摘要
Abstract
Analyses of regional geologic settings and geophysic d ata have yielded following results: 1.The regional tecto nism and material composition of basement had influenceon the Late Mesozoic mag m a activity,and the magmatic division at the surface is consistent with that in the deep.2.Based on the types of magmatic rocks,three tectonic-magma regions are recognized: (a) low-K and high-Al calc-alkaline i ntermediate-ac id volcanic-intrusive complex region,i.e.,SE China Coastal Region; (b) hi gh-K granitic volcanic-intrusive complex region,named as the Wuyishan region and (c) high-K S-type granite region in the west to Ganjiang without acid volcan ic intrusive complex.These three regions are separated by Zhenghe-Dapu and Gan jiang fault zones respectively.The crustal thickness in the SE China Coastal Region is thinner,whose basement is mostly volcanic and granite belongs to I- type; the crustal thicknesses for other two regions are greater than the first,their basements are mostly me lted sedimentary rock series and the granitic rock is S-type.The Ganjiang fau lt zone is called as the Late Mesozoic Volcanic Rock Line.3.In the SE China Co as tal Region,there is a local-low-resistivity-layer,which was related to a pull-rifting.The undeerplating of basaltic magma and the formatio n of alkaline granit were closely related to the pull-rifting in the Late Creta ceou s.4.Zhenghe-Dapu,Ganjiang and Changle-Nan'ao fault zone have apparent geoph ys ic features,which are both the gravity gradient zones and ultra-crust fault zo nes where the geological interaction along the crust-mantle boundary is most co mmon.5.There is a low-velocity zone of 2-4km thick in the middle crust,an d is considered as a result of a part melting of ductile deformation,which is probably a local magmatic source.6.Our study supports the model of plate subd u ction combining with underplating of basalt magma for the origin of the Late Mes ozoic magmatism in the SE China.The fault zone from the Japanese Central Tecto nic Line to Taiwan Longitudinal zone is a Mesozoic subduction and suturing zone wher e the Mesozoic Pacific plate subducted to the East Asian continental margins to form a wide volcanic-intrusive arc.关键词
岩浆作用/地球物理/构造制约/晚中生代/中国东南分类
天文与地球科学
