ZHANG Haijun, ZHU Bopeng. Geochemistry and its tectonic implication for A-type alkali granite in Yundukala area, Xinjiang[J]. Acta Scientiarum Naturalium Universitatis SunYatseni, 2019,58(1):39-49.
ZHANG Haijun, ZHU Bopeng. Geochemistry and its tectonic implication for A-type alkali granite in Yundukala area, Xinjiang[J]. Acta Scientiarum Naturalium Universitatis SunYatseni, 2019,58(1):39-49. DOI: 10.13471/j.cnki.acta.snus.2019.01.005.
Eastern Junggar of Xinjiang Uygur Autonomous Region is an important area of the Central Asian Orogenic belt
where the Siberia and Kazakhstan plates collided. Late Carboniferous granites are widespread in this area
among which alkali granites in Yundukala are investigated and studied in this paper. Yundukala alkali granites are characterized by high SiO
2
(72.40%-74.17%)
high alkaline (Na
2
O+K
2
O=8.41%-10.40%)
low TiO
2
(0.20%-0.40%) and low CaO(0.38%-0.70%) contents. They are significantly enriched in high field strength elements like Zr
Th
and Y
and exhibit highly differentiated REE patterns
showing right dipping lines with strong negative Eu anomaly
whilst their obvious depletion of Sr
Ba and Ti might have resulted from fractional crystallization of feldspar and Ti-oxides. These geochemical characteristics indicate they are typical A-type granites and may be the product of partial melting of the predominantly subducted oceanic crust or Nbrich basalt in the lower crust. The formation of these A-type granites infers that collisional orogenesis ended during late Carboniferous.