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 language | English |
|---|---|
| Pages (from-to) | 288-301 |
| Number of pages | 14 |
| Journal | Journal of Asian Earth Sciences |
| Volume | 79 |
| Issue number | PA |
| DOIs | |
| Publication status | Published - Jan 5 2014 |
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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 journal › Article
}
TY - JOUR
T1 - Continental weathering in the Early Triassic in Himalayan Tethys, central Nepal
T2 - Implications for abrupt environmental change on the northern margin of Gondwanaland
AU - Yoshida, Kohki
AU - Kawamura, Toshio
AU - Suzuki, Shigeyuki
AU - Regmi, Amar Deep
AU - Gyawali, Babu Ram
AU - Shiga, Yuka
AU - Adachi, Yoshiko
AU - Dhital, Megh Raj
PY - 2014/1/5
Y1 - 2014/1/5
N2 - 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.
AB - 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.
KW - Chemical weathering
KW - Climate change
KW - Gondwana
KW - Tethys
KW - Triassic
UR - http://www.scopus.com/inward/record.url?scp=84886480667&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84886480667&partnerID=8YFLogxK
U2 - 10.1016/j.jseaes.2013.09.011
DO - 10.1016/j.jseaes.2013.09.011
M3 - Article
VL - 79
SP - 288
EP - 301
JO - Journal of Asian Earth Sciences
JF - Journal of Asian Earth Sciences
SN - 1367-9120
IS - PA
ER -