- 责任者：Wang Yawei (State Key Laboratory of Continental Dynamics Department of Geology ; Northwest University ; Xi’an 710069 ; China) ; Liao Xiaoying
- 刊名：Northwestern Geology
- 出版年：2013
- 卷期：46(4)
- 关键词：正长岩 ; syenites ; 碱性花岗岩 ; alkali granite ; 杂岩 ; complexes ; 昆仑山 ; Kunlun Mountains
- 页码：p.1-24
- 图表：10 illus., 4 tables, 104 refs.
- 分类号：0801
- issnNo：ISSN1009-6248
- isbnNo：CN61-1149/P
Kuzigan alkaline complex is one of the major parts of the Taxkorgan alkaline complex- terrane. It is mainly composed of aegirine-augite syenite, quartz aegirine-augite syenite, and alkali granite. There is great difference among the three rocks in the content of SiO2, 50.26%-54. 11%, 59.74%-60.43% and 69. 59 %-72.13 % for aegirine-augite syenite, quartz aegirine- augite syenite and alkali granite, respectively. Aegirine-augite syenite and quartz aegirine-augite syenite has similar Rittman index, namely 7.83-10.97 and 8.51-9.05, distinctly differing from 2.49-3.71 of alkali granite. These three rocks are strongly enriched in light rare earth elements （LREE） as well as some large ion lithophile element （LILE）, such as Rb, Ba, St, and depleted in High Field Strength Element （HFSE） such as Nb, Ta and Ti. Abnormal high Sr, Ba and REE content may imply the mixing of enriched mantle materials. LA-ICP-MS in-situ zircon U-Pb dating obtain the ages of 10.9±0.1 Ma and 11.9!0. 4Ma for the quartz aegirine-augite syenite and alkali granite respectively, representing the crystallization ages of the two rocks. The εHf （t） values of the quartz aegirine-augite syenite and alkali granite are of -9.78-3.24 and -13.54- 5.78, showing the crust-mantle mixing in magma source area. According to the comprehensive a- nalysis and combined with regional geological data, we preliminarily hypothesized that the Kuzigan alkaline complex is a product of the crust-mantle mixing, which is caused by the as the- nosphere flowing northward due to the delamination of the Tibetan plateau at -25Ma, and the asthenosphere upwelling as a result of the obstruction of the root of the Tarim craton lithosphere. Therefore, the formation of the complex is a fernwirkung of the magmation after Tibetan plateau large-scale delamination, and it signifies that during - 11 Ma the study area was in extensional tectonic setting.