Origin of the Lake Shuanglianpi and Its Implication for
Environmental Changes
Sheng-Rong Song1, Heui-Fen Chen1, Chai-Mei Liu1 and Te-Quei Lee2
1
Institute of Geosciences, National Taiwan University
2
Institute of Earth Sciences, Academia Sinica
For study the paleo-environmental changes of Holocene in Taiwan areas, as part of
the APEC project, several short holes, 2-4 m long were drilled in the Lake Shuanglianpi in
the spring and summer of 2003. This paper is to report the preliminary results on lithology,
mineralogy and geochemistry of lake sediments from the cores. And furthermore, the
origin and preliminary environmental changes using the images of geomorphology and
lithology, geochemistry and paleomagnetism of lake sediments were proposed.
The Lake Shuanglianpi is located in the low hill of mountain areas, a.s.l. 500 m, of
the Ilan Plain, northeast Taiwan. It is an isolated small basin enclosed by the mountains
with a narrow deep channel in its southwest. According to the location and
geomorphological characteristics, the Lake Shuanglianpi may be a dam lake, which was
originated by the debris slumping nearby. It is supported by a reported paleo-dam lake in
its northeast about 3 km away.
Lithologically, the Core SLP-G2 with 227 cm in length can be divided into 4 units,
which two dark plant-rich fragment layers interbedded with two grayish-white to gray
clay-rich mud. The depths ranging from 0 to126 cm and 160 to 190 cm are dominantly
composed of 80% plant fragments rich in large diatoms and 2M1 illites. Others, 126-160
cm and 190-232 cm are characterized by the detrital fine sediments, which clay minerals
are dominantly composed of smectites and lower crystallinity illites. This sequence
suggests that the water level in the Lake Shuanglianpi was relatively lower and dry in
climate in depositional period of plant-rich layers. However, the detritus-rich muddy
sediments represent the relatively higher water level and wet condition.