Welcome to visit Geoscience!

Geoscience ›› 2020, Vol. 34 ›› Issue (03): 514-531.DOI: 10.19657/j.geoscience.1000-8527.2020.03.016

• Petrology • Previous Articles     Next Articles

Magmatic Activity and Emplacement of the Devonian Intrusive Rocks in Eastern Altay, Northern Xinjiang

LIN Xinwang1,2(), WANG Xing1,2, CHEN Guangting3, ZHAO Duanchang1,2, ZHAO Jianglin1,2   

  1. 1. Shaanxi Mineral Resources and Geological Survey, Xi’an, Shaanxi 710068, China
    2. Shaanxi Institute of Geological Survey, Xi’an, Shaanxi 710054, China
    3. Qinghai Geological Survey Institute, Xining, Qinghai 810012, China
  • Received:2018-06-25 Revised:2019-12-15 Online:2020-07-04 Published:2020-07-05

Abstract:

A large number of magmatic rocks were developed in the eastern Altay, northern Xinjiang. LA-ICP-MS zircon U-Pb dating indicates that the Adeer quartz diorite porphyry and Qiaolakesayi granodiorite were emplaced at (415.7±4.0) Ma and (413.5±3.0) Ma, respectively. These ages revealed that the rocks were emplaced in the Early Devonian. There are significant major-element geochemical differences between the two rock types, but their trace-element (including REE) features are largely similar.The quartz diorite porphyry is medium-low-K calc-alkaline and peraluminous, but the granodiorite is high-K calc-alkaline and metaluminous. The REE distribution patterns reveal that the rocks are LREE-enriched, HREE-depleted, and with strong LREE/HREE fractionation and weakly-moderately negative Eu anomalies. The rocks are enriched in LILEs (Rb, Th, U) and LREEs, and clearly depleted in HFSEs (Nb, Zr, Ti),Sr, and P,demonstrating a subduction-related affinity. Considering also the regional geology, we concluded that magmatism was active in the Early Devonian eastern Altay, and with complex petrogenetic cause and emplacement mode, which formed the various igneous rock assemblages in the region. This plutonism may have been the product of hot mantle and hot crustal structure, and has the potential to generate super-large deposits.

Key words: Early Devonian, oceanic crust subduction, hot mantle and hot crustal structure, eastern Altay, northern Xinjiang

CLC Number: