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首页> 外文期刊>Geochemistry, geophysics, geosystems >Bivalve shell horizons in seafloor pockmarks of the last glacial-interglacial transition: a thousand years of methane emissions in the Arctic Ocean
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Bivalve shell horizons in seafloor pockmarks of the last glacial-interglacial transition: a thousand years of methane emissions in the Arctic Ocean

机译：上一次冰期至冰期间过渡的海底麻点上的双壳类贝壳层：北冰洋的甲烷排放量已有一千年

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We studied discrete bivalve shell horizons in two gravity cores from seafloor pockmarks on the Vestnesa Ridge (approximate to 1200 m water depth) and western Svalbard (79 degrees 00 N, 06 degrees 55 W) to provide insight into the temporal and spatial dynamics of seabed methane seeps. The shell beds, dominated by two genera of the family Vesicomyidae: Phreagena s.l. and Isorropodon sp., were 20-30 cm thick and centered at 250-400 cm deep in the cores. The carbon isotope composition of inorganic (C-13 from -13.02 to +2.36) and organic (C-13 from -29.28 to -21.33) shell material and a two-end member mixing model indicate that these taxa derived between 8% and 43% of their nutrition from chemosynthetic bacteria. In addition, negative C-13 values for planktonic foraminifera (-6.7 parts per thousand to -3.1 parts per thousand), concretions identified as methane-derived authigenic carbonates, and pyrite-encrusted fossil worm tubes at the shell horizons indicate a sustained paleo-methane seep environment. Combining sedimentation rates with C-14 ages for bivalve material from the shell horizons, we estimate the horizons persisted for about 1000 years between approximately 17,707 and 16,680 years B.P. (corrected). The seepage event over a 1000 year time interval was most likely associated with regional stress-related faulting and the subsequent release of overpressurized fluids.
机译：我们研究了两个重力岩心中离散的双壳壳层位，这些岩心来自于Vestnesa Ridge（约1200 m水深）和Svalbard西部（79度00 N，06度55 W）的海底麻点，以洞悉海床的时空动态甲烷渗出。带壳床，由维氏菌科的两个属：Phreagenas.l。和Isoropodon sp。，厚度为20-30厘米，中心位于250-400厘米深。无机（C-13从-13.02至+2.36）和有机（C-13从-29.28到-21.33）壳材料的碳同位素组成和两端成员混合模型表明，这些类群的衍生范围为8％至43他们的营养的％来自化学合成细菌。此外，浮游有孔虫的C-13值为负值（-6.7千分之至-3.1千分之三），被确定为甲烷来源的自生碳酸盐的胶结物以及在壳层范围内包裹有黄铁矿的化石蠕虫管表明了持续的古气候。甲烷渗透环境。将壳层中双壳类物质的沉积速率与C-14年龄相结合，我们估计该层在约17,707至16,680年之间持续了约1000年。 （已更正）。在1000年的时间间隔内发生的渗漏事件很可能与区域应力相关的断层以及随后释放的超压流体有关。

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