The Tienchi Pond on Lanyu Island (Western Pacific): Lake formation and potential as environmental archive
Number of Authors: 8
2015 (English)In: Journal of Asian Earth Sciences, ISSN 1367-9120, E-ISSN 1878-5786, Vol. 114, 435-446 p.Article in journal (Refereed) Published
The formation, evolution, and potential as a climate archive of Tienchi Pond was evaluated using geomor-phology, sedimentology, geochemistry, and AMS radiocarbon measurements of tree ring cores. Tienchi Pond is a small ephemeral lake situated on the subtropical Lanyu Island in the Western Pacific Ocean about 90 km east of southern Taiwan. The lake is situated on a mountain ridge and is today characterized by numerous dead trees and stumps. The position at the boundary between the two main components of the SE Asian monsoon system, the Asian landmass and the Western Pacific, makes this lake particularly interesting as a potential natural climate archive. Since previous studies have shown that the bedrock underlying the lake formed over 2 my ago, a volcanic crater origin was ruled out. Rather, element ratios of K/Ti and Ca/Fe together with Pb-210 dating suggest a recent origin for the lake, probably as the result of a natural damming event in the southern, narrower, part of the lake basin, or as a result of increased precipitation at the end of the Little Ice Age (or a combination of both). Radiocarbon measurements on a dead tree near the lake perimeter show C-14 levels of more than 1.7% modern radiocarbon near the bark, suggesting that the tree died in the early 1970s. In contrast, by correlating a large number of radiocarbon measurements to a northern hemisphere reference curve, it was shown that trees closer to the center of the lake died in the early 20th century. This agrees with a scenario where a small lake formed by initial damming, and gradually grew larger through erosion of the surrounding shore lines caused by rapid lake level oscillations.
Place, publisher, year, edition, pages
2015. Vol. 114, 435-446 p.
Little Ice Age, Radiocarbon, Lake formation, Weathering, Sediment, Environmental change
Earth and Related Environmental Sciences
IdentifiersURN: urn:nbn:se:su:diva-126395DOI: 10.1016/j.jseaes.2015.02.029ISI: 000367857800001OAI: oai:DiVA.org:su-126395DiVA: diva2:901807