摘要
文中参照各家关于台湾海峡及邻区的地质构造和演化的观点,依据作者的野外考察和室内研究成果,列举了一些鲜为人知的事实和困难,以澄清海峡两岸的构造联系和差异,肯定了浙闽结晶基底属于古亚洲大陆并发育为加里东地槽,而台湾结晶基底与板块俯冲密切相关。上覆岩系反映了地壳运动所导致的海侵、海退旋回,中生代的火山活动和板块碰撞。该区的北东向断裂愈临近太平洋板块活动强度愈大,时代较新的北西向断裂在海峡两岸均有走滑压性特征。文中详述了在基底构造、上覆岩系、断裂系统方面需要深化的认识。
The Taiwan Strait and its vicinity are located at a magnificent zone of crustal tectonics- the active continental margin of Eastern Asia. But the Strait is neither a back-arc-basin, a marginal basin nor a rift valley. Mechanism of collision between the Eastern Asian continental margin and the Philippine Sea plate isn' t the same on the north and south of Taiwan.
The basement of the west side of the Strait is an Asian paleo-continent involving a lower structural layer in early and middle Proterozoic and upper structural layer in Sinian and early Paleozoic, and these 2 layers had undergone metamorphisms and folded intensely with same intensity. After Caledonian, the continental crust was broken up into back-arc-basin-a Caledonian geosyncline which experienced the Paleozoic formation and then folded and metamorphosed. This tectonic process resulted in several NE-stretching faults (Zhenghe- Dapu and Shaowu- Heyuan faults) and Shanghang- Yunxiao NW-stretching deep fault-these are the important tectonic faults in the area. The crystalline basement of Taiwan crops out on the eastern limb of the Central Range and belongs to the Tananao Schist system of pre-Tertiary and is intermingled with igneous rocks of Mesozoic. It is a paired metamorphic belts: the Tailuko belt on the west being a low P / T one, and the Yuli belt a high P / T one on the east.
The overlying formations and their geologic background on the 2 sides of the Strait are rather different. On the west side, there were only sandstone and sandy gravel inside plateform deposited at some places until late Devonian, and then the Permian clastic sediments of interlayers with neritic and littoral facies were deposited. These were undergone a regional metamorphism due to diastrophe.
At beginning of Mesozoic, diastrophism went up into a new stage, the Tailuko belt resulted from collision between Changchun Ridge and the Asian Paleo-continent in early middle Jurassic, thus a medium-high pressure metamorphism had occurred and were covered by the later matamorphism which caused by the westward thrust of Kula plate from late Jurassic to late Cretaceous. And thus made the Yuli formation became a high P / T zone. Meanwhile, igneous intrusions took place on the Tailuko belt, which trans-fered as a low P / T zone, and on the Southeastern China coast. And then, in early to late Cretaceous, the volcanic activities were generally occurred all over the coastal zone west to the Strait but not uniform everywhere, which led to tholeiitic andesite and tholeiite extrusion and volcanic flysch deposited. In Cenozoic, the thick sediments covered the whole Taiwan and overlaid uncom-formably on the pre-Tertiary crystalline basement. Correspondingly, the S.E.China coast uplifted at least 1200m for adjusting Taiwan downwarping. In pre-and earliest- Tertiary the Taiwan Strait remained the uplifted state and was covered by volcanic eruptive rocks and terrestrial materials. In Tertiary the Western Taiwan basin had 3 major cycles of marine sediments: Paleo-Eocene, Oligo-mid Miocene and Mio-Pliocene.
As for the tectonic movement, the Taiwan Strait and its vicinity had undergone upilfted and subsided differential movements due to compression from the plate-collision during Meso-Cenozoic period. In the transition zone there were a series of NE-stretching deep-faults occurred. Among them, the major Changle-Nanao fault was an important one which located along the coastal zone west to the Strait. It controlled the distribution of Tertiary clastic beds intercalated with basalt. The others were a series of NE-stretching faults which divided Taiwan Island as several different petro-tectonic zones. In addition, 2 major suture lines were occurred and existed along the eastern Taiwan.
Accompanying with the NE-stretching fractures, there were a series of NW-stretch-ing faults of induced and other origins with compresso-torsionality in Fujian crossing the Strait and linking up with ones in Taiwan, which controlled the recent geomorphological featrues and distribution of hot springs and some small to medium e
出处
《东海海洋》
1992年第2期43-61,共19页
Donghai Marine Science
关键词
台湾海峡
地质构造
演化
Taiwan Strait, geological structure, evolution
