Paired δ13Ccarb and δ13Corg records of Upper Ordovician (Sandbian–Katian) carbonates in North America and China: Implications for paleoceanographic change

Young, Seth A.; Saltzman, Matthew R.; Bergström, Stig M.; Leslie, Stephen A.; Chen, Xu

doi:10.1016/j.palaeo.2008.09.006

Cited by 98 publications

(69 citation statements)

References 56 publications

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“…Several studies have suggested that diagenesis does not significantly affect the δ 13 C of organic matter in sedimentary rocks, particularly in black shales (e.g. Ader et al, 2009;Bekker et al, 2008;Young et al, 2008). It has been suggested that in black shales, removing or altering a portion of the primary organic carbon may not change organic carbon isotopic compositions (Jiang et al, 2012).…”

Section: Carbon and Nitrogen Isotopesmentioning

confidence: 99%

Comparison of isotopic and geochemical characteristics of sediments from a gas- and liquids-prone wells in Marcellus Shale from Appalachian Basin, West Virginia

Chen

Sharma

Bank

et al. 2015

Applied Geochemistry

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The Middle Devonian age Marcellus Shale contains one of the largest shale gas plays in North America. Hydrocarbon production in the eastern part of the play is mostly "dry gas," consisting of essentially pure methane. Production of natural gas liquids (condensate) increases toward the west, which is the area currently, being targeted by developers. Two Marcellus Shale cores from West Virginia were analyzed to compare the isotopic and geochemical characteristics of a liquids-prone well (WV-7) in Wetzel County with a gas-prone well (WV-6) in Monongalia County. The contrasts between the cores indicate that the conditions of the Marcellus Shale deposition were different between the two sites. The dominant organic matter preserved in each core is isotopically different; δ 13 C org values are lighter on average in WV-6 compared with WV-7. A possible explanation is that a larger fraction of terrestrial organic matter was preserved in the WV-6 core, whereas WV-7 may contain a greater percentage of marine organic matter.Clastic-influx proxies (e.g. Ti/Al, Ca/Al and Mg/Al) also suggest that the WV-6 core site received a higher siliciclastic input compared to WV-7, consistent with a more proximal location to dry land and the delivery of greater amounts of terrestrial organic matter. Depleted δ 13 C carb values, low concentrations of redox sensitive elements (e.g. V, Cr, Ni and U), and high 2 variability δ 15 N values in the WV-6 core all suggest the presence of higher dissolved oxygen concentration and short term shifts in an oxic/anoxic boundary near the sediment-water interface during deposition. These lines of evidence indicate that the depositional conditions were favorable for the accumulation of predominantly gas-prone Type III kerogen in the Marcellus Shale at the WV-6 site. In contrast, the Marcellus Shale at the WV-7 site was deposited in a more distal area that received a low terrestrial sediment supply, organic matter primarily derived from marine algae, and bottom water conditions that were dominantly anoxic. Such conditions were favorable for the accumulation of Type II kerogen that has a greater capacity to generate liquid hydrocarbons. Differences between the liquids-prone and gas-prone parts of the Marcellus Shale play have been largely ascribed to depth-of-burial and thermal maturation history; this study indicates that depositional environment and sedimentary facies may have played significant roles as well.

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Section: Carbon and Nitrogen Isotopesmentioning

confidence: 99%

Comparison of isotopic and geochemical characteristics of sediments from a gas- and liquids-prone wells in Marcellus Shale from Appalachian Basin, West Virginia

Chen

Sharma

Bank

et al. 2015

Applied Geochemistry

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“…It has been documented in carbonates from North America, Europe, and Asia (Patzkowsky et al, 1997;Ludvigson et al, 2000;Ainsaar et al, 2004;Kaljo et al, 2004;Ludvigson et al, 2004;Saltzman and Young, 2005;Young et al, 2005;Bergström et al, 2008;Young et al, 2008;Bergström et al, 2010;Buggisch et al, 2010;Metzger and Fike, 2013;Pancost et al, 2013;Metzger et al, 2014). The excursion has been proposed to represent a perturbation in the global carbon cycle causally related to the onset of Late Ordovician cooling culminating in the Hirnantian glaciation (Ainsaar et al, 2004;Saltzman and Young, 2005;Young et al, 2008;2010). Specifically, the GICE is argued to reflect an interval of enhanced organic carbon burial resulting in a decrease in atmospheric CO 2 and reduced greenhouse forcing Young et al, 2008;2010).…”

Section: Introductionmentioning

confidence: 99%

Carbon cycling across the southern margin of Laurentia during the Late Ordovician

Quinton

Herrmann

Leslie

et al. 2016

Palaeogeography, Palaeoclimatology, Palaeoecology

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“…Globally correlatable excursions in marine d 13 C carb records are often thought to be related to global changes in the carbon cycle, such as those induced by snowball Earth events in the Neoproterozoic [1][2][3] , the oxygenation of Earth's atmosphere [4][5][6][7] , the evolution of Ediacaran metazoans 8,9 , as well as marine and terrestrial extinction episodes [10][11][12][13][14] . A common approach used to establish whether the variations in a d 13 C carb record reflect changes in the isotopic composition of the ancient dissolved inorganic carbon pool is to assess the covariation between coeval carbonate and sedimentary organic carbon isotope records [15][16][17][18][19][20][21][22] . Classically, covariant d 13 C carb and d 13 C org records are interpreted as evidence that both the carbonate and organic matter were originally produced in the surface waters of the ocean, and that they have retained their original d 13 C composition 10,[19][20][21][22][23][24][25] , while decoupled d 13 C carb and d 13 C org records have been interpreted as evidence for diagenetic alteration 16,19,20,26 , the 'Rothman ocean' model 27 , or that local syn-sedimentary processes have made the d 13 C org record noisy 8 .…”

mentioning

confidence: 99%

Interpreting carbonate and organic carbon isotope covariance in the sedimentary record

2014

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Many negative d 13 C excursions in marine carbonates from the geological record are interpreted to record significant biogeochemical events in early Earth history. The assumption that no post-depositional processes can simultaneously alter carbonate and organic d 13 C values towards more negative values is the cornerstone of this approach. However, the effects of post-depositional alteration on the relationship between carbonate and organic d 13 C values have not been directly evaluated. Here we present paired carbonate and organic d 13 C records that exhibit a coupled negative excursion resulting from multiple periods of meteoric alteration of the carbonate d 13 C record, and consequent contributions of isotopically negative terrestrial organic matter to the sedimentary record. The possibility that carbonate and organic d 13 C records can be simultaneously shifted towards lower d 13 C values during periods of subaerial exposure may necessitate the reappraisal of some of the d 13 C anomalies associated with noteworthy biogeochemical events throughout Earth history.

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Paired δ13Ccarb and δ13Corg records of Upper Ordovician (Sandbian–Katian) carbonates in North America and China: Implications for paleoceanographic change

Cited by 98 publications

References 56 publications

Comparison of isotopic and geochemical characteristics of sediments from a gas- and liquids-prone wells in Marcellus Shale from Appalachian Basin, West Virginia

Comparison of isotopic and geochemical characteristics of sediments from a gas- and liquids-prone wells in Marcellus Shale from Appalachian Basin, West Virginia

Carbon cycling across the southern margin of Laurentia during the Late Ordovician

Interpreting carbonate and organic carbon isotope covariance in the sedimentary record

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