Welcome to visit Geoscience!

Geoscience ›› 2020, Vol. 34 ›› Issue (03): 466-482.DOI: 10.19657/j.geoscience.1000-8527.2020.023

• Petrology • Previous Articles     Next Articles

Spatial-temporal Distribution of Late Mesozoic Intrusive Rocks in South Daxing’anling Mountains and the Characteristic Contrast of Rocks in the Mid Ridge and the East Slope

WANG Di1,2(), ZHAO Guochun1, SU Shangguo1(), LI Hongxing3   

  1. 1. School of Earth Sciences and Resources, China University of Geosciences,Beijing 100083,China
    2. New Energy Research Institute, SINOPEC Star Petroleum Co.,Ltd, Beijing 100083,China
    3. Beijing Research Institute of Chemical Engineering and Metallurgy, Beijing 101149,China
  • Received:2019-03-23 Revised:2020-01-13 Online:2020-07-04 Published:2020-07-05
  • Contact: SU Shangguo

Abstract:

This work studied the petrology, major and trace element geochemistry, and zircon U-Pb ages of four different granites in the Daxing’anling Mountains (DM), i.e., Malegenba and Chaoyanggou in the DM main ridge,and the Yezhugou and Budunhua in the DM eastern slope,in order to better constrain the magmatic background of the Late Mesozoic DM. LA-ICP-MS zircon U-Pb dating of the Chaoyanggou and Budunhua granites yielded Late Jurassic ages of (154±1) Ma and (154.1±1.6) Ma, respectively, whereas the Malegenba and Yezhugou granites yielded Early Cretaceous ages of (144.62±0.74) Ma and (140.2±2.7) Ma, respectively. According to the petrographic and geochemical characteristics, the DM main-ridge granites are high-K calc-alkaline, metaluminous, and highly-fractionated I-type;whereas those in the DM eastern slope are cal-calkaline to high-K calc-alkaline and metaluminous to peraluminous TTG I-type. The DM main-ridge granites are more depleted in Ba, Nb, Sr, P, Ti, and Eu than their DM eastern-slope counterparts. Combined with the regional geology, the southern DM region was probably co-influenced by the rapid NNW-directed oblique subduction of the Izanagi plate and the Mongolia-Okhotsk Ocean closure during the Late Jurassic to Early Cretaceous. The DM main-ridge granites were probably formed by the partial melting of the lower crust underplated by and mixed with mantle-derived magma, and the granitic magmas were intruded along the fault zones in the DM main ridge. Meanwhile, the DM eastern-slope granites were formed by the collision-related crustal thickening at that time.

Key words: Daxing’anling Mountains, geochemistry, zircon U-Pb dating, Mongolia-Okhotsk Ocean

CLC Number: