Abstract：In order to investigate the formation age and tectonic background of the syengranite in Ulanhot region, the authors have studied its zircon U-Pb age and geochemical characteristics. The results show that LA-ICP-MS zircon U-Pb age is (219.7±1.2)Ma, which represents its formation age. The syengranite is rich in silicon and alkali, while the content of aluminum, calcium, magnesium and iron is low. These rocks also have high rare-earth elements content, inapparent fractional distillation between light rare-earth elements and heavy rare-earth elements, and obvious negative abnormal Eu. For the trace elements, these rocks are rich in large ion lithophile elements (Rb and K) and high field strength elements( U, Th, Hf and HREE), while they are poor in Sr, Eu, Ba and Ti. The 10 000×Ga/Al value (3.53 ~ 5.09) is higher than the lower limit value (2.6) of A-type granite, and significantly higher than the average value of the I-type and S-type granites (2.10 and 2.28, respectively). Therefore, the authors concluded that Triassic syenogranite is A-type granite, and the formation environment belongs to post-orogenic lithospheric extension tectonic setting after the closure of Paleo-Asian Ocean.
邱锦雄, 杨亮, 陈萌超, 王文义, 高勇. 内蒙古乌兰浩特地区正长花岗岩LA-ICP-MS锆石U-Pb年龄及其地质意义[J]. 中国地质调查, 2019, 6(1): 54-60.
QIU Jinxiong, YANG Liang, CHEN Mengchao, WANG Wenyi, GAO Yong. LA-ICP-MS zircon U-Pb age of the syengranite in Ulanhot region of Inner Mongolia, and its geological significance. , 2019, 6(1): 54-60.
[1] 内蒙古自治区地质矿产局.内蒙古自治区区域地质志[M].北京:地质出版社,1991. [2] 邵济安,牟保磊,何国琦,等.华北北部在古亚洲域与古太平洋域构造叠加过程中的地质作用[J].中国科学:D辑,1997,27(5):390-394. [3] 邵济安,张履桥,牟保磊.大兴安岭中生代伸展造山过程中的岩浆作用[J].地学前缘,1999,6(4):339-346. [4] 任纪舜,陈廷愚,牛宝贵,等.中国东部大陆岩石圈的构造演化与成矿[M].北京:科学出版社,1992. [5] Buslov M M,Yu I,Saphonova T,et al.Evolution of the Paleo-Asian ocean (Altai-Sayan region,central Asia) and collision of possible Gondwana-derived terranes with the southern marginal part of the Siberian continent[J].Geosci J,2001,5(3):203-224. [6] Coleman R G.Reconstruction of the Paleo-Asian Ocean[M].Utrecht,Netherlands:VSP International Sciences Publisher,1994. [7] 洪大卫,黄怀曾,肖宜君,等.内蒙古中部二叠纪碱性花岗岩及其地球动力学意义[J].地质学报,1994,68(3):219-230. [8] 吴福元,孙德有,林强.东北地区显生宙花岗岩的成因与地壳增生[J].岩石学报,1999,15(2):181-189. [9] 葛文春,吴福元,周长勇,等.大兴安岭中部乌兰浩特地区中生代花岗岩的锆石U-Pb年龄及地质意义[J].岩石学报,2005,21(3):749-762. [10] 孙德有,吴福元,高山,等.吉林中部晚三叠世和早侏罗世两期铝质A型花岗岩的厘定及对吉黑东部构造格局的制约[J].地学前缘,2005,12(2):263-275. [11] 孙德有,吴福元,高山.小兴安岭东部清水岩体的锆石激光探针U-Pb年龄测定[J].地球学报,2004,25(2):213-218. [12] 孙德有,吴福元,李惠民,等.小兴安岭西北部造山后A型花岗岩的时代及与索伦山—贺根山—扎赉特碰撞拼合带东延的关系[J].科学通报,2000,45(20):2217-2222. [13] 孙德有,吴福元,林强,等.张广才岭燕山早期白石山岩体成因与壳幔相互作用[J].岩石学报,2001,17(2):227-235. [14] Liu Y S,Hu Z C,Gao S,et al.In situ analysis of major and trace elements of anhydrous minerals by LA-ICP-MS without applying an internal standard[J].Chem Geol,2008,257(1/2):34-43. [15] Ludwig K R.User’s Manual for Isoplot/Ex,Version 2.10,A Geochronological Toolkit for Microsoft Excel[M].Berkeley:Berkeley Geochronology Center,Special Publication,1999:1-47. [16] Andersen T.Correction of common lead in U-Pb analyses that do not report 204Pb[J].Chem Geol,2002,192(1/2):59-79. [17] Maniar P D,Piccoli P M.Tectonic discrimination of granitoids[J].Geol Soc Am Bull,1989,101(5):635-643. [18] Peccerillo A,Taylor S R.Geochemistry of Eocene calc-alkaline volcanic rocks from the Kastamonu area,Northern Turkey[J].Contribut Mineral Petrol,1976,58(1):63-81. [19] Sun S S,McDonough W F.Chemical and isotopic systematics of oceanic basalts:implications for mantle composition and proces-ses[J].Geol Soc,London,Spec Publ,1989,42(1):313-345. [20] 张能. 内蒙古东部大石寨地区晚古生代构造格局及演化[D].北京:中国地质大学(北京),2013. [21] 周漪,葛文春,王清海.大兴安岭中部乌兰浩特地区中生代花岗岩的成因——地球化学及Sr-Nd-Hf同位素制约[J].岩石矿物学杂志,2011,30(5):901-923. [22] 张旗,冉皞,李承东.A型花岗岩的实质是什么?[J].岩石矿物学杂志,2012,31(4):621-626. [23] Whalen J B,Currie K L,Chappell B W.A-type granites:geochemical characteristics,discrimination and petrogenesis[J].Contribut Mineral Petrol,1987,95(4):407-419. [24] 洪大卫,王式洸,韩宝福,等.碱性花岗岩的构造环境分类及其鉴别标志[J].中国科学:B辑,1995,25(4):418-426. [25] Pearce J A,Harris N B W,Tindle A G.Trace element discrimination diagrams for the tectonic interpretation of granitic rocks[J].J Petrol,1984,25(4):956-983.
2019, Vol. 6 
