2010 | Tayphoon frequency reconstructed from Taiwanese lake sediments

January–February 2010

January 25

Ludvig and Barbara, who have been coring in Thailand for about three weeks, met up with Christophe in Taipei, Taiwan, to initiate a collaboration with colleagues at the Institute of Earth Sciences at Academia Sinica. After meeting with the director, professor Bor-Min Jahn, we had a meeting to discuss our project with Dr. Tien-Nan Yang and professors S-R Song, T-Q Lee, C-H Wang and P-M Liew.

The next day we started driving south along the east coast where we visited a couple of interesting lake sites and admired some of the geological wonders of Taiwan.

Barbara is admiring the scenery at the several hundreds of meters deep Taroko gorge.
Mud volcano
Mud volcano.
Meihua lake lies perched between two ridges and was probably formed by a landslide or a river levee closing off the outlet.
On the 27th the team crossed the Tropic of Cancer, truly entering the subtropics.

 

The first day of coring started good, blue sky and sunny, and the drive up to the lake from our hotel was much faster than expected (about 45 minutes compared to the 1.5 h suggested by Barbara’s iPhone). Then our luck changed. The first coring station was situated in the middle of the lake where we expected soft, easy to core sediments. To our surprise even the uppermost sediments were quite stiff, and when pulling out the second section from the clay, we had to use such force that the drilling platform on the rubber boat cracked in the middle. After constructing an improvised bamboo platform to reinforce the original one, we went back out on the lake to a new coring position closer to the wetland. Here we managed to get three meters of sediment before we had to stop the operation for the day.

Barbara is inspecting the first core while Christophe and Stephen are watching.

 

We have now finished this year’s coring in Taiwan. In three days we cored three different locations: two in the lake and one in the wetland just next to the lake. After returning to Stockholm we will perform a number of different analyzes that will provide a record of how the monsoon system has changed over the past few thousands of years. However, during the drilling it became clear how important it is to understand the depositional environment in the lake, and we are already thinking about going back to the wetland surrounding the lake to take another set of core

We placed the coring platform directly on the grass, cut a hole through the grassroots and then took a sediment sequence that shows how the lake gradually became shallower and finally turned into a wetland.

 

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