Towards an astrochronological tuned age model for the upper Pliocene–lower Pleistocene Western Foreland Basin of Taiwan
- 1Institute of Earth Sciences (ISTE), University of Lausanne, Geopolis, Lausanne, Switzerland (romain.vaucher@unil.ch)
- 2Applied Research in Ichnology and Sedimentology (ARISE) Group, Department of Earth Sciences, Simon Fraser University, Burnaby, Canada
- 3LIAG – Leibniz Institute for Applied Geophysics, Geozentrum Hannover, Hannover, Germany
- 4Department of Geosciences, National Taiwan University, Taipei, Taiwan
- 5Institute of Geosciences, University of Potsdam, Potsdam-Golm, Germany
- 6Department of Earth Sciences, National Central University, Taiwan
- 7Institute of Earth Sciences, Academia Sinica, Taipei, Taiwan
The stratigraphic records of shallow-marine environments are not commonly regarded as excellent climate archives because of their presumed temporal incompleteness. However, a recent study of lower Pleistocene strata in the Western Foreland Basin, Taiwan, reveals high-resolution records of past climate oscillations preserved within shallow-marine strata. Deriving such narratives is made possible because of the high accommodation and sedimentation rates in the basin, which enhanced the completeness of the stratigraphic record.
Here, we astrochronologically tune the Chinshui Shale and the lower part of the Cholan Formation of the Western Foreland Basin from approximately 3.5 to 2 Ma. These strata are calibrated to global deep-sea stable oxygen isotope (δ18O) records with established time scales detailing global climate change during the studied time period. The Chinshui Shale is mudstone-dominated and was deposited mostly in offshore settings, while the Cholan Formation comprises mainly heterolithic strata deposited in shallower settings (i.e., offshore transition, nearshore) of the paleo-Taiwan Strait. The data used herein are two borehole gamma-ray profiles through the Chinshui Shale and the Cholan Formation that have a proximal-distal relation to Taiwan. High gamma-ray values reflect clay-rich intervals and correlate to lower values of δ18O in the global reference records. Low gamma-ray values point to sand-rich packages and correlate with higher values of δ18O.
Preliminary results show that the alternating clay-rich to sand-rich deposits during the late Pliocene to early Pleistocene are orbitally paced. The results allow us to i) tune the upper Pliocene–lower Pleistocene Chinshui Shale and lower part of the Cholan Formation, ii) refine the magneto-biostratigraphic framework established for this time interval in the Western Foreland Basin of Taiwan, and iii) lay the groundwork for connecting climatic changes in Taiwan during this time period to the wider frame of global climate change.
How to cite: Vaucher, R., Zeeden, C., Hsieh, A., Kaboth-Bahr, S., Lin, A. T., Horng, C.-S., and Dashtgard, S. E.: Towards an astrochronological tuned age model for the upper Pliocene–lower Pleistocene Western Foreland Basin of Taiwan, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1435, https://doi.org/10.5194/egusphere-egu22-1435, 2022.
