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上扬子地区下三叠统飞仙关组下部薄层状、纹层状微晶灰岩、泥质灰岩之上普遍发育与风暴作用有关的角砾状灰岩、“错时相”扁平砾屑灰岩、丘状交错层理颗粒灰岩或粉砂岩,这一现象在南阿尔卑斯、伊朗、克什米尔等地的早三叠世早期地层中也广泛存在,其等时性有待深入研究。从薄层状、纹层状灰岩到砾屑灰岩的岩性转换表明,特提斯洋沿岸陆架地区的古海洋水动力条件在早三叠世早期经历了从停滞到动荡的显著变化。岩石学特征显示纹层状、薄层状灰岩泥质含量较高且普遍缺乏反映浅水暴露的沉积构造标志,表明其形成水体相对较深,为低能环境的产物,指示了当时静止、停滞的海洋环境;角砾状灰岩、扁平砾屑灰岩中丘状交错层理以及“菊花状”构造的大量出现则表明其形成是风暴引起的高度搅动的水体对弱固结的碳酸盐沉积物进行打碎、撕裂、搬运等再改造作用的结果,代表了动荡的海洋环境。薄层灰岩、纹层灰岩中生物扰动较弱,反映了P-T事件后萧条的海洋生态系统对底栖生物垂直钻孔作用的限制,生物扰动作用的缺乏有利于薄层、纹层灰岩的发育和保存;而触发大范围砾屑沉积的风暴活动则可能与当时全球CO2增多导致的全球变暖、海水温度升高,特提斯洋所处的古地理位置以及当时盛行的巨型季风气候等多种因素有关。
Upper part of Lower Triassic Feixianguan Formation Upper Triassic Feixianguan Formation thin layer, laminar micritrite, argillaceous limestone on the development of storm-effect associated with the brecciated limestone, “wrong phase ” flat Boulder limestone, mound-shaped interlayered granular limestone or siltstone. This phenomenon is also widespread in the early Triassic strata in the Southern Alps, Iran and Kashmir. Its isochronicity needs further study. Lithological transformations from thinly layered, laminar limestone to gravelly limestone indicate that paleoceanographic hydrodynamic conditions on the Shelf of the Tethys Ocean experienced a significant change from stasis to turbulence in the early Triassic. Petrological characteristics show that the laminar and thin-layered limestones have high shale content and generally lack sedimentary structures that reflect shallow water exposures, indicating that their formation of relatively deep bodies of water is a product of low-energy environments, indicating the then still and stagnant Marine environments; brecciated-like limestone, mound-like interlayered bedding in flat gravelly limestones, and the large number of “daisy-like” tectons show the formation of highly agitated bodies of water that are highly turbulent to weakly consolidated carbonate Salt sediments broken, tearing, handling and other re-transformation of the results, representing the turmoil in the marine environment. The bioturbation in thin-bedded limestone and laminar limestone is weak, which reflects the limitation of vertical drilling of benthic organisms by depressed marine ecosystems after the PT event. The lack of bioturbation is conducive to thin layer, laminar limestone While the storm activities triggering extensive gravel deposition may be related to the then global warming caused by the increase of global CO2, the increase of seawater temperature, the paleogeographical location of the Tethys Ocean and the then prevailing monsoon climate A variety of factors.