摘要
燕山中晚期，个旧岩浆活动强烈，并形成基性、中性、酸性及碱性杂岩体。对此前人已做过很多工作，但对其成因机制并未做详细探讨。本文以神仙水花岗岩、卡房花岗岩及贾沙辉长-二长岩为研究对象采用XRF、ICP-MS、EMPA-1600等分析测试方法，对个旧岩浆杂岩体的元素地球化学特征做了详细的分析和总结，并初步得出以下结论：
1、贾沙辉长-二长岩富集LILE、LREE，相对亏损HREE，并具有富碱特征和Eu的弱负异常，说明其为富集地幔来源；但与OIB相比，具有Nb、Ta、Ti等元素的亏损，说明其受到地壳混染作用。
2、个旧花岗岩普遍具有高硅、高铝、富碱(尤其富钾)等特征。随着SiO_2含量的增加，Al_2O_3、Fe_2O_3T、MgO、CaO、TiO_2、P_2O_5的含量呈线性降低；当SiO_2含量大于70％时，Na_2O和K_2O含量变化不大。
3、岩石类型上，个旧各花岗岩体的铝质系数A／CNK值为0.92～1.08，属于Ⅰ型花岗岩；构造环境上，个旧花岗岩形成于大陆碰撞环境，为碰撞晚期或后碰撞构造环境；其主要成分来源于地壳，并有基性成分和酸性成分的混合特征。
4、初步研究表明，个旧花岗岩形成于与玄武质岩浆底侵有关的下部大陆壳重熔作用。
In Mid-Late Yanshanian, magmas were intensively active which generated a series of basic, acid and alkaline complex in Gejiu, Yunnan Province. Some scholors have worked on them for many years, but their petrogenesis are deficient. Thus, we take Shenxianshui granites, Kafang granites and Jiasha gabbro-monzonites as main objects. By using XRF, ICP-MS and EMPA-1600 analysis methods, we have described their geochemical characters of Gejiu complex in details, and made some primary conclusions as followings:
1. Gabbro-monzonites of Jiasha are enriched in LILE, LREE, relatively depleted in HREE and characterized by alkaline-rich and slight Eu-depletion, indicating their enriched-mantle sources; but they have characteristics, by comparison to OIB, with depletion of some elements (Nb, Ta, Ti et al.) which suggest crust's contamination.
2. Granites generally have characters of high SiO_2, Al_2O_3, (K_2O+Na_2O) (especially K_2O). The content of Al_2O3, Fe_2O_3T, MgO, CaO, P_2O_5 and TiO_2 are negatively linear with that of SiO_2. When the content of SiO_2 is over 70%, the variation of K_2O and Na_2O is negligent.
3. As for rock types, the values of A/CNK of granites vary from 0.92 to 1.08, attributed to I-type granites; granites of Gejiu formed from continental collision environment, concretely from late-collision or post-collision geological environment; their material sources are mainly from crust with characters of mixing between basic and acid sources.
4. According to the pilot studies, granites generated by re-melting of lower continental crust, which is related to basaltic magma's underplating.
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