(1. 中南大學(xué)地球科學(xué)與信息物理學(xué)院有色金屬成礦預(yù)測(cè)教育部重點(diǎn)實(shí)驗(yàn)室，長(zhǎng)沙410083；
2. 湖南省地球物理地球化學(xué)勘查院，長(zhǎng)沙410116)
摘 要: 長(zhǎng)城嶺鉛鋅銻多金屬礦區(qū)位于南嶺有色金屬成礦帶中段，區(qū)內(nèi)發(fā)育多組燕山期硅鋁質(zhì)巖墻群及少量鎂鐵質(zhì)巖瘤、巖墻。這兩類巖漿巖的產(chǎn)出均受區(qū)域性北東向斷裂帶控制，空間分布交織，同屬燕山期，但玄武巖形成于燕山早期第一階段，輝綠玢巖形成于燕山早期第二階段，花崗斑巖和石英斑巖形成于燕山早期第三階段，輝長(zhǎng)巖可能形成于燕山晚期，因而其研究對(duì)探討南嶺地區(qū)燕山期巖漿演化、巖石成因及成巖構(gòu)造環(huán)境具有重大意義。通過詳細(xì)的野外地質(zhì)調(diào)查、巖相學(xué)和巖石地球化學(xué)綜合研究，試圖系統(tǒng)分析這兩類巖漿巖成因、巖石學(xué)及巖石地球化學(xué)特征，并探討其成巖構(gòu)造環(huán)境及動(dòng)力學(xué)背景。研究表明：本區(qū)硅鋁質(zhì)巖富硅、鋁、鉀，為鈣堿性，強(qiáng)過鋁質(zhì)，∑REE低，稀土配分模式具四分組效應(yīng)，屬S型巖漿巖、石英斑巖；鎂鐵質(zhì)巖富SiO2、貧堿，為鈣堿性，過鋁質(zhì)，∑REE偏高，屬殼幔混染型巖漿巖。相較而言，從玄武巖到輝綠玢巖再到輝長(zhǎng)巖，Mg#值、Zr/Hf值依次增大，玄武巖、輝綠玢巖及輝長(zhǎng)巖的稀土配分曲線均為右傾型，以輝綠玢巖曲線更陡，而輝長(zhǎng)巖曲線平坦。基于殼體構(gòu)造理論與兩類巖漿巖的巖石學(xué)及地球化學(xué)特征，研究認(rèn)為本區(qū)巖漿巖是燕山期陸內(nèi)活化產(chǎn)物。隨著燕山期地幔蠕動(dòng)和熱能聚集強(qiáng)度與方式的有規(guī)律變化，其動(dòng)力學(xué)環(huán)境相應(yīng)變化，巖漿源區(qū)深度、殼幔相互作用程度及物質(zhì)組成也有規(guī)律變化，因而上述巖漿巖無論成因、巖石學(xué)或地球化學(xué)特征都隨燕山期巖漿侵入活動(dòng)階段而明顯變化。
關(guān)鍵字: 長(zhǎng)城嶺；硅鋁質(zhì)巖；鎂鐵質(zhì)巖；巖石地球化學(xué)；構(gòu)造背景
（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. Hunan Institute of Geophysical and Geochemical Exploration, Changsha 410116, China）
Abstract:Changchengling Pb-Zn-Sb polymetallic orefield locates in the middle segment of Nanling nonferrous metals metallogenic belt, there occurs groups of Yanshanian granitic dykes and a few scattered mafic bosses and dykes. These two types of magmatic rocks are mainly controlled by the northeast-trending regional fracture zone, and are spatially interweaving. Basaltic, diabasic porphyry and granitic are respectively intruded at the first, second and third stages of early Yanshanian periods and gabbro dykes are the latest intruded magmatic rocks probably in later Yanshanian period, so their petrologic, genetic and geochemical studies are of great significance in understanding of the Yanshanian regional magmatic evolution, petrogenesis, and tectonic settings of Nanling region. On the base of comprehensive studies on fieldinvestigation, petrography and rock geochemistry, the petrologic, geochemical and genetic characteristics, tectonic and geodynamic settings of these two types of magmatic rocks were discussed systematically. The results show that granitic rocks here with high Si, Al, K and low REE are calc-alkaline and strongly peraluminous, their REE pattern has obvious tetrad effect, therefore they belong to the S-type; the mafic rocks with high SiO2, REE and low alkali are calc-alkaline and peraluminous, thus they derive from the mixed crust-mantle. As for basalt, diabase porphyry and gabbro, their Mg# value and w(Zr)/w(Hf) value increase orderly, the REE partition curves are all right-inclined, but diabase is steeper and gabbro goes flate. According to the theory of Crustobody geotectonics and the petrologic characteristics, these two types of magmatic rocks are the products of Yanshanian continental mobilization. With the regular change of intensity and mode of mantle creep-flow and heat energy convergence in Yanshanian period, the geodynamic setting and crust-mantle interaction extent transform correspondingly, the depth and compositions of the magma source region change accordingly, so the genetic, petrologic and geochemical characteristics of these magmatic rocks are all varied obviously with the magmatic intrusion stages of Yanshanian.
Key words: Changchengling; granitic rock; mafic rock; geochemistry; tectonic setting
