z-logo
open-access-imgOpen Access
Tectonics, topography, and river system transition in E ast T ibet: Insights from the sedimentary record in T aiwan
Author(s) -
Lan Qing,
Yan Yi,
Huang ChiYue,
Clift Peter D.,
Li Xuejie,
Chen Wenhuang,
Zhang Xingchang,
Yu Mengming
Publication year - 2014
Publication title -
geochemistry, geophysics, geosystems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.928
H-Index - 136
ISSN - 1525-2027
DOI - 10.1002/2014gc005310
Subject(s) - geology , unconformity , diachronous , seafloor spreading , paleontology , provenance , cenozoic , sedimentary rock , tectonics , rift , structural basin
The Cenozoic in East Asia is marked by major changes in tectonics, landscapes, and river systems, although the timing and nature of such changes remains disputed. We investigate the geochemistry and neodymium isotope character of Cenozoic mudstones spanning the breakup unconformity in the Western Foothills of Taiwan in order to constrain erosion and drainage development in southern China during the opening of the South China Sea. The La/Lu, Eu/Eu*, Th/Sc, Th/La, Cr/Th, and εNd values in these rocks show an abrupt change between ∼31 and 25 Ma. Generally the higher εNd values in sediments deposited prior to 31 Ma indicate erosion from Phanerozoic granitic sources exposed in coastal South China, whereas the lower εNd values suggest that the main sources had evolved to inland southern China by ∼25 Ma. The SHRIMP U‐Pb ages of zircons from a tuff, together with biostratigraphy data constrain the breakup unconformity to be between ∼39 and 33 Ma, suggesting that the seafloor spreading in the South China Sea commenced before ∼33 Ma. This is significantly older than most of the oceanic crust preserved in the deeper part of the basin. Diachronous westward younging of the breakup unconformities and provenance changes of basins are consistent with seafloor spreading propagating from east to west. Initial spreading of the South China Sea prior to ∼33 Ma corresponds to tectonic adjustment in East Asia, including extrusion of the Indochina block and the rotation and eastward retreat of the subducting Pacific Plate.

The content you want is available to Zendy users.

Already have an account? Click here to sign in.
Having issues? You can contact us here