Continental weathering in the Early Triassic in Himalayan Tethys, central Nepal: Implications for abrupt environmental change on the northern margin of Gondwanaland

Kohki Yoshida, Toshio Kawamura, Shigeyuki Suzuki, Amar Deep Regmi, Babu Ram Gyawali, Yuka Shiga, Yoshiko Adachi, Megh Raj Dhital

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

The geochemistry of Triassic mudstones in the Himalayan Tethys sequence, central Nepal, was studied with respect to changes in sedimentary facies, grain size, and source rocks. The Triassic sedimentary facies of mudstone and carbonates show deposition in offshore to hemiplegic environments. The rare earth element (REE) pattern of the Permian and Triassic mudstones suggests uniformity correlatable to average shale. The major element geochemistry of the Early Triassic Griesbachian-early Smithian mudstones indicates a sediment supply from strongly weathered sources with the chemical index of alteration (CIA) values of 76-81. However, the mudstones in the late Smithian show weakly weathered sources with CIA values of 68-74. The lower part of the Middle Triassic Anisian mudstones return to Early Triassic paleoweathering levels. There are no significant relationships among lithofacies, the grain size of the sediments, and CIA values. Thus, the abrupt change of the degree of paleoweathering in the Early Triassic, late Smithian time, suggests a dramatic decrease in continental weathering, which is related to a predominantly arid climate in the northern marginal area of Gondwana.

Original languageEnglish
Pages (from-to)288-301
Number of pages14
JournalJournal of Asian Earth Sciences
Volume79
Issue numberPA
DOIs
Publication statusPublished - Jan 5 2014

Fingerprint

Tethys
environmental change
Triassic
weathering
mudstone
grain size
geochemistry
Anisian
lithofacies
Gondwana
sediment
source rock
shale
Permian
rare earth element
carbonate
climate
index
chemical

Keywords

  • Chemical weathering
  • Climate change
  • Gondwana
  • Tethys
  • Triassic

ASJC Scopus subject areas

  • Earth-Surface Processes
  • Geology

Cite this

Continental weathering in the Early Triassic in Himalayan Tethys, central Nepal : Implications for abrupt environmental change on the northern margin of Gondwanaland. / Yoshida, Kohki; Kawamura, Toshio; Suzuki, Shigeyuki; Regmi, Amar Deep; Gyawali, Babu Ram; Shiga, Yuka; Adachi, Yoshiko; Dhital, Megh Raj.

In: Journal of Asian Earth Sciences, Vol. 79, No. PA, 05.01.2014, p. 288-301.

Research output: Contribution to journalArticle

Yoshida, Kohki ; Kawamura, Toshio ; Suzuki, Shigeyuki ; Regmi, Amar Deep ; Gyawali, Babu Ram ; Shiga, Yuka ; Adachi, Yoshiko ; Dhital, Megh Raj. / Continental weathering in the Early Triassic in Himalayan Tethys, central Nepal : Implications for abrupt environmental change on the northern margin of Gondwanaland. In: Journal of Asian Earth Sciences. 2014 ; Vol. 79, No. PA. pp. 288-301.
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