(1. 中南大學地球科學與信息物理學院，有色金屬成礦預測教育部重點實驗室，長沙 410083；
2. 西北大學 大陸動力學國家重點實驗室，西安 710069；
3. 湖南有色地質(zhì)勘查局，長沙 410007；
4. 湖南省有色地質(zhì)勘查局一總隊，郴州 423000)
摘 要: 最近在湖南寶山礦區(qū)發(fā)現(xiàn)了煌斑巖脈，巖石樣品具有典型煌斑結(jié)構(gòu)，斑晶礦物主要為輝石、長石、黑云母及石英。SiO2含量為50.23%~51.29%，(Na2O+K2O)為4.65%~5.63%，K2O/Na2O值為1.89~7.77。根據(jù)TAS圖解和SiO2-Nb/Y圖解投點，寶山煌斑巖為堿性系列鈣堿性煌斑巖。煌斑巖過渡族元素配分型式為“W”形，相對富集Ti、Mn 和Zn，明顯虧損Cr、Co和Ni；微量元素表現(xiàn)為Th和LREE強烈富集并伴有K、Sr和Ba相對虧損的特征。煌斑巖中的鋯石為巖漿鋯石，U-Pb定年結(jié)果為(156±2) Ma，煌斑巖漿來源于受到俯沖組分改造的富集地幔。湖南寶山礦區(qū)煌斑巖的產(chǎn)出顯示了燕山期深部巖漿活動的蹤跡，反映燕山期區(qū)域陸內(nèi)伸展的大地構(gòu)造背景。
關(guān)鍵字: 煌斑巖；地球化學；鋯石U-Pb定年；寶山
（1. Key Laboratory of Metallogenic Prediction of Nonferrous Metals, Ministry of Education,
School of Geosciences and Info-Physics, Central South University, Changsha 410083, China;
2. State Key Laboratory of Continental Dynamics, Northwest University, Xi’an 710069, China;
3. Hunan Nonferrous Metal Geo-exploration Bureau, Changsha 410007, China;
4. First General Geological Team, Hunan Nonferrous Metal Geo-exploration Bureau, Chenzhou 423000, China）
Abstract:The lamprophyre vein from Baoshan minning area, southern Hunan Province, is a new discovery, the rock sample has typical lamprophyric texture, the phenocryst minerals are pyroxene, feldspar, biotite and quartz. The contents of SiO2 range from 50.23% to 51.29%, the values of Na2O+ K2O range from 4.65% to 5.63%, the values of K2O/ Na2O range from 1.89 to 7.77. According to figure of TAS and SiO2-Nb/Y, the samples belong to calc-alkaline lamprophyres of alkaline series. Distribution pattern for transitional-metal elements shows enrichment in Ti, Mn and Zn, obvious depletion in Cr, Co and Ni. The characteristics of trace elements show that strong enrichment in Th and LREE, relative depletion in K, Sr, Ba. The zircons collected from lamprophyre are magmatic zircons due to oscillatory zones, U-Pb dating results display the crystal average age of measured zircons is (156±2) Ma, the lamprophyre is derived from metasomatic enrichment lithospheric mantle. The discovery of lamprophyre from Baoshan suggests the trace of Yanhsanian deep basic magma activity, corresponding to regional intra-plate extensional tectonic background in Yanshanian stage.
Key words: lamprophyre; geochemistry; U-Pb dating; Baoshan
