DOI: 10.1007/s00531-013-0996-z
Scopus记录号: 2-s2.0-84896546156
论文题名: Geochronology and geochemistry of the Late Triassic Longtan pluton in South China: Termination of the crustal melting and Indosinian orogenesis
作者: Qiu L. ; Yan D.-P. ; Zhou M.-F. ; Arndt N.T. ; Tang S.-L. ; Qi L.
刊名: International Journal of Earth Sciences
ISSN: 14373254
出版年: 2014
卷: 103, 期: 3 起始页码: 649
结束页码: 666
语种: 英语
英文关键词: Fractional crystallization
; Granitoid genesis
; High-K granodiorite and granite
; Indosinian orogeny
; Partial melting
; South China
Scopus关键词: fractional crystallization
; geochronology
; granitoid
; granodiorite
; orogeny
; partial melting
; petrogenesis
; pluton
; tectonic setting
; Triassic
; China
; Lile
英文摘要: The Indosinian orogeny is recorded by Triassic angular unconformities in Vietnam and South China and by widely occurring granitoids in the Yunkai-Nanling and the Xuefengshan belts of South China. The Longtan pluton in the northwestern part of the Xuefengshan belt is a typical high-K, calc-alkaline, I-type granitoid, which can shed light on the relationship between the Indosinian tectonic and magmatic activity in the region. Three precise zircon U-Pb ages yielded a mean of 218 ± 0.8 Ma, which is taken as the age of crystallization. The pluton consists of both granodiorite (64.59-68.01 % SiO2 and 3.25-4.22 % K2O) and granite (70.49-71.80 % SiO2 and 4.07-4.70 % K2O). The granodiorites are characterized by relatively high Mg# (54-57), low contents of Na2O (3.2-4.3 wt%), low abundances of incompatible elements (LILE, Nb and P), high initial 87Sr/86Sr (0.7175-0.7184) and negative εNd(t) (-9.98 to -9.72). REE patterns show moderate fractionation ((La/Yb)cn = 8.07-18.80) with negative Eu anomalies (Eu/Eu* = 0.62-0.86). Compared with the granodiorite, the granite has a wider range of Mg# (49-59), lower contents of Na2O (2.8-4.2 wt%), higher initial 87Sr/86Sr (0.7232-0.7243) and more negative εNd(t) (-12.07 to -11.24) values. REE patterns are relatively flat ((La/Yb)cn = 14.73-29.37) with smaller negative Eu anomalies (Eu/Eu* = 0.48-0.63). The granodiorite has lower K2O/Na2O and Al2O3/(MgO + FeOTot) values than the granite. Based on major and trace element geochemistry and Sr-Nd isotopes, we interpret the Longtan granodioritic magma to have been derived by partial melting of interlayered Proterozoic metabasaltic to metatonalitic source rocks, whereas the granite was probably derived from a mixture of Proterozoic metagraywackes and metaigneous rocks. Field, petrographic and geochemical evidence indicate that partial melting and fractional crystallization were the dominant mechanism in the evolution of the pluton. The Longtan granodiorites and granites are petrologically and geochemically similar to typical Indosinian varieties and are considered to have been produced in a similar manner. The Indosinian granitoids in the region show a magmatic peak age of ~238 Ma from the Yunkai-Nanling belt in the southeast and a magmatic peak age of ~218 Ma of the Xuefengshan belt to the northwest. These early and late magmatic episodes of the Indosinian granitoids also display slight variations of regular compositions, εNd(t) values and T DM ages. Thus, we propose a syncollisional extension model that Indosinian granitoids were generated by decompressional partial melting of crustal materials triggered by two extensions during collision of the Indochina and South China blocks. The Longtan pluton in the northwesternmost part of the orogenic belt marks the termination of the Indosinian magmatism and orogenesis. © 2014 Springer-Verlag Berlin Heidelberg. URL: https://www.scopus.com/inward/record.uri?eid=2-s2.0-84896546156&doi=10.1007%2fs00531-013-0996-z&partnerID=40&md5=574d93ee3736a2e55256f75648eb13d0
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/70443
Appears in Collections: 影响、适应和脆弱性 气候减缓与适应
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作者单位: State Key Laboratory of Geological Processes and Mineral Resources, School of Earth Sciences and Resources, China University of Geosciences, Beijing, 100083, China; Department of Geoscience, University of Nevada, Las Vegas, Las Vegas, NV, United States; Department of Earth Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China; ISTerre, Université de Grenoble, Grenoble, France; State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550002, China
Recommended Citation:
Qiu L.,Yan D.-P.,Zhou M.-F.,et al. Geochronology and geochemistry of the Late Triassic Longtan pluton in South China: Termination of the crustal melting and Indosinian orogenesis[J]. International Journal of Earth Sciences,2014-01-01,103(3)