Study of an unconformity boundary between the Liuchungchi and Kanhsialiao Formations, southeastern Taiwan
Date Issued
2007
Date
2007
Author(s)
Xu, Wei- Jie
DOI
zh-TW
Abstract
The Penglai orogeny is forming a foreland basin in the southwestern Taiwan since the Pliocene. Because the foreland basin was a highly subsidence, that it was deposited a hugely Plio-Pleistocene sediments. Since the Plio-Pleistocene, the global sea-level changes make the foreland basin for recording lot of the high-frequence sequence stratigraphy of the sixth order glacio-eustatic fluctuation (c. 41ky). Based on the well-done biostratigraphy and magnetostratigraphy of Plio-Pleistocene deposits, the study is focus on the first para-sequence from the bottom of the Kanhsialiao Formation which had been correlated to the oxygen isotope stage 36. For the purpose to understand the absolute eustatic sea-level change during the para-sequence in Taiwan, nine synchronous sections have been done by laterally tracing and depositional environments analysis.
Based on the lithofacies analysis, the depositional environments indicated that the deeper offshore located in the south area and shallowing to the north subaerial environment during the lowstand sea-level stage. The coastal line can be interpreted around the Kuohsi area (the Liouchung river) where dominated by tidal-dominated shoreface environment. Indeed, following the sea-level rise epoch (transgression), the Kuohsi section became to the middle offshore and finally shallowing back to the tidal-dominated shoreface environment at the end of the sequence. Since the shoreline environment can be as a marker of the shoreline, the accommodation also can be estimate by the Kuohsi section. To consider the tectonic subsidence, there are still having 105 m to account for the eustatic sea level rise without the decompaction calculation. The result of sea level fluctuation indicates more higher than the reports deduced by the 41ky cycle in the world. Upon to the observation, the sixth-order glacio-eustatic fluctuation (c. 41ky) must be affected by fifth-order glacio-eustatic fluctuation (c. 100ky).
Subjects
西南部
六重溪層
崁下寮層
假整合界面
Liuchungchi Formations
Kanhsialiao Formations
southeastern Taiwan
Type
thesis
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