Petrogenesis of the diamondiferous Pipe-8 ultramafic intrusion from the Wajrakarur kimberlite field of Southern India and its relation to the worldwide Mesoproterozoic(~1.1 Ga) magmatism of kimberlite and related rocks  

作　　者：Ashish Dongre K.S.Viljoen G.Belyanin Petrus Le Roux M.Malandkar 

机构地区：[1]Department of Geology,Savitribai Phule Pune University,Pune,411007,India [2]Department of Geology,University of Johannesburg,P.O.Box 524,Auckland Park,2006,South Africa [3]Department of Geology,University of Cape Town,Rondebosch,7700,South Africa [4]Department of Geology,Institute of Science,Aurangabad,431004,India

出　　处：《Geoscience Frontiers》2020年第3期793-805,共13页地学前缘（英文版）

摘　　要：Detailed mineralogy,bulk rock major,trace and Sr-Nd isotope compositions,and ^(40)Ar/^(39)Ar dating of the Pipe-8 diamondiferous ultramafic intrusion in the Wajrakarur cluster of southern India,is reported.Based on the presence of Ti-rich phlogopite,high Na/K content in amphibole,Al-and Ti-rich diopside,a titanomagnetite trend in spinel and the presence of Ti-rich schorlomite garnet and carbonates in the groundmass,the Pipe-8 intrusion is here more precisely classified as an ultramafic lamprophyre(i.e.,aillikite).An aillikite affinity of the Pipe-8 intrusion is further supported by the bulk rock major and trace element and Sr-Nd isotope geochemistry.Sr-Nd isotope data are consistent with a common,moderately depleted upper mantle source region for both the Pipe-8 aillikite as well as the Wajrakarur kimberlites of southern India.A phlogopite-rich groundmass ^(40)Ar/^(39)Ar plateau age of 1115.8±7.9 Ma(2σ) for the Pipe-8 intrusion falls within a restricted 100 Ma time bracket as defined by the 1053-1155 Ma emplacement ages of kimberlites and related rocks in India.The presence of ultramafic lamprophyres,carbonatites,kimberlites,and olivine lamproites in the Wajrakarur kimberlite field requires low degrees of partial melting of contrasting metasomatic assemblages in a heterogeneous sub-continental lithospheric mantle.The widespread association of kimberlite and other mantle-derived magmatism during the Mesoproterozoic(ca.1.1 Ga) have been interpreted as being part of a single large igneous province comprising of the Kalahari,Australian,West Laurentian and Indian blocks of the Rodinia supercontinent that were in existence during its assembly.In India only kimberlite/lamproite/ultramafic lamprophyre magmatism occurred at this time without the associated large igneous provinces as seen in other parts of Rodinia.This may be because of the separated paleo-latitudinal position of India from Australia during the assembly of Rodinia.It is speculated that the presence of a large plume at or close to 1.1 Ga within the Rodini

关 键 词：KIMBERLITE and RELATED ROCKS ULTRAMAFIC LAMPROPHYRE Lamproites Wajrakarur KIMBERLITE FIELD Mantle plume Rodinia supercontinent 

分 类 号：P597[天文地球—地球化学] P588.1[天文地球—地质学] P581