Mesozoic large-scale metallogenic pulses in North China and corresponding geodynamic settings
中国北方中生代大规模成矿作用的期次及其地球动力学背景

We describe the temporal-spatial distribution of the main Mesozoic metallogenic belts and regions in North China, comprising the Middle Lower Yangtze River valley, the Xiaoqinling-Xiong'ershan (eastern Qinling) and western Qinling, North margin of the North China craton, and southern part of the Daxing'anling as well as the eastern Shandong peninsular and Wulugetu-Jiawula ( Manzhuli). After collecting and documenting the precise radiometric age data of the ore deposits there appear three metallogenic pulses, i. e. 190 - 160 Ma, ca. 140 Ma, and ca. 120 Ma. Almost all the gold only depoists in eastern Shandong peninsular formed at time of ca. 120 Ma. It is obvious there are two pulses of mineralization at ca. 140 Ma and ca. 120 Ma in the Middle Lower Yangtze River valley, and Xiaoqinling-Xiong'ershan region, where the porphyry-skarn-manto Cu-Au-Mo-Fe and Mo-(W) deposits occurred at the age of ca. 140 Ma whereas the gold deposits and terrestrial volcanic rock related iron deposits appeared at age of ca. 120 Ma. The Mesozoic mineralization in the northern margin of the North China craton developed in three pulses and their ages are getting older from the eastern margin of the Euroasian continent inward. The gold deposits in the western Qinling are dated to be an age range of 190 -160 Ma. In southern part of the Daxing'anling the granite-related Cu-Ag and Pb-Zn-Cu deposits are ca. 160 - 177 Ma, granite-related Sn-Cu-Pb-Zn and Sn deposits are ca. 140 Ma, and Nb-Y-Zr deposit is 127 Ma. Based on the study of Mesozoic tectonic evolution, we propose these three pulses of large-scale mineralization are the consequences of the postcollisional process of the Triassic convergence between the northern China craton and the Yangtze craton, late stage of the tectonic regime changing its main stress from NS-trending to EW-trending, and lithosphere thinning process, repectively. The gold deposits associated with S-type granite of 200 - 160Ma develop in the extension setting of postcollisional stage. At ca. 140 Ma a great amount of I-type granite porphyry derived from the upper mantle and lower crust emplcaced at the shllow crust and are accompanied by porphyry-skarn-( manto ) Cu-Mo-Fe-Au and Mo-W mineralization. Due to lithosphere rapid thinning at ca. 120 Ma the asthenosphere got into the curst, which gave up to the mixed fluids from the mantle, metamorphic process, and crust to leach the metallic elements so as to form the gold ore-forming system as well as the iron deposit association related to terrestrial volcanic activity.