西藏驱龙斑岩铜矿含矿斑岩的年代学与地球化学

Geochronology and geochemistry of the ore-bearing porphyry in Qulong Cu(Mo)ore deposit,Tibet.

驱龙斑岩铜(钼)矿是冈底斯斑岩成矿带上的重要矿床之一,由于其被发现较晚、海拔高、工作条件差,总体研究程度较低。本文通过野外工作和对岩心样品分析,在岩石学和地球化学研究基础上,采用离子探针(SHRIMP)锆石U-Pb方法和辉钼矿Re-Os方法研究了驱龙矿区的成矿和成岩年龄。选择两种方法测定了驱龙斑岩铜矿黑云母花岗闪长岩成岩与成矿年龄,其中两个样品的SHRIMP锆石U-Pb谐和年龄分别为16．35±0．40Ma和16．38±0．46Ma;4个样品中辉钼矿的Re-Os模式年龄为15．82～16．85Ma。获得的结果与已有定年结果一致。综合分析表明,驱龙矿床的成岩与成矿作用是一个连续的岩浆作用过程,整个冈底斯斑岩成矿带成矿时间介于12～17Ma,成矿时间持续大约5Ma。

The discovery and further study of the Gangdese porphyry copper ore deposit belt in Lhasa block, Tibetan plateau, is One of the most attractive findings in the ore exploration in Tibet in the past 5 years. It has potential of being a giant copper and polymetallic ore-forming belt in the future. Study on the belt is still under going now. Qulong porphyry Cu （Mo） ore deposit is located in eastern part of the belt and only a small amount works has been performed. This mostly attributes to its inconvenient condition for field work in Qulong region. New geochemical studies and isotopic dating results on the ore-bearing granodiorites were presented in this paper. On the basis of detailed field work and geochemical study, SHRIMP zircon U-Pb method and Re-Os dating of molybdenites method were used for determining the rock-forming and ore-forming ages. Analysis of two SHRIMP zircon U-Pb ages （ 16.35 ± 0.40Ma and 16.38 ±0.46Ma） and four Re-Os model age of molybdenites （15.82-16.85Ma） sampled in the drilling core of ZK003 in Qulong ore deposit were carried out. Data in this paper are very close to the other published data, further supporting the conclusion that the rockforming and ore-forming processes are continuously in Qulong ore deposit, which lasting for a short period of less than approximately 1Ma. The time for ore-forming in Gangdese porphyry copper ore deposit belt range from 12 to 17Ma, lasting for about 5Ma.