Carbonaceous Remains Research Articles

Fossil Biomarkers and Biosignatures Preserved in Coprolites Reveal Carnivorous Diets in the Carboniferous Mazon Creek Ecosystem.

Simple SummaryCoprolites (fossilised faeces) can preserve important dietary information through geological time, offering insights into extinct animal diets. When digestion of dietary items leaves no unambiguous morphology to reconstruct the food spectrum of a coprolite producer, preserved biomolecular information can offer unique perspectives into the individual dietary composition and trophic relationships in ancient ecosystems. In this study we combine a uniquely diverse array of chemical techniques to demonstrate that biomarkers and macromolecular biosignatures from Carboniferous coprolites can reveal the dietary spectrum and trophic position of their extinct producers: an overwhelming abundance of cholesteroids, biomarkers of animal cholesterol, and an animal-affinity of the preserved macromolecular phase revealed by the statistical analysis of in situ Raman spectra, indicate a likely carnivorous diet for the coprolite producer. The presence of intact primary metabolites, such as sterols, and informative fossilization products of biopolymers, demonstrates the significance of siderite (iron carbonate) concretions in the exceptional preservation of biomolecular information in deep time, facilitated by the rapid encapsulation and remineralisation of organic matter within days to months.The reconstruction of ancient trophic networks is pivotal to our understanding of ecosystem function and change through time. However, inferring dietary relationships in enigmatic ecosystems dominated by organisms without modern analogues, such as the Carboniferous Mazon Creek fauna, has previously been considered challenging: preserved coprolites often do not retain sufficient morphology to identify the dietary composition. Here, we analysed n = 3 Mazon Creek coprolites in concretions for dietary signals in preserved biomarkers, stable carbon isotope data, and macromolecular composition. Cholesteroids, metazoan markers of cholesterol, show an increased abundance in the sampled coprolites (86 to 99% of the total steranes) compared to the surrounding sediment, indicating an endogenous nature of preserved organics. Presence of unaltered 5α-cholestan-3β-ol and coprostanol underline the exceptional molecular preservation of the coprolites, and reveal a carnivorous diet for the coprolite producer. Statistical analyses of in situ Raman spectra targeting coprolite carbonaceous remains support a metazoan affinity of the digested fossil remains, and suggest a high trophic level for the coprolite producer. These currently oldest, intact dietary stanols, combined with exquisitely preserved macromolecular biosignatures in Carboniferous fossils offer a novel source of trophic information. Molecular and biosignature preservation is facilitated by rapid sedimentary encapsulation of the coprolites within days to months after egestion.

Spinicaudatans from the Yixian Formation (Lower Cretaceous) and the Daohugou Beds (Jurassic) of Western Liaoning, China

The Jehol and Yanliao Biota constitute two world-famous Mesozoic lacustrine Konservat Lagerstätten. In contrast to numerous comparative studies on their different fossil assemblages, their taphonomic features have rarely been compared. Here we investigate the diagenetic pathways of spinicaudatans from the Lower Cretaceous Yixian Formation and the Jurassic Daohugou Beds to figure out whether they are similar. The specimens were categorized into eight types based on the colors of the carapaces and the characteristics of the surrounding matrix and subsequently were studied under the scanning electron microscope (SEM) and energy dispersive X-ray spectrometer (EDS). Spinicaudatan carapaces from the Yixian Formation are phosphatized lacking any traces of organic remains, whereas those from the Daohugou Beds contain a mineralized layer and a carbonaceous layer. Phosphatization apparently was a common taphonomic pathway of spinicaudatan carapaces in the Yixian Formation, while in the Daohugou Beds carbonaceous remains, probably the diagenetic products of chitin, are common. This suggests that the taphonomic environment and water chemistry, to which the Jehol and Yanliao Biota were subjected, differed.

New Data on Vegetation and Climate Reconstruction in the Baikal-Patom Highland (Eastern Siberia) in the Last Glacial Maximum and Early Holocene

The first results of anthracological investigation for Eastern Siberia on the carbonaceous remains of woody and shrubby plants at the archaeological sites Kovrizhka III and IV in the lower reaches of the Vitim River are presented. The results of anthracological studies enabled us to obtain new data on changes in vegetation and climate along the lower reaches of the Vitim River. As a result, new data on human habitation in the lower reaches of the Vitim River in the last glacial maximum and early Holocene were obtained.

