内蒙古阿拉善北缘陆缘弧区火成岩的地质地球化学特征及构造演化

通过区内镁铁质和超镁铁质岩、花岗岩类以及中酸性火山岩的地质地球化学特征的研究,认为显生宙该陆缘弧经历了拉张、挤压和再次拉张的演化过程。在早古生代的拉张环境下,形成了镁铁质和超镁铁质岩、深熔花岗岩以及海西早期以地壳熔体为特征的花岗岩;海西中、晚期典型的Ⅰ型花岗岩和二叠纪钙——碱性系列的火山岩是挤压环境的产物;印支期的A型花岗岩是造山期后形成的。

THE GBOLOGAL AND GEOCHEMICALEEATURE OF IGNEOUS ROCKS AND THE TECTONIC EVOLUTION OF THE CONTINENTAL MARGIN ARC ZONE IN NORTHERN ALASHAN,NEIMENGGU

According to the study of geological and geochemical Characteristics of mafic, ultramafic rocks, granitoids and intermediate-acidic volcanic rocks,it's concluded in the paper that extension,compression and reextension have ta-Ken place in the study area during the Phanerozoic. In the Early Palaeozoic mafic and ultramafic rocks, as well as anatectic granites formed in an extensional tectonic regime, so did early Hercynian granites. Mid-iate Hercynian I-type granitoid bodies and the Permian calk-alkaline volcanic rocks formed typically in a compressional tectonic setting. Indosinian A-type guanites formed in a post-orogenic Period with a extension regime.