摘要
雪如岩体主要由中细粒二长花岗岩、中粗粒斑状二长花岗岩组成,在其与郎山组灰岩接触带附近发育有大量的矽卡岩型铜铁矿床或矿化点.岩石及锆石LA-ICP-MS U-Pb、XRF、ICP-AES等分析显示,雪如岩体富K2O、SiO2、LREE及Rb、Ba、Pb、Th等大离子亲石元素,而Nb、Ta、Sr、Ti等高场强元素含量相对较低,稀土元素配分曲线为明显的右倾曲线,具有中等的负Eu异常,属高钾钙碱性-钾玄岩岩石系列和后碰撞花岗岩类,成岩时代分别为79.25±0.97 Ma和79.72±0.51 Ma,形成于早白垩世末-晚白垩世初班公湖-怒江缝合带闭合后、羌塘地体与拉萨地体的后碰撞阶段.综合认为,雪如岩体岩浆源区为下地壳富含流体的石榴石角闪岩相-斜长角闪岩相的镁铁质岩石,是在后碰撞环境下经部分熔融形成的花岗岩类,对班戈地区铜铁多金属成矿非常有利;矽卡岩型铜铁成矿作用发生于80 Ma左右,该认识为区域找矿指明了方向.
The Xueru intrusion is chiefly composed of medium-fine-grained monzogranite and medium-coarse-grained porphyritic monzogranite. There are a large number of skarn iron and copper deposits around the contact zone with the Langshan Formation limestone. The rock and zircon LA-ICP-MS U-Pb, XRF, ICP-AES and other analysis show that the monzogranite is enriched in K2（, SiO2, LREE and Rb, Ba, Pb, Th and other large ion lithophile elements; high field strength elements such as Nb, Ta, St, Ti are relatively poor; REE distribution curve is significantly rightward, with moderate negative Eu anomaly. The granites belong to high-K calc-alkaline-shoshonitic rock series, and the post-collision granite, which formed in 79.25±0. 97 Ma and 79. 72±0. 51 Ma, in the stage of post-collision between Qiangtang block and the Lhasa block after the late of Early Cretaceous-the beginning of Late Cretaceous Bangonghu-Nujiang suture closed. It is concluded that the source of Xueru intrusion is the lower crust garnet amphibolite facies-plagioclase amphibolite facies mafic rocks which are rich in fluid, the granites formed by partial melting of the mafic rocks in the post-collision environment, which is very conductive to the formation of copper-polymetallic deposit in Ban＇ge area, the mineralization of skarn iron and copper deposits occurred around 80 Ma. This study can greatly facilitate regional mineral exploration.
出处
《地球科学（中国地质大学学报）》
EI
CAS
CSCD
北大核心
2011年第4期729-739,共11页
Earth Science-Journal of China University of Geosciences
基金
青藏高原矿产调查评价专项项目(No.1212010818038)
关键词
岩石学
地球化学
成矿作用
petrology
geochemistry
mineralization.
