Large-Scale Metallogeny In The Continental Evolution: Examples Of Three Typical Orogenic Belts In China

The relationship of geodynamic evolution and deposits formation has been one of important problems focused by geologists in the past twenty years. Although we known much about the metallogeny occurred during the main processes such as continent rifting, ocean spreading and plate subducting as well as continent-continent or continent-arc collision, the model of metallogeny occurred after collision has not been established. The three orogenic belts of Sanjiang, Qinling and Xingan-Mongolia developed in China from south to north , not only record the perfect history of the paleo-Asia plates evolutionary process, and also reflect the effects of Pacific Plate subducting and Indian-Asia continent collision on continental margin and intern, especially these orogenic belts have experienced the main processes and metallogeny during the collision to post-collision and . these geological and metallogenic records provide the good condition to delve further into the model of large-scale metallogenic processes during the intracontinent evolutionary processes.Based on the analysis of the data on global metallogeny in the framework of geodynamics and study of the processes of continental evolution and metalloeny of of Sanjiang, Qinling and Xingan-Mongolia orogenic belts, we have reconsidered the geodynamic evlution and metallogeny during Indosinian to Early-Yanshan movement in China , and established large-scale metallogenic model on intracontinental evolution we in orogenic belts. The main results are summarized as follow.(1) Systematically gathering the data about large-scale and superlarge-scale deposits in the world and drawing up the Map of Global Tectonics and Metallogeny; finding out the segmentation of Circle-Pacific Ocean Metallogenic Belt and informing that the giant deposit clusters are the prominent feature of global metallogeny.(2) providing the new information on large-scale , superlarge-scale deposits evolution in time and characteristic metallogenic events of the main stages during geodynanmic evolution; summarizing the feature of large-scale metallogenic processes in some giant deposit clusters in the world and concluding the main type of large-scale metallogenic processes in the tectonic cycle of lithosphere.(3) Summing up the metallogenic feature in different stages of intra-continent evolution of Sanjiang, Qinling and Xinan-Mongolia orogenic belts; giving up the model of delamination and extension occurred in orogenic belts.(4) based on the analysis and summary of typical orogenic belt in China, advancing the marker to distinguish the exist of delamination occurred in orogenic belt, especially giving up some new marker such as ring ultrabasic-basic-medium acid rock body, local bimodal continental rifting volcanic activity; rapakivi granite, etc.(5) collating the main stages of south part of Sanjiang orogenic belts evolution after the close of old Nanchangjiang Ocean, i. e. continent block colliding duringlate-Permian to middle-Triassic; lower part delamination and upper part rifting of lithosphere during late-Triassic; delayed compression and uplift during early-Jurassic; crust extension from middle-Jurassic to early-Cretaceous; large-scale strike sliping from late-Cretacoues to present.(6) roughly expounding the deposits distribution feature in south part of Sanjiang orogenic belts , especially in detail to set forth the characters of southern Nanchangjiang Cu, Pb, Zn, Ag, Sn, Fe metallogenic belt.(7) showing and determining the evidence and timing of the lithophere delamination occurred in Qinling orogenic belt. Pointing out the gold deposit in Xiaoqinling-Xiongershan region are mostly formed during Indosinian to Early-Yanshan movement, related to mantle fluid injecting caused by lithosphere delamination and plutonic activity caused by further large-scale tectonic extension.(8)suggesting the deposit information in central south part of Xingan-Mongolia orogenic belt relate to the two events of mantle upwell and lithosphere extension since late-Paleozoic. First is th...