The Tectono-Thermal Events of Taiwan and Their Relationship with SE China


We present a new synthesis of the tectono-thermal events of Taiwan, excluding the Coastal Range, based on existing isotopic, geochemical and geochronological data for granitic, metamorphic, volcanic and sedimentary rocks. Nd model ages (TDM) and the inherited zircon ages consistently yielded Proterozoic ages, suggesting that the source rocks from the exposed rocks in Taiwan were formed in the Proterozoic, starting from about 2 Ga ago. The crustal evolution of Taiwan began in the Late Paleozoic (250 ± 20 Ma). Since then, five tectono-thermal events can be delineated: (I) an Early Jurassic event (200 - 175 Ma) registered in the marble and metapelites of the Tananao metamorphic basement complex of northern Taiwan and crystalline limestone of the basement rocks in western Taiwan; (II) a Late Jurassic event (~153 Ma) revealed by a meta-granite of the Tananao metamorphic basement complex of southern Taiwan; (III) a Late Mesozoic event (97 - 77 Ma) recorded in the rocks of the Tananao metamorphic basement complex and offshore of northern and western Taiwan; (IV) a Cenozoic of pre-Pliocene event (episodic from 56 to 9 Ma) registered in the dikes in the Central Range and the intraplate basalts of mainland Taiwan and offshore of northern and western Taiwan; and (V) an ongoing Late Cenozoic event (since 5 Ma) shown in the recent volcanics of onshore and offshore northern Taiwan and offshore northeastern Taiwan.

In comparison with the Cathysia foldbelts, Taiwan demonstrates similar Paleoproterozoic crustal residence ages, coeval Jurassic magmatism (Early Yanshanian) and Late Cretaceous (Late Yanshanian) orogeny. However, subduction-related magmatism was prevalent in Taiwan in comparison with both extension- and subduction-related magmatism in Cathaysia foldbelts during the Yanshanian orogeny. Rifting-related magmatism has continued in the Cathaysia foldbelts ever since Jurassic. Since Late Cretaceous, rifting-related magmatism migrated from the interior toward the coastal region in the Cathaysia foldbelts but it did not reach Taiwan until Paleogene. Since 5 Ma, subduction-related activity started in northern Taiwan. The volcanism in northern Taiwan was attributed to the Late Pliocene extensional collapse of the northern Taiwan mountain belt in response to the oblique collision of the northern Luzon arc with the Asian continent, but not directly related to the magmatism of the Ryukyu subduction zone. However, volcanism resulting from the spreading of the Okinawa trough manifests in the offshore region of northeastern Taiwan.

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