Mid-Holocene relative sea-level changes along Atlantic Patagonia: New data from Camarones, Chubut, Argentina

Abstract

This paper concerns the relative sea-level changes associated with the Atlantic Patagonian coast derived from sea-level index points whose elevation was determined by a differential global position system (DGPS). Bioencrustations from outcrops located near Camarones, Chubut, Argentina, consist of autochthonous deposits characterized by Austromegabalanus psittacus (Molina, 1782), encrusting acervulinid foraminifera, coralline red algae and bryozoans. The association of the different organisms is interpreted as being associated with an intertidal environment, and they have been used as index points to establish the relative sea-level position. The main conclusion is that the relative sea-level between c. 7000 and 5300 cal. yr BP was in the range of c. 2â\u80\u934 m a.s.l., with a mean value of c. 3.5 m a.s.l. Our data seem to support the existence of different rates of relative sea-level fall in different sectors of Atlantic Patagonia during the Holocene and highlight the importance of a more precise and accurate relative sea-level estimation by producing new data and revisiting the indicative meaning of most of the indicators so far used in the area

Higher than present global mean sea level recorded by an Early Pliocene intertidal unit in Patagonia (Argentina)

“…From these measurements, we calculate that Unit Cp has an average elevation of 36.2 ± 0.9 m (1σ) above the GEOIDEAR16 geoid 40 , which is the best approximation for present sea level in Argentina. Using modern tidal values 36 , and assuming no post-depositional movement, we calculate that the two outcrops in the area of Camarones are indicative of a paleo RSL at 36.2 ± 2.7 m (1σ) above present (see "Methods" section for details).…”

“…This means that its indicative meaning 62 spans from Mean Lower Low Water (MLLW) to Mean Higher High Water (MHHW). Based on predicted tidal data for the harbor of Camarones, Bini et al 36 report that the maximum tidal range (MHHW to MLLW) in Camarones is 5 m. We use this value (5 m) as the indicative range (IR) for a foreshore deposit in our area, and the midpoint between MHHW and MLLW (0 m) as reference water level (RWL). Then, using the formulas described in Rovere et al 1 , we calculate paleo RSL and its associated uncertainty as follows:…”

Accuracy of the TanDEM-X Digital Elevation Model for Coastal Geomorphological Studies in Patagonia (South Argentina)

“…Their elevations are the result of the interplay between tectonic uplift, glacioisostatic rebound and eustatic rise. However, an accurate measurement of the elevation of these features above sea-level by a Differential Global Positioning System (DGPS) has been rarely performed [20,21]. Most previous data sets have been referred only to the local mean high-tide e.g., [15,17,18], so as to make correlations in a global setting difficult to perform.…”

A Holocene tephra layer within coastal aeolian deposits north of Caleta Olivia (Santa Cruz Province, Argentina)

“…A system of Holocene raised beaches started to form since ca. 6,000 a cal BP organised by successions of beach ridges and littoral terraces discontinuously preserved along the coast (e.g., Bini et al, 2014Bini et al, , 2018Codignotto et al, 1988;Ribolini et al, 2011;Schellmann and Radtke, 2010;Isla and Bujalesky, 2008;Isola et al, 2011;Zanchetta et al, 2012aZanchetta et al, , 2014.…”