Palaeozoic tectonic evolution and magmatism in the Kalatag area, East Tianshan, NW China: Evidence from the geochronology and geochemistry of intrusive rocks

Abstract

The Kalatag area contains many intrusive rocks of Late Ordovician to Permian age and hosts polymetallic deposits that are associated with magmatism. It is a key area for revealing the nature and genesis of the Palaeozoic rocks in East Tianshan. The intrusive rocks of different periods preserve useful information regarding the tectonomagmatic history of the Kalatag area. Zircon U–Pb geochronological, Hf isotopic, Sr–Nd isotopic, and whole‐rock geochemical analyses are reported for the intrusions from the Meiling ore district, Yudai ore district, and Kalatag pluton to reveal their petrogenesis and geodynamic setting. The LA–ICP–MS zircon U–Pb analyses suggest that the quartz diorite from the Kalatag pluton formed at 420–432 Ma, and the quartz diorite porphyry from the Yudai ore district formed at 436–439 Ma. The zircons from the quartz diorite and quartz diorite porphyry mainly yield high εHf(t) values (12.2–16.2) and very young Hf model ages (TDM = 0.41–0.56 Ga; TDMC = 0.49–0.56 Ga), which are consistent with a depleted mantle origin. The geochemical characteristics of the granites and quartz diorites from the Kalatag pluton and diorite porphyry from the Meiling ore district exhibit typical subduction‐related features such as enrichment in LILEs and LREEs and depletion in HFSEs. These diorites have moderate Mg# (30–47), positive εNd(t) values (4.2–5.6), and young Nd model ages (0.62–0.83 Ga), which are consistent with a depleted mantle origin that is accompanied by limited crustal assimilation. Based on the regional geology and geochemical evidence and previous studies, the Ordovician–Carboniferous rocks from the Kalatag area are considered to have formed in an island‐arc setting and were probably formed by a subduction event.

Metallogenic Model and Prospecting Progress of the Qiandongshan–Dongtangzi Large Pb-Zn Deposit, Fengtai Orefield, West Qinling Orogeny

“…The intermediate felsic dikes are well developed in the Fengtai orefield. The major intrusions are the Xiba and the Huahongshuping granitic plutons, which are distributed in the central part of the Fengtai orefield and are basically consistent with the direction of the main structural line (NW direction) within the area [6,9] (Zhang, 2010;Hu, 2015). The largest Xiba pluton is mainly composed of granodiorite, quartz diorite, and monzogranite, with hornstone and andalusite developed in the outer contact zone.…”

“…The largest Xiba pluton is mainly composed of granodiorite, quartz diorite, and monzogranite, with hornstone and andalusite developed in the outer contact zone. A combination of previous zircon U-Pb ages indicate that the granitic complex intruded between 219 and 215 Ma [9][10][11]. The previous geochronoloical and geochemical data suggested that the Xiba pluton was formed in the Late Indosinian period, and was emplaced under the post-collision setting after the collision between the North China Craton and the Yangtze Craton along the Mianlue suture zone [1,12,13] The Shuangwang large gold deposit is developed approximately 5 km north of the Xiba pluton, and the Yinmusi medium-sized lead-zinc deposit is developed approximately 15 km in the NW direction.…”