摘要
滇中老街子铅-银矿床位于金沙江-哀牢山富碱斑岩成矿带内的姚安铅多金属成矿区。区内富碱岩脉广泛发育,与构造活动关系密切,按矿物组合主要分为正长斑岩脉、粗面斑岩脉、煌斑岩脉和白榴石斑岩脉。铅-银矿(化)体主要赋存于正长斑岩体内,在粗面斑岩脉上、下盘加富。富碱岩脉受断裂构造控制,主要呈NE向展布,其次为NW向;岩脉(体)间的穿插关系显示侵位顺序为:(粗面岩→)正长斑岩脉(体)→粗面斑岩脉→白榴石斑岩脉→煌斑岩脉。岩石地球化学特征指示,4类富碱岩脉均属钾玄岩系列岩石,形成于俯冲背景下碰撞后的板内拉张环境,主要来源于下地壳,并混入少量地幔组分。由于不同程度的岩浆演化及源区岩浆房内的分带,导致岩浆在逐层上升侵位后,形成不同矿物组合和化学组分的富碱岩脉(体)。对比分析4类富碱岩脉的时空分布及源区特征,结合其与构造、成矿的耦合关系,构建富碱岩脉时空结构模型,为深部及外围找矿预测提供依据。
The Laojiezi Pb-Ag deposit,central Yunnan,is located in Yao'an lead-polymetallic mine district in Jinshajiang-Ailaoshan alkali-rich porphyry metallogenic belt.Alkali-rich dikes,widely developed in the area and closely related to the structure,according to mineral assemblage,are divided into syenite porphyry dikes,trachyte porphyry dikes,lamprophyre dikes and leucite porphyry dikes.Pb-Ag mineralized bodies mostly occur in syenite porphyry and are enriched in the hanging wall and footwall of trachyte porphyry dikes.The alkali-rich dikes are controlled by the fault structure and are mainly distributed in NE and NW direction.Combined with the interspersed relationship of alkali-rich dikes(masses),the sequence of emplacement is inferred as follows:trachyte→syenite→trachyte porphyry→leucite porphyry→lamprophyre.Through the petrogeochemical characteristics,it is considered that the four types of alkali rich dikes are belong to the shoshonite,formed in the intraplate extensional environment after collision in the subduction background,mainly derived from the thickened lower crust and mixed with a small amount of enriched mantle components.Different degrees of magma evolution,zonation in the magma chamber in the source area and emplacement layer by layer of magma lead to the the finally formation of several types of alkali-rich dikes(masses)with different mineral assemblages and chemical components.Comprehensively comparing and analyzing the temporal and spatial distribution and source characteristics of the four types of dikes,and exploring the coupling relationship with tectonic and mineralization,constructing a time-space model of alkali-rich dikes,so as to provide a basis for deep and peripheral prospecting predictions.
作者
黄仲金
吴静
吴鹏
姜龙燕
杨航
HUANG Zhongjin;WU Jing;WU Peng;JIANG Longyan;YANG Hang(Kunming University of Science and Technology,College of Land and Resources Engineering,Kunming 650093,Yunnan,China;Southwest Institute of Geological Survey,Geological Survey Center for Non-ferrous Mineral Resources,Kunming 650093,Yunnan,China)
出处
《地质通报》
CAS
CSCD
北大核心
2023年第2期285-306,共22页
Geological Bulletin of China
基金
云南省“万人计划”青年拔尖人才专项(编号:YNWR-QNBJ-2018-272)
云南省矿产资源预测评价工程实验室(2010)
云南省地质过程与矿产资源创新团队(2012)项目。
关键词
富碱岩脉
岩石学
地球化学
时空结构
铅-银矿床
云南
alkali-rich dikes
petrology
petrogeochemistry
temporal and spatial structure
Pb-Ag deposit
Yunnan Province
