Zircon U‐Pb age, Lu‐Hf Isotopic Characteristics and Origin of the Banshanping Granitoid Rocks in East Qinling Orogenic Belt

Abstract

The Banshanping granitoid rocks distribute in the east of the North Qinling orogenic belt. It is a diorite‐quartz diorite‐granodiorite‐granite series, spreading in a NW‐SE direction, and intrudes into the Erlangping Group. The SiO2 content ranges from 57.04% to 76.56%, Na2O from 2.05% to 4.65%, K2O from 0.84% to 3.40%. Major element characteristics indicate that Banshanping granitoid rocks have properties of I type granotoids. SREE ranges from 36.51 ppm to 473.25 ppm, and LREE/HREE ratios lie between 3.95 and 22.18. Negative Eu anomalies are not obvious in most samples, though there are obvious Nb, P and Ti positive anomalies. The zircon LA‐ICP‐MS ages of Banshangping granitoid rocks are 496.0±8.1 Ma–486.9±9.3 Ma. Hf isotope shows that 176Hf/177Hf ratios range from 0.282721 to 0.282876, εHf(t) values from 8.5 to 14, all positive, and corresponding modal ages (TDM2) range from 559 Ma to 908 Ma. Based on Hf isotope characteristics and existing Sm‐Nd and Rb‐Sr isotope data, we consider that the Banshanping granitoid rocks originate from mantle‐derived material, i.e. the igneous rocks that formed in Neoproterozoic, and there may be a certain amount of crust‐derived material during the formation of Banshanping granitoid rocks.

Magma convection in hybird granitic chamber and formation of cognate mafic enclaves

“…The Xichuanjie unit, which have the greatest occurrence and essentially represents the main lithology of the Zhashui pluton, served as the study's sample location (Cui et al,1999;Liu et al,2014). Several chronology works have been reported for the monzogranite in the Zhashui pluton, i.e., Rr-Sr isochronal age of 185 ± 8Ma, biotite 40 Ar- 39 Ar age of 196.…”

Geochronology and Geochemistry of the Granite Porphyry from the Qinglingou Gold Deposit, South Qinling, China: Implication for Petrogenesis and Mineralization

“…In addition, both Indosinian and Yanshanian gold mineralization events have been identified in Zhaishang and Baguamiao gold deposits. 4 for the detail) (a) [37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54], and intrusive age of Zhashui-Shanyang area (b) [6][7][8][9][10][11][12][13]20]. The Zhashui-Shanyang area is one of the most important metallogenetic districts in the Qinling orogenic belt.…”

“…This age is similar to the previously reported zircon LA-ICPMS U-Pb ages for the Zhashui plutons, which suggests that both the Zhashui plutons and Qinglingou granite porphyries formed during Late Triassic (Table 5). In addition, granitoids from Dongjiangkou, Zhashui, Shahewan and Caoping (Figure 2) also gave zircon LA-ICPMS U-Pb ages of 246-209 Ma [8][9][10]14], 234-214 Ma [9,12], 212-205 Ma [11,13] and 224-220 Ma [6,9], respectively. Hence, the Qinglingou granite porphyry in the area has an affinity with the Dongjiangkou, Zhashui, Shahewan, and Caoping plutons, and all of them were the products of the Late Triassic magmatic event.…”

“…These mineralizations were closely related to Triassic, Late Jurassic, and Early Cretaceous magmatic events that have been strongly developed in the area [4,5]. Previous studies mainly focused on petrology, geochemistry, and geochronology [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19],…”

“…The intensive Indosinian (e.g., the Dongjiangkou, Zhashui, Shahewan, and Caoping pluton) and Yanshanian (e.g., Lengshuigou, Chigou, Baishagou, and Shuangyungou pluton) magmatic activity resulted in the emplacement of a number of some granitoids, accompanied by a variety of mineralization [14,[17][18][19]. Several hydrothermal porphyry-skarn Cu, Mo, Au, and Fe deposits or occurrences were discovered within hypabyssal intrusions, such as the Xiaohekou, Lengshuigou, and Chigou [7,9]. However, little has been reported on the comprehensive understanding of the tectonic magmatic evolution and mineralization of the district.…”