RUI: P2C2--Reconstruction of Recent and Late Holocene Tropical Cyclone Landfalls in Northwestern Australia using Flood Deposits in Aragonite Stalagmites

Cornell College, Mount Vernon IA

Investigators

Abstract

This award helps develop a record of tropical cyclone activity from speleothems recovered from the Kimberley region of tropical Western Australia and dated to the late Holocene (~4,000 yr B.P.). Previous research by the researcher demonstrated that aragonite stalagmites are abundant in caves in the Kimberley through the late Holocene and up to the present time, are characterized by extremely high growth rates, and the caves trap clays deposited on stalagmite surfaces only during tropical cyclone-induced flooding. Because these stalagmites contain elevated Uranium abundances, high delta 234-Uranium values, and are largely devoid of detritus (other than in flood deposits), they can be dated with extremely high precision using Uranium-Thorium mass spectrometry (±1 year within the last century). In order to constrain the cyclone distance/intensity threshold required to flood the caves, the researcher will combine the stalagmite sedimentological flood records with stable isotopic analyses over the last 100 years of growth; an interval for which historical records of tropical cyclone intensity and storm track are available. This analysis will help establish a baseline for estimating the intensity-distance ratio of past storms recorded as clay layers in individual caves. The broader impacts involve the potential for greater understanding of the history of cyclonic activity and the developement of a new climate proxy. The research also involves substantive undergraduate student participation in the project.