Organic matter accumulation, redox, and diagenetic history of the Marcellus Formation, southwestern Pennsylvania, Appalachian basin

2014 ◽  
Vol 57 ◽  
pp. 244-263 ◽  
Author(s):  
Gary G. Lash ◽  
David R. Blood
2015 ◽  
Vol 3 (3) ◽  
pp. SV17-SV33 ◽  
Author(s):  
Anna K. Wendt ◽  
Mike A. Arthur ◽  
Rudy Slingerland ◽  
Daniel Kohl ◽  
Reed Bracht ◽  
...  

Debate continues over paleoenvironmental conditions that prevail during deposition of organic-carbon (C)-rich marine source rocks in foreland basins and epicontinental seas. The focus of disagreement centers largely on paleowater depth and the prevalence of anoxia/euxinia. The issues of paleodepth and water column conditions are important for prediction of lateral variations in source quality within a basin because the viability of a hydrocarbon play depends on a thorough understanding of the distribution of source rock quality and depositional environments. We used inorganic geochemical data from the Middle Devonian Marcellus Shale in the Appalachian Basin to illustrate interpretive strategies that provided constraints on conditions during deposition. Source evaluation typically relies on the analysis and interpretation of organic geochemical indicators, potentially also providing evidence of the degree of thermal maturity and conditions of the preservation of the organic matter. The Marcellus Formation is thermally mature, making the evaluation of the organic-carbon fraction for geologic interpretation inadequate. Because most labile organic matter has largely been destroyed in the Marcellus Formation, analysis of inorganic elements may be used as an alternative interpretative technique. Several inorganic elements have been correlated to varying depositional settings, allowing for their use as proxies for understanding the paleodepositional environments of formations. A high-resolution geochemical data set has been constructed for the Union Springs Member along a transect of cores from proximal to distal in the Appalachian Basin in central Pennsylvania using major, minor, and trace elemental data. Our results suggested that during deposition, the sediment-water interface, and a portion of the water column, was anoxic to euxinic. As deposition continued, euxinia was periodically interrupted by dysoxia and even oxic conditions, and a greater influx of clastic material occurred. Such variations were likely related to fluctuations in water depth and progradation of deltaic complexes from the eastern margin of the Appalachian Basin.


2019 ◽  
Vol 64 (6) ◽  
pp. 585-593
Author(s):  
A. E. Kontorovich ◽  
L. I. Bogorodskaya ◽  
L. S. Borisova ◽  
L. M. Burshtein ◽  
Z. R. Ismagilov ◽  
...  

A representative suite of 276 samples was used to study the isotopic and element geochemistry of kerogens from the Bazhenov horizon (Bazhenov Formation and its time equivalents) of the West Siberian sedimentary basin and to construct maps reflecting changes in the elemental composition of kerogen. The elemental composition of kerogen was used to determine the types of organic matter (H and C contents), the initial components of the living matter, the sources of kerogen (H and N contents), diagenetic history of organic matter (S content), the level of catagenetic transformation (C and O contents). Kerogen from the central, western and southern regions of the West Siberian basin toward the boundary of the Bazhenov horizon pinch-out shows strong enrichment in hydrogen (up to 8–9%) and 12С (δ13С‰ from -35 to -29), suggesting its derivation from the polymer lipids of aquatic origin. Kerogen from the Bazhenov horizon (catagenetic grade MC1) in the northeast of the basin contains much lower hydrogen concentrations (2–4%). A map of organic matter types in the Bazhenov horizon was constructed.


Clay Minerals ◽  
2011 ◽  
Vol 46 (4) ◽  
pp. 561-582 ◽  
Author(s):  
J. Środoń ◽  
M. Paszkowski

AbstractThe evolution of the nitrogen and boron content of shales during diagenesis and anchimetamorphism was studied in the Carboniferous rocks of Donbas by means of the bulk rock chemical analysis and the XRD quantification of mineral composition, aided by CEC and EGME sorption measurements. The contributions of the organic-bound N and B were taken into account, based on the literature data (B) and on the relationship established in the course of this study (N). 28–98% of the total N and 80–100% of the total B are contained in the mineral fraction of the investigated shales.The mineral nitrogen is located mostly in illite and accounts for 3 to 64% of the sites available for its fixation in 1Md illite. The fixation of N by illite seems to diminish in the course of diagenesis, but additional fixation occurs in newly formed 2M1 illite during the anchimetamorphic stage. The volume of N contained in illite in most samples greatly surpasses the N available locally from the organic matter contained in shale. Modelling indicates that the measured level of N for K substitution in illite corresponds to the capture in 30 vol.% of shale of all N released in a basin containing 5 vol.% of coal.Boron is held predominantly by the 1Md fraction (illite+smectite). During diagenesis boron is redistributed into the 1Md illite, and during anchimetamorphism it is released from the 1Md illite and incorporated into new 2M1 illite. No indication of the net enrichment of pore water in B due to the clay alteration process was found.


Derrida Today ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 72-94
Author(s):  
Bernard Stiegler

These lectures outline the project of a general organology, which is to say an account of life when it is no longer just biological but technical, or when it involves not just organic matter but organized inorganic matter. This organology is also shown to require a modified Simondonian account of the shift from vital individuation to a three-stranded process of psychic, collective and technical individuation. Furthermore, such an approach involves extending the Derridean reading of Socrates's discussion of writing as a pharmakon, so that it becomes a more general account of the pharmacological character of retention and protention. By going back to Leroi-Gourhan, we can recognize that this also means pursuing the history of retentional modifications unfolding in the course of the history of what, with Lotka, can also be called exosomatization. It is thus a question of how exteriorization can, today, in an epoch when it becomes digital, and in an epoch that produces vast amounts of entropy at the thermodynamic, biological and noetic levels, still possibly produce new forms of interiorization, that is, new forms of thought, care and desire, amounting to so many chances to struggle against the planetary-scale pharmacological crisis with which we are currently afflicted.


2016 ◽  
Author(s):  
Rachel Fliflet ◽  
◽  
Justin M. Poirier ◽  
Brian J. Mahoney ◽  
Kent M. Syverson

2016 ◽  
Author(s):  
Rachel Fliflet ◽  
◽  
Justin M. Poirier ◽  
J. Brian Mahoney ◽  
Kent M. Syverson

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