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对西藏革吉县米多南地石英闪长岩地球化学特征分析,岩石A/CNK=0.962-0.965<1,属于准铝质花岗岩;里特曼指数σ为0.89~1.0,为钙性;岩石CIPW标准矿物组合为:Q+Or+An+Ab+Di+Hy,含透辉石标准分子;岩石中大离子亲石元素Rb、K、Ba富集,高场强元素Nb、Ta、Ti亏损。对石英闪长岩中锆石U-Pb年龄进行加权平均得出其年龄为124.8±1.7Ma,形成时代为早白垩世。该石英闪长岩为班公湖-怒江特提斯洋向北俯冲的产物。
Geochemical characteristics of quartz diorite from Midon, Geji, Tibet are analyzed. The rock A / CNK = 0.962-0.965 <1 belongs to the quasi-aluminous granite. The Rittman index σ is 0.89-1.0, CIPW standard mineral assemblage is: Q + Or + An + Ab + Di + Hy, containing diopside standard molecules; large ion lithophile elements Rb, K, Ba are enriched in rocks, and depletion of high field strength elements Nb, Ta, Ti . The zircon U-Pb ages of quartz diorite were weighted averagely and the age was 124.8 ± 1.7Ma, forming the Early Cretaceous. The quartz diorite is the product of subduction north of the Bangong-Nujiang Tethyan.