四川峨眉山地区白垩系物源

Study of Cretaceous provenance in Emeishan area,Sichuan,China

在对四川峨眉山地区白垩系夹关组、灌口组进行野外剖面研究和薄片鉴定的基础上,对岩石的地球化学特征进行分析,探讨峨眉山地区白垩系沉积时期的主要物源区。研究发现:岩石颗粒的磨圆度和分选性反映出近源沉积的特征;碎屑成分特征表明其主要来源于含有较多中酸性岩浆岩的源区;地球化学特征表明物源区是以长英质岩石为主的大陆岛弧构造背景。结合前人对四川盆地白垩纪古地形特征的研究成果,认为夹关组和灌口组沉积时期峨眉山地区的主要物源区为龙门山构造带。

Based on the field profile study and thin section identification of the Cretaceous Jiaguan Formation and Guankou Formation in Emeishan area,Sichuan Province,the geochemical characteristics of the rocks are analyzed,and the main provenances of the Cretaceous sedimentary period in Emeishan area are discussed.It is found that the roundness and sorting of rock particles of Jiaguan Formation and Guankou Formation reflect the characteristics of near-source deposits.The characteristics of the detrital composition show that it is mainly from the source area containing more intermediate acid magmatic rocks.The study of geochemical characteristics indicates that the provenance area is a continental island arc tectonic setting dominated by felsic rocks.Combined with the previous research results on the Cretaceous paleo-topographic features of Sichuan Basin,it is considered that the main provenance of Emeishan area during the depositional period of Jiaguan and Guankou Formations is the Longmenshan tectonic belt.