Pyrite framboid evidence for oxygen-poor deposition during the Permian-Triassic crisis in Kashmir
Pyrite framboid evidence for oxygen-poor deposition during the Permian-Triassic crisis in Kashmir
复制标题
DOI：
10.1016/j.palaeo.2004.10.009
复制
发表时间：
2005-02
期刊：
影响因子：
--
通讯作者：
P. Wignall;R. Newton;M. Brookfield
中科院分区：
文献类型：
--
作者：
P. Wignall;R. Newton;M. Brookfield
克什米尔Guryul峡谷剖面的Khunamuh组提供了Perigondwanan古纬度的二叠纪末大灭绝的最详细的深水记录之一。对草莓状黄铁矿粒度分布和沉积物微结构的研究表明，在二叠系上部地层中，从非层状、不含黄铁矿的粉质泥岩到在地层底部上方约1 m处富含草莓状黄铁矿的粉质页岩发生了明显的变化。树状体的大小频率分布与来自严重缺氧的现代沉积环境的种群相同。这种底栖动物缺氧条件的变化与二叠纪各种腕足动物和苔藓虫群落的迅速消亡相吻合。因此，灭绝与缺氧之间的联系在Guryul峡谷清晰可见，它与其他在较浅水域发育的Perigondwanan剖面形成了有趣的对比，在较浅水域缺氧的开始和灭绝都发生在早三叠纪晚些时候。
The Khunamuh Formation of the Guryul Ravine section in Kashmir provides one of the most detailed deep-water records of the end-Permian mass extinction in Perigondwanan palaeolatitudes. Examination of pyrite framboid size distributions and sediment microfabric reveals a distinct change in the uppermost Permian strata from nonlaminated, pyrite-free silty mudstones to finely laminated, silty shales rich in framboidal pyrite around 1 m above the base of the formation. The size frequency distribution of the framboids is identical to populations from severely oxygen-restricted modern depositional environments. This change to dysoxic benthic conditions coincides with the rapid demise of diverse Permian brachiopod and bryozoan assemblages. Thus, the link between extinction and anoxia is clearly seen at Guryul Ravine and it provides an interesting contrast to other Perigondwanan sections developed in shallower water where both the onset of anoxia and the extinction occurred somewhat later in the earliest Triassic.