横断山区花岗岩类研究

横断山区位于青藏高原东部,包括昌都地区、川西和云南西半部。花岗岩类出露广泛,呈带状产出,与本区南北和北西向区域构造线一致。岩浆岩时代从前寒武纪的晋宁期到第三纪的喜马拉雅期;岩性从超基性、基性,中性到酸性和碱性岩石都有发育。     

西藏南部花岗岩类稀土元素地球化学

REE abundances of granitoids in Southern Xizang were estimated to be within the range of 190 ppm (REE oxides), which are much lower than the average REE abundance of intermediate-acidic intrusive rocks in the crust. The REE abundances show a progressive decrease from late Yenshanian to late Himalayan (195--128 ppm). Four types of REE distribution patterns have been distinguished: (1) rightly deelined smooth curves, showing little Eu anomaly (δEu-values are 0.78-0.95) and relative enrichment of heavy REE (Diorite and granodiorite, fore example, are characterized by such a pattern) ; (2) rightly declined V-shape curves, displaying negative Eu anomaly(δEu: 0.50--0.70) (Biotite-granite shows sneh a pattern.) ; (3) righly declined V-shape curves with noticeable Eu anomaly (δEu : 0.36--0.39) (Two-mica granite and tourmalinemuscovite granite possess this pattern) ; and (4) rightly declined V-shape eurves with strong Eu anomaly (δEu : 0.27--0.86) (Porphyritie biotite-granite has such a pattern). In summary, the granitoids in this given area could be divided into two types, i. e.,the abyssal type (e. g. diorite, granodiorite) and the hypabyssal type (e.g. two-mica granite and tourmaline muscovite granite).     

从中酸性的岩浆活动论西藏高原地壳运动特征

In view of their distinct NWW trending and their decreasing geological age from north to south, intermediate-acid magmatic rocks in the southern part of Xizang can be divided into three petrographical belts in general: (1) the Kangdese belt (120--10 m.y.). The major part of the belt is mainly composed of diorite, granodiorite, etc.,more intermediate in chemical composition and ranges from 120---70 m. y. in age; (2)the Lhangoi Kangri belt (30 m. y.) ; and (8) the Himalaya belt (20--10 m. y.). From their intruding features, spatial-temporal consistency, intruding scale, petrological characters and chemical Composition, it is suggested that these three petrographical belts secm to be closely related to plate underthrust and collision. It may be concluded that the major part of the Kangdese belt is resulted from the underthrust of the Indian Ocean Plate towards the Eurasian Continental Plate while the Lhagoi Kangri belt and the Himalaya belt are the results:of collision of the Indian sub-Continental Plate overlying the .Indian Plate with the Eurasian Continental Plate.     

西藏南部某些中酸性岩体的铷-锶同位素研究

西藏高原南部广泛分布着中酸性岩类岩石。涂光炽教授等根据K-Ar年龄数据,探讨了冈底斯岩带(北带)、拉轨岗日岩带(中带)和喜马拉雅岩带(南带)在时空分布上的规律性。为了进一步探讨这三个岩带的时代和成因,我们对北带曲水岩体中的花岗闪长岩、中带康马岩体的片麻状二云母花岗岩和南带告乌岩体的电气石白云母花岗岩的岩石样品进行了Rb-Sr全岩等时线年龄测定,并分别求得了它们的锶同位素初始比值。     

藏东玉龙斑岩铜矿带扎拉尕含矿斑岩体锆石U-Pb年龄及其地质意义

玉龙斑岩铜矿带扎拉尕斑岩铜钼矿床位于玉龙斑岩铜矿带中北部,赋矿岩体侵入下二叠统火山岩及三叠系砂泥岩中,主要由早阶段为二长花岗斑岩及晚阶段正长花岗斑岩组成。分析了早阶段二长花岗斑岩及晚阶段正长花岗斑岩锆石 LA-ICP-MS U-Pb 年龄。早阶段二长花岗斑岩该年龄为（38.5±0.2） Ma, MSWD=1.12,晚阶段正长花岗斑岩该年龄为（38.5±0.2） Ma, MSWD=1.08,早阶段和晚阶段含矿斑岩体锆石U-Pb 年龄完全一致。这表明早晚两阶段成矿岩体是在很短的时间间隔内形成的。扎拉尕赋矿斑岩体形成年龄为（38.5±0.2） Ma。据扎拉尕斑岩矿床形成时代及藏东地区在始新世至渐新世地质构造背景,提出扎拉尕斑岩矿床和玉龙斑岩铜矿带的形成与印度板块-欧亚板块碰撞在藏东地区形成的走滑构造活动诱发的岩浆活动有关,为陆陆碰撞走滑构造环境的斑岩矿床。