Sulfur isotope's signal of nanopyrites enclosed in 2.7 Ga stromatolitic organic remains reveal microbial sulfate reduction.

Microbial sulfate reduction (MSR) is thought to have operated very early on Earth and is often invoked to explain the occurrence of sedimentary sulfides in the rock record. Sedimentary sulfides can also form from sulfides produced abiotically during late diagenesis or metamorphism. As both biotic and abiotic processes contribute to the bulk of sedimentary sulfides, tracing back the original microbial signature from the earliest Earth record is challenging. We present in situ sulfur isotope data from nanopyrites occurring in carbonaceous remains lining the domical shape of stromatolite knobs of the 2.7-Gyr-old Tumbiana Formation (Western Australia). The analyzed nanopyrites show a large range of δ34 S values of about 84‰ (from -33.7‰ to +50.4‰). The recognition that a large δ34 S range of 80‰ is found in individual carbonaceous-rich layers support the interpretation that the nanopyrites were formed in microbial mats through MSR by a Rayleigh distillation process during early diagenesis. An active microbial cycling of sulfur during formation of the stromatolite may have facilitated the mixing of different sulfur pools (atmospheric and hydrothermal) and explain the weak mass independent signature (MIF-S) recorded in the Tumbiana Formation. These results confirm that MSR participated actively to the biogeochemical cycling of sulfur during the Neoarchean and support previous models suggesting anaerobic oxidation of methane using sulfate in the Tumbiana environment.

ЛІТОЛОГО-ФАЦІАЛЬНІ ПЕРЕДУМОВИ ФОРМУВАННЯ НОВОУТВОРЕНИХ ТЕХНОГЕННИХ КОЛЕКТОРІВ ЛЬВІВСЬКО-ВОЛИНСЬКОГО ВУГЛЕГАЗОВОГО БАСЕЙНУ

The studies conducted have revealed possible litho-facies composition of the man-made reservoirs in the coal seams mined out within the gas-bearing Lviv-Volyn coal basin where sedimentary rocks of the Lower Carboniferous, Tournaisian, Visean, Serpukhovian and lower part of Middle Carboniferous formations occur. They are represented by crushed shales, siltstones, sandstones, limestones and carbonaceous remains in the of the coal rock sequence.Conglomerates and gravelstones make only 0.25% of coal-bearing formation to form thin (0.2-1.5, occasionally to 3-4 meters) lenses.Gravel sandstones have a limited distribution, making lenses and interbeds of 0.5-1.5 m thick.The sandstones are composed by fine-, medium- and coarse-grained types.Siltstones are of dark gray color, often caused by clay and carbonaceous minerals.The most typical shales are composed by finely dispersed material with silty admixture, limited carbonaceous and calcareous varieties. Their dark, mostly gray color is due to the presence of humus or sapropel material.Limestones are grey, dark grey, sometimes with a brown tint; they are usually fine- or medium crystalline, often with re-crystallized areas.Coal is mostly of humus type, the sapropel occurs occasionally in the form of interbeds, mainly in the top and bottom humic layers. Coal is dense, viscous, black and black and gray in color.The core set of the coal rock massif taken from well #7427, located in the northern part of the Lubel coal field, is well represented in the geological section.The upper alluvial-limnic-swampy-lagoonal coal-bearing sub-formation (middle part) consists of four litho-cycles of the higher order (first one is a lagoon-marine transgressive; the second one is a marine-lagoon regressive; the third one is an uniformly lagoonal, and fourth one is a lagoon-marine transgressive cycle) with one another of lower order, the open marine cycle.

