西秦岭岷县地区二叠纪裂陷带斜坡沉积及其构造意义

秦岭造山带西段，二叠纪裂陷作用非常活跃。位于西秦岭中部的岷县红崖、梅州一带，二叠系以粉碎屑沉积为主，泥质较少。根据对其岩石类型、沉积构造、岩石组合和生物特征的分析，认为这套地层主要形成于海底扇体系的内扇和中扇环境，外扇不发育，系由碎屑流和浊流沉积组成，包括内扇的水道和水下天然堤沉积及中扇的网状水道和朵叶体沉积。这套地层沿中秦岭南缘呈ＮＷＷ－ＳＥＥ方向延伸，代表了二叠纪西秦岭裂谷的存在及其继续裂陷的活动特征。

SLOPE DEPOSITS AND THEIR TECTONIC SIGNIFICANCE OF PERMIAN RIFT-AND-SAG BELT IN MINXIAN AREA, WEST QINLING

he slope deposits and their tectonic significance of Permian rift-and-sag belt in Minxian area,the west Qinling are studied. The west Qinling orogenic belts were in an active rifting period in the Permian. The deposits of Permian in Hongya and Meichuan areas,Minxian county consist mainly of coarse elastic sediments and rare mudrocks. On the basis of analysing the rock types, sedimentary structures, rock assemblages and fossil features,the deposits can be recognized as submarine fan system chiefly including inner-fan and midfan associations and rare outer fan, and were deposited by debris flow and turbid flow. The sediments of inner-fan are composed of that in channels and submarine levees the mid-fan are made up of network channels and lobe. The strata extending along the southern margin of the mid-Qinling in NWW -SEE direction represent the existence of the west Qinling rift and its active characters in the Permian.