西秦岭北缘漳县中-新生代红层地层格架厘定及其地质意义  

Stratigraphic Framework of Mesozoic-Cenozoic Red Bed in Zhang County,Northern Margin of Western Qinling and Its Geological Significance

作　　者：郭进京[1] 韩文峰[1] 赵海涛[1] 胡晓隆 王利晓[1] 

机构地区：[1]天津城建大学地质与测绘学院,天津300384 [2]甘肃省地质矿产勘查开发局第一地质矿产勘查院,甘肃天水741020

出　　处：《西北地质》2016年第1期82-91,共10页Northwestern Geology

基　　金：国家自然科学基金项目资助(41340002、41072149)

摘　　要：西秦岭北缘潭县地区分布的中—新生代红层地层格架和时代一直存在争议。该地区红层地层格架的正确厘定对于重建西秦岭北缘中—新生代构造地貌演化过程和认识印度-欧亚板块汇聚碰撞过程在青藏高原东北缘的远程地质响应具有重要的科学意义。通过对红层地层与下伏老地层以及不同红层地层之间的角度不整合、红层沉积序列及岩石学特征和红层地层与西秦岭北缘断层之间关系的研究,结合孢粉分析资料,重新厘定了西秦岭北缘漳县地区的红层沉积地层地质格架。研究表明,西秦岭漳县地区分布的中—新生代红层地层自下而上可分为三套地层系统,即①下白垩统紫红色砂岩、砾岩。②中新统红色砾岩、砂岩、黏土岩和深紫色-灰色泥岩、灰色泥灰岩、蒸发岩系。③上新统河流相砾岩层(韩家沟砾岩)和F1断层以北的红色洪积砾岩层。三套红层地层之间都为角度不整合面分割,相对地质关系清晰,沉积岩石特征差异明显,尽管由于断层的破坏,但没有影响到整体地层格架。三套红层地层系统反映了西秦岭北缘中—新生代不同阶段的沉积构造环境和古地貌演化过程,为研究西秦岭中—新生代陆内构造过程和青藏高原隆升、构造变形向东北缘的扩展远程效应等科学问题提供了基本的地质约束。The Mesozoic-Cenozoic red beds are distributed in Zhang County, northern margin of Western Qinling, their stratigraphic frameworks and ages have long been controversial. The stra- tigraphic framework of these red beds has been established in this paper, which is essential for re- storing the Mesozoic-Cenozoic tectonic evolution about the northern margin of Western Qinling,and for understanding the remote geological responses to the collision and convergence process of India-Eurasian plate in the northeastern margin of Qinghai-Tibet plateau. After studying the an- gular unconformities between these red beds and their underlying strata, the angular unconformi- ties among different red beds, analysing the sedimentary sequence and stratigraphic characteris- tics of these red beds, and discussing the relationships between these red beds and the faults in the northern margin of Western Qinling, the stratigraphic framework of these red beds in Zhang County has been revised through combining the data of pollen analysis. The results confirm that the Mesozoic-Cenozoic red beds in Zhang County can he divided into three different stratigraphic units separated by angular unconformities, which include① Lower Cretaceous purple red sand- stone and conglomerate. ② Oligocene-Miocene red conglomerate, sandstone and claystone, deep purple-grey mudstone, grey marl and evaporation rocks. ③ Pliocene fluvial conglomerate layer, that is, Hanjiagou conglomerate and pluvial conglomerate layer north of F1 fault. Three sedimen- tary stratigraphic units for these red beds in Zhang County stand for the sedimentary tectonic en- vironment and ancient landform evolution process in the northern margin of Western Qinling, providing the basic geological constraints to understand the Mesozoic- Cenozoic intracontinental tectonic processes of Western Qinling, as well as the uplift, tectonic deformation of Qinghai-Ti- bet plateau and the remote geological responses to the collision and convergence process of India- Eurasian plate in the northeaste

关 键 词：西秦岭北缘 中一新生代 红层地层 角度不整合 砾岩 地层格架 

分 类 号：P534[天文地球—古生物学与地层学]