Early Cenozoic decoupling of the global carbon and sulfur cycles
Tóm tắt
Changes in carbon and sulfur cycling over geologic time may have caused considerable modification of atmospheric and oceanic composition and climate. Here we calculate pyrite sulfur (Spy) and organic carbon (Corg) burial rates from recently improved Cenozoic stable isotope records, and from these rates we infer global changes in Corg burial environments. Given predominantly normal shelf‐delta organic carbon burial, the global Spy burial flux should be coupled to Corg burial. However, we find that the major early Cenozoic peak in Corg burial coincides with a minimum in Spy burial. Although the calculated magnitude of variations in global pyrite burial flux is sensitive to our assumptions about the concentration of sulfate in paleoseawater, a non‐steady‐state isotope mass balance model indicates very low Spy burial rates during the Paleocene and a dramatic increase starting near the Paleocene‐Eocene boundary, dropping off to a fairly constant Cenozoic rate beginning in the middle Eocene. High Corg/Spy burial ratios (C/S mole ratio ≈15–30) coinciding with the Paleocene carbon isotope maximum most likely reflect enhanced accumulation of terrestrial organic carbon in Paleocene terrestrial swamps. We suggest that rapid burning of accumulated Paleocene terrestrial organic carbon could have significantly contributed to the short‐lived negative carbon isotope excursion at the Paleocene‐Eocene boundary in addition to or possibly even as an alternative to release of gas hydrates from the continental slopes. An early Eocene minimum in calculated Corg/Spy burial ratios (C/S mole ratio ≈2–4) suggests that the predominant locus of organic carbon burial shifted to euxinic environments in a warm early Eocene ocean.
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Aller R. C., 2003, Coupling of early diagenetic processes and sedimentary dynamics in tropical shelf environments: The Gulf of Papua deltaic complex, Cont. Shelf Res.
Baqri S. R. H., 1997, European Coal Geology and Technology, 237
Collinson M. E. Early Paleogene floras and land environments paper presented atClimate and Biota of the Early Paleogene International Meeting Nat. Sci. Found. Powell Wyo. July2001.
Corfield R. M., 1998, Late Paleocene‐Early Eocene Climatic and Biotic Events in the Marine and Terrestrial Records, 124
C. deBoor 1999 The Math Works Natick Mass.
Duff P. M. D., 1987, Mesozoic and Tertiary coals: A major world energy resource, Mod. Geology, 11, 29
Ellis M. S. G. L.Gunther A. M.Ochs S. B.Roberts E. M.Wilde J. H.Schuenemeyer H. C.Power G. D.Stricker andD.Blake Coal resources Powder River basin U.S. Geol. Surv. Prof. Pap. P 1625‐A 32 pp. 1999.
Holser W. T., 1988, Chemical Cycles in the Evolution of the Earth, 105
Jaleel A. G. S.Alam andS. A. A.Shah Coal resources of Thar Sindh Pakistan report vol.110 59 pp. Geol. Surv. of Pakistan 1999.
King C., 1981, The stratigraphy of the London Clay and associated deposits, Tertiary Res. Spec. Pap., 8, 1
Kump L. R., 1997, Tectonic Uplift and Climate Change, 400
Miller K. G., 1997, Cenozoic evolution of the New Jersey coastal plain: Changes in sea level, tectonics, and sediment supply, Proc. Ocean Drill. Program, Sci. Results, 150, 361
Oberhansli H., 1990, The Paleocene 13C‐event: Was it due to changes in the storage rate of terrestrial biomass?, Veroff. Ubersee Mus. Bremen Reihe A, 10, 99
Raymo M. E., 1997, Tectonic Uplift and Climate Change, 368
C. A. Ross J. R. P. Ross 1984 John Wiley Hoboken N. J.
W. H. Schlesinger 1997 Academic San Diego Calif.
Shackleton N. J., 1987, Marine Petroleum Source Rocks, 423
Shackleton N. J., 1984, Carbon isotope data from Leg 74 sediments, Initial Rep. Deep Sea Drill. Proj., 74, 613
Shackleton N. J., 1984, Oxygen and carbon isotope data from leg 74 foraminifers, Initial Rep. Deep Sea Drill. Proj., 74, 599
Shah M. R. I. A.Abbasi M.Haneef andA.Khan Nature origin and mode of occurrence of Hangu‐Kachai area coal district Kohat NWFP Pakistan: A preliminary study Geol. Bull.26 p.87–94 Univ. of Peshawar Peshawar Pakistan 1993.
Tucholke B. E., 1979, Western North Atlantic: Sedimentary evolution and aspects of tectonic history, Initial Rep. Deep Sea Drill. Proj., 43, 791
Wolfe J. A. A method of obtaining climatic parameters from leaf assemblages U.S. Geol. Surv. Bull. B 2040 71 pp. 1993.