摘要
甘肃省平凉崆峒山地区是崆峒山组地层命名所在地,该套地层主要由大套红色砾岩层组成,通常称为崆峒山组砾岩.长期以来,对崆峒山组砾岩的成因、形成时代和物源存在争议.本文选取崆峒山组砾岩层中的3块砾石为研究对象,运用LA-ICP-MS方法对砾石样品中的碎屑锆石进行了年代学研究.结果表明,崆峒山组砾岩碎屑锆石年龄谱可分为380 ～ 479Ma、561 ～ 1198Ma、1285 ～ 1982Ma、2319 ～ 2612Ma和2714～2764Ma共5个年龄区间.依据崆峒山组砾岩碎屑锆石年龄谱分布特征,以及前人研究成果,认为崆峒山组砾岩的主要物源来源于秦祁造山带,少量来源于阿拉善地块和鄂尔多斯地块.崆峒山组砾岩的沉积时代为中三叠世至晚三叠世,崆峒山组砾岩是秦祁造山带造山过程的沉积响应,而非板内造山带的产物.
Kongtongshan Formation is nominated in Kongtongshan region of Pingliang, Gansu Province. The strata is mainly composed of thick-bedded red Conglomerate and is usually named Kongtongshan Formation Conglomerate. It has been controversial about genetic mechanism, provenance and sedimentary age of Kongtongshan Formation Conglomerate. In this paper, the authors conducted LA-ICP-MS zircon U-Pb isotope geochronologic method to analyze the age of detrital zircon from three samples of Kongtongshan Formation Conglomerate. The results show that the age spectra of detrital zircon can be evidently divided into five groups ： 380 479Ma,561 - 1198Ma, 1285 - 1982Ma, 2319 -2612Ma and 2714 -2764Ma. Based on the age of detrital zircon features and combined with previous research results, the authors contend that the provenance of Kongtongshan Formation Conglomerate mainly from Qinling—Qilian Orogenic belt and minor from Alxa massif and Ordos Block. The sedimentary age of Kongtongshan Conglomerate is the middle to late Triassic Epoch. The Kongtongshan Formation Conglomerate should be sedimentary response of interplate Orogenic Belt rather than intraplate Orogenic Belt.
出处
《地质论评》
CAS
CSCD
北大核心
2014年第3期677-692,共16页
Geological Review
基金
国家重大科技专项(编号2011ZX05044)项目的成果
关键词
鄂尔多斯盆地
崆峒山组砾岩
碎屑锆石
物源
沉积时代
Ordos Basin
Kongtongshan Formation Conglomerate
detrital Zircons
provenance
sedimentaryage
