Sedimentary Environment of the Chiayi Coastal Plain Since the Last Glacial Epoch
Date Issued
2007
Date
2007
Author(s)
Wu, Tsung-Jen
DOI
zh-TW
Abstract
The study used 18 cored boreholes in Chiayi coastal plain which were provided by the Central Geological Survey. Based on the grain size, sedimentary textures and bioturbation,
it can be divided into fifteen lithofacies. The sediment composition was classified into three types of Type 1, Type 2, and Type 3, and explaining that the sediments were formed
by the longshore current and fluvial processes. Based on the modern environment of the coast, it can be subdivided nine environments of meander river, river mouth bar, marsh,
tidal flat, tidal channel, lagoon, longshore bar, subtidal and offshore transition zones.
Based on the depositional environment analysis and radiocarbon dating data, wedescript five stages of depositional environment during the late Pleistocene - Holocene.
(1) Before 18000 yr BP (the last glacial epoch) : This area formed a subaerial
environment and developed two incised valleys.
(2) During 14000 yr BP: Due to the sea-level rising, the shoreline was migrated to the
eastward, and the incised valley was formed a drowned valley.
(3) During 12000-11000 yr BP (the Younger Dryas event): The sea-level rising rate is
slightly slow. The shoreline was migrated eastward to the frontal foothills.
(4) During 8000 yr BP: The maximum marine flooding stage was formed at 8000 –
8500 yr BP. The shoreline was still at frontal foothills.
(5) During 5000 yr BP: The sediments continuously progradated to the seaward, hence,
the shoreline was retreated and migrated to the westward.
Subjects
嘉義
海岸平原
沉積環境
末次冰期
環境變遷
Chiayi
coastal plain
depositional environment
the last glacial epoch
Type
thesis
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