Home | Contact Us | Sitemap | 中文 | CAS | Director's Email
 
Location:Home > Papers > Recent Papers
Crustal Contamination of the Mantle-Derived Liuyuan Basalts: Implications for the Permian Evolution of the Southern Central Asian Orogenic Belt TEXT SIZE: A A A
The Permian basalts in the Central Asian Orogenic Belt (CAOB) are crucial for constraining the closure of the Paleo-Asian Ocean. However, the origin of these basalts is still under discussion. Here, we present comprehensive bulk-rock geochemical, Sr-Nd-Pb-Hf isotopic, and zircon U-Pb-Lu-Hf isotopic data of the Liuyuan basalts and coexisting gabbros, which are located in the Beishan Orogen in the southern CAOB, to constrain their emplacement setting and tectonic implications. Our new gabbro ages of ca. 288-294 Ma are interpreted to represent the formation time of the Liuyuan basaltic belt. The Liuyuan basalts show MORB-like rare earth element (REE) patterns and bulk-rock epsilon(Hr)(t) and epsilon(Nd)(t) values of 11.0-15.4 and 4.6-9.2, respectively, suggesting an origination mainly from a depleted mantle source. However, positive Pb anomalies, Nb-Ta depletions, and high Th/Yb ratios as well as evolved Sr-Nd-Pb-Hf isotopic compositions of some samples indicate variable continental crustal contribution. According to the covariation of Pb anomalies (Pb* =2xPb(N)/(Ce-N+Pr-N)) with Sr-Nd-Pb-Hf isotopic compositions, we speculate that parent magma of the Liuyuan basalt was contaminated by continental crustal materials during the eruption rather than having been generated from an enriched mantle source. As revealed by mixing modelling, the Liuyuan basaltic magmas would require a minor (<10%) upper continental crustal assimilation to explain the enriched trace elemental and radiogenic Sr-Nd-Pb-Hf isotopic signatures. Consequently, the Liuyuan basaltic belt is believed to have been generated in a continental extensional environment instead of an oceanic setting and does not constitute a Permian ophiolitic suture zone as previously suggested, since the Paleo-Asian Ocean was already closed in the southern Beishan Orogen in the Early Permian.

Publication name

 Journal Of Earth Science, Volume 33, Issue 5, Page 1081-1094, Special Issue SI, DOI 10.1007/s12583-022-1706-1, Published OCT 2022

Author(s)

 Yu, Yuanyang; Zong, Keqing; Yuan, Yu; Klemd, Reiner; Wang, Xin-Shui; Guo, Jingliang; Xu, Rong; Hu, Zhaochu; Liu, Yongsheng

Corresponding author(s) 

 Zong, Keqing
 kqzong@hotmail.com
 China Univ Geosci, Sch Earth Sci, State Key Lab Geol Proc & Mineral Resources, Wuhan 430074, Peoples R China

Author(s) from IGCAS   Xu, Rong

View here for the details 

Copyright © Institute Of Geochemistry, Chinese Academy of Sciences All Rights Reserved.
Address: 99 West Lincheng Road, Guanshanhu District, Guiyang, Guizhou Province 550081, P.R.China
Tel: +86-851-85895239 Fax: +86-851-85895239 Email: web_en@mail.gyig.ac.cn