Abstract: The Taipei Basin is located in the northern part of the Taiwan Orogen. Although this extensional basin was developed in an active orogen,it has peculiar formation mechanism different from that of basins resulted from the collapse of orogen in general sense. However,little attention has been paid to this peculiarity in previous studies,so that the problem concerning the formation of the Taipei Basin has evoked much controversy. Recently,bore holes and seismic prospecting data have revealed that the Shanjiao Fault,which has controlled the formation of the basin,consists of 3 segments,rather than a fault. Each segment controlled one center of subsidence,and has not connected with the other segments. The activity of different segments is not uniform,and it becomes stronger with time toward northeast. At present,the strongest activity is concentrated on the middle and northern segments,while the southern segment is no longer active. A series of NW-trending faults in the basin are the secondary structures produced during the subsidence of the different subsidence centers. There are a series of volcanoes that had erupted around the basin,so the formation of the basin should be affected by magmatic activities around the basin. Because the development of the basin treaded on the heels of these volcanic activities,there were essential relationship between the formation of the basin and the volcanic activities around the basin. Geophysical data,the structural characteristics and the migration of depocenter have shown that the development of the Taipei Basin was resulted from the cooling and contraction of the magma body at depth. The magma body beneath the Taipei Basin is connected with the magma body beneath the Tatun volcanic cluster,and the cooling of the magma has migrated from southwest to northeast. Moreover,the Tatun volcanic cluster is currently in its stage of subsidence,so the formation of the Taipei Basin was not an independent phenomenon. Both the Taipei Basin and Tatun volcanic cluster belong to one larger extensional basin.

Key words: Taiwan orogen, Taipei Basin, magma activity, cooling and contraction

摘要： 台北盆地位于台湾造山带的北部,它的形成有其特殊的机制而不同于一般意义上由于造山带的垮塌直接导致的盆地。钻井、地震勘探等资料表明,控制盆地形成的山脚断层并不是一条完整的正断层,而是由3个段落组成,每个段落控制1个沉积中心,彼此之间没有沟通。山脚断层各段落的活动性并不相同,向NE方向随时间逐渐增强,目前最为活动的段落集中在中段和北段,南段已不活动。台北盆地并不是一个孤立发育的盆地,是与金山断层东南的大屯火山群同时陷落的,具有一致的地球物理场背景、沉降规模以及正断层活动,广义的台北盆地从沉降范围和机制上还应该包括金山断层以南的大屯火山群。盆地周围发育了一系列的火山(群),由于盆地的发育是紧随这些火山主要活动之后的,盆地的形成与周围火成活动有着必然联系,一些地球物理资料和盆地内的构造发育及沉积迁移特征表明,台北盆地的发育是深部岩浆体的冷却收缩所致。台北盆地深部存在与大屯火山群深部相通的岩浆体,岩浆体的冷却由南向北迁移。

关键词: 台湾造山带, 台北盆地, 火成活动, 冷却收缩