The first LCT-type mineralized pegmatite in China:Discovery and significance of Yanlingguan spodumene pegmatite in central Shandong
The Neoarchean was an important period in the evolution history of the Earth,when cratons completed aggregation and tended to stabilize.During this process,the large-scale accumulations of microcontinents and accompanying collision orogenic events formed a global peak of rare-metal mineralization.However,rare-metal mineralization events in China are mainly occurred in Phanerozoic,with few reports of Archean mineralization events.By establishing the metallogenic pedigree of rare metal pegmatites in China and combing the relationship between tectonic evolution and rare metal mineralization,we propose that the North China Craton has the best conditions for producing Archean pegmatites in China.Through detailed field investigation,we have discovered the Archean LCT type(Li-Cs-Ta)mineralized pegmatite in China for the first time in Yanlingguan area of central Shandong Province.Through the columbite-tantalite U-Pb dating,the two-stage Li-Nb-Ta metallogenic events in the Archean 2609.0±13.0Ma and 2501.6±8.6Ma in North China have been accurately determined.The 2609Ma mineralization event corresponds to the formation of the Yanlingguan greenstone belt in the Eastern Block of the North China Craton,while the 2502Ma mineralization event corresponds to the large-scale crust-melt granite event related to the cratonization of the North China Craton.Based on mineralogical research,the measured Li2O of spodumene in the Yanlingguan pegmatite is 7.66％～7.93％,which is close to the theoretical upper limit of Li2O in spodumene,and thus this pegmatite might has a high-quality lithium resource potential.The Yanlingguan pegmatite also contains elbaite,Cs-rich feldspar,manganotantalite and apatite,making it a typical LCT-type pegmatite.Compared with the same type deposits,the crystallization temperature and pressure conditions of Yanlingguan pegmatite are higher,so there is no production of petalite.The frequent continental-continental collision in the～2.50Ga North China Craton,accompanied by multi-stage magmatic activities,created a continuous heat supply for the progressive partial melting of the Archean basement,and provided ideal conditions for the enrichment of rare-metal elements and the formation of LCT-type pegmatites.The"terrigenous component-rich basement+microcontinental tectonic belt"can be used as an important prospecting indicator for pegmatite-type rare-metal resources in the North China Craton.
Rare metalLCT-type pegmatiteArcheanYanlingguanNorth China Craton
万方数据
维普
