Detrital Zircon U-Pb Ages of River Sands from Taiwan: Implications for Sedimentary Provenance and Its Source Link with the East Chinese Mainland

Abstract:

In order to investigate the provenances of sedimentary rocks in Taiwan Island, we report the U-Pb geochronology of 630 concordant detrital zircons separated from the sandy sediments of the Zhuoshui River in west Taiwan and the Lanyang River in east Taiwan. In addition, 1472 published ages of detrital zircons from different rivers draining the east Chinese mainland are compiled to reveal the source-sink relationship between Taiwanese sedimentary rocks and east mainland. Detrital zircons from the two Taiwanese Rivers show seven major age groups of 100-200 Ma, 200-300 Ma, 360-550 Ma, 700-850 Ma, 0.9-1.1 Ga, 1.8-2.0 Ga and 2.4-2.6 Ga, which correspond well with major tectonic and magmatic events in east mainland. Nevertheless, the U-Pb age distributions have significant difference between east and west Taiwan terranes, showing high proportion of Phanerozoic zircons in east Taiwan and more complex age population and more Precambrian zircons in west Taiwan. This reveals obviously different sedimentary evolution between east and west Taiwan terranes. A series of methods (kernel density estimation plot, cumulative probability plot, overlap and similarity and a simple provenance model) are carried out to compare the U-Pb age distributions between Taiwan and east Chinese mainland, hence the source-sink relationship between them can be investigated. The Eocene-late Oligocene sequences of the Hsuehshan Range and the Miocene turbidity sequences of the east Central Range in east Taiwan are mainly sourced from the west Cathaysia Block (contributing about 81% of total zircon age population). The Yangtze Block (about 43%) and the North China Block (about 34%) may be the dominant provenances of the Eocene-Pleistocene sequences in west Taiwan.