24 Quaternary Geology (Posters)

MEJILLONES PENINSULA COASTAL TERRACE SEQUENCE: A USEFUL PIECE OF INFORMATION IN DECIPHERING THE LATE QUATERNARY LANDSCAPE EVOLUTION OF THE ATACAMA DESERT, NORTHERN CHILE

Paper number: 24-21
Program: Technical Sessions
Time: 8:00 AM – 12:00 PM

Authors

Abstract

Mejillones Peninsula, a distinctive feature of the coast of Northern Chile, preserves 12 different levels of coastal terraces due to favorable hyper-arid conditions, and uplifting governing this portion of the Nazca subduction zone during the Quaternary. Along with the evidence of uplifting, an array of N-S trending faults dominates the deformation observed on the terraces. Several structures have been documented offsetting more than one level at different magnitudes in the sequence.

Articulated mollusk shells have been collected to perform Electron Spin Resonance dating and obtain an age model for the levels. Two of the most persistent levels elevated at ~50 and ~180 m a.s.l have given consistent ages in different sites along the northeast boundary of the peninsula. The ages have been interpreted as belonging to IS5 and IS9.

Our objective is to present a spatial and age model for the coastal sequence which allows taking a closer look into the structures and their activity. Due to its exceptionally close location to the trench, Mejillones Peninsula presents an opportunity to document the link between the hyper-arid conditions, a stronger coupling of the plates, and the anticipated intensification on surface deformation suggested for this part of the margin during the Neogene.