Permo-Triassic Extinctions: Relation to Sea-Floor Spreading
Permo-Triassic Extinctions: Relation to Sea-Floor Spreading
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二叠纪-三叠纪灭绝：与海底扩张的关系
DOI：
10.1086/627955
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发表时间：
1974
期刊：
影响因子：
--
通讯作者：
T. Schopf
中科院分区：
文献类型：
--
作者：
T. Schopf
对二叠纪-三叠纪动物群和古地理的分阶段分析支持了之前更一般性的总结，得出的结论是，在最后三个二叠纪阶段（32 m.y.），海洋无脊椎动物科的数量显着减少（基本上减半），并且灭绝没有明显的选择性。浅海覆盖率从早二叠世的40%减少到晚二叠世的不到15%，然后在下三叠世扩大到34%。如果浅海的明显减少是由于二叠纪晚期沉积物的选择性侵蚀造成的，那么除非海平面显着下降，否则似乎没有办法解释这一现象。或者，二叠纪晚期的海洋可能永远不会广泛分布，同样是由于海平面下降。明显的二叠纪晚期海洋退缩归因于水流入加深的海洋盆地。在板块连接增加期间，玄武岩海底在横向扩张的海脊异常长时间的冷却（和浮力下降）期间继续下沉，相应地海底扩张速度下降。最近的灭绝很可能是由于竞争和捕食造成的，通常是由于栖息地的改变而造成的。如果广阔的栖息地区域缩小为栖息地岛屿，竞争和捕食的影响就会大大增强。随着海平面显着降低，浅陆海将仅限于大陆边缘。浅海物种的地理范围将相应缩小，灭绝的可能性因此增加。也许不需要特殊的生物过程、大气变化或天文事件来解释“古生物学的突出困境”。
An analysis of the Permo-Triassic fauna and paleogeography on a stage-by-stage basis supports previous more general summaries by concluding that the number of families of marine invertebrates was significantly reduced (essentially halved) during the last three Permian stages (32 m.y.), and that the extinctions were not markedly selective. Shallow marine seas were reduced from a coverage of 40% of their possible distribution in the early Permian to less than 15% coverage in latest Permian, and then were expanded to 34% coverage in the lower Triassic. If this apparent reduction in shallow marine seas is due to selective erosion of late Permian sediments, there seems no way to account for it unless there was significant reduction in sea level. Alternatively, late Permian marine seas may never have been widespread, again due to lowering of sea level. The apparent late Permian marine regression is attributed to water withdrawing into a deepening ocean basin. The basaltic ocean bottom continued to sink during an unusually long period of cooling (and decreased buoyancy) of laterally spreading ocean ridges during a time of increased linking together of plates, and corresponding decreased rate of sea-floor spreading. Extinctions during the Recent are likely to result from competition and predation, often aided by habitat alteration. The effects of competition and predation are greatly enhanced if extensive habitat regions are reduced to habitat islands. With significant lowering of sea level, shallow epicontinental seas would become limited to continental margins. Geographic ranges of shallow marine species would correspondingly be reduced, and the probability of extinction therefore increased. Perhaps no extraordinary biologic process, atmospheric change, or astronomical event is necessary to account for "paleontology's outstanding dilemma."