Zircon U-Pb Ages and Their Geological Significance of Aoguotunwulan Pluton in South Qilian, China(PDF)
《地球科学与环境学报》[ISSN:1672-6561/CN:61-1423/P]
- Issue:
- 2018年第05期
- Page:
- 546-562
- Research Field:
- 基础地质与矿产地质
- Publishing date:
Info
- Title:
- Zircon U-Pb Ages and Their Geological Significance of Aoguotunwulan Pluton in South Qilian, China
- Author(s):
- ZHANG Xin-yuan; WANG Chun-tao; OUYANG Guang-wen; LI Rui-bao
- 1. Qinghai Provincial Key Laboratory of Geological Process and Mineral Resources of Northern Qinghai Tibetan Plateau, Qinghai Geological Survey Institute, Xining 810012, Qinghai, China; 2. School of Earth Science and Resources, Chang’an University, Xi’an 710054, Shaanxi, China
- Keywords:
- geochemistry; zircon U-Pb age; petrogenesis; tectonic environment; syn-collision; Early Silurian; granite; South Qilian
- PACS:
- P588.12；P597
- DOI:
- -
- Abstract:
- The petrology, geochemistry and zircon U-Pb age of Aoguotunwulan pluton in South Qilian were studied to determine the age of pluton and explore its petrogenesis and tectonic significance. The results show that the zircon U-Pb age of porphyroid biotite granodiorite in Aoguotunwulan pluton is (443.9±2.1)Ma, indicating that it is formed in the early period of Early Silurian; the SiO2 contents of rocks are 65.72%-69.87%, total alkali contents are 5.13%-6.70%, Al2O3 contents are 12.69%-13.82%, Fe2O3 contents are 0.75%-1.24%, MgO contents are 1.67%-2.38%, showing the characteristics of silicon-rich, alkali-rich, aluminum-rich, iron-poor and magnesium-poor; A/CNK values mainly range from 0.96 to 1.20, manifesting the rocks belong to weak peraluminous-strong peraluminous, high-K calc-alkaline series; light rare earth elements are relatively enriched (w(La)N/w(Yb)N=6.84-11.36), Eu has a significant negative anomaly (0.47-0.62); the rocks enrich large ion lithophile elements (K, Rb, B, Th and Sr), deplete the high field strength elements (Nb, Ta, P and Ti). The above characteristics indicate that the rocks of Aoguotunwulan pluton in South Qilian are I-type granites. Combining with the regional data, it is believed that Aoguotunwulan pulton is formed in the syn-collisional tectonic setting, and is the product of the early period of Early Silurian when the South Qilian ocean is closed, and the continental blocks on both sides collide and enter the collisional orogenic stage.
Last Update: 2018-10-01