(1. 湖南省地質(zhì)調(diào)查院，長沙 410116；
2. 中南大學(xué) 地球科學(xué)與信息物理學(xué)院，長沙 410083)
摘 要: 對(duì)分布在江南造山帶中段湘黔桂地區(qū)的火山-侵入基性-超基性巖類的地質(zhì)、地球化學(xué)特征進(jìn)行研究。結(jié)果表明：新元古代“南華紀(jì)”沉積盆地基底火山巖屬于島弧型，基底沉積建造為活動(dòng)大陸邊緣或大陸型島弧盆地沉積；成盆早期的區(qū)域伸展，在揚(yáng)子?xùn)|南緣發(fā)育了一個(gè)斷階式陸坡盆地環(huán)境，接受次穩(wěn)定型多元性陸緣碎屑沉積，形成的火山巖為鈣堿性，屬于初始裂谷火山巖。盆地大地構(gòu)造背景解釋為具較強(qiáng)構(gòu)造活動(dòng)的被動(dòng)大陸邊緣環(huán)境。“南華紀(jì)”中期盆地進(jìn)一步伸展，沿桂北—湘西形成大量的低鈣鋁質(zhì)、強(qiáng)堿-堿質(zhì)的堿性玄武巖類，屬于板內(nèi)裂谷環(huán)境。至此，盆地完成由擠壓造山—初始裂解—全面伸展的體制轉(zhuǎn)換，盆地進(jìn)入穩(wěn)定發(fā)展階段，直至震旦紀(jì)初的廣泛海侵，淹沒碳酸鹽臺(tái)地形成。
關(guān)鍵字: 火山巖；盆地演化；“南華紀(jì)”；揚(yáng)子?xùn)|南緣
（1. Hunan Institute of Geological Survey, Changsha 410116, China;
2. School of Geosciences and Info-Physics, Central South University, Changsha 410083, China）
Abstract:The geological and geochemical characteristics of the volcanic intrusive basic-ultrabasic complex in the central section of the Jiangnan Orogen in Hunan—Guizhou—Guangxi region were studied. The results indicate that the basement volcanic rocks of sedimentary basin in Nanhuaian period of Proterozoic Era belongs to island arc type. The basement sedimentary formation is active continental margin or continental island arc basin sediments. The initial regional extension built a fault-step continental slope basin in the southeastern margin of Yangtze platform, accepting sub-stable plural clastic deposit from continental margin. This calc-alkaline volcanic rock is initial swifting volcanic rock. The basin’s tectonic setting is passive continental margin. In middle Nanhuaian period, the basin further extended along northern Guangxi—western Hunan to form a large quantity of alkaline basaltic rock with low calcium aluminum, belonging to intraplate rift environment. So far, the basin transformation has finished from compressive orogeny to initial splitting to full expansion, and then the basin began to develop steadily until the wildly transgression in early Sinian Era and submerged carbonate platform formed.
Key words: volcanic rocks; basin evolution; Nanhuaian period; southeastern margin of Yangtze platform
