Facies and bounding surfaces of Paraná’s Holocene regressive barrier

Abstract

The Holocene regressive barrier of Paraná was formed when the relative sea level was higher than present and is one of the depositional systems that form the coastal plain of Paraná. This work aims to demonstrate the correlation between the barrier bounding surfaces with their sedimentary facies and facies associations. The outcrops were exposed by excavations next Praia de Leste, coast of the state of Paraná. The characterization and interpretation of facies, facies associations and bounding surfaces were performed from the description of 5 geological sections. The barrier is composed of very fine to fine quartz sand which may contain hight concentrate of heavy minerals and plant debris in the form of swaley and hummocky cross stratification. There were identified 13 facies corresponding to the facies associations foreshore, upper shoreface and middle shoreface. Surfaces of 1st, 2nd and 3rd order were identified. The 3rd order surfaces were identified in the three facies associations and were related to architectural elements of the barrier, called: beach face, bars and ebb-tidal delta deposits.