DOI: 10.1111/gbi.12284
Scopus记录号: 2-s2.0-85044238972
论文题名: The taphonomic fate of isorenieratene in Lower Jurassic shales—controlled by iron?
作者: Reinhardt M. ; Duda J.-P. ; Blumenberg M. ; Ostertag-Henning C. ; Reitner J. ; Heim C. ; Thiel V.
刊名: Geobiology
ISSN: 1472-4677
EISSN: 1472-4669
出版年: 2018
卷: 16, 期: 3 起始页码: 237
结束页码: 251
语种: 英语
英文关键词: biomarkers
; Bächental
; catalytic hydropyrolysis (HyPy)
; kerogen
; Posidonia Shale
; Proterozoic ocean
Scopus关键词: Chlorobi
; Posidonia
Scopus学科分类: Earth and Planetary Sciences: General Earth and Planetary Sciences
; Environmental Science: General Environmental Science
; Agricultural and Biological Sciences: Ecology, Evolution, Behavior and Systematic
英文摘要: Fossil derivatives of isorenieratene, an accessory pigment in brown-colored green sulfur bacteria, are often used as tracers for photic zone anoxia through Earth's history, but their diagenetic behavior is still incompletely understood. Here, we assess the preservation of isorenieratene derivatives in organic-rich shales (1.5–8.4 wt.% TOC) from two Lower Jurassic anoxic systems (Bächental oil shale, Tyrol, Austria; Posidonia Shale, Baden-Württemberg, Germany). Bitumens and kerogens were investigated using catalytic hydropyrolysis (HyPy), closed-system hydrous pyrolysis (in gold capsules), gas chromatography–mass spectrometry (GC–MS) and gas chromatography combustion isotope ratio-mass spectrometry (GC-C-IRMS). Petrography and biomarkers indicate a syngenetic relationship between bitumens and kerogens. All bitumens contain abundant isorenieratane, diverse complex aromatized isorenieratene derivatives, and a pseudohomologous series of 2,3,6-trimethyl aryl isoprenoids. In contrast, HyPy and mild closed-system hydrous pyrolysis of the kerogens yielded only minor amounts of these compounds. Given the overall low maturity of the organic matter (below oil window), it appears that isorenieratene and its abundant derivatives from the bitumen had not been incorporated into the kerogens. Accordingly, sulfur cross-linking, the key mechanism for sequestration of functionalized lipids into kerogens in anoxic systems, was not effective in the Jurassic environments studied. We explain this by (i) early cyclization/aromatization and (ii) hydrogenation reactions that have prevented effective sulfurization. In addition, (iii) sulfide was locally removed via anoxygenic photosynthesis and efficiently trapped by the reaction with sedimentary iron, as further indicated by elevated iron contents (4.0–8.7 wt.%) and the presence of abundant pyrite aggregates in the rock matrix. Although the combined processes have hampered the kerogen incorporation of isorenieratene and its derivatives, they may have promoted the long-term preservation of these biomarkers in the bitumen fraction via early defunctionalization. This particular taphonomy of aromatic carotenoids has to be considered in studies of anoxic iron-rich environments (e.g., the Proterozoic ocean). © 2018 John Wiley & Sons Ltd Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/85006
Appears in Collections: 影响、适应和脆弱性
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作者单位: Department of Geobiology, Geoscience Centre, University of Göttingen, Göttingen, Germany; Planets and Comets, Max Planck Institute for Solar System Research, Göttingen, Germany; ‘Origin of Life’ Group, Göttingen Academy of Sciences and Humanities, Göttingen, Germany; Federal Institute for Geosciences and Natural Resources, Hannover, Germany
Recommended Citation:
Reinhardt M.,Duda J.-P.,Blumenberg M.,et al. The taphonomic fate of isorenieratene in Lower Jurassic shales—controlled by iron?[J]. Geobiology,2018-01-01,16(3)