DOI: 10.1016/j.epsl.2018.03.034
Scopus记录号: 2-s2.0-85044479177
论文题名: 118–115 Ma magmatism in the Tethyan Himalaya igneous province: Constraints on Early Cretaceous rifting of the northern margin of Greater India
作者: Chen S.-S. ; Fan W.-M. ; Shi R.-D. ; Liu X.-H. ; Zhou X.-J.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2018
卷: 491 起始页码: 21
结束页码: 33
语种: 英语
英文关键词: bimodal magmatism
; continental rift
; Early Cretaceous
; Sr–Nd–Hf–Os isotopes
; Tethyan Himalaya igneous province
Scopus关键词: Analytical geochemistry
; Geochronology
; Geologic models
; Isotopes
; Lithology
; Silicate minerals
; Tectonics
; Zircon
; Continental rift
; Early Cretaceous
; Igneous province
; Magmatisms
; Os isotopes
; Igneous rocks
; bimodal association
; Cretaceous
; hafnium
; igneous province
; magmatism
; neodymium isotope
; osmium isotope
; rifting
; strontium isotope
; Tethys
; Himalayas
英文摘要: Understanding the dynamics of Large Igneous Provinces (LIPs) is critical to deciphering processes associated with rupturing continental lithosphere. Microcontinental calving, the rifting of microcontinents from mature continental rifted margins, is particularly poorly understood. Here we present new insights into these processes from geochronological and geochemical analyses of igneous rocks from the Tethyan Himalaya. Early Cretaceous mafic dikes are widely exposed in the eastern and western Tethyan Himalaya, but no such rocks have been reported from the central Tethyan Himalaya. Here we present an analysis of petrological, geochronological, geochemical, and Sr–Nd–Hf–Os isotopic data for bimodal magmatic rocks from the center-east Tethyan Himalaya. Zircon U–Pb dating yields six weighted-mean concordant 206Pb/238U ages of 118±1.2 to 115±1.3 Ma. Mafic rocks display MORB-like compositions with flat to depleted LREE trends, and positive εNd(t) (+2.76 to +5.39) and εHf(t) (+8.0 to +11.9) values. The negative Nb anomalies and relatively high 187Os/188Os ratios (0.15–0.19) of these rocks are related to variable degrees (up to 10%) of crustal contamination. Geochemical characteristics indicate that mafic rocks were generated by variable degrees (2–20%) of partial melting of spinel lherzolites in shallow depleted mantle. Felsic rocks are enriched in Th and LREE, with negative Nb anomalies and decoupling of Nd (εNd(t) = −13.39 to −12.78) and Hf (εHf(t) = −4.8 to −2.0), suggesting that they were derived mainly from garnet-bearing lower continental crust. The geochemical characteristics of the bimodal magmatic associations are comparable to those of associations that form in a continental rift setting. Results indicate that Early Cretaceous magmatism occurred across the whole Tethyan Himalaya, named here as the “Tethyan Himalaya igneous province”. Separation of the Tethyan Himalaya from the Indian craton may have occurred during ongoing Early Cretaceous extension related to the Kerguelen mantle plume during the nascent stages of a global plate-reorganization event. If this is the case, our findings provide clues to the nature of the Tethyan Himalaya, challenging traditional view of the India–Asia single-stage collision model. © 2018 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/109919
Appears in Collections: 影响、适应和脆弱性 气候变化事实与影响
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作者单位: Key Laboratory of Continental Collision and Plateau Uplift, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, 100101, China; Chinese Academy of Sciences, Center for Excellence in Tibetan Plateau Earth Sciences, Beijing, 100101, China; Graduate University of Chinese Academy of Sciences, Beijing, 100049, China
Recommended Citation:
Chen S.-S.,Fan W.-M.,Shi R.-D.,et al. 118–115 Ma magmatism in the Tethyan Himalaya igneous province: Constraints on Early Cretaceous rifting of the northern margin of Greater India[J]. Earth and Planetary Science Letters,2018-01-01,491