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海洋缺氧被认为是导致二叠纪末生物大灭绝的重要原因之一,但是缺氧时限和缺氧程度在不同地区的差异仍未得到很好的解决.为深入探索二叠纪-三叠纪之交浅水相区海洋缺氧的演变过程和形成机理,对位于“大贵州滩”台地内部打讲剖面的二叠系-三叠系界线地层中的生物组成和关键地球化学指标进行了系统研究.大灭绝前的浅水碳酸盐岩台地表现出低硫(总硫,黄铁矿硫),低黄铁矿硫/有机碳比值(硫黄铁矿/C有机),低黄铁矿化系数(DOP)的特征,同时记录了碳同位素的负偏和硫化氢气体释放事件,表明该时期以氧化环境为主;大灭绝后的各种地球化学指标显示浅水台地开始向贫氧-缺氧环境转变,但缺氧程度不高,主要为贫氧-缺氧相.以此为基础,本文提出该时期南盘江盆地古氧相的基本演变模式,即大灭绝前频繁的火山活动释放大量CO2,SO2等气体,使得气温出现上升,导致陆地生态系统开始瓦解,陆地风化速率加快,陆源输入的增加引发碳同位素负偏;与此同时,陆源物质输入的增加还导致海洋贫氧层(OMZ)扩张.当OMZ间歇性入侵透光带时,导致H2S气体向浅水台地释放,从而引发黄铁矿埋藏脉冲式上升的现象.大灭绝后,气温急剧上升,陆地风化速率加剧,OMZ急剧扩张,“大贵州滩”浅水台地开始向贫氧-缺氧环境转变.由此可见,二叠纪末的生物大灭绝是由火山活动增强,升温事件和海洋缺氧等一系列环境因素引发的.结合最新的研究结果,笔者认为该时期的升温事件是引发生物大灭绝的主导因素,同时也是导致海洋缺氧加剧的主要原因.此外,本文新的地球化学数据进一步证实了该地区的微生物岩形成于贫氧-缺氧环境.
Marine hypoxia is considered to be one of the most important causes of the extinction of Permian extinct organisms, but the difference of hypoxia duration and hypoxia in different areas has not yet been well solved.In order to further explore the Permian-Triassic The evolutionary process and formation mechanism of marine hypoxia in the shallow marine facies and the key geochemical indicators of the Permian-Triassic boundary stratigraphic stratigraphy located within the “Da Guizhou Beach” platform (Sulfur, pyrite sulfur), low pyrite sulfur / organic carbon ratio (pyrite / C organic), low-pyrite (DOP). At the same time, the negative partial bias of carbon isotopes and the release of hydrogen sulphide gas were recorded, indicating that the oxidation environment was dominant during this period. The various geochemical indicators after the mass extinction indicated that the shallow water platform started to move towards oxygen-deficient Oxygen environment changes, but the degree of anoxia is not high, mainly for the oxygen-poor phase.On the basis of this, this paper presents the basic evolution pattern of the Paleox phase in the Nanpanjiang Basin in this period, that is, frequent volcanic activity release before the mass extinction A large number of CO2, SO2 and other gases, making the temperature rise, resulting At the same time, the increase of terrestrial material input also led to the expansion of the oceanic oxygen-depleted layer (OMZ) .When the OMZ intermittently invaded the translucent zone , Leading to the release of H2S gas to the shallow platform, which led to the pulsatile pyrite burial.After the mass extinction, the temperature rose sharply, the weathering rate of the land increased, OMZ expanded rapidly, Oxygen - hypoxia environment change.Thus, the end of the Permian extinction was triggered by a series of environmental factors such as volcanic activity, warming events and marine hypoxia.According to the latest research results, I believe that during the period In addition, the new geochemical data of this paper further confirm that the microbial rocks formed in this region are in an oxygen-deficient-anoxic environment.