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Alaskan-type Kedanshan intrusion (central Inner Mongolia, China) : superimposed subduction between the Mongol-Okhotsk and Paleo-Pacific oceans in the Jurassic.

Dong, Jinlong and Song, Shuguang and Wang, Mingming and Allen, Mark B. and Su, Li and Wang, Chao and Yang, Liming and Xu, Bei (2018) 'Alaskan-type Kedanshan intrusion (central Inner Mongolia, China) : superimposed subduction between the Mongol-Okhotsk and Paleo-Pacific oceans in the Jurassic.', Journal of Asian earth sciences., 167 . pp. 68-81.

Abstract

The Xing’an-Inner Mongolia accretionary belt in the eastern Central Asian Orogenic Belt (CAOB) was produced by the subduction of three oceanic plates: the Paleo-Asian, Mongol-Okhotsk and Paleo-Pacific oceanic plates. The interactions between these plates remain unclear. Here we report an Alaskan-type ultramafic-mafic intrusion in the Kedanshan area, central Inner Mongolia, China. The main lithologies of this intrusion include cumulate dunite, pyroxene peridotite, olivine pyroxenite and cumulate gabbro, with late gabbroic/anorthositic dykes. Minerals and whole-rock compositional variations display characteristics of an arc cumulate trend (Alaskan-type), through fractional crystallization of Mg-rich and hydrous basaltic magma associated with oceanic subduction. Zircons from two gabbro samples yield Early Jurassic ages of 193 ± 6 Ma and 179 ± 4 Ma, respectively. We conclude that this ultramafic-mafic complex is an accumulated intrusion from an arc-related, high-Mg magma chamber above a supra-subduction zone. Considering the ages, location and tectonic setting of the complex, we suggest that it was most likely generated by melting of a large and triangle-shaped mantle wedge during superimposed subduction between the Mongol-Okhotsk and the Paleo-Pacific oceanic plates in the Jurassic.

Item Type:Article
Full text:(AM) Accepted Manuscript
First Live Deposit - 30 November 2017
Available under License - Creative Commons Attribution Non-commercial No Derivatives.
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Status:Peer-reviewed
Publisher Web site:https://doi.org/10.1016/j.jseaes.2017.11.010
Publisher statement:© 2017 This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/
Record Created:30 Nov 2017 10:58
Last Modified:13 Nov 2018 09:37

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