Late Cretaceous-Cenozoic Multi-Stage Denudation at the Western Ordos Block： Constraints by the Apatite Fission Track Dating on the Langshan  

作　　者：CUI Xianyue ZHAO Qihua ZHANG Jin WANG Yannan ZHANG Beihang NIE Fengjun QU Junfeng ZHAO Heng 

机构地区：[1]State Key Laboratory of Geohazard Prevention and Geoenvironment Protection (Chengdu University of Technology), Chengdu 610059, China [2]The Institute of Geology, Chinese Academy of Geological Seiences, Beijing 100037, China [3]Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Orumqi 830011, China [4]Donghua Polytechnic University, Nanchang 330013, China

出　　处：《Acta Geologica Sinica(English Edition)》2018年第2期536-555,共20页地质学报（英文版）

基　　金：funded by Natural Science Foundation of China(41572190);National Basic Research Program of Ministry of Science and Technology of the People's Republic of China(2015CB453002);China Geological Survey(121201102000150009-16,12120115069601)

摘　　要：The apatite fission track dating of samples from the Dabashan （i.e., the Langshan in the northeastern Alxa Block） by the laser ablation method and their thermal history modeling of AFT ages are conducted in this study. The obtained results and lines of geological evidence in the study region indicate that the Langshan has experienced complicated tectonic-thermal events during the the Late Cretaceous-Cenozoic. Firstly, it experienced a tectonic-thermal event in the Late Cretaceous （-90-70 Ma）. The event had little relation with the oblique subduction of the Izanagi Plate along the eastern Eurasian Plate, but was related to the Neo-Tethys subduction and compression between the Lhasa Block and Qiangtang Block. Secondly, it underwent the dextral slip faulting in the Eocene （-50-45 Ma）. The strike slip fault may develop in the same tectonic setting as sinistral slip faults in southern Mongolia and thrusts in West Qinling to the southwest Ordos Block in the same period, which is the remote far-field response to the India-Eurasia collision. Thirdly, the tectonic thermal event existed in the late Cenozoic （since -10 Ma）, thermal modeling shows that several samples began their denudation from upper region of partial annealing zone （PAZ）, and the denudation may have a great relationship with the growth of Qinghai-Tibetan Plateau to the northeast. In addition, the AFT ages of Langshan indicate that the main body of the Langshan may be an upper part of fossil PAZ of the Late Cretaceous （-70 Ma）. The fossil PAZ were destroyed and deformed by tectonic events repeatedly in the Cenozoic along with the denudation.The apatite fission track dating of samples from the Dabashan （i.e., the Langshan in the northeastern Alxa Block） by the laser ablation method and their thermal history modeling of AFT ages are conducted in this study. The obtained results and lines of geological evidence in the study region indicate that the Langshan has experienced complicated tectonic-thermal events during the the Late Cretaceous-Cenozoic. Firstly, it experienced a tectonic-thermal event in the Late Cretaceous （-90-70 Ma）. The event had little relation with the oblique subduction of the Izanagi Plate along the eastern Eurasian Plate, but was related to the Neo-Tethys subduction and compression between the Lhasa Block and Qiangtang Block. Secondly, it underwent the dextral slip faulting in the Eocene （-50-45 Ma）. The strike slip fault may develop in the same tectonic setting as sinistral slip faults in southern Mongolia and thrusts in West Qinling to the southwest Ordos Block in the same period, which is the remote far-field response to the India-Eurasia collision. Thirdly, the tectonic thermal event existed in the late Cenozoic （since -10 Ma）, thermal modeling shows that several samples began their denudation from upper region of partial annealing zone （PAZ）, and the denudation may have a great relationship with the growth of Qinghai-Tibetan Plateau to the northeast. In addition, the AFT ages of Langshan indicate that the main body of the Langshan may be an upper part of fossil PAZ of the Late Cretaceous （-70 Ma）. The fossil PAZ were destroyed and deformed by tectonic events repeatedly in the Cenozoic along with the denudation.

关 键 词：apatite fission track cooling history thermal modeling Late Cretaceous-Cenozoic Langshan 

分 类 号：P597.3[天文地球—地球化学] P542[天文地球—地质学]