CARBON ISOTOPES, KEROGEN TYPES AND THE PERMIAN-TRIASSIC BOUNDARY IN AUSTRALIA: IMPLICATIONS FOR EXPLORATION

1997 ◽  
Vol 37 (1) ◽  
pp. 472 ◽  
Author(s):  
C.B. Foster ◽  
G.A. Logan ◽  
R.E. Summons ◽  
J.D. Gorter ◽  
D.S. Edwards
Keyword(s):  
Organic Matter ◽  
Carbon Isotopes ◽  
Secular Change ◽  
Simple Relationship ◽  
Predictive Tool ◽  
Marine Fauna ◽  
Isotopic Signatures ◽  
Carbon Isotopic ◽  
Eastern Australia ◽  
Plant Microfossils

A global stratotype section for the boundary between the Permian and Triassic Systems is yet to be agreed internationally. However, in many parts of the world, there is evidence of massive extinction of marine fauna at or near the P-T boundary. In the absence of marine fauna, as is the case in most of Australia, changes in plant microfossils, in carbon isotopic signatures, and radiometric dates using SHRIMP, have been used to mark the boundary. The leading questions which arise from this are whether these events are synchronous and how they affect exploration.In eastern Australia, the top of the coal measures has been used as the top of the Permian, although presently only plant microfossils can be used to determine if the youngest seam is present. This has important economic consequences for determination of volumes of effective source rock and for estimates of coal-bed methane. It has been suggested that changes in the carbon isotopic signatures (δ13C) of either organic matter (δ13Corg) or carbonates (δ13Ccarb) can be used to delimit the P-T boundary. From studies of (δ13Ccarb data, Scholle (1995) concluded that 'the establishment of a secular variation curve which has enough detail and reliability to be used as a chemostratigraphic tool still lies in the future'. We concur, and demonstrate for organic carbon that, while there is evidence for secular change, the 13C signature is complicated and overprinted by contributions from different parent plant types; wood-dominated organics are typically −24 %o, while non-woody matter is significantly lighter (−30 %o). There is no simple relationship of δ13Corg to geological age. The consistency of our data, from both the east and west of Australia, allows us to construct a model to predict probable depositional and organic facies using either carbon isotopes (from kerogen or oil) or quantitative estimates of organic matter from standard palynlogical slides. This offers a novel and usefl predictive tool for hydrocarbon exploration.

scholarly journals Investigating oxygen and carbon isotopic relationships in speleothem records over the last millennium using multiple isotope-enabled climate models

2021 ◽  
Author(s):  
Janica C. Bühler ◽  
Josefine M. Axelsson ◽  
Franziska A. Lechleitner ◽  
Jens Fohlmeister ◽  
Allegra N. LeGrande ◽  
...  
Keyword(s):  
Carbon Isotopes ◽  
Future Climate Change ◽  
Last Millennium ◽  
Oxygen And Carbon Isotopes ◽  
Proxy Data ◽  
Isotopic Signatures ◽  
Carbon Isotopic ◽  
Water Isotopologues ◽  
The Relationship ◽  
Water Isotope

Abstract. The incorporation of water isotopologues into the hydrology of general circulation models (GCMs) facilitates the comparison between modelled and measured proxy data in paleoclimate archives. However, the variability and drivers of measured and modelled water isotopologues, and indeed the diversity of their representation in different models are not well constrained. Improving our understanding of this variability in past and present climates will help to better constrain future climate change projections and decrease their range of uncertainty. Speleothems are a precisely datable paleoclimate archive and provide well preserved (semi-)continuous multivariate isotope time series in the lower and mid-latitudes, and are, therefore, well suited to assess climate and isotope variability on decadal and longer timescales. However, the relationship between speleothem oxygen and carbon isotopes to climate variables also depends on site-specific parameters, and their comparison to GCMs is not always straightforward. Here we compare speleothem oxygen and carbon isotopic signatures from the Speleothem Isotopes Synthesis and AnaLysis database version 2 (SISALv2) to the output of five different water-isotope-enabled GCMs (ECHAM5-wiso, GISS-E2-R, iCESM, iHadCM3, and isoGSM) over the last millennium (850–1850 common era, CE). We systematically evaluate differences and commonalities between the standardized model simulation outputs. The goal is to distinguish climatic drivers of variability for both modelled and measured isotopes. We find strong regional differences in the oxygen isotope signatures between models that can partly be attributed to differences in modelled temperatures. At low latitudes, precipitation amount is the dominant driver for water isotope variability, however, at cave locations the agreement between modelled temperature variability is higher than for precipitation variability. While modelled isotopic signatures at cave locations exhibited extreme events coinciding with changes in volcanic and solar forcing, such fingerprints are not apparent in the speleothem isotopes, and may be attributed to the lower temporal resolution of speleothem records compared to the events that are to be detected. Using spectral analysis, we can show that all models underestimate decadal and longer variability compared to speleothems, although to varying extent. We found that no model excels in all analyzed comparisons, although some perform better than the others in either mean or variability. Therefore, we advise a multi-model approach, whenever comparing proxy data to modelled data. Considering karst and cave internal processes through e.g. isotope-enabled karst models may alter the variability in speleothem isotopes and play an important role in determining the most appropriate model. By exploring new ways of analyzing the relationship between the oxygen and carbon isotopes, their variability, and co-variability across timescales, we provide methods that may serve as a baseline for future studies with different models using e.g. different isotopes, different climate archives, or time periods.

