Tectonic setting of the rare metal belt in the Western Kunlun Orogenic Belt:Geochemical constraints from the Langdaban quartz monzonite
The Langdaban quartz monzonite is located in the Muji area on the south side of the Kangxiwa tectonic belt at the western end of the Western Kunlun orogenic belt.Zircon LA-ICP-MS U-Pb dating yielded an age of 214.3±0.8 Ma,indicating that the pluton was emplaced in the Late Triassic.The quartz monzonite is shoshonitic and strongly peraluminous.The Langdaban quartz monzonite samples are relatively enriched in light rare earth elements(LREEs)with moderate Eu negative anomalies(δEu=0.59-0.77).The chondrite-normalized REE patterns showed that the heavy rare earth elements were not obvious differentiated(DyN/YbN=1.24-1.66).Significant negative anomalies of Ba,Nb,Sr,P,and Ti are shown in the trace-element spider diagrams.The quartz monzonite exhibits significant arc geochemical affinities,indicating an active continental margin setting associated with the northward subduction of the Qiaoertianshan Paleo-Tethys Ocean.The rare metal pegmatite metallogenic belt in Western Kunlun formed at 209-204 Ma,slightly later than the Langdaban quartz monzonite and the closure of the Mazha-Kangxiwa Paleo-Tethys Basin,but earlier than the closure of the Qiaoertianshan Paleo-Tethyan Ocean.Considering the tectonic location of the metallogenic belt and previous research,we propose that the rare metal pegmatite metallogenic belt may be formed in a composite tectonic environment superimposed by the post-collision following the closure of the Mazha-Kangxiwa Paleo-Tethys and the active continental margin associated with the northward subduction of the Qiaoertianshan Paleo-Tethys.
Langdaban intrusionS-type granitetectonic settingLate TriassicWestern Kunlun rare metal metallogenic belt
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维普
