DOI: 10.1016/j.palaeo.2015.03.022
论文题名: Nearshore euxinia in the photic zone of an ancient sea
作者: Słowakiewicz M. ; Tucker M.E. ; Perri E. ; Pancost R.D.
刊名: Palaeogeography, Palaeoclimatology, Palaeoecology
ISSN: 0031-0182
出版年: 2015
卷: 426 起始页码: 242
结束页码: 259
语种: 英语
英文关键词: Carbon isotopes
; Late Permian
; Nearshore euxinia
; Organic matter
英文摘要: Evidence for photic zone euxinia (PZE) in ancient oceans is widespread and commonly associated with global climate change and biotic events. However, evidence of PZE in marginal settings is commonly extrapolated to infer basin-scale characteristics. To explore the relationship between euxinia in marginal settings and the wider basin in one Palaeozoic context, we have conducted a detailed spatial and temporal examination the palaeowater-column redox state from the Polish sector of the Southern Permian Basin (SPB) during deposition of the Zechstein (Lopingian) second carbonate (Main Dolomite) cycle. Sediments from toe-of-slope, slope and hypersaline lagoonal settings of the northeastern margin of the SPB contain abundant chlorobactane, isorenieratane and their likely degradation products (C15 to C31 2,3,6-aryl isoprenoids). These indicate that part of the photic zone was euxinic during significant intervals of the Main Dolomite deposition. Further evidence for strongly anoxic conditions includes the occurrence of C28 -bisnorhopane, high concentrations of pentakishomohopanes (i.e. high homohopane indices), and the occurrence of framboidal and native sulphur crystals in slope facies. However, a lack of these signatures in basinal settings indicates that strongly reducing conditions were restricted to the slope, and toe-of-slope locations. Even in these settings, however, highly variable homohopane indices and concentrations of isorenieratene and chlorobactene derivatives, as well as the presence of benthic fauna and bioturbation, indicate that anoxia fluctuated throughout deposition of the Main Dolomite, likely on a variety of timescales. Sterane distributions are also variable, suggesting a dynamic ecosystem, likely exhibiting a strong response to environmental forcing. Overall, it appears that high but episodic primary bioproductivity of organic matter was concentrated on the northeastern slope and restricted lagoons leading to the formation of source rocks for petroleum; however, the temporal and geographical restriction of anoxia appears to have prevented the accumulation of large or more widespread quantities of organic matter, and in fact TOC contents exhibit poor correlation with ecological and anoxia indicators. This model indicates that strong evidence for PZE in shelf and slope facies need not be associated with widespread, basin-scale anoxia, with implications for organic matter burial, carbon cycling and biotic crises. © 2015 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/68972
Appears in Collections: 过去全球变化的重建
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作者单位: Organic Geochemistry Unit, School of Chemistry, University of Bristol, Cantock's Close, United Kingdom; Polish Geological Institute, Rakowiecka 4, Warszawa, Poland; Cabot Institute, University of Bristol, Cantock's Close, United Kingdom; Department of Earth Sciences, University of Bristol, United Kingdom; Dipartimento di Biologia, Ecologia e Science della Terra, Università della Calabria, Via P. Bucci Cubo 15b, Rende, Italy
Recommended Citation:
Słowakiewicz M.,Tucker M.E.,Perri E.,et al. Nearshore euxinia in the photic zone of an ancient sea[J]. Palaeogeography, Palaeoclimatology, Palaeoecology,2015-01-01,426