古地理学报2018，Vol.20Issue(2)：207-218,12.DOI:10.7605/gdlxb.2018.02.015
四川龙门山区中泥盆统金宝石组核形石岩石学特征及其成因
Petrologic characteristics and genesis analysis of oncoids from the Middle Devonian Jinbaoshi Formation in Longmenshan area, Sichuan Province
摘要
Abstract
A set of oncoidal limestone was developed in the top of Jinbaoshi Formation of Middle Devonian in Longmenshan area,Sichuan Province.Based on field profile survey and detailed observation under the microscope,the oncoidal limestone could be divided into three sedimentary cycles vertically.Each cycle was composed of oncoidal limestone and micrite.Girvanella filaments can be seen in both the core nd cortex of oncoids,and they played an important role in the formation of oncoid.Combined with the types of laminae,morphology of Girvanella filaments,and the relationship between infiltration sand and laminae,it can be concluded that the oncoids were formed in bank and lagoon in the reef back.There are two types of infiltration sands,intragranular and intergranule sands,subjected to leaching of meteoric water during the exposure after the oncoids deposition.By analysis of the formation environment of oncoids,it can be concluded that the hydrodynamic condition gradually diminished from bottom to top,reflecting agradual rise of the relative sea level at that time.关键词
核形石特征/环境分析/成因分析/金宝石组/龙门山区Key words
characteristics of oncoid/environmental analysis/genesis analysis/Jinbaoshi Formation/Longmenshan area分类
天文与地球科学引用本文复制引用
成晓雨,李凤杰,荆锡贵,沈凡,张昊..四川龙门山区中泥盆统金宝石组核形石岩石学特征及其成因[J].古地理学报,2018,20(2):207-218,12.基金项目
国家自然科学基金项目(编号:41172100),成都理工大学沉积地质学科研创新团队项目(编号:KYTD201703)共同资助.Co-funded by the National Natural Science Foundation of China(No.41172100) and Project of Sedimentary Geology Subject Innovation Team in Chengdu University of Technology (No.KYTD201703) （编号:41172100）
