- 责任者：Lü Shujun (No.407 Team ; Bureau of Geology and Mineral Exploration and Development of Hunan Province ; Huaihua 418000 ; China) ; Yang Fuquan
- 刊名：Geological Review
- 出版年：2013
- 卷期：59(5)
- 关键词：花岗岩 ; granite ; 准噶尔盆地 ; Junggar Basin
- 页码：p.971-982
- 图表：7 illus., 1 table, 69 refs.
- 分类号：0801
- issnNo：ISSN0371-5736
- isbnNo：CN11-1952/P
The Laoshankou granitoids located on the northern margin of the Junggar, Xinjiang, are composed of diorite, adamellite, syenite porphyry and diorite （porphyrite）. Geochemical characteristics of biotite diorite and syenite porphyry show that the concentration of SiO2 of biotite diorite is 54.43% - 55.10%, A1203 16.92% 17.64% and CaO 5.35% - 5.94%. They are high in total alkali （K20 ＋ Na20） content （9.00% - 9.43% ） and enriched in potassic （ K20/Na20 = 1.32 - 1.74 ）. Compared with biotite diorite, the syenite porphyry is high in the concentrations of SIO2（59.96% - 63.60%）, A1203（18.15% - 19.13%） and Mg~（51.95 55.96）, total alkali （K20 ＋ Na20 = 11.81% - 13.17% ）, and low in the concentrations of CaO（1.13% 2.47% ） and Mg#（30. 16 - 48.20）, K20/Na20 ratio （1.1 - 1.53）. They are belong to shoshonitic high-K alkaline granitoids. In addition, they display noticeable enrichment on LREE, Rb, K, Pb, Sr and Zr, obvious depleted in Nb, Ta and Ti. These features, together with the regional geology characteristics, indicate that Laoshankou granitoids are formed under a subducted tectonic setting. The parental magma of syenite porphyry was residual melt left by elinopyroxene and amphibole fractional crystallization from biotite diorite parental magma derived from the mixed melt of riched potassium minerals mantle peridotites and subducted oceanic slab.