Organic geochemistry of margin sediments and its significance for hydrocarbon generation

1980 ◽  
Vol 294 (1409) ◽  
pp. 187-187
Keyword(s):  
Organic Matter ◽  
Atlantic Ocean ◽  
Lower Cretaceous ◽  
Western Europe ◽  
North Atlantic Ocean ◽  
Thermal Evolution ◽  
Organic Geochemistry ◽  
Black Shales ◽  
Hydrocarbon Generation ◽  
Marine Origin

Organic-rich shales and mudstones have been drilled during the D.S.D.P. legs 47a off northwestern Africa and legs 47b and 48 off western Europe. Early Miocene black shales of the Tarfaya Basin contain an organic matter of marine origin and deposited in a reducing environment. Cretaceous dark shales and mudstones are widespread in the north Atlantic Ocean, but they contain mainly detrital organic matter of terrestrial origin. Thus, their potential for petroleum generation is rather low. An immature stage of thermal evolution can be assigned to all Miocene and Cretaceous cores. In other parts of the Atlantic Ocean black shales containing abundant organic matter of marine origin have been found in the same series of Lower Cretaceous age. The widespread occurrence of Lower Cretaceous organic rich sediments from very different sources suggests that the conditions of preservation may be the controlling factor for black shale sediments.

scholarly journals Geochemical Considerations from the Carboniferous Unconventional Petroleum System of SW Iberia

Minerals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 811
Author(s):  
Gabriel A. Barberes ◽  
Rui Pena dos Reis ◽  
Nuno L. Pimentel ◽  
André L. D. Spigolon ◽  
Paulo E. Fonseca ◽  
...  
Keyword(s):  
Random Distribution ◽  
Thermal Evolution ◽  
Organic Geochemistry ◽  
Black Shales ◽  
Petroleum System ◽  
Point Of View ◽  
Gas Reservoir ◽  
Thermal Maturation ◽  
Petrographic Analyses ◽  
Rock Eval

The Baixo Alentejo Flysch Group (BAFG) is an important stratigraphic unit that covers over half of the South Portuguese Zone (SPZ) depositional area, and it is composed by three main tectono-stratigraphic units: the Mértola, Mira, and Brejeira formations. All of these formations contain significant thicknesses of black shales and have several wide areas with 0.81 wt.%, 0.91 wt.%, and 0.72 wt.% average total organic carbon (TOC) (respectively) and thermal maturation values within gas zones (overmature). This paper is considering new data from classical methods of organic geochemistry characterization, such as TOC, Rock–Eval pyrolysis, and organic petrography, to evaluate the unconventional petroleum system from the SPZ. A total of 53 samples were collected. From the stratigraphical point of view, TOC values seem to have a random distribution. The Rock–Eval parameters point out high thermal maturation compatible with gas window (overmature zone). The samples are dominated by gas-prone extremely hydrogen-depleted type III/IV kerogen, which no longer has the potential to generate and expel hydrocarbons. The petrographic analyses positioned the thermal evolution of these samples into the end of catagenesis to metagenesis (wet to dry gas zone), with values predominantly higher than 2 %Ro (dry gas zone). The presence of thermogenic hydrocarbon fluids characterized by previous papers indicate that the BAFG from SPZ represents a senile unconventional petroleum system, working nowadays basically as a gas reservoir.

Hydrocarbon Generative Properties and Maturity of Cretaceous and Eocene Sediments in the Middle Kura Depression, Azerbaijan

2021 ◽  
Author(s):  
Shahin Khosrov Akhundov ◽  
Mushfig Farhad Tagiyev ◽  
Arastun Ismail Khuduzade ◽  
Natig Namig Aliyev
Keyword(s):  
Organic Matter ◽  
Brown Coal ◽  
Lower Cretaceous ◽  
Vitrinite Reflectance ◽  
Sedimentary Cover ◽  
Hard Coal ◽  
Marine Origin ◽  
Formation Conditions ◽  
Lesser Caucasus ◽  
Reflectance Data

