DOI: 10.1016/j.palaeo.2015.08.020
论文题名: Carbon cycling across the southern margin of Laurentia during the Late Ordovician
作者: Quinton P.C. ; Herrmann A.D. ; Leslie S.A. ; MacLeod K.G.
刊名: Palaeogeography, Palaeoclimatology, Palaeoecology
ISSN: 0031-0182
出版年: 2016
卷: 458 起始页码: 63
结束页码: 76
语种: 英语
英文关键词: Carbon cycle
; Carbon isotopes
; GICE
; Guttenberg isotope carbon excursion
; Ordovician
英文摘要: The Guttenberg Isotope Carbon Excursion (GICE), a positive carbon isotope excursion that occurs near the base of the Katian Stage, is thought to be a global event possibly related to Late Ordovician cooling. Documenting how much regional and global variability exists in carbon isotopic trends prior to and during the GICE is a critical aspect in understanding the implications of the excursion for interpreting changes in the global carbon cycle, paleoclimate, and chemostratigraphic correlation during the Ordovician. To investigate carbon isotopic trends along the southern margin of the Laurentian carbonate platform during the Late Ordovician, we measured bulk carbonate δ13Ccarb and δ18Ocarb as well as organic carbon δ13Corg values from four locations in Alabama. These sections are excellent study sites because they are well exposed, contain the regionally well-correlated Deicke and Millbrig K-bentonites, and are in a region where δ13C trends have not been studied. Carbonate δ13Ccarb results from one section (i.e. Fort Payne) in northeastern Alabama record a 1.5‰ positive excursion above the Millbrig K-bentonite. We interpret the 1.5‰ positive excursion as a primary feature and identify it as the GICE. The characteristic GICE excursion is absent in the other study sections and we attribute this absence to the presence of unconformities (either non-depositional or erosional) in these sections. We find neither evidence for sea level control on δ13C trends nor conclusive evidence for δ13CDIC gradients along the southeast margin of Laurentia's epeiric sea. Combined with the proximity to the Iapetus Ocean, these results suggest that carbon isotopic trends in Alabama are a reliable proxy for open ocean conditions. Therefore, despite the absence of GICE excursion in all but one of our study sections, increasing δ13C values in Alabama prior to the GICE provides evidence for a steady 13C enrichment of the global surficial carbon reservoir consistent with a drawdown of atmospheric CO2 during the early Late Ordovician © 2015 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/68326
Appears in Collections: 过去全球变化的重建
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作者单位: Department of Geological Sciences, University of Missouri, Columbia, MO, United States; Department of Geology and Geophysics, Coastal Studies Institute E301/302 Howe-Russell Geoscience Complex, Louisiana State University, Baton Rouge, LA, United States; Department of Geology and Environmental Science, James Madison University, 395 South High St., MSC 6903, Harrisonburg, VA, United States
Recommended Citation:
Quinton P.C.,Herrmann A.D.,Leslie S.A.,et al. Carbon cycling across the southern margin of Laurentia during the Late Ordovician[J]. Palaeogeography, Palaeoclimatology, Palaeoecology,2016-01-01,458