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含矿与无矿侵入体的区分是阐明岩浆型矿床成因的基础,也是深部找矿预测的依据。本文选择四川米易青皮村岩体为例,通过岩相学及矿物成分剖面和定量化结构分析,试图阐明无矿岩浆侵入体的固结过程,并与攀枝花含矿岩体对比,进一步揭示含矿与无矿侵入体形成过程的区别。岩相学分析表明,青皮村岩体中粒辉长岩的造岩矿物可以划分为四个世代:1粗粒斜长石→2中粒斜长石+单斜辉石→3黑云母+铁钛氧化物→4伟晶状斜长石,展示了封闭系统的固结过程。加上粗晶辉长岩脉的矿物组合钠长石+单斜辉石+角闪石+磷灰石,可以将青皮村岩体的组成矿物划分为5个世代,进而划分成四个晶体群:通道晶体群、岩浆房晶体群、基质晶体群和流体晶体群。晶体成分剖面分析表明,通道晶和岩浆房晶显示正环带,具有封闭系统降温结晶的特点,其中通道晶的生长伴随着减压作用;基质晶初始为正环带,末期显示反环带,反映了残余流体的聚集与逃逸;而流体晶体群的产出则反映了超临界流体的相分离和排气作用。定量化结构分析揭示了岩浆固结晚期的粗化过程,是封闭岩浆系统固结过程的重要证据,与岩相学和晶体成分剖面分析结果一致。此外,青皮村岩体中Fe-Ti氧化物含量甚低,其体积分数仅为4%,暗示它们不可能聚集成矿。与攀枝花岩体相比,青皮村岩体固结过程中缺失先存晶体的溶蚀结构,后者被认为是高温含矿流体输入的结果。据此,本文提出,外来含矿流体(透岩浆流体)输入与否决定了镁铁质岩浆侵入体的产矿能力;进而认为,是流体输入导致了岩浆分异,而不是岩浆分异产生了含矿流体。
The distinction between ore-bearing and ore-free intrusions is the basis for elucidating the genesis of the magmatic deposits and also the basis for the prospecting of deep deposits. This paper chooses the Qingyi village of Miyi in Sichuan Province as an example. By means of petrography and mineral composition analysis and quantitative structure analysis, this paper tries to clarify the consolidation process of ore-free magma intrusive body and contrast with the ore-bearing rock mass of Panzhihua, The difference between ore and mine-free intrusion formation process. Petrographic analysis shows that the rock-forming minerals of granulite-gabbro in Qingpi village can be divided into four generations: 1 coarse-grained plagioclase → 2 medium-grained plagioclase + clinopyroxene → 3 biotite + iron Titanium oxide → 4 vitrinite plagioclase, showing the consolidation of the closed system. Together with the mineral assemblages of albite + clinopyroxene + amphibole + apatite in the coarse-grained gabbro, it is possible to classify the mineral components of the Qingpi village into five generations and divide them into four crystal groups : Channel crystal group, magmatic chamber crystal group, matrix crystal group and fluid crystal group. The analysis of the crystal composition shows that the channel crystal and magma chamber show the positive zone, which has the characteristics of cooling crystallization in the closed system. The crystal growth of the channel is accompanied by depressurization; the matrix crystal is initially positive zone, Reflects the accumulation and escape of residual fluid; and the output of the fluid crystal group reflects the phase separation and exhaust of the supercritical fluid. Quantitative structural analysis reveals the late coarsening process of magmatic consolidation, which is an important evidence of the consolidation process of the closed magmatic system, which is consistent with the results of petrographic and crystal composition analysis. In addition, the content of Fe-Ti oxides in Qingpi village is very low, only 4% of the volume fraction, suggesting that they are unlikely to accumulate into ore. Compared with the Panzhihua pluton, the dissolution structure of the pre-existing crystal is absent from the consolidation of the rock mass in Qingpi village, which is considered to be the result of the input of the high-temperature ore-bearing fluid. Accordingly, this paper proposes that the input of ore-bearing fluid (trans-magmatic fluid) determines the ore-producing ability of mafic magma intrusions. It is further considered that the input of fluid leads to magmatic differentiation instead of magmatic differentiation Minerals fluid.