Burgess Shale-type Preservation and its Distribution in Space and Time

Burgess Shale-type fossil assemblages provide a unique record of animal life in the immediate aftermath of the so-called “Cambrian explosion.” While most soft-bodied faunas in the rock record were conserved by mineral replication of soft tissues, Burgess Shale-type preservation involved the conservation of whole assemblages of soft-bodied animals as primary carbonaceous remains, often preserved in extraordinary anatomical detail. Burgess Shale-type preservation resulted from a combination of influences operating at both local and global scales that acted to drastically slow microbial degradation in the early burial environment, resulting in incomplete decomposition and the conservation of soft-bodied animals, many of which are otherwise unknown from the fossil record. While Burgess Shale-type fossil assemblages are primarily restricted to early and middle Cambrian strata (Series 2–3), their anomalous preservation is a pervasive phenomenon that occurs widely in mudstone successions deposited on multiple paleocontinents. Herein, circumstances that led to the preservation of Burgess Shale-type fossils in Cambrian strata worldwide are reviewed. A three-tiered rank classification of the more than 50 Burgess Shale-type deposits now known is proposed and is used to consider the hierarchy of controls that regulated the operation of Burgess Shale-type preservation in space and time, ultimately determining the total number of preserved taxa and the fidelity of preservation in each deposit. While Burgess Shale-type preservation is a unique taphonomic mode that ultimately was regulated by the influence of global seawater chemistry upon the early diagenetic environment, physical depositional (biostratinomic) controls are shown to have been critical in determining the total number of taxa preserved in fossil assemblages, and hence, in regulating many of the important differences among Burgess Shale-type deposits.

Megascopic carbonaceous compression fossils from the Neoproterozoic Bhima Basin, Karnataka, South India

Abstract An abundant well-preserved assemblage of annulated carbonaceous compressions and impressions has been recorded from the intra-cratonic argillaceous sedimentary sequence of the Bhima basin in south India. Impressions and carbonaceous compressions recorded in the Hulkal Formation belong to annulated forms similar to the previously reported Sinosabellidites huainanensis , Protoarenicola baiguashanensis and Pararenicola huaiyuanensis from China. This paper discusses the diversity, systematics, affinity, biostratigraphical potential and global significance of these remains. The previously proposed worm-like body fossil affinity for these organisms, based on similarity with the Chinese assemblage, has been reinterpreted as with pre-Ediacaran epibenthic organisms. Fresh investigations of the Indian assemblage of such specimens reveal their close proximity to the algal affinity. The occurrence of global marker events, such as phosphatization, the presence of complicated annulated carbonaceous remains in the Hulkal Formation and the absence of stromatolites in the carbonate sequences of the Bhima basin, collectively indicate a Neoproterozoic, possibly pre-Sturtian age for the Bhima Group.

CHARGE CONTRAST IMAGING OF EXCEPTIONALLY‐PRESERVED FOSSILS

Abstract: Charge contrast images are a variant of secondary electron images acquired by operating a variable pressure scanning electron microscope in low vacuum mode; i.e. a gas is present in the specimen chamber. Spatial variation in the amount of charge that accumulates on the surface of the specimen is expressed as differences in greyscale tone; areas that are charging less are darker in tone. The precise mechanisms by which charge contrast images are generated are not known fully. Various different properties of a mineral may create a charge contrast; electrical conductivity is known to be one potentially important variable. As carbon is highly conductive but typical host lithologies (carbonates, silicates) less so or dielectric, the technique is potentially very suitable for imaging organically preserved fossils such as those from the Solite and Jehol biotas. It can also be applied to Burgess Shale fossils: complex films comprising ‘aluminosilicates’ with or without carbonaceous remains. Charge contrast images reveal anatomical detail not visible using either optical or other scanning electron microscope‐based imaging methods.

NanoSIMS: Insights to biogenicity and syngeneity of Archaean carbonaceous structures

