Methane-derived carbonate conduits from the late Aptian of Salinac (Marne Bleues, Vocontian Basin, France): Petrology and biosignatures
Methane-derived carbonate conduits from the late Aptian of Salinac (Marne Bleues, Vocontian Basin, France): Petrology and biosignatures
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DOI：
10.1016/j.marpetgeo.2015.05.029
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发表时间：
2015-09-01
影响因子：
4.2
通讯作者：
Duda, Jan-Peter
中科院分区：
文献类型：
--
作者：
Reitner, Joachim;Blumenberg, Martin;Duda, Jan-Peter
特殊的碳酸盐体出现在Marnes Bleues组（Aptian-Albian，Vocontian盆地，法国南部）的不同泥灰岩层中。碳酸盐管道呈管状或香肠状，并有一条中央水道。它们的大小在30至60厘米长和5至10厘米直径之间。导管碳酸盐岩由沉积物中自生的自晶灰岩组成。毫米大小的聚集体framboidal黄铁矿丰富的导管内automicrites，可能代表前殖民地的硫酸盐还原菌。中央通道反映了碳酸盐岩导管中还原流体的前路径。在中央腔的边缘处的Ni富集可能是由于甲烷相关代谢的活性，因为Ni是相应微生物的重要生物元素。导管自凝灰岩的轻稳定碳同位素比（-25.86 ‰至-23.10 ‰，VPDB）表明与甲烷厌氧氧化（AOM）有关的碳酸盐沉淀，而中央开口边缘区的微晶石的稳定碳同位素比（-8.96 ‰ VPDB）与微生物硫酸盐还原一致。导管碳酸盐的甲烷相关起源通过存在自生脂质生物标志物来证实，这些生物标志物暂时来源于古生菌，其中大部分特征在于强烈的C-13消耗（Δ C-13值降至千分之-104）。有机结合硫的存在与微生物硫酸盐还原完全一致。Isorenieratane可能表明存在棕色绿色硫细菌。甲烷可能来源于较老的OAE黑色页岩，已知这些页岩含有同位素（δ C-13）重的古生菌生物标志物，如其他地方所报道的。(C)2015爱思唯尔有限公司版权所有。
Peculiar carbonate bodies occur in distinct marl layers of the Marnes Bleues Formation (Aptian-Albian, Vocontian Basin, Southern France). The carbonate conduits exhibit pipe- or sausage-like forms and a central channel. Their sizes range between 30 and 60 cm in length and 5-10 cm in diameter. The conduit carbonates consist of automicrite authigenically formed within the sediment. Millimeter-sized aggregates of framboidal pyrite are abundant within the conduit automicrites, probably representing former colonies of sulfate reducing bacteria. The central channel reflects former pathways of reduced fluids in the carbonate conduit. Ni-enrichments at the margins of the central cavity are may be due to the activity of methane-related metabolism as Ni is an important bio-element for respective microbes. Light stable carbon isotope ratios of the conduit automicrites (-25.86 parts per thousand, to -23.10 parts per thousand, VPDB) point to carbonate precipitation linked to anaerobic oxidation of methane (AOM), while less depleted stable carbon isotope ratios of microspar in marginal zones of the central opening (-8.96 parts per thousand VPDB) are in line with microbial sulfate reduction. A methane-related origin of the conduit carbonates is confirmed by the presence of authigenic lipid biomarkers tentatively sourced by archaea most of which are characterized by strong C-13 depletions (delta C-13 values down to -104 parts per thousand). The presence of organically bound sulfur is well in line with microbial sulfate reduction. Isorenieratane potentially point to the presence of brown pigmented green sulfur bacteria. The methane was probably sourced by older OAE black shales which are known to contain isotopically (delta C-13) heavy biomarkers of archaea as reported elsewhere. (C) 2015 Elsevier Ltd. All rights reserved.