【作者】 张岩； 陈小友； 董学发；

【Author】 Zhang Yan, Chen Xiao - you, Dong Xue - fa (Zhejiang Institute of Geology Survey , 311203)

【机构】 浙江省地质调查院；

【摘要】 浙江富阳、萧山地区晋宁晚期两次大规模岩浆活动,具有典型的双峰式岩浆岩组合特征,早期以玄武岩喷发伴随有基性辉绿岩侵位;晚期则以流纹岩喷发伴有钾长花岗岩产出。即火山岩Sm-Nd等时年龄894-806Ma;侵入岩单颗粒锆石Pb-Pb年龄816-738Ma。岩石地球化学特征表明:SiO2含量处于基性和酸性两个端元,即SiO2小于57％和大于74％,具有明显的戴里间断。早晚两个阶段的火山岩作用与侵入岩作用,具有典型的火山-侵入杂岩属性。它们构成晋宁晚期双峰式岩浆组合,代表了中元古代末扬子、华夏古陆碰撞造山运动结束之后,在造山带转变为拉伸并导致造山带的崩塌,岩石圈强烈伸展减薄、热流值上升的构造背景下,形成的一套完整的造山后岩浆岩组合,它揭示了华南古陆新元古代早期罗迪尼亚超大陆裂解的开始。更多还原

【Abstract】 In later Jinnin period,it was happened massive magma movement twice which were typically characteristic of bimodal magma combination in Zhejiang Fuyang and Xiaoshan area. In earlier period, basalt broke forth with the intruding of busic diabase. In later period, rhyolite broke forth with the outputting of potassic - feldspar granite. The Sm - Nd isochron age of the lava range were from 894Ma to 806Ma, the single - zircon Pb - Pb age range from 816Ma to 734Ma. The geochemical features of rock show that the content of SiO2 which less than 57% and more than 74% lie in busic domain and acid domain and have obvious Daili gap. The volcanism and intruding in earlier period and later period had the attribute of volcanic - intrusive complex rock. They consist of the bimodal magma combination in later Jinnin and present a set of integrated post - orogenesis magmatic rock combination which formed after the Yange land and the Huaxia land colliding in later Mesoproterozoic and the orogenesis strap extending and falling and the lithosphere extending strongly to thin and the heat flow rising. It was suggested that the Rodinia super continent of South China land began to split in earlier Neoproterozioc period.更多还原