Cosmic Ray Exposure (CRE) dating in a wet tropical domain: late Quaternary fan emplacements in central Sulawesi (Indonesia)

Abstract

International audienceAccurate chronological records are critical for studying the alluvial fan sequences emplaced during local/global climatic changes but, in general, there are no satisfactory, quantitative dating methods available. In situ-produced Be-10 concentrations have been measured in quartz boulders exposed on Sulawesian late Quaternary fan surfaces. These concentrations suggest that the two fan units evidenced by geomorphic study were emplaced during two distinct major climatic events. The calculated minimum exposure ages imply abandonment ages of 11 kyr and 120 kyr, for the younger and older units, respectively. This study demonstrates that using both the neutron and muon components implicated in the in situ Be-10 production, surficial erosion rates can be estimated and alluvial fans dated. ln particular, it shows that in situ Be-10 may be used to date fan emplacement during the last 120 kyr under humid tropical conditions, significantly helping to constrain continental palaeoclimatology