银根-额济纳旗盆地苏红图坳陷早白垩世火山岩幔源特征

Characteristics of the Early Cretaceous Mantle-Derived Volcanic Rocks in the Suhogntu Depression of Inggen-Ejin Qi Basin

银根-额济纳旗盆地位于塔里木、哈萨克斯坦、西伯利亚和华北四个板块的结合部位,在早白垩世发生了强烈的火山喷发,形成了一套中基性火山岩。野外和室内研究表明,该盆地中的苏红图火山岩属高钾玄武岩,岩浆来源于富集软流圈地幔,岩浆上升过程中没有经历明显的地壳物质混染。通过将研究区与位于华北板块北缘的四子王旗及辽西义县组火山岩的地球化学特征对比研究认为,地跨四个性质不同的大地构造单元的银—额盆地地块岩浆源区特征是亲华北型的,或是在它下方有一独立的和华北板块相似的富集地幔源区。

Inggen-Ejin Qi basin is located in the convergent area of Tarim, Kazakhstan, Siberia, and North China plates. In the Early Cretaceous, it underwent strong volcano eruption, forming one suite of mafic and intermediate volcanic rocks. Field and laboratory studies show that the Suhongtu volcanic rocks in the basin belong to high-K basalts, with magma deriving mainly from enriched asthenosphere mantle. There is no crustal material contamination during the rising of magma. Comparative study of geochemical characteristics of volcanic rocks from studied area, Siziwangqi in the northern margin of North China plate, and Yixian Formation in western Liaoning shows that magma source of the Inggen-Ejin Qi Basin covering four different tectonic units has affinity to North China type, or that under the basin there was an independent mantle material-enriched source area which is similar to the North China plate.