ZHU Jiang1,2, LÜ Xinbiao1,2*, CAO Xiaofeng1,2, MO Yalong1,2, and CHEN Chao1,2
1 Faculty of Earth Resources, China University of Geosciences, Wuhan 430074, China
2 State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, China
Abstract The Huaniushan granite is located at the Beishan orogenic belt, northwestern China. At the contact zone between the granite and marble, a hydrothermal Pb-Zn and skarn Au deposit is formed. LA-ICP-MS zircon U-Pb dating yielded a weighted mean 206Pb/238U age of 229.5±2.6 Ma (MSDW=0.93) for the Huaniushan granite, implying its Late Triassic intrusion. Geochemistry analyses show that the Huaniushan granite is enriched in Si, K, Na, and REE, and depleted in Mg and Ca, with contents of SiO2 (70.8% to 74.4%), Na2O+K2O (8.8% to 10.2%), CaO (0.93% to 1.44%), and MgO (0.14% to 0.48%). REE is characterized by obvious negative Eu anomaly. Rb, Th, U, K, Pb, Nb, Zr and Hf elements are rich in the granite while Ba, Sr, P, Ti and Eu are deplete. The granite has a high (Zr+Nb+Ce+Y) abundance and 104 Ga/Al ratios. Petrology, major and trace elements data all indicate that the Huaniushan granite is A-type granite which intruded in a post-collisional extensional tectonic setting. The magma was dominantly sourced from partial melting of crustal intermediate-felsic igneous rocks. Intensive magmatic activities and Au-Cu-Mo mineralization occurred throughout the Beishan orogenic belt during the period from ca. 240 to 220 Ma.
Key words A-type granite; geochronology; geochemistry; tectonic setting; Beishan orogenic belt
* Corresponding author, E-mail: Lvxb_01@163.com
CHINESE JOURNAL OF GEOCHEMISTRY Vol. 31, No. 1, 2012, page 85-94
© Science Press and Institute of Geochemistry, CAS and Springer-Verlag Berlin Heidelberg 2012
