The samples for this study were adopted from the drilling cores for the slope-stability monitoring project inside the campus of NSYSU. Stratigraphically the strata belongs to the Gutingken Formation and is lain below the Kaohsiung Limestone. Two cores were selected for this research, one is W-2 (N: 2504008.088; E: 174168.943, 60m in length) and the other is S-4 (N: 2503968.458; E: 174009.179, 55m in length). The thickness of the Gutingken Mudstone in cores W2 and S4 is 38.7m and 21.8m, respectively. Each sample was obtained at every 10 cm interval for W2 and 30~40 cm for S4 with an average weight of 40 g.
This study mainly contains two parts: analyzing the planktonic foraminifera for their carbon and oxygen stable isotopic compositions and dating the downcore records by correlating with the nannobiostratigraphy. Particular is the stable isotopic compositions of planktonic foraminifera in these terrestrial sedimentary sequences which has not been done in Taiwan before.
Overall the mudstone analyzed in this study falls in the biostratigraphic range of small Gephyrocapsa Subchron, which spreads within 1.242 Ma~1.031 Ma. according to previous report. The age range is further constrained at about 1.186~1.065 Ma based on the oxygen isotope record and thus can be regarded as a high-resolution isotopic stratigraphy within the small Gephyrocapsa subchron. The average sedimentation rate inferred by the best age model from these cores is about 31cm/ky. It shows a progressive decrease in sedimentation rates: the younger the strata, the lower the sedimentation rate. On the contrary, the sedimentation rate varies dramatically at the lower part of the record. The turbidity current might be a potential factor responsible for the change. In addition, the spectral analysis of £_18O data presents a comparatively significant cycle of about 2.5ky through out the record. It might indicate a periodic forcing which influenced the environment during sediment depositation. The £_13C record obtained from this study fail to reflect the high productivity during the glacials. The mechanism that might affect the productivity in the area is not clear and still needs advanced research.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0621104-134154 |
| Date | 21 June 2004 |
| Creators | Tseng, Wen-chien |
| Contributors | Hui-Ling Lin, James-T Liu, none, none |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0621104-134154 |
| Rights | withheld, Copyright information available at source archive |
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