fine-grained till matrix inhibits glacial comminution, because it facilitates buildup of high pore-water pressures and hinders interparticle stress concentrations. Our observations are consistent with the conjecture that subglacial deformation of weak, fine-grained tills does not produce significant comminution of till debris (Elson 1988). Based on our findings, we hypothesize that extensive layers of weak till may develop preferentially where ice overrides preexisting, poorly indurated, fine-grained sediments. Since such weak till layers create a permissive condition for ice streaming, subglacial geology may have an indirect but strong control over the location, extent, and basal mechanics of ice streams.
Scanning electron microcopy (SEM) and energy-dispersive X-ray (EDX) microanalysis are powerful techniques for forensic and wider environmental analysis of a range of materials, including rocks, sediments, soils and dusts. Methods of analysis have evolved rapidly over the past 40 years and computer-controlled, variable pressure SEMs with integrated EDX now provide the opportunity for rapid, automated analysis of large numbers of samples and particulates within individual samples. However, interpretation of the data requires care and experience on the part of the operator, and samples should always be checked by visual inspection. Early SEM work on rocks and sediments mainly used the secondary electron (SE) mode to produce topographical contrast on rough surfaces, but more recent studies have utilized the capacity of backscattered electron (BSE) imaging to image both topographical and atomic number contrast. BSE microscopy, combined with X-ray mapping, provides a rapid means of locating unusual particles and grain coatings, and of mapping their distribution, which may be of diagnostic or discriminatory importance. In the past, much attention has been given to grain surface textural features (mainly of quartz) but many such studies have suffered from a high degree of subjectivity, poor reproducibility, lack of discriminatory power, and high cost both in terms of time and money. The application of digital imaging and statistical data-processing techniques can to some extent reduce these problems but, in general, chemical characterization of particles offers a more powerful approach. This paper provides an overview of these techniques, discusses their limitations and illustrates some of the forensic and wider environmental applications.
Quartz is regarded as one of the minerals most resistant to chemical weathering. Nevertheless, quartz does weather under certain conditions. Several geographic phenomena, including downstream sorting of fluvial sediments, the distribution of loess, and the absence of silica in tropical soils, may be directly or indirectly related to quartz weathering. Weathering may impact the use of quartz in geographic applications of geochronology and paleoenvironmental analysis. This paper defines the molecular-scale mechanisms of chemical weathering in quartz, and presents the first examination of quartz weathering in the terrestrial environment using high resolution transmission electron microscopy (HRTEM). HRTEM images illustrate crystalline disintegration, or amorphization, of exterior surfaces and internal fractures of quartz sand grains collected from tills of the Eastern Sierra Nevada, California. Of several alternative mechanisms, in situ hydration of the crystalline matrix is the most plausible for quartz amorphization. Scale and mineral structure appear to be prominent factors in quartz amorphization; microenvironment and weathering rates may also be significant, but data are insufficient to make more precise generalizations.
Climatic interpretations of the upper Paleozoic (Permo-Pennsylvanian) Fountain Formation, a coarse-grained fan-delta system that formed in western equatorial Pangea, are difficult to constrain owing to a general lack of climatic indicators so typical of coarse clastic systems. We applied scanning electron microscopy (SEM) to analyze quartz grains in this system in an attempt to test the hypothesis of a glacial influence on these strata. SEM observations of first-cycle quartz grains from these strata reveal microtextures formed from fracturing during grain transport, even after diagenetic overprinting occurred under moderate burial conditions (up to 3.5 km depth and 100uC). Transport-induced microtextures can be grouped based on inferred fracture process into: (1) high-stress fractures, consisting of fractures created through sustained high shear stress, such as grooves, deep troughs, and gouges, and are inferred to occur predominantly during glacial transport; (2) percussion fractures, consisting of fractures created by grain-to-grain contact during saltation or traction flow, such as randomly oriented v-shaped cracks and edge rounding; and (3) polygenetic fractures, such as conchoidal fractures, arc-shaped steps, linear steps, and linear fractures, that occur under a wide range of transport processes and thus possess no environmental significance. Delineation of high stress, percussion, and polygenetic fracture types demonstrate that the Fountain Formation quartz grains exhibit microtextures similar to both till and glaciofluvial deposits, suggesting that periods of upland glaciation occurred in the source region of the Fountain Formation (Ute Pass uplift). The abundance of high-stress fractures peaks at two stratigraphic intervals. These intervals are inferred to record the presence of ice in the Ute Pass uplift and are correlative with polygonally fractured paleosurfaces in the Fountain Formation that are interpreted to reflect cold-temperature weathering. Moreover, the peak intervals are approximately coeval with inferred episodes of ice maxima from high-latitude localities, as well as other low-latitude localities. Geologically reasonable stream gradients and estimated transport distance suggest a best-estimate elevation of the ice terminus of , 1500 m, but possibly ranging to 3000 m. These data suggest that upland glaciers episodically existed within this equatorial setting and that further use of this technique may reveal more evidence of ice in other proximal deposits of the ancestral Rocky Mountains, as well as other systems of various geologic ages.
