【作者】 李青；

【导师】 杜杨松；

【作者基本信息】 中国地质大学（北京） ， 矿产普查与勘探， 2009， 硕士

【摘要】 普朗复式岩体位于云南省义敦-中甸岛弧带南缘,与普朗大型斑岩铜矿有密切的成因联系。本文对普朗复式岩体进行了年代学、岩石学和地球化学研究,在此基础上分析了岩体的成因和成矿意义。根据接触关系和岩石特征将普朗复式岩体划分为三个阶段侵入岩,即第一阶段的石英闪长玢岩,第二阶段的石英二长斑岩和第三阶段的花岗闪长斑岩。利用单颗粒锆石U-Pb法测定的早、中、晚三个阶段侵入岩的结晶年龄分别为220.98±0.96Ma、211.81±0.5Ma和206.33±0.71Ma。普朗复式岩体主要岩石类型为钙碱性系列-碱性系列。岩石总体富硅富钾,Rb、K和Th高度富集,Nb、Ta、Ti和Yb明显亏损。从早至晚,岩石向富硅、富钾、贫铝、贫镁方向演化。Sr-Nd同位素分析表明形成普朗铜矿含矿斑岩的岩浆来源于上地幔和下地壳。含矿斑岩主要为石英二长斑岩,其次为石英闪长玢岩、花岗闪长斑岩。含矿与非含矿斑岩相比,更富集过亲岩浆元素和活动性元素,而稀土总量和轻稀土总量明显偏低,稀土元素分馏不明显。铜矿化作用伴随着钾长石对斜长石的交代作用和石英的沉淀。相对富钾贫钠的铝质过饱和斑岩具有较强的形成斑岩型铜矿床的潜在能力。更多还原

【Abstract】 The Pulang porphyry complex is located in the southern margin of the Yidun-Zhongdian island arc belt in Yunnan Province, southeastern China, and closely associated with the Pulang porphyry copper deposit. A chronological, petrological and geochemical study has been carried out on the Pulang porphyry complex, with a focus on analysis of its origin and metallogenic significance based on this study.The Pulang porphyry complex is divided into three stages of intrusions based on their contacting relationship and petrological characteristics. The lithologies of the intrusions include quartz dioritic porphyrite formed in the first stage, quartz monzonitic porphyrite in the second stage, and granodioritic porphyrite in the third stage. The crystallization ages of the intrusions were determined by using the single-grain zircon U-Pb method. The single-grain zircon U-Pb isotopic ages are defined as 221.0±1.0 Ma, 211.8±0.5 Ma; and 206.3±0.7 Ma for the first, second and third stages of intrusions, respectively.The porphyry rocks belong to a calc to alkaline series. They have high SiO2 and K2O content, and are rich in Rb, K, and Th, and poor in Nb, Ta, Ti, and Yb. There exist an evolution trend of SiO₂ and K₂O increasing and Al₂O₃, CaO and MgO decreasing in the rocks from early to late. The Sr, Nd isotopic data support derivation of the magma responsible for the formation of the complex from a mixing source of upper mantle with lower crust.The ore host rocks are firstly quartz monzonitic porphyrite, and secondly quartz dioritic porphyrite and granodioritic porphyrite. Compared with the ore-free porphyrites, the ore-bearing porphyrites are higher in magmatophile and mobile elements, and lower in REE, especially LREE, with no evident fractional distillation of REE. The cupper mineralization is associated with replacement of plagioclase by K-feldspar and precipitation of quartz. The peraluminous porphyrites with higher K₂O and lower Na₂O content have larger potential for the formation of porphyry copper deposit.更多还原