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| Titel |
Lacustrin magnetic parameters reveal the last 3,000 years environmental variation of the Ilan Plain, northeastern Taiwan |
| VerfasserIn |
Yin-Sheng Huang, Teh-Quei Lee |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250106137
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| Publikation (Nr.) |
 EGU/EGU2015-5790.pdf |
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| Zusammenfassung |
| We discuss the paleo-environmental variation of the Ilan Plain in northeastern Taiwan for the
last 3,000 years by using lacustrine magnetic records obtained from Meihua Lake (the
MHL-5A core; 24Ë 38.58’ N, 121Ë 43.96’ E) and Longtan Lake (the LTL-9C core; 24Ë
47.70’ N, 121Ë 44.40’ E). The magnetic parameters analyzed in the study include magnetic
susceptibility (Ï), SIRM (saturated isothermal remnant magnetization), ARM (anhysteretic
remnant magnetization), ARM/Ï, and ARM/SIRM. The most notable feature in the magnetic
records of both cores is an anomaly appeared at ~1,800 years. In the MHL-5A core, the
parameters representing magnetic abundance variation (Ï, SIRM, and ARM) are relatively
higher before ~1,800 years and become lower after the time. On the contrary, the magnetic
abundance parameters are lower before ~1,800 years but become higher after the time in the
LTL-9C core. Besides, for the last ~700 years, the magnetic parameters in the MHL-5A core
show a clear period variation. Also in the LTL-9C core, this period variation could
be observed though the period is relatively ambiguous. Moreover, the magnetic
grain size parameter ARM/SIRM shows that the grain size of magnetic minerals in
both cores became finer gradually for the last ~3,000 years. The reason could be
preliminary deduced: The Ilan Plain is a flooding plain and the main river in the
plain is a braided river, the Lanyang River. Before ~1,800 years, the channel of the
Lanyang River should be in the south of the plain (closer to the Meihua Lake). More
sediment was brought into the lake by the flooding of the Lanyang River. After
~1,800 years, the channel of the Lanyang River shifted northward (closer to the
Longtan Lake), and therefore the input to the Longtan Lake from the flooding might
increase. The period variation after ~700 years could be roughly attributed to the
rainfall effect. That is, precipitation variation resulting from the influence of the
monsoon system might become significant for the last ~700 years in the Ilan Plain. |
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