Geochemical characteristics of the Chongba leucogranites, southern Tibet: Formation mechanism and tectonic implications

被引：0
|
作者：
Wang X. [1 ,2 ]
Zhang J. [2 ]
Yan S. [2 ,3 ]
Liu J. [2 ,4 ]
Guo L. [4 ]
机构：
[1] Key Laboratory of Crustal Dynamics, Institute of Crustal Dynamics, China Earthquake Administration, Beijing
[2] Key Laboratory of Orogenic Belts and Crustal Evolution (Ministry of Education), School of Earth and Space Sciences, Peking University, Beijing
[3] Petroleum Exploration and Development Research Institute, PetroChina, Beijing
[4] State Key Laboratory of Continental Tectonics and Dynamics, Institute of Geology, Chinese Academy of Geological Sciences, Beijing
来源：
Earth Science Frontiers | 2016年 / 23卷 / 01期
关键词：
Chongba leucogranites; Formation mechanism; Geochemistry; Southern Tibet; Sr-Nd isotopes;
D O I：
10.13745/j.esf.2016.01.024
中图分类号：
学科分类号：
摘要：
The Chongba leucogranite pluton is situated in the eastern part of the Greater Himalayan leucogranite belt. Geochemical data show that these rocks are characterized by high SiO2 (73.87%-74.95%), Al2O3 (14.20%-14.74%), K2O (4.44%-4.89%), K2O/Na2O (1.19-1.42), A/CNK values (1.18-1.22), and enrichment in Rb, Th, U, depletion in Ba, Nb, Sr, Zr, and strong negative Eu anomalies (δEu=0.27-0.37). These features suggest that they are high potassium calc-alkaline and peraluminous S-type granites. The high Rb/Sr (2.6-8.6) and low CaO/Na2O (0.18-0.20) ratios imply that the source rocks were probably pelites. The relatively high (87Sr/86Sr)i (0.763199-0.778799) and low εNd(t) (-16.7-16.3) compared with those of the metasedimentary rocks in the Greater Himalaya crystalline complex (GHC), indicating that the leucogranites were generated from partial melting of the GHC metasedimentary rocks. The features of high (87Sr/86Sr)i and low Sr content, and the Rb/Sr values decreasing with increased Ba content indicate that the Chongba leucogranites were derived from muscovite dehydration melting of the GHC metapelite under water-absent condition, which is probably closely associated with the structural decompression caused by the extensional decollement of the south Tibet detachment system (STDS). © 2016, Editorial Office of Earth Science Frontiers. All right reserved.
引用
收藏
页码：264 / 275
页数：11
相关论文
共 78 条
  • [1] Guo Z.F., Wilson M., The Himalayan leucogranites: Constraints on the nature of their crustal source region and geodynamic setting, Gondwana Research, 22, 2, pp. 360-376, (2012)
  • [2] Harrison T.M., Grove M., McKeegan K.D., Et al., Origin and episodic emplacement of the Manaslu intrusive complex, central Himalaya, Journal of Petrology, 40, 1, pp. 3-19, (1999)
  • [3] Lee J., Dinklage B.R., Wang W.S., Et al., Evolution of the Kangmar Dome, southern Tibet: Structural, petrologic, and thermochronologic constrains, Tectonics, 19, 5, pp. 872-895, (2000)
  • [4] Le Fortp, Himalayas, the collided range: Present knowledge of the continental arc, American Journal of Science, 275, pp. 1-44, (1975)
  • [5] Searle M.P., Godin L., The South Tibetan Detachment system and the Manaslu leucogranite: A structural re-interpretation and restoration of the Annapurna Manaslu Himalaya, Nepal, Journal of Geology, 111, 5, pp. 505-523, (2003)
  • [6] Searle M.P., Parrish R.R., Hodges K.V., Shisha Pangmaleucogranite, south Tibetan Himalaya: Field relations, geochemistry, age, origin, and emplacement, Journal of Geology, 105, 5, pp. 295-317, (1997)
  • [7] Zeng L.S., Gao L.E., Xie K.J., Et al., Mid-Eocene high Sr/Y granites in the Northern Himalayan Gneiss Domes: Melting thickening lower continental crust, Earth and Planetary Science Letters, 303, 3-4, pp. 251-266, (2011)
  • [8] Annen C., Scaillet B., Sparks R.S.J., Thermal constraints on the emplacement rate of a large intrusive complex: The Manaslu leucogranite, Nepal Himalaya, Journal of Petrology, 47, 1, pp. 71-95, (2006)
  • [9] Chambers J., Parrish R.R., Argles T., Et al., A short-duration pulse of ductile normal shear on the outer South Tibetan detachment in Bhutan: Alternating channel flow and critical taper mechanics of the eastern Himalaya, Tectonics, 30, 2, (2011)
  • [10] Coleman M.E., U-Pb constraints on Oligocene-Miocene deformation and anatexis within the Central Himalaya, Marsyandi valley, Nepal, American Journal of Science, 298, 7, pp. 553-571, (1998)
12345678