从华北燕辽岩床群到哥伦比亚超大陆巨型裂谷系OA北大核心CSTPCD

Twenty years of research on the Yanliao sill swarms intruding into the Mesoproterozoic strata in the northern North China Craton(NCC)shows that the Yanliao sill swarms constitute a ca.1.32 Ga mafic large igneous province(LIP)termed as the Yanliao LIP,which is coeval with the REE-Nb rich carbonatites in the Bayan Obo giant REE deposit on the northwestern margin of the NCC.A comparison of intraplate mafic events interpreted as LIPs or portions of LIPs(LIP fragments/remnants due to continental breakup or erosion)from the NCC and North Australian Craton(NAC),in combined with paleomagnetic data indicate that the northern-northeastern margin of the NCC had been connected to the northern margin of the NAC for almost 500 Ma from ca.1.8 Ga to 1.3 Ga.Spatial and temporal distributions of the 1.4～1.3 Ga LIPs and smaller intraplate mafic magmatic events(interpreted as LIP fragments/remnants)in the refined paleogeographic reconstruction map of Columbia(Nuna)supercontinent,together with previous petrological,geochemical and isotopic results reveal a 1.4～1.3 Ga large-scale continental rift system extending about 15000 km across the Columbia supercontinent.This huge continental rift zone extends along the western Laurentia(North America and Greenland),western-northern Siberia,southeastern Baltica,western-northern West Africa,southwestern Amazonia,southern-eastern Congo/Sao Francisco,eastern Kalahari,northern NCC and northern NAC and consists of a main rift zone and three branch rift zones.The main rift zone along western Laurentia,western-northern Siberia,southeastern Baltica,western-northern West Africa,southwestern Amazonia,southern-eastern Congo/São Francisco,eastern Kalahari,northern NCC and northern NAC and the rift zone branch between the NAC and NCC had developed to the drifting stage(new oceans)and resulted in fragmentation and final breakup of Columbia supercontinent.However,the other two rift zone branches including one extending to eastern Siberia,northern Greenland and eastern Baltica(1.38 Ga),and another extending to northern North America and southwestern Siberia(1.35～1.32 Ga)are most likely failed rifts and haven't resulted in separation of Siberia from Laurentia and Baltica,respectively.The 1.4～1.3 Ga large-scale continental rift system is considered as the main indicator and a proximal reason for final breakup of the Columbia supercontinent.This newly identified huge continental rift zone system had also controlled the distributions of the world's first and second largest REE-Nb deposits(the Bayan Obo deposit on northwestern margin of the NCC and Mountain Pass deposit in western Laurentia)and is most likely a favorable metallogenic belt for other carbonatite-related REE(-Nb)deposits and other metallogenic types such as giant clastic-dominated Zn-Pb-Ag deposits.Future research directions are suggested to focus on the emplacement mechanism and magma plumbing system of the Yanliao LIP,quantitative estimation of greenhouse gases released during emplacement of the Yanliao sill swarms and their environmental effects,the mechanism and deep processes for formation of the 1.4～1.3 Ga huge rift system,and global environmental effects and resource potentials of the 1.4～1.3 Ga large-scale rift system.