Study of the Structure of Benzene- and Alcohol–Benzene-Extractable Resins and Kerogen of Rock Organic Matter (By Example of Bazhenovo Formation Rocks from the North of the Gyda Peninsula)

A total of 27 samples of the Moschopotamos area lignite-bearing strata were studied in regard of their geochemical and sedimentary characteristics. Organic content and calcium carbonate evaluation, sieve analysis and micropaleontological observations were used and combined to investigate the paleoenvironment and the depositional conditions of the study area. TOC analysis showed that organic matter values range from 0.07% up to 13.42% with an average of ~3.26 %. The high average of organic carbon content indicates a promising basis for the sediments’ source rock potential, inquiring further and thorough examination. CaCO3 measurements present a range between 4% and 23%. A comparison between TOC-CaCO3 content throughout the stratigraphic column presented certain synchronous and inverse trends, due to alterations of the depositional conditions. This study provides new insights for the understanding of the broader Axios-Thermaikos basin, and depositional conditions in the North Aegean area.

Download Full-text

Regional assessment of the Eagle Ford Group of South Texas, USA: Insights from lithology, pore volume, water saturation, organic richness, and productivity correlations

Interpretation ◽

10.1190/int-2015-0099.1 ◽

2016 ◽

Vol 4 (1) ◽

pp. SC125-SC150 ◽

Cited By ~ 9

Author(s):

Ursula Hammes ◽

Ray Eastwood ◽

Guin McDaid ◽

Emilian Vankov ◽

S. Amin Gherabati ◽

...

Keyword(s):

Organic Matter ◽

Pore Volume ◽

Water Saturation ◽

Production Quality ◽

South Texas ◽

Eagle Ford Shale ◽

Eagle Ford ◽

The North ◽

The Impact ◽

Sweet Spots

A comprehensive regional investigation of the Eagle Ford Shale linking productivity to porosity-thickness (PHIH), lithology ([Formula: see text]), pore volume (PHIT), organic matter (TOC), and water-saturation ([Formula: see text]) variations has not been presented to date. Therefore, isopach maps across the Eagle Ford Shale play west of the San Marcos Arch were constructed using thickness and log-calculated attributes such as TOC, [Formula: see text], [Formula: see text], and porosity to identify sweet spots and spatial distribution of these geologic characteristics that influence productivity in shale plays. The Upper Cretaceous Eagle Ford Shale in South Texas is an organic-rich, calcareous mudrock deposited during a second-order transgression of global sea level on a carbonate-dominated shelf updip from the older Sligo and Edwards (Stuart City) reef margins. Lithology and organic-matter deposition were controlled by fluvial input from the Woodbine delta in the northeast, upwelling along the Cretaceous shelf edge, and volcanic and clastic input from distant Laramide events to the north and west. Local oxygen minimum events along the South Texas margin contributed to the preservation of this organic-rich source rock related to the Cenomanian/Turonian global organic anoxic event (OAE2). Paleogeographic and deep-seated tectonic elements controlled the variations of lithology, amount and distribution of organic matter, and facies that have a profound impact on production quality. Petrophysical modeling was conducted to calculate total organic carbon, water saturation, lithology, and porosity of the Eagle Ford Group. Thickness maps, as well as PHIH maps, show multiple sweet spots across the study area. Components of the database were used as variables in kriging, and multivariate statistical analyses evaluated the impact of these variables on productivity. For example, TOC and clay volume ([Formula: see text]) show an inverse relationship that is related to production. Mapping petrophysical parameters across a play serves as a tool to predict geologic drivers of productivity across the Eagle Ford taking the geologic heterogeneity into account.

Download Full-text

A Mesoproterozoic iron formation

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1720529115 ◽

2018 ◽

Vol 115 (17) ◽

pp. E3895-E3904 ◽

Cited By ~ 17

Author(s):

Donald E. Canfield ◽

Shuichang Zhang ◽

Huajian Wang ◽

Xiaomei Wang ◽

Wenzhi Zhao ◽

...

Keyword(s):

Organic Matter ◽

Time Window ◽

Iron Formation ◽

The North ◽

Fe Oxidation ◽

Organic Biomarkers ◽

Rock Eval ◽

Fe Reduction ◽

Rule Out ◽

Xiamaling Formation

We describe a 1,400 million-year old (Ma) iron formation (IF) from the Xiamaling Formation of the North China Craton. We estimate this IF to have contained at least 520 gigatons of authigenic Fe, comparable in size to many IFs of the Paleoproterozoic Era (2,500–1,600 Ma). Therefore, substantial IFs formed in the time window between 1,800 and 800 Ma, where they are generally believed to have been absent. The Xiamaling IF is of exceptionally low thermal maturity, allowing the preservation of organic biomarkers and an unprecedented view of iron-cycle dynamics during IF emplacement. We identify tetramethyl aryl isoprenoid (TMAI) biomarkers linked to anoxygenic photosynthetic bacteria and thus phototrophic Fe oxidation. Although we cannot rule out other pathways of Fe oxidation, iron and organic matter likely deposited to the sediment in a ratio similar to that expected for anoxygenic photosynthesis. Fe reduction was likely a dominant and efficient pathway of organic matter mineralization, as indicated by organic matter maturation by Rock Eval pyrolysis combined with carbon isotope analyses: Indeed, Fe reduction was seemingly as efficient as oxic respiration. Overall, this Mesoproterozoic-aged IF shows many similarities to Archean-aged (>2,500 Ma) banded IFs (BIFs), but with an exceptional state of preservation, allowing an unprecedented exploration of Fe-cycle dynamics in IF deposition.

Download Full-text

Biogeochemical processes in the Barents sea

10.29006/978-5-6045110-0-8/(23) ◽

2021 ◽

pp. 287-306

Author(s):

A.Yu. Lein ◽

◽

A.S. Savvichev ◽

Keyword(s):

Organic Matter ◽

Water Column ◽

Methane Concentration ◽

Barents Sea ◽

Biogeochemical Processes ◽

Total Abundance ◽

The North ◽

The Barents Sea ◽

Continental Origin ◽

Biomass Of Microorganisms

Biogeochemical processes involving microorganisms play an important role in marine sedimentogenesis. The study of biogeochemical processes in the Barents Sea was carried out from 1997 with interruptions until 2019. Using a complex of geological-geochemical, microbiological, radioisotope and stable isotope methods, it was possible to obtain a quantitative estimate of the total abundance and biomass of microorganisms, rates of biogeochemical processes, methane content and organic matter suspended. In the course of work in four expeditions, it was found that in the surface (0–10 m) water column south of 74° N the magnitude of the total abundance and the biomass of microorganisms increased by 2019 by about 5 times compared to 1998. To the north, in colder waters, the total abundance and the biomass of organisms were lower than in the southern region of the sea. The methane concentration in the surface layer of the water column at the border with the atmosphere did not change much for 20 years (1976–1997) and increased noticeably from 1997 to 2017, from 3.3 to 15.8 nM. The increase in FFM, the biomass of organisms and the concentration of methane in the water column is associated with the melting of glaciers, with the release of organic matter of continental origin released from ice into the water. The results of the work indicate changes in the ecosystem of the Barents Sea.

Download Full-text