scholarly journals Carbon isotopic signatures of soil organic matter correlate with leaf area index across woody biomes

2014 ◽  
Vol 102 (6) ◽  
pp. 1606-1611 ◽  
Author(s):  
Brenton Ladd ◽  
Pablo L. Peri ◽  
David A. Pepper ◽  
Lucas C. R. Silva ◽  
Douglas Sheil ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Leaf Area Index ◽  
Leaf Area ◽  
Area Index ◽  
Isotopic Signatures ◽  
Carbon Isotopic

scholarly journals High Contribution of Recalcitrant Organic Matter to DOC in a Japanese Oligotrophic Lake Revealed by 14C Measurements

Radiocarbon ◽  
2010 ◽  
Vol 52 (3) ◽  
pp. 1078-1083 ◽  
Author(s):  
Fumiko Watanabe Nara ◽  
Akio Imai ◽  
Masao Uchida ◽  
Kazuo Matsushige ◽  
Kazuhiro Komatsu ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Organic Matter ◽  
Carbon Isotopes ◽  
Oligotrophic Lake ◽  
Small Contribution ◽  
Low Carbon ◽  
Carbon Isotopic ◽  
High Contribution ◽  
Recalcitrant Organic Matter ◽  
Data Points

Carbon isotopes (14C and 13C) of dissolved organic carbon (DOC) in a Japanese oligotrophic lake (Lake Towada) were measured to study the origin and cycling of dissolved organic matter (DOM) in Lake Towada. Lake water samples were collected at 3 depths (0, 30, and 80 or 85 m) during 4 months (April, June, August, and October) in 2006. 14C measurements of DOC were performed by accelerator mass spectrometry (AMS) at the National Institute for Environmental Studies (NIES-TERRA) in Japan. Δ14C and δ13C values of DOC in Lake Towada showed light carbon isotopic values ranging from –750 to −514‰ and –29.0 to –27.8‰, respectively. These values are similar to those of humic substances reported. The very low carbon isotopic values of DOC in Lake Towada suggest a very small contribution of DOC derived from fresh phytoplankton to the lake DOC. There is an extremely high linear relationship between the Δ14C and δ13C of DOC in Lake Towada when all data points are plotted (r2 =0.818, p < 0.01), suggesting that the DOC in Lake Towada has 2 specific sources contributing heavy and light carbon isotopes. Although the freshly produced DOC of phytoplankton origin can be decomposed easily, the variation in the autochthonous DOC should influence the carbon isotopic values of DOC in Lake Towada.

Carbon Isotopic Characteristics of Different Genetic Type Condensates in China

2011 ◽  
Vol 29 (6) ◽  
pp. 699-710 ◽  
Author(s):  
Shipeng Huang ◽  
Zecheng Wang ◽  
Xiaoqi Wu ◽  
Fengrong Liao ◽  
Jinxing Dai
Keyword(s):  
Organic Matter ◽  
Isotopic Composition ◽  
Carbon Isotopes ◽  
Organic Matters ◽  
Total Hydrocarbon ◽  
Carbon Isotopic ◽  
Wide Range ◽  
Different Types ◽  
Organic Matter Type ◽  
Petroliferous Basin

