Central Santa Catarina coastal dunefields chronology and their relation to relative sea level and climatic changes

During the past decades, there have been contrarian explanations for the formation and stabilization of coastal dunefields: while many authors believe the dunes formation would be enhanced by falling sea level, others argue that a rising or stable sea level context would be favorable. For Brazilian coastal dunefields, the second hypothesis seems to be more consistent with the luminescence ages found so far; however, most of these data were obtained without using the SAR protocol. Another point of concern is the role of climate change in the aeolian system, which is still not very clear. The aim of this paper is to try to clarify these two questions. To this end, five coastal dunefields were selected in central Santa Catarina coast. The remote sensing and dating results allowed the discrimination and mapping of at least four aeolian generations. Their age distribution in relation to the global curve of relative sea level variation during the Late Pleistocene allows us to suggest that the formation of Aeolian dunefields in the coastal context is supported by stable relative sea level. However, relative sea level is not the only determinant for the formation and preservation of the aeolian coastal dunes. Evidences of climatic control indicate that the initiation of dunefields would be favored by periods of less humidity while their stabilization would occur preferably during the periods of rain intensification, connected to monsoon activity

Dose estimation using quartz OSL in the non-linear region of the growth curve

The reliability of equivalent-dose determinations on quartz made with the single-aliquot regenerative-dose (SAR) protocol is examined using a suite of sedimentary samples for which the equivalent dose is expected to be >200 Gy. Experiments on one sample were used to evaluate the precision obtained using the standard measurement procedure with (a) a range of preheat temperatures, and (b) a single pre-heat temperature. The precision is compared with that achieved using SAR for a repeated dose point after an initial pre-heat, and for a known dose given before the initial pre-heat. It is concluded that, at least for this sample, the scatter in OSL measurements dominates the spread in the estimates of De.</p