滇中小水井金矿煌斑岩特征及与金矿化的关系  

Geological Characteristics of Lamprophyres and their Relations with Gold Mineralization of the Xiaoshuijing Gold Deposit in Central Yunnan Province

作　　者：符德贵[1] 周云满[1] 张长青[2] 陈庆广[3] 覃修平[1] 

机构地区：[1]云南黄金矿业集团股份有限公司,昆明650224 [2]中国地质科学院矿产资源研究所,北京100037 [3]云南省地质矿产勘查开发局第一地质大队,曲靖655000

出　　处：《地质与勘探》2010年第3期414-425,共12页Geology and Exploration

基　　金：云南黄金矿业集团股份有限公司科研项目"云南省楚雄市龙岗金矿带成矿规律及成矿预测"的资助

摘　　要：小水井金矿床煌斑岩呈树枝状、环状、不规则状沿断裂带侵入,岩石为致密块状细晶辉石云斜煌斑岩,其SiO2含量32.28%～49.72%,属基性-超基性范围,为碱性系列的富钾钙碱性煌斑岩,以富集大离子亲石元素和轻稀土元素,而亏损高场强元素(Ta-Nb-Ti)为特征,稀土元素分布型式类似于大陆玄武岩。煌斑岩为富含稀土元素的俯冲带流体交代过的富集地幔部分熔融所产生的岩浆,在上升过程中受到部分地壳混染的产物。对煌斑岩的黑云母进行Ar-Ar法年龄测定,获得煌斑岩40Ar-39Ar坪年龄值为(32.08±0.32)Ma,等时线年龄值为(31.86±0.40)Ma,形成时代属于新生代古近纪渐新世早期。煌斑岩与金矿化在空间分布、形成时间及成因上有密切的内在联系,煌斑岩与金元素均来自地幔,煌斑岩与金矿体均受控于断裂破碎带,共用了相同的断裂构造空间;金主成矿期早于煌斑岩,煌斑岩切穿了断裂破碎带及金矿体,煌斑岩的侵入为金进一步富集提供了物源、热能、含矿流体,使金矿化叠加富集。煌斑岩是寻找金矿的重要标志之一。The lamprophyre veins of the Xiaoshuijing gold deposit are intrusive bodies of dendrite,ring and irregular shapes.Its rock is dense block-shaped fine-crystal pyroxene kersantite,with content of SiO2 ranging from 32.28% to 49.72%,which can be attributed to ultra-basic,potassic to ultra-potassic lamprophyre of the calc-alkaline rock series.The lamprophyre veins are characterized by significat LILE and LREE enrichment and a depletion in HFS elements （Ta-Nb-Ti）.There is moderate to strong fractionation between the light and heavy REE.The lamprophyre formed by the magma derived from partial melting in the mantle with metasomatism fluids rich in REE at a subduction zone,and contamination with crustal materials during rising process of the magma.40Ar-39Ar dating of biotite in lamprophyre gives the 40Ar-39Ar plateau age of （32.08±0.32）Ma and 40Ar/39Ar isochronal age of （31.86±0.40）Ma,respectively,suggesting that the lamprophyre was formed at early Oligocene in Palaeogene of Cenozoic time.The lamprophyre veins are closely related with gold mineralization in space distribution,metallogenensis time and genesis.Lamprophyre and Au element are originated from mantle sources.When they developed,they were controlled by faults and shared the same fault structure.The Au mineralization time was slightly earlier than lamprophyre veins,and lamprophyre veins cut the fault fragmentation zones and gold ore bodies.The intrusion of lamprophyre provided the mineralization source,heat energy and ore-bearing fluids for the further gold enrichment,and promoted superposition of gold mineralization.Therefore lamprophyre is one of the important indicators for gold prospecting.

关 键 词：破碎带 煌斑岩 地质-地球化学特征 金矿化 滇中小水井 

分 类 号：P581[天文地球—岩石学] P596[天文地球—地质学]