CAJ | 학술논문

研究了南秦岭晚三叠世（～200 Ma）7个花岗岩类岩体的 Sr、Nd、Pb 同位素组成，包括白马山岩体在内的南秦岭花岗岩类以低放射成因 Pb 同位素组成为特征，初始87Sr/86Sr 比值范围为0.70495～0.70908，εNd（t）值变化于-2.40～-8.55之间，Nd 同位素模式年龄（TDM）变化于1.2～1.7 Ga 之间，从东部到西部，呈现εNd（t）逐渐降低而 TDM 逐渐增高的变化规律。白马山岩体的初始87Sr/86Sr 比值为0.70637，εNd（t）=-6.75，具有较高的 TDM 值（1.53 Ga），暗示其岩浆源区主要来自于南秦岭的大陆下地壳，岩浆源区以类似南秦岭耀岭河群基性火山岩为主，南秦岭较古老的地壳物质仅有少量参与。基性下地壳增厚，岩石圈地幔拆沉，软流圈上涌，下地壳部分熔融形成有利于铜、金成矿的白马山“C”型埃达克岩。
연구료남진령만삼첩세（～200 Ma）7개화강암류암체적 Sr、Nd、Pb 동위소조성，포괄백마산암체재내적남진령화강암류이저방사성인 Pb 동위소조성위특정，초시87Sr/86Sr 비치범위위0.70495～0.70908，εNd（t）치변화우-2.40～-8.55지간，Nd 동위소모식년령（TDM）변화우1.2～1.7 Ga 지간，종동부도서부，정현εNd（t）축점강저이 TDM 축점증고적변화규률。백마산암체적초시87Sr/86Sr 비치위0.70637，εNd（t）=-6.75，구유교고적 TDM 치（1.53 Ga），암시기암장원구주요래자우남진령적대륙하지각，암장원구이유사남진령요령하군기성화산암위주，남진령교고로적지각물질부유소량삼여。기성하지각증후，암석권지만탁침，연류권상용，하지각부분용융형성유리우동、금성광적백마산“C”형애체극암。
This paper studies Sr,Nd,Pb,isotopic compositions of 7 granitoids from South Qinling,which were all formed about 200 Ma B.P.The results indicate that the granitic rocks including the Baimashan rock mass from the South Qinling are characterized by low radiogenic Pb isotopic composition.Their initial (87Sr/86Sr)t ratios range from 0.70495 to 0.70908,εNd(t)values from -2.40 to -8.55,and Nd isotopic model ages(TDM)from 1.2 Ga to 1.7 Ga. their εNd(t) values gradually decrease from east to west,whereas TDM values gradualy increase.The Baimashan rock mass has much lower(87Sr/86Sr)t(0.70637),lower εNd(t)(-6.75) and much higher TDM(1.53 Ga).This study reveals that the magmatic source of the Baimashan rock mass was derived from the deep continental crust.In the magmatic source,basic magmatic material in the crust similar to the Yaolinghe Group basic volcanic rocks in South Qinling,is the major source for the formation of granitoids with less significant old continental crust material.The Baimashan adakite which is in favor of copper and gold mineralization,may resulted from partial melting of mafic lower crust in the thickened lower crust due to the lithospheric delamination and the asthenospheric upwelling,which can provide some clues to the direct copper-gold prospecting.