Condensate pools with reservoir ages of Ordovician, Permian, Triassic, Jurassic, Cretaceous, Eogene, and Neogene were found in every giant petroliferous Basin in China. Condensates generated by sapropelic organic matters (sapropelic condensates) are of high- to over-mature stages, while the maturities of those generated by humic organic matters (humic condensates) cover a wide range, from early mature to over-mature. Carbon isotopes of 143 condensate samples were analyzed in this work, and we found that both the organic matter type and the maturity significantly influenced the isotopic composition of the condensates. The total hydrocarbon isotopic values of the humic condensates range from −29.9% to −21.7%, with an average of −26.0% (94 samples), while those sapropelic condensates are lighter generally, covering a range of −33.9% to −26.0% with an average of −29.5% (40 samples). δ13Caromatics value is strongly inheritable to the organic matter type and it combined with the δ13Csaturates value can be used to distinguish condensates of different types. δ13Caromatics value of sapropelic condensate is less than −27.5%, while the δ13Caromatics and the δ13Csaturates values of humic condensate are larger than −27.5% and −29.5%, respectively.

scholarly journals Methane from microbial hydrogenolysis of sediment organic matter before the Great Oxidation Event

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Xinyu Xia ◽  
Yongli Gao
Keyword(s):  
Organic Matter ◽  
Greenhouse Gas ◽  
Hydrogen Gas ◽  
Sediment Organic Matter ◽  
Geochemical Data ◽  
Gas Generation ◽  
Isotopic Signatures ◽  
Metasedimentary Rocks ◽  
Great Oxidation Event ◽  
Carbon Isotopic

AbstractMethane, along with other short-chain alkanes from some Archean metasedimentary rocks, has unique isotopic signatures that possibly reflect the generation of atmospheric greenhouse gas on early Earth. We find that alkane gases from the Kidd Creek mines in the Canadian Shield are microbial products in a Neoarchean ecosystem. The widely varied hydrogen and relatively uniform carbon isotopic compositions in the alkanes infer that the alkanes result from the biodegradation of sediment organic matter with serpentinization-derived hydrogen gas. This proposed process is supported by published geochemical data on the Kidd Creek gas, including the distribution of alkane abundances, stable isotope variations in alkanes, and CH2D2 signatures in methane. The recognition of Archean microbial methane in this work reveals a biochemical process of greenhouse gas generation before the Great Oxidation Event and improves the understanding of the carbon and hydrogen geochemical cycles.

CHEMOSTRATIGRAPHY AND THE COMPOSITION OF OILS IN THE PERTH BASIN, WESTERN AUSTRALIA

1995 ◽  
Vol 35 (1) ◽  
pp. 613 ◽  
Author(s):  
R. E. Summons ◽  
C. J. Boreham ◽  
C. B. Foster ◽  
A. P. Murray ◽  
J. D. Gorter
Keyword(s):  
Isotopic Signature ◽  
Secular Change ◽  
Multiple Sources ◽  
Triassic Boundary ◽  
Isotopic Signatures ◽  
Carbon Isotopic ◽  
Source Correlation ◽  
Basal Section ◽  
Oil Source ◽  
Permian Triassic Boundary

The known global secular change in the distribu­tion of carbon isotopes between the Palaeozoic and Mesozoic is the basis of a new oil-source correlation tool. The carbon isotopic signatures of n-alkanes, in combination with information about the distribu­tions of diagnostic biomarkers have been used to classify Perth Basin oils according to the age of the source. These data confirm that most of the oil in the northern Perth Basin originates from the basal section of the Kockatea Shale.Oils exclusively from Triassic sources are isotopically light with n-alkane 813C values near −34%o PDB. Jurassic oil from Gage Roads-1 is isotopically heavy (~24%o) and is also distinctive in its relatively high content of conifer-derived aromatic hydrocar­bons. Condensates from Jurassic source intervals in the Dandaragan Trough are isotopically heteroge­neous with n-alkane 813C values between −25%o and −29%o. The Whicher Range-1 condensate, of appar­ent Permian origin, is isotopically heavy with n-alkane 5l3C values near −25%o. The isotopic data provide information about variation in sedimen­tary facies and possible multiple sources that is not evident from the biomarker signatures. All the Jurassic oils have significant amounts of bicadinanes, resin-derived biomarkers until recently attributed exclusively to tropical angiosperms.A strong excursion in the isotopic signature of organic carbon is present in core at 2,293 m in the Woodada-2 borehole and occurs with no obvious lithological change. Similar isotope shifts are known to mark the Permian-Triassic boundary globally and have been previously recognised in the Bonaparte, Bowen, Canning, Carnarvon and tenta­tively in the southern Perth basins. The excursion in Woodada-2 is abrupt and suggests a significant time break in sedimentation. However, diagnostic Permian palynoflora or fauna have not been de­tected below 2,293 m in the Woodada-2 core, and hence, the assignment of a Permian-Triassic con­tact cannot be made unequivocally with the exist­ing data.

