地质通报2025，Vol.44Issue(4)：552-573,22.DOI:10.12097/gbc.2023.12.004
柴北缘查干哈克花岗伟晶岩年代学、地球化学及其成因和构造环境
Chronology,geochemistry,petrogenesis and tectonic setting of Chaganhake granitic pegmatite in North Qaidam
摘要
Abstract
[Objective]The determination of the formation age,petrogenesis,and tectonic environment of Chaganhake granite pegmatite is of great significance for the study of the evolution of the Paleo-Tethyan and the metallogenesis of rare metals in the northern margin of the Tibetan Plateau.[Methods]In this paper,monazite U-Pb dating and zircon U-Pb dating have been carried out for granite pegmatite and its surrounding rocks,and their geochemistry has been studied.[Results]The results show that the monazite U-Pb age of granite pegmatite is 250.4±0.7 Ma(MSWD=0.1,n=27),while the zircon U-Pb age of biotitite syenogranite is 374.3±8.5 Ma(MSWD=0.15,n=8).The granite pegatite is characterized by high Si,alkali,Al and low Ti,with A/CNK value of 1.15 to 1.32 and low rare earth element contents,showing a right-leaning partition pattern with weak enrichment of light rare earth elements(LREE),strong Eu deficit,δEu of 0.07 to 0.18,showing a four-group effect of M-type rare earth elements,significant enrichment of Rb,K,U and P,strong depletion of Ba,Sr and Ti,moderate enrichment of high field strength elements(HFSE)Nb,Ta,Zr,Hf.Biotite synenite granite is rich in Si,K,and poor Ti,with A/CNK value of 1.13 to 1.32 and moderate rare earth element contents,showing a right-leaning partition pattern of strong enrichment of LREE,obvious Eu deficit,δEu of 0.19 to 0.32,strong enrichment of Rb,K,Th,and strong depletion of Sr,P and Ti.[Conclusions]Combined with the regional geological background,it is believed that the Chaganhake granite pegmatite in the western part of the North Qaidam margin is different from the Zongwulong granite pegmatite.The Zongwulong granite pegmatite evolved from the granite formed in the process of accretionary orogeny and collision orogeny of the Paleo-Tethys Ocean continental margin through high differentiation,while the Chaganhake granite pegmatite was formed in the continental interior of the Qaidam block under the Paleo-Tethys Ocean subduction environment of the Early Triassic.It is the product of small proportion partial melting of the Dakendaban rock group during the process of extrusion migmatization within the continent,and has the metallogenic potential of niobium-tantalum deposit.关键词
年代学/地球化学/岩石成因/构造环境/花岗伟晶岩/黑云正长花岗岩/查干哈克/柴北缘Key words
chronology/geochemistry/petrogenesis/tectonic setting/granite-pegmatite/biotitite syenogranite/Chaganhake/North Qaidam分类
地质学引用本文复制引用
张勇,张爱奎,袁万明,刘光莲,湛守智,王宗胜,张大明..柴北缘查干哈克花岗伟晶岩年代学、地球化学及其成因和构造环境[J].地质通报,2025,44(4):552-573,22.基金项目
国家自然科学基金项目《柴北缘花岗伟晶岩型锂铍等关键金属超常富集成矿的可能机制》(批准号:9206220026)和青海省地质矿产勘查开发局基金项目《柴周缘钴镍成矿规律及靶区优选》(批准号:青地矿科[2023]79) （批准号:9206220026）
