Zircon U–Pb dating, geochemistry and Sr–Nd–Pb–Hf–O isotopes for the Nan'getan granodiorites and mafic microgranular enclaves in the East Kunlun Orogen: record of closure of the Paleo-Tethys

Xia, Rui, Wang, Changming, Qing, Min, Li, Wenliang, Carranza, Emmanuel John M., Guo, Xiaodong, Ge, Liangsheng, and Zeng, Guangzhong (2015) Zircon U–Pb dating, geochemistry and Sr–Nd–Pb–Hf–O isotopes for the Nan'getan granodiorites and mafic microgranular enclaves in the East Kunlun Orogen: record of closure of the Paleo-Tethys. Lithos, 234-235. pp. 47-60.

[img] PDF (Published Version) - Published Version
Restricted to Repository staff only

View at Publisher Website: http://dx.doi.org/10.1016/j.lithos.2015....
 
44
3


Abstract

The East Kunlun Orogen in the Northern Qinghai–Tibet Plateau is an ideal region to investigate the geodynamic processes of magmatism related to the closure of the Paleo-Tethys Ocean. Here, we report petrology, zircon U–Pb geochronology, whole-rock geochemistry and multiple isotope data from granodiorites and the associated dioritic enclaves in a dominant Nan'getan granitoid in the East Kunlun Orogen. Zircon U–Pb ages indicate that the host granodiorites and dioritic enclaves were synchronously emplaced at ~243 Ma. The granodiorites are medium- to high-K calc-alkaline, metaluminous (A/CNK = 0.93–0.98), with high Al(2)O(3) content (15.28%–16.10%), Mg# (47–49), very low Sr/Y ratios (127–217), high abundances of incompatible elements (Y = 3.87–8.36 ppm, Nb = 3.04–5.71 ppm, Th = 3.04–5.71 ppm), low (87Sr/86Sr)i (0.7050–0.7079), negative whole-rock εNd(t) (− 8.2 to − 5.8), (206Pb/204Pb) 243Ma of 18.520 to 18.772, (207Pb/204Pb) 243Ma of 15.611 to 15.650, (208Pb/204Pb) 243Ma of 38.227 to 38.528, δ18OSMOW = 6.8‰–9.1‰, εHf(t) of − 1.2 to + 2.4. The dioritic enclaves (SiO(2) = 51.08%–56.29%) have Mg# values of 48–51, with negative Eu anomalies (δEu = 0.59–0.79), low (87Sr/86Sr)i (0.7058–0.7080), negative whole-rock εNd(t) (− 8.2 to − 5.8), (206Pb/204Pb) 243Ma of 18.376 to 18.809, (207Pb/204Pb)243Ma of 15.606 to 15.661, (208Pb/204Pb)243Ma of 38.244 to 38.540, δ18OSMOW = 5.6‰–10.0‰, εHf(t) of − 3.5 to + 1.7. These isotopic features of arc-type rocks from the East Kunlun suggest that the parental magmas of the Nan'getan granodiorites and the dioritic enclaves originated from an enriched lithospheric mantle. The Nan'getan granitoids might have recorded the northward subduction of the Paleo-Tethys ocean lithosphere following the initial collision of the Bayan Har–Songpan Ganzi–East Kunlun terrane and the closure of the Paleo-Tethys Ocean at ~243 Ma.

Item ID: 40282
Item Type: Article (Research - C1)
ISSN: 1872-6143
Keywords: zircon U–Pb geochronology; Sr–Nd–Pb–Hf–O isotopes; mafic microgranular enclaves; arc magmatism; closure of Paleo-Tethys Ocean; East Kunlun
Funders: National Basic Research Program (NBRP), China Scholarship Council (CRC), Fundamental Research Funds for the Central Universities (FRFCU), Program for Changjiang Scholars and Innovative Research Team in University (PCSIRT), 111 Project
Projects and Grants: NBRP No. 2015CB452606, NBRP No. 2009CB421008, CRC No. 201406405006, FRFCU No. 2652013034, 111 Project No. B07011
Date Deposited: 29 Sep 2015 00:22
FoR Codes: 04 EARTH SCIENCES > 0402 Geochemistry > 040203 Isotope Geochemistry @ 50%
04 EARTH SCIENCES > 0403 Geology > 040303 Geochronology @ 20%
04 EARTH SCIENCES > 0402 Geochemistry > 040202 Inorganic Geochemistry @ 30%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970104 Expanding Knowledge in the Earth Sciences @ 100%
Downloads: Total: 3
More Statistics

Actions (Repository Staff Only)

Item Control Page Item Control Page