NanoSIMS is a relatively new technology that is being applied to ancient carbonaceous structures to gain insight into their biogenicity and syngeneity. NanoSIMS studies of well preserved organic microfossils from the Neoproterozoic (∼0.8 Ga) Bitter Springs Formation have established elemental distributions in undisputedly biogenic structures. Results demonstrate that sub-micron scale maps of metabolically important elements (carbon [C], nitrogen [measured as CN ion], and sulfur [S]) can be correlated with kerogenous structures identified by optical microscopy. Spatial distributions of C, CN, and S in individual microfossils are nearly identical, and variations in concentrations of these elements parallel one another. In elemental maps, C, CN, and S appear as globules, aligned to form remnant walls or sheaths of fossiliferous structures. The aligned character and parallel variation of C and CN are the strongest indicators of biogenicity. Nitrogen/carbon atomic ratios (N/C) of spheroids, filaments, and remnants of a microbial mat suggest that N/C may reflect original biochemical differences, within samples of the same age and degree of alteration. Silicon (Si) and oxygen (O) maps illustrate that silica is intimately interspersed with organic carbon of the microfossils. This relationship is likely to reflect the process of silica permineralization of biological remains and thus may be an indicator of syngeneity of the fossilized material with the mineral matrix. The NanoSIMS characterization of Bitter Springs microfossils can be used as a baseline for interpreting less well preserved carbonaceous structures that might occur in older or even extraterrestrial materials. An example of such an application is provided by comparison of Bitter Springs results with NanoSIMS of Archaean carbonaceous structures from Western Australia, including a spheroid in the ∼3 Ga Farrel Quartzite and material in a secondary vein in the 3.43 Ga Strelley Pool Chert. Results reinforce a biogenic, syngenetic interpretation for the Archaean spheroid. NanoSIMS has several advantages in the study of ancient organic materials: the technique allows characterization of extremely small structures that are present in low concentrations; organic matter does not have to be isolated by acid treatment but can be analyzed in polished thin section; preparation is simple; samples are minimally altered during analysis; results provide sub-micron scale spatial distribution coupled with concentration information for at least five elements; the biologically important elements of carbon and nitrogen can be assessed; and the ability to study organic remains in situ permits petrographic assessment of spatial relationships between organic matter and mineral constituents. These advantages could be of significant benefit for interpretation of poorly preserved and fragmentary carbonaceous remains that might occur in some of Earth's oldest samples as well as in meteorites or extraterrestrial material brought to Earth in future planetary missions.

First non-calcified dasycladalean alga from the Carboniferous

A non-calcified dasycladalean alga is described from the Mississippian of Scotland. This occurrence constitutes the first Carboniferous record of non-calcified dasyclads. The fossils are preserved as carbonaceous remains within siderite nodules. Preservation of their delicate structure suggests that the algae were preserved in situ or experienced minimal transport from life habitat. Associated fauna include small adult shells of the bivalve Naiadites obesus, palaeoniscid fish and a distinctive tooth of the shark Ageleodus pectinatus. The presence of these algae provides further evidence that some of the Strathclyde Group sediments of the Midland Valley of Scotland were deposited in relatively shallow water marine conditions.

Carbonaceous cherts of the Barberton Greenstone Belt, South Africa: Isotopic, chemical and structural characteristics of individual microstructures

Carbonaceous matter occurring in chert deposits of the 3.4–3.2 Ga old Barberton Greenstone Belt (BGB), South Africa, has experienced low grade regional metamorphism and variable degrees of local hydrothermal alteration. Here a detailed study is presented of in situ analysis of carbonaceous particles by LRS (laser Raman spectroscopy) and SIMS (secondary ion mass spectrometry), reporting degree of structural disorder, carbon isotope ratio and nitrogen-to-carbon ratio. This combination of in situ analytical tools is used to interpret the δ 13C values of only the best preserved carbonaceous remains, enabling the rejection of non-indigenous (unmetamorphosed) material as well as the exclusion of strongly hydrothermally altered carbonaceous particles. Raman spectroscopy confirmed that all carbonaceous cherts studied here have experienced a regional sub- to lower-greenschist facies metamorphic event. Although this identifies these organics as indigenous to the cherts, it is inferred from petrographic observations that hydrothermal alteration has caused small scale migration and re-deposition of organics. This suggest that morphological interpretation of these carbonaceous particles, and in general of putative microfossils or microlaminae in hydrothermally altered early Archean cherts, should be made with caution. A chert in the Hooggenoeg Formation, which is older than and has been hydrothermally altered by a volcanic event 3445 Ma ago, contains strongly altered carbonaceous particles with a uniform N/C-ratio of 0.001 and a range of δ 13C that is shifted from its original value. Cherts of the Kromberg Formation post-date this volcanic event, and contain carbonaceous particles with a N/C-ratio between 0.002 and 0.006. Both the Buck Reef Chert and the Footbridge Chert of the Kromberg Formation have retained fairly well-preserved δ 13C values, with ranges from −34‰ to −24‰ and −40‰ to −32 ‰, respectively. Abiologic reactions associated with hydrothermal serpentinization of ultramafic crust (such as Fischer–Tropsch synthesis) were an unlikely source for carbonaceous material in these cherts. The carbonaceous matter in these cherts has all the characteristics of metamorphosed biologic material.

