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.

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

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 Substrate potential of Eemian to Holocene permafrost organic matter for future microbial greenhouse gas production

2017 ◽  
Author(s):  
Janina G. Stapel ◽  
Georg Schwamborn ◽  
Lutz Schirrmeister ◽  
Brian Horsfield ◽  
Kai Mangelsdorf
Keyword(s):  
Organic Matter ◽  
Microbial Communities ◽  
Greenhouse Gas ◽  
Gas Production ◽  
Last Interglacial ◽  
Gas Generation ◽  
The Holocene ◽  
Substrate Potential ◽  
Mis 3 ◽  
Mis 5E

Abstract. Multiple permafrost cores from Bol'shoy Lyakhovsky Island in NE Siberia comprising deposits from Eemian to modern time are investigated to evaluate the stored potential of the freeze-locked organic matter (OM) to serve as substrate for the production of microbial greenhouse gases from thawing permafrost deposits. Deposits from Late Pleistocene glacial periods (comprising MIS 3 and MIS 4) possess an increased aliphatic character and a higher amount of potential substrates, and therefore higher OM quality in terms of biodegradation compared to interglacial deposits from the Eemian (MIS 5e) as well as from the Holocene (MIS 1). To assess the potential of the individual permafrost deposits to provide substrates for microbially induced greenhouse gas generation, concentrations of free and bound acetate as an excellent substrate for methanogenesis are used. The highest free (in pore water and segregated ice) and bound (bound to the organic matrix) acetate-substrate pools of the permafrost deposits are observed within the interstadial MIS 3 and stadial MIS 4 period deposits. In contrast, deposits from the last interglacial MIS 5e show only poor substrate pools. The Holocene deposits reveal a significant bound-acetate pool, representing at least a future substrate potential upon release during OM degradation. Biomarkers for past microbial communities (branched and isoprenoid GDGTs) show also highest abundance of past microbial communities during the MIS 3 and MIS 4 deposits, which indicates higher OM quality with respect to microbial degradation during time of deposition. On a broader perspective, Arctic warming will increase permafrost thaw and favour substrate availability from freeze-locked older permafrost deposits. Therefore, especially those deposits from MIS 3 and MIS 4 show a high potential for providing substrates relevant for methanogenesis.

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

Petroleum Geochemistry of the Loperot-1 Well in Lokichar Basin, Kenya

2016 ◽  
Author(s):  
David M. Katithi ◽  
David O. Opar
Keyword(s):  
Organic Matter ◽  
Source Rock ◽  
Shale Gas ◽  
Source Rocks ◽  
Geochemical Data ◽  
Mature Stage ◽  
Type I ◽  
Hydrocarbon Generation ◽  
Gas Generation ◽  
Gas Targets

ABSTRACT The work reports an in-depth review of bulk and molecular geochemical data to determine the organic richness, kerogen type and thermal maturity of the Lokhone and the stratigraphically deeper Loperot shales of the Lokichar basin encountered in the Loperot-1 well. Oil-source rock correlation was also done to determine the source rocks’ likelihood as the source of oil samples obtained from the well. A combination of literature and geochemical data analyses show that both shales have good to excellent potential in terms of organic and hydrogen richness to act as conventional petroleum source rocks. The Lokhone shales have TOC values of 1.2% to 17.0% (average 5.16%) and are predominantly type I/II organic matter with HI values in the range of 116.3 – 897.2 mg/g TOC. The Lokhone source rocks were deposited in a lacustrine depositional environment in episodically oxic-dysoxic bottom waters with periodic anoxic conditions and have Tmax values in addition to biomarker signatures typical of organic matter in the mid-mature to mature stage with respect to hydrocarbon generation and immature for gas generation with Ro values of 0.51 – 0.64%. The Loperot shales were shown to be possibly highly mature type II/III source rocks with TOC values of 0.98% – 3.18% (average 2.4%), HI of 87 – 115 mg/g TOC and Ro of 1.16 – 1.33%. The Lokhone shale correlate well with the Loperot-1 well oils and hence is proposed as the principal source rock for the oils in the Lokichar basin. Although both source rocks have good organic richness to act as shale gas plays, they are insufficiently mature to act as shale gas targets but this does not preclude their potential deeper in the basin where sufficient gas window maturities might have been attained. The Lokhone shales provide a prospective shale oil play if the reservoir suitability to hydraulic fracturing can be defined. A basin wide study of the source rocks thickness, potential, maturation and expulsion histories in the Lokichar basin is recommended to better understand the present-day distribution of petroleum in the basin.

The Middle Jurassic Source Rock Condition of Circumjacent Depressions and Exploration Potential of Camck-Aral Sea Zones

2013 ◽  
Vol 703 ◽  
pp. 127-130
Author(s):  
Hui Ting Hu ◽  
Hai Tao Xue ◽  
Yi Han Wang ◽  
Xiao Dong Chen
Keyword(s):  
Organic Matter ◽  
Source Rock ◽  
Middle Jurassic ◽  
Thermal Evolution ◽  
Aral Sea ◽  
Geochemical Data ◽  
Maturation Stage ◽  
Organic Carbon Content ◽  
Gas Generation ◽  
Quantitative Calculation

In order to evaluate the exploration potential of CamckAral sea zones, the geological and geochemical data, qualitative appraisement and quantitative calculation method are used to study the Middle Jurassic source rock conditions of circumjacent depressions of CamckAral sea zones. This research indicates that: the Middle Jurassic source rock in these depressions are relatively development, with type II2 and III organic matter which have a higher gas generation potential; and organic carbon content is relatively higher; the thermal evolution of the organic matter has reached maturation stage. It means that the north Camck zone and water area of Aral sea have more exploration potential.

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