Volume 97, Issue 1 pp. 90-105
Original Article

Petrogenesis of the Carboniferous Intrusive Rock in the Xiaobaishitou District of East Tianshan, Northwest China: Magma Evolution and Tectonic Significance

Ning LI

Ning LI

Department of Earth Science and Engineering, College of Mining Engineering, Taiyuan University of Technology, Taiyuan, 030024 China

Search for more papers by this author
Zhixin ZHANG

Corresponding Author

Zhixin ZHANG

Xinjiang Research Center for Mineral Resources, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, 830011 China

Corresponding author. E-mail: [email protected]Search for more papers by this author
Fuquan YANG

Fuquan YANG

Key Laboratory of Metallogeny and Mineral Assessment, Ministry of Natural Resources, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing, 100037 China

Search for more papers by this author
Dongna LIU

Dongna LIU

Department of Earth Science and Engineering, College of Mining Engineering, Taiyuan University of Technology, Taiyuan, 030024 China

Search for more papers by this author
First published: 25 July 2022
Citations: 2

About the first author:

LI Ning, male, born in 1991 in Datong, Shanxi Province; doctor; graduated from Chinese Academy of Geological Science; lecturer of Taiyuan University of Technology. His study focused on the magmatic petrology and genesis of metal deposits. E-mail: [email protected].

About the corresponding author:

ZHANG Zhixin, male, born in 1984 in Shuozhou, Shanxi Province; doctor; graduated from University of Chinese Academy of Sciences; research assistant of Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences. He is now interested in the study of metallogenesis of ore deposits. E-mail: [email protected].

Abstract

The Xiaobaishitou gabbro-diorite pluton comprises a medium-grained gabbro-diorite suite and a fine-grained diorite suite, which intrude the Kawabulag Group in the East Tianshan Orogen of the Central Asian Orogenic Belt (CAOB). A combination of mineral chemistry, zircon U-Pb age, whole-rock geochemistry, Sr-Nd isotopes, and in situ zircon Hf isotopes for newly found gabbro-diorite from the Xiaobaishitou district in the Central Tianshan Terrane (CTT) is presented to investigate the petrogenesis and tectonic or even crustal evolution of the East Tianshan Orogen. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) zircon U-Pb analyses indicate that the gabbro-diorite was formed at 324.7 ± 2.4 Ma. The isolated clinopyroxene formed under higher P-T-ƒO2 melt conditions (10.7–14.6 kbar; 1199–1269°C; high ƒO2) than those for the hornblende, plagioclase, and zircon (557–687°C; moderate ƒO2) in the gabbro-diorite, which reveals a multilevel, magmatic storage system. The gabbro-diorite is characterized by fractioned REE patterns, enriched LILEs (e.g., Ba and Pb), negative anomalies of HFSEs (e.g., Nb and Ta), and low La/Yb and Sr/Y ratios, which are typically indicative of crustal contamination and accounted for by subduction-related fluids. The rock also characterized by typical features of high compatible elements (MgO = 3.14–11.65 wt%, Cr = 1–157 ppm, Ni = 6–830 ppm), high Mg# (47 –74), positive ɛHf(t) values (+5.1 to +10.3) and ɛNd(t) values (+2.3 to +4.4). These features suggest that the Xiaobaishitou gabbro-diorite was most likely derived from metasomatic mantle and contaminated minor crustal components. Taking into account the spatial and temporal distribution of the Carboniferous magmatic rocks in the CTT, we suggest the formation of the Xiaobaishitou gabbro-diorite was attributed to southward subduction of the Kangguer Ocean.

The full text of this article hosted at iucr.org is unavailable due to technical difficulties.