Proterozoic carbonaceous remains from the Chorhat Sandstone: oldest fossils of the Vindhyan Supergroup, Central India

According to new radiometric determinations, the Chorhat Sandstone (Kheinjua Formation, Semri Group) is much older (1628 and 1632 Ma) than previously thought. This makes the carbonaceous fossils here described not only the oldest, but also the only reliably dated fossil record of the Vindhyan Supergroup, India. The new fossils represent a Chuaria-Tawuia assemblage with other carbonaceous remains of uncertain biologic affinities. Their size range (0.02–3.5 mm) indicates a transitional phase in the evolution from micro- to mega scopic organisms. Alternatively, low oxygen levels may have induced small size.

Landscape-level seagrass–sediment relations in a coastal lagoon

We investigated the relationships between sediment (subaqueous soil) properties and eelgrass ( Zostera marina L.) distribution to develop landscape-level soil-based strategies for choosing eelgrass restoration locations. Subaqueous soils were sampled and eelgrass cover determined for 14 soil-landscape units within a 116 ha area of Ninigret Pond, a coastal lagoon in Rhode Island, USA. Of the 14 soil-landscape units sampled for eelgrass cover, 52% had virtually no eelgrass cover (<10%), while 18% had high eelgrass cover (>90%). The Lagoon Bottom, Shallow Lagoon Bottom, Flood-tidal Delta Slope, and Barrier Cove subaqueous soil-landscape units had the highest eelgrass cover (66–100%). A weak relationship between eelgrass cover and water depths ( r 2 = 0.10) was observed suggesting that properties other than water depth may also control eelgrass distribution. Subaqueous soils on landscapes with >60% eelgrass cover had relatively high levels of acid-volatile sulfides (>90 μg/g), high soil salinity levels (34–44 ppt), fine textures (silt loam), and relatively high total nitrogen levels (>0.15%). Four principal components accounted for 81% of the variability in eelgrass cover. The first component reflected particle-size distribution (i.e. sand, silt, and clay contents) effects and accounted for 43% of the variability. The other components suggested that eelgrass cover is correlated to carbonaceous remains, non-calcareous rock fragments and soil salinity. These data suggest that the current distribution of eelgrass within the study area is strongly influenced by physical and chemical subaqueous soil characteristics. Soil survey techniques proved useful for the delineation of sediment characteristics (e.g. texture, salinity) that influence eelgrass distribution patterns at landscape-level scales.

The Proterozoic biosphere: a multidisciplinary study

List of contributors Preface Part I: 1. Geology and paleobiology of the Archean Earth 2. Geological evolution of the Proterozoic Earth 3. Proterozoic biochemistry 4. Proterozoic atmosphere and ocean 5. Proterozoic and selected early Cambrian microfossils: prokaryotes and protists 6. Modern mat-building microbial communities: a key to the interpretation of Proterozoic stromatolitic communities 7. Proterozoic and earliest Cambrian carbonaceous remains, trace and body fossils 8. The Proterozoic-early Cambrian evolution of metaphytes and metazoans 9. Molecular phylogenetics, molecular paleontologym and the Proterozoic fossil record 10. Biostratigraphy and paleobiology of the Proterozoic 11. Biotic diversity and rates of evolution during Proterozoic and earliest Phanerozoic time 12. A paleogeographic model for Vendian and Cambrian time 13. Evolution of the Proterozoic biosphere: benchmarks, tempo and mode Part II: 14. Geographic and geologic data for PPRG rock samples 15. Flow chart and processing procedures for rock samples 16. Procedures of whole rock and kerogen analysis 17. Abundances and isotopic compositions of carbon and sulphur species in whole rock and kerogen samples 18. Procedures for analysis of extractable organic matter 19. Composition of extractable organic matter 20. Modern mat-building microbial communities: methods of investigation and supporting data 21. Construction and use of geological, geochemical and paleobiological databases 22. Proterozoic and selected early Cambrian microfossils and microfossil-like objects 23. Described taxa of Proterozoic and selected earliest Cambrian Carbonaceous remains, trace and body fossils 24. Atlas of representative Proterozoic microfossils 25. Informal revised classifications of Proterozoic microfossils 26. Models for Vendian-Cambrian biotic diversity and for Proterozoic atmospheric and ocean chemistry 27. Glossary of technical terms References cited Subject index Index to geologic units Taxonomic index.

