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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; Song, Shuguang; Wang, Mingming; Allen, Mark B.; Su, Li; Wang, Chao; Yang, Liming; Xu, Bei

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


Authors

Jinlong Dong

Shuguang Song

Mingming Wang

Li Su

Chao Wang

Liming Yang

Bei Xu



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.

Citation

Dong, J., Song, S., Wang, M., Allen, M. B., Su, L., Wang, C., …Xu, B. (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, 68-81. https://doi.org/10.1016/j.jseaes.2017.11.010

Journal Article Type Article
Acceptance Date Sep 24, 2017
Online Publication Date Nov 4, 2017
Publication Date Nov 30, 2018
Deposit Date Nov 22, 2017
Publicly Available Date Mar 29, 2024
Journal Journal of Asian Earth Sciences
Print ISSN 1367-9120
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 167
Pages 68-81
DOI https://doi.org/10.1016/j.jseaes.2017.11.010

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