四川北川甘溪地区下泥盆统风暴沉积研究及其地质意义

发布时间：2018-07-28 18:24

【摘要】：本文以四川北川甘溪下泥盆统甘溪剖面的野外风暴沉积剖面实测资料为依据,通过对甘溪组、谢家湾组和养马坝组野外剖面结构和沉积演化等的研究,进而建立甘溪组、谢家湾组和养马坝组风暴沉积序列及分布模式,结合风暴岩铸体薄片微观分析,初步探讨风暴岩的的形成及其地质意义。北川甘溪下泥盆统甘溪组、谢家湾组和养马坝组广泛发育着风暴沉积,多期次风暴沉积垂向叠置,风暴沉积特征明显,侵蚀冲刷面、渠模构造、生物介壳滞留沉积、平行层理、丘状交错层理和生物成因构造等风暴沉积构造发育,其中发育7类风暴沉积序列类型与3类风暴沉积类型:近源砂质风暴沉积、近源混积风暴沉积和远源砂质风暴沉积,其中,甘溪组、谢家湾组下段发育近源砂质风暴沉积,谢家湾组上段上部和养马坝组发育近源混积风暴沉积,而谢家湾组上段下部发育远源砂质风暴沉积。发育较典型的风暴序列由侵蚀冲刷面和渠模(Sa)、生物介壳滞留层段(Sb)、平行层理段(Sc)、丘状交错层理段(Sd)和泥岩段(Se)组成。北川甘溪下泥盆统甘溪组、谢家湾组和养马坝组风暴岩岩性主要有:粉砂岩、泥质粉砂岩、含生屑泥质粉砂岩和砂质生屑灰岩,其中粉砂岩泥质杂基含量较少,颗粒分选磨圆较好,指示风暴对其改造具有一定建设性作用。风暴沉积研究的地质意义包括等时意义,古纬度意义,古地理意义,研究讨论后确定甘溪地区下泥盆统地层当时所处热带亚热带的低纬度地区,沉积环境为浅海陆棚。
[Abstract]:Based on the field storm sedimentary profile of the lower Devonian Ganxi section in Ganxi, Beichuan, Sichuan Province, this paper studies the structure and sedimentary evolution of the field profile of Ganxi formation, Xie Jiawan formation and Yangmaba formation, and then establishes the Ganxi formation. The formation of storm rock and its geological significance are preliminarily discussed by combining the storm sedimentary sequence and distribution model of the Xiejiawan and Yangmaba formations with the microscopic analysis of the thin section of the storm rock cast. Storm deposits are widely developed in the lower Devonian Ganxi formation, Xie Jiawan formation and Yangmaba formation in Beichuan, Ganxi Basin, and Yangmaba formation, with vertical superposition of multi-stage storm deposition, obvious storm deposition characteristics, erosion surface, canal model structure, biological crust retention deposition, parallel stratification, etc. There are 7 types of storm sedimentary sequence types and 3 types of storm sedimentary types: near source sand storm deposition, near source mixed storm deposition and distant source sand storm deposition, among which, 7 types of storm sedimentary sequence and 3 types of storm sedimentary types are developed. Near source sandstorm deposits were developed in the lower member of Ganxi formation and Xijiawan formation, near source mixed storm deposition in upper part of the upper member of Xie Jiawan formation and Yangmaba formation, and distant sandstorm deposit in lower part of upper member of Xie Jia Wan formation. The typical storm sequence is composed of erosion surface and channel model (Sa), biologic shell retention section (Sb), parallel bedding segment (Sc), mound staggered bedding segment (Sd) and mudstone segment (Se). The storm lithology of the lower Devonian Ganxi formation, Xiejiawan formation and Yangmaba formation in Beichuan Ganxi Basin are mainly composed of siltstone, argillaceous siltstone, shredded siltstone and sandy shredded limestone. The particle separation and grinding round is better, indicating that the storm has a constructive effect on its transformation. The geological significance of storm sedimentary research includes isochronous, paleolatitude and paleogeographic significance. It is determined that the lower Devonian strata of Ganxi area were located in the low latitude of tropical subtropics at that time, and the sedimentary environment was shallow sea shelf.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P512.2

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