Quaternary marine terraces on Sal Island (Cape Verde archipelago)

Abstract

The Quaternary sedimentary record of Sal Island includes marine and related aeolian and alluvial fan deposits. The substratum of the
island is volcanic, with ages between 25 and 0.6 Ma. Quaternary marine units generally occur as raised marine terraces forming a broad
staircase between elevations of 55–60m and present sea level. Terraces include a basal conglomerate overlaid by calcarenite; both host
corals, algae and molluscs.
A chronostratigraphic framework for the Middle Pleistocene to Holocene units has been generated based on a geomorphologic map of
the Quaternary landforms and associated deposits and morphosedimentary analysis, with support of laboratory dating: U-series by
TIMS in corals, 14C analyses, palaeomagnetic measurements, and K/Ar ages from other literature. U-series dating of corals from marine
terraces provides benchmarks for the Last Interglacial (Oxygen Isotope Substage 5e) and Holocene deposits. The present elevation of the
marine terraces and their staircase arrangement suggest a change in vertical movement trend around 330 ka from an uplift to either
subsidence or stabilization.