Late Triassic Magma Mixing in the East Kunlun Orogenic Belt: A Case Study of Helegang Xilikete Granodiorites
详细信息
- 责任者：Chen Guochao (Key Laboratory of Western China’s Mineral Resources and Geological Engineering ; Ministry of Education ; Faculty of Earth Science and Resources ; Chang’an University ; Xi’an 710054 ; China) ; Pei Xianzhi
- 刊名：Geology in China
- 出版年：2013
- 卷期：40(4)
- 页码：p.1044-1065
- issnNo：ISSN1000-3657
- isbnNo：CN11-1167/P
摘要
In the East Kunlun orogenic belt(EKOB),mafic microgranular enclaves(MME) occur frequently in Late Permian-Triassic granitic rocks.In this paper,the authors took Helegang Xilikete granodiorites in the eastern part of the EKOB as an example to study their host rocks and MME in detail.Characteristics of the host rocks and the MME,such as field occurrence,morphology,texture and structure and mineralogy,together with the geochemistry,show that they were cooled and crystallized in a short time immediately after the intrusion of basaltic magma into intermediate-acidic magma and thus have similar distribution patterns to the host rocks in the REE diagram and trace element spider diagram,such as the enrichment of the LREE and LILE and the depletion of the HREE and HFSE,reflecting a typical feature of magma mixing.The result of LA-ICP-MS zircon geochronology implies that the crystallization age of the MME is about 224.9±4.1 Ma,very close to that of the host rock(225±5 Ma),suggesting a crust-mantle magma mixing event at the stage of post-collision in the EKOB in Late Triassic.
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