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.
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.
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|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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