新疆西南天山下石炭统图尤克阿秀组火山岩地质及地球化学特征、构造环境及年代依据

GEOLOGICAL AND GEOCHEMICAL CHARACTERISTICS, TECTONIC ENVIRONMENT AND AGE BASIS OF LOWER CARBONIFEROUS TUYOUKEAXIU GROUP VOLCANIC ROCKS IN SOUTHWESTERN TIANSHAN MOUNTAINS, XINJIANG

西南天山下石炭统图尤克阿秀组火山岩为爆发相火山角砾(集块)岩、喷溢相致密状玄武岩、枕状杏仁状玄武岩,与沉积相结晶灰岩或放射虫硅质互层组成,其沉积相岩性在走向上相变明显.火山岩主要元素地球化学特征、稀土微量元素特征与典型的大洋岛屿玄武岩相似.岩石组合特征、岩相特征、主量元素、微量及稀土元素特征表明,该火山岩形成于板内大洋岛屿(海山)环境,具板内裂谷特征.综合硅质岩中放射虫组合和玄武岩全岩40Ar/39Ar年龄测试结果,确定火山岩形成地质时代为早石炭世.

Volcanic rocks of lower Carboniferous Tu-you-ke-a-xiu group in Southwestern Tianshan Mountains, Xinjiang, are phase of the outbreak of volcanic breccia （set pieces） rocks, dense-phase-like eruption of basalt, pillow-shaped almond-shaped basalt, sedimentary facies limestone or radiolarian siliceous.Its sedimentary facies lithological change significantly in moving toward a photogenic.Geochemical characteristics of volcanic rocks in major elements, rare earth trace characteristics are similar to typical oceanic island basalts.Rock assemblage characteristics, facies characteristics, characteristics of major elements, trace and rare earth element indicate that the volcanic rocks were formed in intraplate oceanic islands （seamounts） environment, with characteristics of intraplate rift.Integrated radiolarian siliceous rocks of the basalt whole-rock composition and 40Ar / 39Ar age of the test results to determine the geological formation age of volcanic rocks is Early Carboniferous