UPb zircon dating of volcanic rocks, close to the Silurian-Devonian boundary, from Vendée (western France)

The detrital volcanic horizons in Vendée, called “porphyroïdes” correspond to an important period or rhyolitic volcanism in the Armorican part of the Western European Hercynian Belt. Their stratigraphical assignment is still debated. Using the UPb zircon dating method, acid volcanic and volcanic clastic rocks from the Mareuil-sur-Lay Formation in Vendée are found to be 405 ± 5 Ma old. Interbedded black cherts yield tubular elements of unknown organic origin, up to now only previously recorded in the Upper Silurian and the Early Devonian of Bohemia (Czechoslovakia) and Artois (northern France). On the other hand, closely related carbonaceous remains have been discovered in other south Armorican “porphyroödes” formations. Therefore, the age of 405 ± 5 Ma is an additional datum for the understanding of the calibration of the Silurian-Devonian boundary. Thereby, there exist at least two major episodes of acidic volcanism with porphyritic characteristics. One, well represented in the Iberian Peninsula (Ollo de Sapo), is situated at the base of the Paleozoic; it results from a period of crustal melting at the end of the Ca-domian Orogeny. The other, of Siluro-Devonian age, is studied in this paper. It has a calc-alkaline trend and is marked by ancient crustal contamination. It is linked to an acidic volcanism related to an active continental margin, contemporaneous with eo-Hercynian metamorphic events. Les “porphyroïdes” de Vendée appartiennent à un important épisode de volcanisme rhyolitique, connu dans le Massif Armoricain et dans d'autres parties de la Chaîne Hercynienne d'Europe occidentale. L'attribution stratigraphique de ces volcanites et volcanoclastites a été l'objet de nombreuses controverses. Deux méthodes différentes ont été utilisées ici pour tenter de résoudre ce problème de datation. Ainsi, en Vendée, le matériel rhyolitique de la Formation de Mareuil-sur-Lay a fourni un âge UPb sur zircons de 405 ± 5 Ma. Des niveaux phtanitiques, interstratifiés dans cette formation, ont d'autre part livré des micro-restes charbonneux, d'affinité incertaine, mais, pour l'instant, uniquement cités dans le Silurien supérieur et le Dévonien inférieur de Tchécoslovaquie et du Nord de la France. Des éléments organiques similaires existen également dans des niveaux phtanitiques associés aux “porphyroïdes” de Bretagne méridionale. L'âge de 405 ± 5 Ma obtenu sur les zircons de Mareuil-sur-Lay vient compléter d'autres datations concernant le calibrage de la limite Silurien-Dévonien. En Europe de l'Ouest, deux épisodes majeurs de volcanisme acide à caractère porphyrique peuvent au moins être dénombrés. L'un (“Ollo de Sapo”), représenté en Péninsule Ibérique, se place à la base du Paléozoique et résulte d'une fusion crustale fini-cadomienne. L'autre, étudié dans ce travail, se situe près de la limite Silurien-Dévonien. Il montre une tendance calco-alcaline et porte la trace d'une contamination crustale ancienne. Ce volcanisme acide parait liéà l'existence d'une marge continentale active, contemporaine d'événements métamorphiques éohercyniens.

Witwatersrand gold deposits

Studies of the morphology and other properties of the gold particles in the fossil placer gold deposits of the Witwatersrand provide fascinating glimpses of the conditions under which they were formed. In particular they indicate that in some areas primitive plant life on the deltas on which the gold was deposited acted not only like the legendary golden fleece in concentrating fine gold particles, but probably also reacted biochemically with these particles to determine the forms in which gold is observed in the carbonaceous remains of this plant life today.

Reproductive and Vegetative Morphology of a Cretaceous Angiosperm

Recent collections from plant-bearing deposits of Cenomanian age in central Kansas have yielded angiosperm axes with helically arranged, seed-bearing, conduplicate carpels. Large leaves associated with these fruits are thought to represent parts of the same kind of plant because the leaves and fruits are the only plant fossils at this locality to have distinctive, morphologically identical, yellow bodies within their carbonaceous remains. These fossils provide a rare opportunity to study the morphology of an ancient angiosperm and illustrate the antiquity of certain features considered primitive by comparative angiosperm morphologists.