• 责任者：Zhang Ying (State Key Laboratory of Ore Deposit Geochemistry ; Institute of Geochemistry ; Chinese Academy of Sciences ; Guiyang 550002 ; China) ; Huang Zhilong
• 刊名：Geochimica
• 出版年：2013
• 卷期：42(6)
• 关键词：辉长岩 ; gabbros ; 二长岩 ; monzonites ; 铀—铅计时 ; U-Pb dating ; 云南 ; Yunnan Province
• 页码：p.523-543
• 图表：15 illus., 2 tables, 75 refs.
• 分类号：0801
• issnNo：ISSN0379-1726
• isbnNo：CN44-1398/P

     The Jiasha intrusion, located in the westem Gejiu district, consist of gabbros and monzonites. We conducted geochronological and geochemical studies to understand the timing, mantle source and tectonic environment of the Jiasha intrusion, a basic end-member of the late-Mesozoic magma activities in the Gejiu area. These rocks have zircon U-Pb ages of-84.0 Ma, synchronous with granitic, alkaline and lamprophyric rocks and Sn mineralization in the Gejiu area （76.0-85.0 Ma）. Both gabbros and monzonites have variable SiO2 （47.3%-60.0%） and K20＋Na20 （7.31%-10.12%）. They have high REE contents, and display LREE-enriched chondrite-normalized patterns with slightly Eu anomalies. In the primitive mantle-normalized spidergram, both of them are enriched in LIIE including REE, Rb, K and Pb but depleted in HSFE including Nb, Ta, Ti and P. Our research suggests that monzonites have formed the gabbric magma by fractional crystallization. Geochemical data indicate that the parental magma of the Jiasha intrusion have derived from subduction-related metasomatized mantle, and have formed by low-degree partial melting （〈5.0%） of garnet-lherzolite. The primary magmas have undergone extensive crustal contamination and fractional crystallization of olivine and pyroxene during emplacement. Our study suggests that the Jiasha intrusion has an age similar to the magma activities in the nearby Diandongnan-Guixi area, indicating that production of these magmatic rocks are possibly related to extension of lithosphere.