STUDIES ON THE GEODIVERSITY OF THE NORTHERN SECTOR OF THESAN MATIAS GULF, RIO NEGRO, ARGENTINA

MEDINA WALTER; CHARO MELISA; MONTENEGRO, DAVID ALFREDO

Oxford

Conferencia; OXFORD GEOHERITAGE VIRTUAL CONFERENCE; 2022

Universidad de Oxford

This work deals with the study of the geodiversity of the northern San Matías Gulf, following the coastline of the province of Río Negro, Argentina. The area of analysis is relatively small, where important geological coexist features that allow us to describe the events that occurred in the Cenozoic that led to the formation of the gulf. The objective is to analyze and assess the geodiversity of the northern coast of San Matias Gulf. The methodology used was based on the sum of partial numerical indices, calculated on different maps that represent the greatest number of geodiversity elements. The Geodiversity Index is obtained from the sum of these partial indices, the latter being the the result of the sum of units and occurrences in units in areas defined by a grid. They were georeferenced under the same reference system (POSGAR 2007, Faja 3) served as input for the different indexes that make up the geodiversity index. As result, 45 squares of 5x5 km each were created. From this grid, the number of structures present in each square was number of structures present in each square, and thus the partial indices were partial indexes. Finally, the partial was summed to generate a single geodiversity index in the study area. As a result, a geodiversity map with a minimum value of 1 and a maximum of 10, ordered in three intervals: Low (1-5), Medium (5-8) and High (8-10).As results, it can be seen that, following the coastal zone, it is the highest index, on the other hand, the zones with the lowest indexes cover the areas with the lowest indices cover less areal extension even smaller than those with average index values. Indexes results in an area of significant geological diversity, in an area that, in the last decades, has consolidated as a tourist corridor in the Patagonian coast. The Geodiversity Index Map of the northern San Matias Gulf shows high values in areas coinciding with the littoral and the Pleistocene littoral ridges associated with the fossil mollusks of the Tegula atra and Anomalocardia brasiliana and a smaller stretch to the east and a smaller section located to the east where eolian deposits (dunes) of fine sands with beachrocks associated by Chama iudica. The sectors of medium values coincide with the tidal plains and and edaphically correspond to aridisols. Finally, the areas with the lowest values of the Geodiversity Index are located in the sectors where the tidal plains of the estuarial system.