TY - JOUR
T1 - Paleoclimate and sea level response to orbital forcing in the Middle Triassic of the eastern Tethys
AU - Liu, Dongyang
AU - Huang, Chunju
AU - Kemp, David B.
AU - Li, Mingsong
AU - Ogg, James G.
AU - Yu, Meiyi
AU - Foster, William J.
N1 - Funding Information:
This work is supported by the National Natural Science Foundation of China ( 41772029 , 41322013 , 41888101 and 42072040 ). We are grateful to Editor Maoyan Zhu for his guidance. Slah Boulila and another anonymous reviewer are thanked for their constructive and meticulous reviews. We are grateful to Geological Survey Institution of Guizhou Province for provide the E-book and 1:500000 geological map of Guizhou Province. D.L. thank Zhang Rui, Wang Zhixiang and Sui Yu for suggestions on time-series analysis.
Publisher Copyright:
© 2021
PY - 2021/4
Y1 - 2021/4
N2 - The Middle Triassic is thought to have had a greenhouse paleoclimate with a few short humid phases. However, the timing of these humid events, and the extent to which orbital forcing influenced the evolution of climate, are unclear. Here, a cyclostratigraphic analysis has been carried out based on the integrated study of magnetic susceptibility, elemental chemistry and lithofacies from two shallow-marine carbonate platform sections in Guizhou, South China. Combined, these sections (Pohong and Yongyue) span the late Anisian to early Carnian. Spectral analyses of magnetic susceptibility, Fe/Al and P through the studied sections show significant cycles of ~85-m, ~7-m and ~ 4-m. Based on independent age constraints and sedimentation rate modelling, these cycles are interpreted as orbital cycles that reflect 405-kyr long-eccentricity, ~33-kyr obliquity, and ~ 20-kyr precession forcing, respectively. Tuning of the records to the stable 405-kyr long-eccentricity parameter in each section yields a tuned astronomical time scale spanning ~7.4 ± 0.2 Myr, which covers from ca. 244.4 to 237.0 Ma and includes the entire Ladinian Stage. Magnetic susceptibility and Fe/Al data from the studied sections show intervals with relatively high values in the middle-late Anisian (ca. 244.0 to 242.6 Ma), and the latest Anisian to early Ladinian (ca. 241.8 to 240.9 Ma). These geochemical changes, combined with lithological changes, indicate enhanced terrigenous flux caused by the acceleration of hydrological circulation under a warmer and more humid climate. In addition, P data records two sharp falls that appear broadly coeval with the previously postulated late Ladinian ecological crisis. Our new astrochronology also reveals that ~1.2-Myr obliquity amplitude modulation cycles are expressed in the Middle Triassic. The regional sea level changes inferred from sequence stratigraphy and sedimentary noise modelling can be correlated with Tethyan and global sea level change. This work demonstrates the utility and power of sedimentary noise modelling in shallow marine environments for inferring past sea level dynamics. It also furthers constrains the timing of putative Middle Triassic climatic and ecological events.
AB - The Middle Triassic is thought to have had a greenhouse paleoclimate with a few short humid phases. However, the timing of these humid events, and the extent to which orbital forcing influenced the evolution of climate, are unclear. Here, a cyclostratigraphic analysis has been carried out based on the integrated study of magnetic susceptibility, elemental chemistry and lithofacies from two shallow-marine carbonate platform sections in Guizhou, South China. Combined, these sections (Pohong and Yongyue) span the late Anisian to early Carnian. Spectral analyses of magnetic susceptibility, Fe/Al and P through the studied sections show significant cycles of ~85-m, ~7-m and ~ 4-m. Based on independent age constraints and sedimentation rate modelling, these cycles are interpreted as orbital cycles that reflect 405-kyr long-eccentricity, ~33-kyr obliquity, and ~ 20-kyr precession forcing, respectively. Tuning of the records to the stable 405-kyr long-eccentricity parameter in each section yields a tuned astronomical time scale spanning ~7.4 ± 0.2 Myr, which covers from ca. 244.4 to 237.0 Ma and includes the entire Ladinian Stage. Magnetic susceptibility and Fe/Al data from the studied sections show intervals with relatively high values in the middle-late Anisian (ca. 244.0 to 242.6 Ma), and the latest Anisian to early Ladinian (ca. 241.8 to 240.9 Ma). These geochemical changes, combined with lithological changes, indicate enhanced terrigenous flux caused by the acceleration of hydrological circulation under a warmer and more humid climate. In addition, P data records two sharp falls that appear broadly coeval with the previously postulated late Ladinian ecological crisis. Our new astrochronology also reveals that ~1.2-Myr obliquity amplitude modulation cycles are expressed in the Middle Triassic. The regional sea level changes inferred from sequence stratigraphy and sedimentary noise modelling can be correlated with Tethyan and global sea level change. This work demonstrates the utility and power of sedimentary noise modelling in shallow marine environments for inferring past sea level dynamics. It also furthers constrains the timing of putative Middle Triassic climatic and ecological events.
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U2 - 10.1016/j.gloplacha.2021.103454
DO - 10.1016/j.gloplacha.2021.103454
M3 - Article
AN - SCOPUS:85101738112
SN - 0921-8181
VL - 199
JO - Global and Planetary Change
JF - Global and Planetary Change
M1 - 103454
ER -