首页 | 本学科首页   官方微博 | 高级检索  
     检索      


Palaeomagnetism of metadolerite dykes and sills from Proterozoic Shillong basin,NE India: Implications related to the age and magmatism
Authors:K P Sarma  M Venkateshwarlu  S K Patil  J J Laskar  Niva Rani Devi  J Mallikharjuna Rao
Institution:1. Department of Geological Sciences, Gauhati University, Guwahati, 781 014, India
2. CSIR-National Geophysical Research Institute, Uppal Road, Hyderabad, 500 606, India
3. Dr.K.S.Krishnan Geomagnetic Research Laboratory, Jhunsi, Allahabad, 221 505, India
4. Arya Vidyapeeth College, Guwahati, 781 016, India
Abstract:The basement gneiss of the Shillong plateau and the overlying rocks of the Shillong basin have been dissected by a number of mafic dyke swarms represented by older Proterozoic dolerite dykes and sills named as Khasi greenstone and the younger set of Cretaceous dykes. The older dolerites dykes of Shillong basin are partly metamorphosed and have undergone low-grade metamorphism compared to the fresh unmetamorphosed Cretaceous dykes dominantly exposed in the BGC of West Garo hills region. The Khasi greenstones are tholeiitic in composition and range from basalt to basaltic andesite. Most of the metamorphosed mafic dykes indicate continental nature with some amount of overlapping oceanic tectonic setting. Palaeomagnetic study of the metadolerite dykes show a direction of magnetization of Dm=29, Im=38 (α95 = 28.84; k = 48.33; N = 2) with a palaeolatitude of 21.3° N to the Indian sub-continent that clearly support the Proterozoic dyke/dyke swarm emplacement in the region. The magnetic carrier as inferred from IRM studies is magnetite in the range of psuedosingle to multi domain (MD) states with minor contribution from hematite.
Keywords:
本文献已被 SpringerLink 等数据库收录!
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号