High-frequency fluctuations in redox conditions during the latest Permian mass extinction
High-frequency fluctuations in redox conditions during the latest Permian mass extinction
复制标题
DOI：
10.1016/j.palaeo.2017.06.014
复制
发表时间：
2017-11
期刊：
影响因子：
--
通讯作者：
C. Mettam;A. Zerkle;M. Claire;G. Izon;C. J. Junium;R. Twitchett
中科院分区：
文献类型：
--
作者：
C. Mettam;A. Zerkle;M. Claire;G. Izon;C. J. Junium;R. Twitchett
来自东格陵兰岛费斯凯格拉夫的新的高分辨率地球化学和沉积学数据揭示了与最近二叠纪大灭绝(LPME)期间生物扰动生物最终消失有关的海洋氧化还原条件的波动。沉积学观察表明这是一次海侵事件，与氧可获得性降低和持续富铁(Fe2+-富)条件的建立相关的地球化学证据表明，缺氧水域向岸边迁移。提高水温、降低氧的溶解度并促进热分层，可能会加剧溶解氧(DO)有效性的长期下降。淡水的流入可能会进一步抑制水柱的混合，这可能会产生盐度反差，从而加强热分层。径流增加也可能增加营养物质向海洋陆架的输送，刺激生物需氧量(BOD)。在过渡到持续的铁质条件期间，我们确定了间歇性底栖小型底栖动物重新定居的间歇性，我们将这些事件归因于DO可获得性的小幅瞬时增加。控制这些波动的机制仍然是推测的，但考虑到这些变化可能在百年到千年尺度上的频率，我们假设晚二叠世费斯凯格拉夫的中纬度环境对大气环流模式的变化很敏感，这可能影响了当地的降水，并间歇性地调制了一些促进缺氧的过程。
New high-resolution geochemical and sedimentological data from Fiskegrav, East Greenland, reveal fluctuations in marine redox conditions associated with the final disappearance of bioturbating organisms during the latest Permian mass extinction (LPME). Sedimentological observations imply a transgressive episode, and associated geochemical evidence for decreasing oxygen availability and the establishment of persistently ferruginous (Fe2 +-rich) conditions implies the shoreward migration of oxygen deficient waters. The long-term decline in dissolved oxygen (DO) availability could have been exacerbated by increasing water temperatures, reducing the solubility of oxygen and promoting thermal stratification. Mixing of the water column could have been further inhibited by freshwater influxes that could have generated salinity contrasts that reinforced thermal stratification. Enhanced runoff could also have increased the delivery of nutrients to the marine shelf, stimulating biological oxygen demand (BOD). During the transition to persistently ferruginous conditions we identify intervals of intermittent benthic meiofaunal recolonization, events that we attribute to small transient increases in DO availability. The mechanism controlling these fluctuations remains speculative, but given the possible centennial- to millennial-scale frequency of these changes, we hypothesise that the mid-latitude setting of Fiskegrav during the Late Permian was sensitive to changes in atmospheric circulation patterns, which may have influenced local precipitation and intermittently modulated some of the processes promoting anoxia.