米仓山前缘早志留世软沉积物变形构造及其触发机制

发布时间：2018-05-01 12:08

本文选题：软沉积物变形构造 + 风暴作用　；参考：《沉积学报》2017年02期

【摘要】：地质历史时期软沉积物变形构造在不同时空沉积岩中均有分布,然而学术界对其变形过程、作用力及触发机制等仍存在许多争议。通过对米仓山前缘野外露头观测,早志留世砂岩、粉砂岩、页岩地层中,发育有多套软沉积物变形构造,其层位分布稳定,但不同层位的形态特征差异较大,包括波浪状变形层构造、包卷层理、枕状(椭球状)构造、火焰构造等,多与丘状交错层理相伴生,可分为三种组合类型,均发育于中陆棚沉积环境中。基于该区软沉积物变形构造特征,结合碳同位素分析、古气候、古板块资料,并与现代飓风研究成果对比,认为研究区早志留世时大体上处于风暴频繁的炎热环境,区内软沉积物变形构造多为风暴作用的结果,较强的风暴触及海底,使未固结成岩的沉积物的孔隙压力增加,切变强度降低,使之液化,进而发生变形。米仓山前缘早志留世软沉积物变形构造的发现及其触发机制的探讨对区内古地理、古气候的恢复,以及古扬子板块的演化具有重要的意义。
[Abstract]:In geological history, the deformation structures of soft sediments are distributed in different space-time sedimentary rocks. However, there are still many controversies in academic circles about their deformation process, force and trigger mechanism. Through field outcrop observation on the front edge of Micang Mountain, it is found that there are many sets of soft sediment deformation structures developed in early Silurian sandstone, siltstone and shale strata, and their horizon distribution is stable, but the morphological characteristics of different strata are quite different. It includes wavy deformed layer structure, encrusted bedding, pillow (ellipsoid) structure, flame structure and so on, which are associated with mound interlaced bedding, and can be divided into three kinds of assemblage types, all of which are developed in the middle shelf sedimentary environment. Based on the structural characteristics of soft sediment deformation, combined with carbon isotope analysis, paleoclimate and paleo-plate data, and compared with the results of modern hurricane research, it is considered that the early Silurian period in the study area was generally in a hot environment with frequent storms. The deformation structure of soft sediment in this area is mostly the result of storm action, and the stronger storm touches the seabed, which increases the pore pressure of unconsolidated diagenetic sediments, decreases the shear strength, and results in the liquefaction and deformation of the unconsolidated diagenetic sediments. The discovery of early Silurian soft sediment deformation structure and its triggering mechanism are of great significance to paleogeography, paleoclimate recovery and paleo-Yangtze plate evolution.
【作者单位】：西南石油大学油气藏地质与开发工程国家重点实验室;西南石油大学地球科学与技术学院;
【基金】：国家自然科学基金项目(41272135)~~
【分类号】：P534.43;P512.2

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