东昆仑东段香加南山花岗岩基斜长石成分组成与岩浆演化和混合作用

发布时间：2018-10-13 10:25

【摘要】：东昆仑东段香加南山花岗岩基岩浆混合作用明显,斜长石作为主要造岩矿物,是研究岩石成因、示踪岩浆演化和岩浆混合过程的有效工具。对香加南山花岗岩基中寄主岩及暗色微粒包体中的斜长石进行岩相学和矿物化学研究。电子探针结果显示:寄主岩中正常环带斜长石(39~48,21~36)、包体中斜长石捕掳晶(41~49,35~36,43~49,31~47,27~38)和寄主岩矿物中包裹斜长石(29~45,14~32)具有演化的An值;部分寄主岩斜长石核部由于受到后期蚀变具有较高的An值(59~72)。包体中基质斜长石大部分具核边结构,核部(52,31)和边部(33~37,25)An值存在间断;少量斜长石核部受到蚀变,An值较低(49),幔部(55~71)An值高于边部(46~49);部分包体中基质斜长石核部呈补丁状,暗色部分An值较高(66),浅色部分An值较低(33~39)。包体中斜长石捕掳晶主要分为干净斜长石捕掳晶和含有矿物的斜长石捕掳晶两大类,干净斜长石环带明显或聚片双晶发育,An值变化范围较小(41~49,35~36);含有暗色矿物的斜长石捕掳晶An值整体也呈震荡变化(43~49,31~47,27~38),但由于受到蚀变,部分测点An值较高(78),少量斜长石具有高An值增生边(73)。以上研究显示,结晶于寄主岩的斜长石正常演化序列反映寄主岩从演化早期到晚期,岩浆逐渐从偏基性向酸性转变;包体基质斜长石为包体进入寄主岩温度、压力和水饱和度降低导致斜长石受到熔蚀后继续结晶结果;包体中斜长石捕掳晶来自寄主岩,由于进入包体后温度和压力产生变化,以及后期生长,导致斜长石的成分和构造有所不同。香加南山花岗岩基及暗色微粒包体中斜长石的复杂环带为幔源镁铁质岩浆注入长英质岩浆混合作用的结果。
[Abstract]:The magma mixing of Xiangganshan Granitoid in the eastern part of East Kunlun is obvious. Plagioclase, as the main rock-forming mineral, is an effective tool to study the petrogenesis, trace magmatic evolution and magmatic mixing process. The lithofacies and mineral chemistry of plagioclase in the host rocks and dark particle inclusions of the Xiangganshan granite base were studied. The electron microprobe results show that the An values of the plagioclase in the host rock (3948821136), the plagioclase in the inclusions (41O49N35 / 35) and the plagioclase (2945141432) in the host rock minerals are evolutional, and the results of electron microprobe (EPMA) show that the plagioclase in the host rock (2945141432) has evolutionary An values, and the plagioclase in the host rock (2945141432) has the evolutionary An value. The partial host rock plagioclase core has a high An value (5972) due to late alteration. In the matrix plagioclase, most of the matrix plagioclase has a nuclear edge structure with discontinuous An values in the nuclear part (52n31) and the edge part (333725), a small amount of plagioclase core is altered, the An value is lower (49), and the An value of the mantle part (5571) is higher than that of the edge part (460.49), and some of the matrix plagioclase nuclei are patched, and some of the matrix plagioclase nuclei are patched. The An value of the dark part was higher (66), and the An value of the light color part was lower (33 ~ 39). The plagioclase in the inclusion is divided into two types: clean plagioclase and plagioclase containing minerals. The An value of clean plagioclase is obvious or polycrystalline, and the range of An value is small (41 ~ 4935 ~ 36), and the An value of plagioclase with dark minerals is also oscillating (434991n31n47772738), but due to alteration, the An value of plagioclase has been changed. Some of the measured points have higher An value (78), and a few plagioclase have high An proliferative edge (73). The above studies show that the normal evolution sequence of plagioclase crystallized in host rocks reflects the gradual transition of magma from the early to the late stage of host rocks from partial basicity to acidity, and the inclusion matrix plagioclase enters the host rock temperature. The decrease of pressure and water saturation results in the crystallization of plagioclase after corrosion, the pericrystals of plagioclase come from the host rock, and the change of temperature and pressure after entering the inclusion, as well as the later growth of plagioclase. The composition and structure of plagioclase are different. The complex ring belt of plagioclase in Xiangganshan granite base and dark granular inclusion is the result of magmatic mixing of mantle source magnesia-iron magma injected into feldspar magma.
【作者单位】：长安大学地球科学与资源学院西部矿产资源与地质工程教育部重点实验室国土资源部岩浆作用与找矿重点实验室;南阳理工学院土木工程学院;中国地质大学(北京)
【基金】：国家自然科学基金项目(编号41472191;41502191;41172186) 中央高校基本科研业务费专项资金项目(310827161002;310827161006) 青海省国土资源厅-中国铝业公司公益性区域地质矿产调查基金项目(编号:200801)的成果
【分类号】：P588.121

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