tailieunhanh - Paleomagnetism of upper permian basaltic rocks of Cam Thuy formation from Thuan Chau locality, Son La, Northwest Vietnam

This result implies that insignificant cumulative displacement has occurred along the Ailao Shan/Red River fault system during the Cenozoic India-Eurasia collision. | Vietnam Journal of Earth Sciences 37 (2015) 289-298 Vietnam Academy of Science and Technology Vietnam Journal of Earth Sciences (VAST) Website: Paleomagnetism of upper permian basaltic rocks of Cam Thuy formation from Thuan Chau locality, Son La, Northwest Vietnam Cung Thuong Chi1, John W. Geissman2, Hoang Van Quy1, Tran Viet Anh1, Nguyen Thi Phuong Dung1, Nguyen Thi Hoc1 1 Institute of Geological Sciences, Vietnam Academy of Science and Technology 2 Department of Geosciences, University of Texas at Dallas Accepted 25 December 2015 ABSTRACT Oriented-core samples (74) from eight sites collected from the Late Permian basaltic Cam Thuy formation exposed at Thuan Chau locality, Son La Province, northwestern Vietnam yield interpretable magnetizations in progressive demagnetization. The characteristic remanent magnetization (ChRM) components carried by magnetite and hematite are successfully isolated from secondary components reveal a mean, stratigraphic coordinates paleomagnetic direction of Ds = , Is = (α95 = , k = , N = 7 site mean directions), corresponding to a virtual geomagnetic pole located at λ = oN, = oE and a paleolatitude for the study area situated at ± oN during the Late Permian. A comparison of the pole we report in this study with the Late Permian pole of South China Block shows that this basaltic terrane of northwest Vietnam has been close to if not a coherent part of the South China Block since Late Permian. This result implies that insignificant cumulative displacement has occurred along the Ailao Shan/Red River fault system during the Cenozoic India-Eurasia collision. ©2015 Vietnam Academy of Science and Technology 1. Introduction The Permian was a particularly important period in the geological evolution of Southeast Asia, where involved successive dispersion and northwards translation of continental blocks during the opening and closing the Paleo-, Meso-, and Neo-Tethys