| The dong zhong la ore deposit located in middle east of Tibet Gan gdise zone ,it is explored in recent years as a lead zinic polymetallic Ore deposits.The deposit located in the south margin of se ri rong–ga ba rift basin in middle east of Gan gdise-Nyanqêntanglha plate .the plotting scale in the deposit area and the route of this area had confirmed that the dong zhong la ore deposit form from the south margin towards north overturned nappe structure system of se ri rong–ga ba Neopaleozoic rift basin ,it is a typical Secondary lead-zinc polymetallic deposits.Dong zhong la ore deposit in south margin towards north overturned nappe structure system of serirong–baga Neopaleozoic rift basin, combined by eopaleo-oic rift valley system (UpperCarboniferous-lower PermianC2P1lclastic mingled calcarneyte and pperPermianseries luobadui P2l carbonatite-clastic rock), Indosiian, ift valley along the areal area Songduo Group Complex shut up because of collision , on one side ,resulting in the south of rift valley northward growth fault.not only character over-turned, but also trend over-turned toward southern , forced the Songduo Group Complex nappe structure on the top of rift valley system .on the other hand, forced the northern rift valley system occur the bottom burst,northward overridden and formed the large scale With inclined overturned fold drape.the Early stage of late Yanshan period. After the collision ,it slack stretch ,and Brahmaputra northward subduction extensional reactivation,it made the mediosilicic -acid magma and medium-basic magma (110-130Ma±)along over-turned fracture system in large scale rising and eructating injection nappe structure system.it forced magma hydrothermalism and carbonatite,calcarneyte occurred skarnization,marbleization,tonhaltig,siliciclastic rocks occurred the hornstone lithification. The early Himalayan period,the remote effection of Brahmaputra closed collision .forced the back of the over-turned structure-ystem ,and at the slack period occurred the medium acid magma intruded,erupted(40-60Ma±),accompanied with lead zinc polyvalent metallization. The middle period of Himalayan, regional orogenetic stretch to back. Among the nappe structure system mediosilicic-acid magma vein intrusion are prospect growth(13-17Ma±).Se ri rong–ga ba Neopaleozoic south margin of rift basin back margin,located in de zong-ze nong-dong zhong la-yuan lang-na gun,it showed us that Songduo Group Complex over-turned and overridden at Neopaleozoic rift basin system or the upper of late Yanshanian medium acid rock. the adjacent rock normaly grow the axial surface trend to south of the joint drape.the region in north of nappe structure system effected, It did not have the defined bounds,but it can reach the north of se ri rong at least .the region of se ri rong to de zong , the distance between south and north is about 25km ,it is a axial surface trend to south fold and overturned anticline .the part of turning located in qiong duo aand en longduo ,growing as the typeof"M"fold. se ri rong to de zong large scale compound inclined reversal anticline, the south wing grow series inclined reversal-inclined fold, thereinto,the secondary anticline of the back marign of nappe structure system,it also controlled lead-zinc polymetallic deposit. now we had found lead zinic polymetallic Ore deposits of dong zhong la,dongzhsongduo,long ma la,meng ya a .The dong zhong la ore field located in back of nappe structure system, Se Ri Rong to De Zong compound anticline south wing , broadly growing the late Yanshanian quartz porphyry(127.4±1.9Ma,Fei Guang chun etc,2009),porphyrite(117±1.0Ma,Fei guang chun etc,2009),granite porphyry. we need give a special explanation. Igneous rocks never recognized for a long time. But it refer to the medium acid tuff and basalt(the second geology team of tibet,2007),named after(P2l)Carbonate- clasolite. Inclined folds, accompanied with the occurrence of 145°～175°∠50°～80°axial plane fracture system,orefield has found ore body formed vein shape produced on the top of fold axial plane fracture. Mineralization is confined in skarnization and marbleization carbonate under the carbonaceous slate shielding layer. the clasolite prominence shielding effect. TheⅡbody includes veiny quartz Ar-Ar isochron age 42.2±1.7Ma(Fei Guang chun etc,2009),it indicates metallogenesis occurred in the early Himalaya.at the same time ,the existingof polyphase hypabyssal magma intrusion activities. We did not get rid of we will find the possibility of porphyre deposit existed.The study of ore-controlling structure in lead zinic polymetallic Ore deposits in Tibet Maizhokunggar County, not only make a clear direction to Dongzhongla and outside deposit, but also have a important significant to lead zinic polymetallic Ore deposits in south margin of se ri rong–ga ba rift basin in middle east of Gan gdise-Nyanqêntanglha zone.
|
PDF Full Text Request