CENTRAL GEOLOGICAL SURVEY, MOEA

	Introduction
	Earlier Geologic Maps of Taiwan
	Geographic Setting
	General Geology And Geologic Provinces Of Taiwan
	Explanation Of Legend And Representation Of Geologic Data
	Eastern Central Range
	Western Central Range Backbone Ridges
	Western Foothills
	Eastern Coastal Range
	Geology Of The Hengchun Peninsula
	Major Geologic Features Of Taiwan
	Plate Tectonic Setting
	References

:::Plate Tectonic Setting

Mesozoic plate tectonic setting	Cenozoic plate tectonic setting

The plate tectonic systems of Taiwan have been discussed in a monograph 'Tectonic evolution of Taiwan" (Ho, 1982) and the reader can refer to that book for detailed information. Supplemented with recent geologic data, a brief review is given in this chapter to delineate the relation of plate tectonics to the geologic evolution of Taiwan. Two principal episodes of plate interaction are recognized in the plate tectonic history of Taiwan: a Mesozoic arc-trench system and a Cenozoic or Plio-Pleistocene arc-trench system, both characterized by subduction systems. The former system is recorded in the Tananao Schist and is related to the Nanao Orogeny. The latter event affected the entire island of Taiwan and produced the Penglai Orogeny.

Mesozoic Plate Tectonic Setting

The metamorphic complex on the eastern flank of the Central Range represents a part of the Asiatic continental crust. The original sediments of the complex range in age from Permian to Mesozoic. In the evolutionary history, all the rocks in the complex could have experienced several stages of crustal deformation and metamorphism, involving arc-trench systems of different ages. The latest and most important arc-trench system, however, may occur in late Mesozoic time. This is shown by the paired metamorphic belts in the metamorphic complex, a characteristic signature of subduction that can be used to reconstruct ancient plate convergence. The two metamorphic belts are (see Fig. 3):
Western Tailuko belt

- composed of various schists, gneisses, marble, amphibolite and a little mafic igneous block; acid intrusions in the northern part.
Eastern Yuli belt

- a monotonous series of politic schist with numerous included mafic to ultramafic igneous blocks of oceanic affinities, marble and acid igneous intrusions are wanting.

The two metamorphic belts of contrasting lithology and metamorphic facies are comparable to the paired metamorphic belts of different P-T conditions in an island arc system of the western Pacific region (Miyashiro, 1961). They constitute the Mesozoic arc-trench system on the Asiatic continental margin. The western Tailuko belt represents the inner high-temperature and low-pressure belt characterized by greenschist to amphibolite facies metamorphism. The eastern Yuli belt is the outer high-pressure and low-temperature belt characterized by blueschist and epidote-amphibolite facies metamorphism (Ernst, 1983). The Tailuko belt represents the pre-existing Pacific margin of Asia, which was converted into a plutonic/volcanic arc during Mesozoic subduction. The Yuli belt represents an oceanward volcanogenic argillaceous trench deposit that was transformed into a trench and melange complex during the subduction event.

The Mesozoic plate convergence took place by a westward underthrust of the oceanic Yuli belt beneath the continental Tailuko belt on the ancient Asiatic continental margin. The complex history of the Mesozoic plate interactions is still not entirely clear because the rocks have been strongly deformed and metamorphosed.

:::© CENTRAL GEOLOGICAL SURVEY, MOEA

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