Recent analyses of microtextures on quartz particles (63–2000 μm) from Quaternary tills in Antarctica, Germany, southern Ontario, western Wyoming, Tibet, the Austrian Alps, and Mount Kenya show that glacial fracture and abrasion microfeatures may be used to infer the thickness, transport history and ice dynamics of Pleistocene and Holocene glaciers. Quartz sands emplaced by continental and mountain ice were studied by SEM after transport over variable distances in glaciers estimated to range from 150 m to 1500 m in thickness. Relative differences in ice thicknesses, distances of transport, and/or ice dynamics appear to have determined the frequency of occurrence and type of microtextures occurring on sand-size particles. Subparallel fracture microfeatures tend to increase in frequency over a greater proportion of particle surfaces with increasing ice thickness and distance of transport. Conchoidal fractures, the most typical in quartz, and to some degree crescentic gouges abound on fragments emplaced by continental ice. Other possible fracture and fragmentation mechanisms, producing features of generally glacial origin, involve low velocity impacts induced by stick-slip mechanisms, under variable cryostatic stresses, producing fracturing and abrasion across particle surfaces. Their generation implies high local contact stresses associated with high strain rates.
Traditional views have attributed the formation of loess-sized quartz silt particles to glacial processes. Glacial grinding was considered to be the only mechanism capable of producing loessic silt in the quantities necessary for the formation of loess deposits. This idea has been strengthened by the apparent close association between present or former glacierised regions and major global loess deposits. However, some doubts exist as to whether or not glacial grinding is capable of producing sufficient quantities of quartz silt. Because of the difficulties entailed in the observations and direct measurement of subglacial abrasion and crushing, this paper describes and discusses the results of a simulation study designed to examine abrasion and size reduction of quartz grains under “grinding” conditions analogous to those experienced in a subglacial environment. The findings from these experimental runs suggest that, although particle breakage and comminution does occur, little silt-sized material is actually produced. The amount of silt produced ranges from approximately 9% of the original sample in one experimental run to less than 1% for the other seven runs. It is suggested that the results obtained may show considerably less abrasion and loessic silt production than may be expected to occur within a natural subglacial environment because: (1) subglacial grains experience much greater overburden pressures for much longer periods of time; (2) the use of sand-sized grains may represent a stable component resistant to further size reduction through crushing or abrasion; and (3) the use of a monomineralic sample of relatively sound quartz grains. Although care must be taken when relating results obtained from these experimental runs to silt production within a glacial environment, findings from this work do question whether large amounts of quartz silts are produced within subglacial environments. The importance of glacial processes in the formation of loess deposits may lie in the reworking of pre-existing sediments by ice rather than the actual production of vast quantities of silt. This in turn suggests that care should be taken in the interpretation of the provenance of particles comprising loess deposits.
A portable and reusable special core liner (spcl) has been developed to accomplish real-time sub-sampling of aqueous sediments. Besides being revolutionary, inexpensive and user-friendly, the spcl is capable of collecting undisturbed sediment sub-sections. The spcl also facilitates rapid sub-sampling of sediments onboard with remote possibility of core shortening, sample outflow, contamination or mixing. The proposed method of sub-sampling by spcl saves time, money and manpower, without inducing changes in the physical and biogeochemical properties of the sediments.
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