Abstract Meso-Cenozoic sedimentary cover in the Middle Kura depression located between the Greater and Lesser Caucasus mountain structures contains numerous oil accumulations. According to studies in the Cretaceous and Paleogene strata, sedimentary organic matter is of mixed clastic-marine origin. Moderate amounts of organic matter have been recorded in the Eocene sediments (on average 0.70%), in the Upper and Lower Cretaceous average values made up 0.39% и 0.42%, respectively. Analysis of bitumoid composition suggests that in a number of areas bitumoids have experienced a widespread movement across the sedimentary strata. The results of measurements on isolated samples indicate that the Cretaceous strata have only advanced to the initial hard-coal stage of organic transformation (0.48-0.55%Ro). On vitrinite reflectance data the Eocene deposits in studied areas of the Middle Kura depression have reached initial (brown-coal) stage of catagenetic transformation (±0.48Ro%; est. paleotemperature of 85°C). Nonetheless, analysis of formation conditions of commercial HC accumulations found earlier in the Eocene strata allows considering them the most prospective in the Middle Kura depression.

scholarly journals Methylphosphonate Oxidation inProchlorococcusStrain MIT9301 Supports Phosphate Acquisition, Formate Excretion, and Carbon Assimilation into Purines

2019 ◽  
Vol 85 (13) ◽  
Author(s):  
Oscar A. Sosa ◽  
John R. Casey ◽  
David M. Karl
Keyword(s):  
Organic Matter ◽  
Atlantic Ocean ◽  
Dissolved Organic Matter ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Carbon Assimilation ◽  
Unicellular Cyanobacterium ◽  
Content Type ◽  
The North ◽  
Oxidative Pathway

ABSTRACTThe marine unicellular cyanobacteriumProchlorococcusis an abundant primary producer and widespread inhabitant of the photic layer in tropical and subtropical marine ecosystems, where the inorganic nutrients required for growth are limiting. In this study, we demonstrate thatProchlorococcushigh-light strain MIT9301, an isolate from the phosphate-depleted subtropical North Atlantic Ocean, can oxidize methylphosphonate (MPn) and hydroxymethylphosphonate (HMPn), two phosphonate compounds present in marine dissolved organic matter, to obtain phosphorus. The oxidation of these phosphonates releases the methyl group as formate, which is both excreted and assimilated into purines in RNA and DNA. Genes encoding the predicted phosphonate oxidative pathway of MIT9301 were predominantly present inProchlorococcusgenomes from parts of the North Atlantic Ocean where phosphate availability is typically low, suggesting that phosphonate oxidation is an ecosystem-specific adaptation of someProchlorococcuspopulations to cope with phosphate scarcity.IMPORTANCEUntil recently, MPn was only known to be degraded in the environment by the bacterial carbon-phosphorus (CP) lyase pathway, a reaction that releases the greenhouse gas methane. The identification of a formate-yielding MPn oxidative pathway in the marine planctomyceteGimesia maris(S. R. Gama, M. Vogt, T. Kalina, K. Hupp, et al., ACS Chem Biol 14:735–741, 2019,https://doi.org/10.1021/acschembio.9b00024) and the presence of this pathway inProchlorococcusindicate that this compound can follow an alternative fate in the environment while providing a valuable source of P to organisms. In the ocean, where MPn is a major component of dissolved organic matter, the oxidation of MPn to formate byProchlorococcusmay direct the flow of this one-carbon compound to carbon dioxide or assimilation into biomass, thus limiting the production of methane.

Metabolic poise in the North Atlantic Ocean diagnosed from organic matter transports

2004 ◽  
Vol 49 (4) ◽  
pp. 1084-1094 ◽  
Author(s):  
Dennis A. Hansell ◽  
Hugh W. Ducklow ◽  
Alison M. Macdonald ◽  
Molly O-Neil Baringer
Keyword(s):  
Organic Matter ◽  
Atlantic Ocean ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
The North ◽  
The North Atlantic
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