摘要
该断裂位于鱼山列岛到久米岛一线,它横贯东海中部,长400km 以上,宽约100km;由三条左旋平推正断层组成,其最大平移距离达50km,深切地壳。它从白垩纪开始形成,至今仍在强烈活动。断裂带本身为具有重、磁力高值的地垒,其南北海区的地球物理场、新生代沉积、构造特征、岩浆和地震活动以及莫霍面深度等均有明显区别。
Abstract
Yushan-Kume fault belt,situated along Yushan Archipelago of Eastern Zhejiang coast and Kume Islands in the west side of Kyukyu Archipelago,across the central part of East China Sea the strike direction of 300-305?,more than 1000km long and 100km wide,consists of three factures of Yushan-Kume,Yuzhong-Niaodao and Taohua-Suguo.It shows a relative high value zone on both gravity and magnetic maps,and a horst structure on a seismic profile section,the dip angle of which are about 70-80皌o NNE and SSW,the fault throw about 540-2260m respectively.The sea bottom topography in Okinawa Trough presents a uplift towards NWW.The belt is considered to be a normal anticlockwise fault with its north block moved westwards and south block eastwards,the offset distance is about 5-50km.The distribution of basalts can be found on the west part of the belt,showing that the belt has deeply cut the earth crust.The belt is huge to the west,which expands to the northeast of Zhejiang,passing through Kyukyu Trench to Okidaito Isiands of the west Pacific Ocean.The belt has been intensely activating since its formation in Cretaceous.The formation and development of wich is a result of the underthrusting of the Pacific Plate towards Eurasia Plate,and the creeping of Chinese Continental margin continously eastwards.It has played a role of dividing structural features of East China Sea into south and north sea area.The geophysical fields,sea floor features,Cenozoic sediments,major structural direc-tions,reginal structures,fault characteristics,volcanicities,the value of thermal flow in the sea floor and Moho depth within the south and north part of East China Sea are distinctly different.
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