岩石矿物学杂志2011，Vol.30Issue(1)：25-33,9.
三江上叠裂谷盆地人支雪山组火山岩锆石U-Pb定年与地质意义
Zircons U-Pb dating of volcanic rocks from Renzhixueshan Formation in Shangdie rift basin of Sanjiang area and its geological implications
摘要
Abstract
It is generally accepted that the volcanics-hosted massive sulfide deposits were widely derived from the marine settings, such as island arc, back-arc basin, mid-ocean ridges, and intraplate spreading centers.Different tectonic regimes are typically marked by changes in the composition of the associated marine volcanic rocks and different ore mineral assemblages in volcanic massive sulfide deposits.Volcanic rocks from Renzhixueshan Formation in Shangdie rift basin of Sanjiang is an important layer hosting volcanic massive sulfide deposits.However, the time of their formation has been controversial.The major rock types of Renzhixueshan Formation are basalt, rhyolites and bimodal volcanic rocks.LA-ICPMS U-Pb zircon dating of two rhyolite samples from Renzhixueshan Formation in Jijiading area yields concordant 206Pb/238U ages of 247.4 ±2.1 Ma and 249.1 ± 1.6 Ma, respectively, implying that these rocks were erupted in early Triassic (249～247 Ma).The geochemical and isotopic characteristics indicate that the basaltic volcanic rocks were probably produced by partial melting of an enrichment mantle.The similar Sr-Nd isotopic compositions of rhyolite to the basalt suggest that they were probably triggered by the same tectonic event.These characteristics of volcanic rocks in Renzhixueshan Formation suggest that they were probably formed in an extending dynamic settings.Therefore, the authors hold that Jinshajiang suture had already been an extending setting after the arc-continental collision during the early Triassic in the Jijiading area of east Tibet.At the same time, the extensional settings probably played an important role in the formation of volcanics-hosted massive sulfide deposits in the Jinsha orogenic belt.关键词
U-Pb年代学/碰撞后伸展/块状硫化物矿床/人支雪山组/上叠裂谷盆地分类
天文与地球科学引用本文复制引用
王保弟,王立全,王冬兵,张万平..三江上叠裂谷盆地人支雪山组火山岩锆石U-Pb定年与地质意义[J].岩石矿物学杂志,2011,30(1):25-33,9.基金项目
国家重点基础研究发展规划项目(2009CB421003) （2009CB421003）
国家自然科学基金(41073033,40872055) （41073033,40872055）
中国地质调查局项目(1212010610101) （1212010610101）
