Petrogenesis of the Donghouding A-Type Granite in Northern Hebei Province: Constraints from Geochemistry, Zircon U-Pb Dating and Sr-Nd-Pb-Hf Isotopic Composition
详细信息
- 责任者：Liang Qingling (No.606 Exploration Team ; Sichuan Metallurgical and Geological Exploration Bureau ; Chengdu 611730 ; China) ; Jiang Sihong
- 刊名：Geological Review
- 出版年：2013
- 卷期：59(6)
- 关键词：A型花岗岩 ; A-type granite ; 铀—铅计时 ; U-Pb dating ; 河北 ; Hebei Province
- 页码：p.1119-1130
- 图表：8 illus., 5 tables, 52 refs.
- 分类号：0801
- issnNo：ISSN0371-5736
- isbnNo：CN11-1952/P
摘要
This study presents bulk geochemical,Zircon U-Pb dating and Sr—Nd—Pb—Hf isotopic results for the Donghouding A-type granite in northern Hebei. LA-MC-ICP-MS zircon U-Pb dating results and petrological characteristics show that the Donghouding magmatic rock is the Early Cretaceous( 129. 3 ~ 129. 5Ma) K-feldspar granite porphyry,not Jurassic—Cretaceous syenite porphyry and quartz syenite porphyry regarded by the former researchers. The Donghouding K-feldspar granite porphyry is High-K calc-alkaline,and characterized by high contents of SiO2( 72. 15% ~73. 00%),alkali( Na2O + K2O: 9. 42% ~ 9. 60%),and high FeO / MgO ratios. It is enriched in LREE and K,Rb,Zr,Hf,Th,U,Y,and depleted in Ca,Ba,Sr,P,Ti,Cr,Ni,Co,with negative Eu anomalies( δEu: 0. 25 ~ 0. 41),high Ga / Al ratios. The Donghouding K-feldspar granite porphyry is typical Atype granite,and may be formed in the extensional setting. The isotope( Sr—Nd— Pb—Hf) data of the Donghouding K-feldspar granite porphyry show the following characteristics: relatively high initial Sr n(87Sr) / n(86[ Sr)]i= 0. 70815 ~ 0. 71197),negative εNd( t) values(-13. 2 ~-16. 8) and the values of twostage model ages( T2DM) ranging from 2. 0 to 2. 3 Ga; n(206Pb) / n(204[ Pb)]i= 16. 745 ~ 16. 765,n(207Pb) / n(204[ Pb)]i= 15. 372 ~ 15. 394, n(208Pb) / n(204[ Pb)]i= 37. 706 ~ 37. 794; negative εHf( t) values from- 20. 7 to- 9. 2 and the values of two-stage model ages( T DM C) ranging from 1. 9 to 2. 6Ga. Although the Sr—Nd—Pb—Hf isotopic compositions suggest that the magma was sourced from Paleoproterozoic crust,the main growth period of eastern North China Craton crust is the Late Archean. Therefore,this paper concludes that the Donghouding K-feldspar granite porphyry was mainly derived from partial melting of Archean crust with some depleted mantle components. Geochronological and isotopic characteristics suggest that the Donghouding K-feldspar granite porphyry were the products of North China Craton lithospheric thinning and crustal extension during late Mesozoic.
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