Discovery of High-alumina Basalt of Tuoranggekuduke Formation in Yematan of Qinghe Area, East Junggar, China and Its Geological Significance(PDF)
《地球科学与环境学报》[ISSN:1672-6561/CN:61-1423/P]
- Issue:
- 2019年第01期
- Page:
- 1-14
- Research Field:
- 基础地质与矿产地质
- Publishing date:
Info
- Title:
- Discovery of High-alumina Basalt of Tuoranggekuduke Formation in Yematan of Qinghe Area, East Junggar, China and Its Geological Significance
- Author(s):
- LI Yong-jun; TAO Xiao-yang; WANG Zuo-peng; XU Qian
- 1. School of Earth Science and Resources, Chang’an University, Xi’an 710054, Shaanxi, China；2. Key Laboratory for the Study of Focused Magmatism and Giant Ore Deposits of Ministry of Land and Resources, Xi’an 710054, Shaanxi, China
- Keywords:
- high-alumina basalt; mantle wedge; delayed crystallization; island arc; Early Devonian; Tuoranggekuduke Formation; East Junggar
- PACS:
- P588.14；P597；P581
- DOI:
- -
- Abstract:
- The high-alumina basalts of Lower Devonian Tuoranggekuduke Formation occur in Yematan of Qinghe area, East Junggar, China. The high-alumina basalts are rich in a large number of plagioclase phenocrysts, belonging to a sub-alkaline series. The basalts have significantly high A12O3 (the mass fraction is 17.22%-21.31%), low SiO2 (47.12%-49.45%), and high TFe2O3 (8.50%-11.98%), MgO (2.64%-5.63%), Ni ((5.75-27.87)×10-6), Cr ((0.99-25.62)×10-6), and high Sm/Yb ratio (1.13-1.96), U/Th ratio (0.42-0.81), and they relatively enrich in large ion lithophile elements and deplete in high field strength elements, indicating the characteristics of the typical geochemical features of high-alumina basalts. The further research shows that the magma is derived from the partial melting of the mantle wedge modified by the subduction zone fluid. In addition, the basalts with high Sr/Y ratio (43.16-47.07), low Y (the mass fraction is (15.69-19.09)×10-6) and Yb ((1.64-2.13)×10-6) indicate that the source of basaltic magma may contain subduction zone oceanic crust materials. The characteristics of high Al are likely to be related to the delayed crystallization of plagioclase under high pressure conditions. Geochemical characteristics indicate that these high-alumina basalts are formed in an island arc environment. The discovery of Early Devonian high-alumina basalts enriches the petrographic data of volcanic rocks in East Junggar and provides an important basis for the study of tectonic evolution.
Last Update: 2019-01-25