Publication details for Professor Yaoling NiuHuang, H., Niu, Yaoling & Mo, X.X. (2016). Syn-collisional granitoids in the Qilian Block on the Northern Tibetan Plateau: A long-lasting magmatism since continental collision through slab steepening. Lithos 246-247: 99-109.
- Publication type: Journal Article
- ISSN/ISBN: 0024-4937
- DOI: 10.1016/j.lithos.2015.12.018
- Further publication details on publisher web site
Author(s) from Durham
In this paper we present a new model that can explain the large zircon age spectrum of ~ 510 – 420 Ma within a single sample from the Gangcha (Gcha) biotite granodiorite and the Huangyuan (HY) two-mica monzogranite on the northern Tibetan Plateau. The large age spread recorded in zircons is characteristic of granitoid samples from the studied region, which is best explained by the long-lasting magmatism since the onset of continental collision at ~ 500 Ma, followed by slab steepening and the ultimate slab break-off at ~ 450 Ma. These granitoids have a large major and trace element compositional variation, but limited initial Sr (ISr = 0.709 to 0.715), Nd (ԐNd = − 6.5 to − 3.7), Hf (ԐHf = − 4.3 to 1.5) and Pb (206Pb/204Pb = 17.70 to 17.17; 207Pb/204Pb = 15.60 to 15.69; 208Pb/204Pb = 38.04 to 38.73) isotopic variation. The small negative whole rock ԐNd and ԐHf values are most consistent with the granitoid source being dominated by subducted seafloor materials. The inherited zircons with large negative ԐHf values (e.g. − 50) are indicative of input from the lower continental crust and subducted sediments. The correlated variations among major elements, trace elements and radiogenic isotopes are best interpreted as reflecting melting-induced mixing of a compositionally heterogeneous source with superimposed effect of varying extent of fractional crystallization and crustal assimilation. The inherited zircons of Palaeo-Proterozoic age and the Archean crustal model ages signify the involvement of ancient basement rocks.