Welcome to visit Geoscience!

Geoscience ›› 2017, Vol. 31 ›› Issue (04): 683-696.

• Petrology • Previous Articles     Next Articles

Petrogenesis and Tectonic Implication of Volcanic Rocks from Manitu Formation in the Western Great Xing’an Range

LI Yinglei1(), XU Guo1,2, LIU Huichuan3(), BAI Lingqi1, SU Yinchun1, LIU Xiaonü1   

  1. 1. Inner Mongolia Key Laboratory of Magmatic Mineralization and Ore-Prospecting,Geological Survey Institute of Inner Mongolia, Hohhot, Inner Mongolia 010020, China
    2. School of Earth Sciences, China University of Geosciences, Wuhan, Hubei 430074, China
    3. School of Earth Science and Engineering, Sun Yat-sen University, Guangzhou, Guangdong 510275, China
  • Received:2016-06-25 Revised:2017-01-12 Online:2017-08-10 Published:2017-09-15

Abstract:

Different tectonic settings have been proposed for the Mesozoic volcanic rocks in northeast China, including the mantle plume, subduction of the Pacific Ocean and post-collisional extension associated with the closure of the Mongol-Okhotsk ocean. In this paper, we carried out geochemical studies on the andesite-dacite-rhyolite in Manitu Formation of the western Great Xing’an Range (NE China). Samples show variable major and trace element compositions with SiO2=56.71%-71.85%, Na2O+K2O=5.92%-10.18%, Na2O/K2O=0.78-1.33,Mg#=30.6-56.4. Chondrite and primitive mantle normalized REE patterns and spidergrams show significant Nb, Ta, Ti, Sr and Eu negative anomalies (Nb*=0.17-0.71, Sr*=0.24-1.15, Eu*=0.49-0.77) and high total REEs contents. These results suggest that the source magmas of the Manitu volcanic rocks were derived from a preexistent juvenile crust and a subordinate recycled crustal component. A fractional assemblage of hornblende+plagioclase+K-feldspar+apatite+titanomagnetite was responsible for the systematic elements variations from the andesite to rhyolite. This interpretation is consistent with the tectonic model that the Manitu volcanic rocks were generated in an arc/back-arc tectonic setting in response to the Pacific Ocean subduction.

Key words: Great Xing’an Range, Manitu Formation, volcanic rock, subduction of the Pacific Ocean, calc-alkaline rock

CLC Number: