Zircon U–Pb ages, geochemistry, and Sr–Nd–Pb–Hf isotopes of the Mugagangri monzogranite in the southern Qiangtang of Tibet, western China: implications for the evolution of the Bangong Co‐Nujiang Meso‐Tethyan Ocean

Huang, Han‐Xiao, Dai, Zuo-Wen, Liu, Hong, Li, Guang‐Ming, Huizenga, Jan Marten, Zhang, Lin‐Kui, Huang, Yong, Cao, Hua‐Wen, and Fu, Jian‐Gang (2021) Zircon U–Pb ages, geochemistry, and Sr–Nd–Pb–Hf isotopes of the Mugagangri monzogranite in the southern Qiangtang of Tibet, western China: implications for the evolution of the Bangong Co‐Nujiang Meso‐Tethyan Ocean. Geological Journal. (In Press)

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Abstract

We present in-situ zircon laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) U–Pb ages, whole-rock geochemistry, and Sr–Nd–Pb–Hf isotopes of the Mugagangri monzogranite in the southern margin of the Qiangtang Block, Tibet, western China. The zircons yield a U–Pb age of ca. 123 Ma. The hornblende-bearing monzogranite shows metaluminous to weak peraluminous and high-K calc-alkaline characteristics exemplified by high silica (SiO2 = 67.57–70.57 wt%), high aluminium (Al2O3 = 14.68–15.78 wt%), high potassium (K2O = 4.00–5.14 wt%), high alkali (K2O + Na2O = 7.88–8.62 wt%), and low calcium contents (CaO = 1.72–2.17 wt%), with the aluminium saturation index (A/CNK) ranging from 0.98 to 1.09, suggesting that the Mugagangri monzogranite is a metaluminous to weak peraluminous I-type high-K calc-alkaline granite. Geochemically, similar to the arc magmas, the monzogranite is enriched in large-ion lithophile elements, and relatively depleted in high-field-strength elements. The monzogranite displays relatively high(87Sr/86Sr)i values (0.70972–0.71240), uniform εNd(t) values (−2.24 to −3.40), variable zircon εHf(t) values (−14.1 to +8.0), and high radiogenic Pb isotopic values (206Pb/204Pb = 18.588–18.790, 207Pb/204Pb = 15.616–15.642, and 208Pb/204Pb = 38.838–39.053). These geochemical characteristics indicate that the monzogranite was derived from a mixed source comprising ancient crustal and mantle materials, and experienced frac- tional crystallization during emplacement. We propose that the parental magma of the Mugagangri monzogranite was most likely generated during northward subduction of the Bangong Coujiang Meso-Tethys Ocean.

Item ID: 66007
Item Type: Article (Research - C1)
ISSN: 1099-1034
Keywords: Bangong Co-Nujiang Suture Zone; geochemistry; I-type granite; Qiangtang; Sr–Nd–Pb–Hf isotopes; Tibet; zircon U–Pb
Copyright Information: © 2021 John Wiley & Sons Ltd
Funders: National Natural Science Foundation of China (NNSFC), National Key R&D Program of China (NKRDPC), China Geological Survey (CGS)
Projects and Grants: NNSFC Grant/Award Number: 91955208, NKRDPC Grant/Award Number: 2016YFC0600308, NKRDPC Grant/Award Number: 2018YFC0604103, CGS Grant/Award Number: 202008000000200611
Date Deposited: 16 Feb 2021 23:13
FoR Codes: 37 EARTH SCIENCES > 3703 Geochemistry > 370303 Isotope geochemistry @ 50%
37 EARTH SCIENCES > 3703 Geochemistry > 370399 Geochemistry not elsewhere classified @ 25%
37 EARTH SCIENCES > 3705 Geology > 370503 Igneous and metamorphic petrology @ 25%
SEO Codes: 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280107 Expanding knowledge in the earth sciences @ 100%
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