scholarly journals Microstructure-specific carbon isotopic signatures of organic matter from ∼3.5 Ga cherts of the Pilbara Craton support a biologic origin

2016 ◽  
Vol 275 ◽  
pp. 429-449 ◽  
Author(s):  
Navot Morag ◽  
Kenneth H. Williford ◽  
Kouki Kitajima ◽  
Pascal Philippot ◽  
Martin J. Van Kranendonk ◽  
...  
Keyword(s):  
Organic Matter ◽  
Isotopic Signatures ◽  
Carbon Isotopic ◽  
Pilbara Craton

scholarly journals Biosignatures of ancient microbial life are present across the igneous crust of the Fennoscandian shield

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Henrik Drake ◽  
Nick M. W. Roberts ◽  
Manuel Reinhardt ◽  
Martin Whitehouse ◽  
Magnus Ivarsson ◽  
...  
Keyword(s):  
Fennoscandian Shield ◽  
Stable Carbon ◽  
Deep Biosphere ◽  
Isotopic Signatures ◽  
Microbial Life ◽  
Carbon Isotopic ◽  
Terrestrial Life ◽  
Vein Mineral ◽  
Methyl Branched Fatty Acids

AbstractEarth’s crust contains a substantial proportion of global biomass, hosting microbial life up to several kilometers depth. Yet, knowledge of the evolution and extent of life in this environment remains elusive and patchy. Here we present isotopic, molecular and morphological signatures for deep ancient life in vein mineral specimens from mines distributed across the Precambrian Fennoscandian shield. Stable carbon isotopic signatures of calcite indicate microbial methanogenesis. In addition, sulfur isotope variability in pyrite, supported by stable carbon isotopic signatures of methyl-branched fatty acids, suggest subsequent bacterial sulfate reduction. Carbonate geochronology constrains the timing of these processes to the Cenozoic. We suggest that signatures of an ancient deep biosphere and long-term microbial activity are present throughout this shield. We suggest that microbes may have been active in the continental igneous crust over geological timescales, and that subsurface investigations may be valuable in the search for extra-terrestrial life.

scholarly journals How Does Diet Influence Our Lives? Evaluating the Relationship between Isotopic Signatures and Mortality Patterns in Italian Roman Imperial and Medieval Periods

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3895
Author(s):  
Marica Baldoni ◽  
Alessandra Nardi ◽  
Flavio De Angelis ◽  
Olga Rickards ◽  
Cristina Martínez-Labarga
Keyword(s):  
Middle Ages ◽  
Dietary Habits ◽  
Roman Period ◽  
Survivorship Analysis ◽  
Linear Effect ◽  
Isotopic Signatures ◽  
Carbon Isotopic ◽  
Religious Aspects ◽  
The Relationship ◽  
Source Of Information

The present research investigates the relationship between dietary habits and mortality patterns in the Roman Imperial and Medieval periods. The reconstructions of population dynamics and subsistence strategies provide a fascinating source of information for understanding our history. This is particularly true given that the changes in social, economic, political, and religious aspects related to the transition from the Roman period to the Middle Ages have been widely discussed. We analyzed the isotopic and mortality patterns of 616 individuals from 18 archeological sites (the Medieval Latium sites of Colonna, Santa Severa, Allumiere, Cencelle, and 14 Medieval and Imperial funerary contexts from Rome) to compile a survivorship analysis. A semi-parametric approach was applied, suggesting variations in mortality patterns between sexes in the Roman period. Nitrogen isotopic signatures influenced mortality in both periods, showing a quadratic and a linear effect for Roman Imperial and Medieval populations, respectively. No influence of carbon isotopic signatures has been detected for Roman Imperial populations. Conversely, increased mortality risk for rising carbon isotopic values was observed in Medieval samples.

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