Afloramientos intermareales de beachrock holocenos en playas del sur del municipio de Telde (Este de Gran Canaria)

Abstract

The Holocene beachrocks studied crop out in the southern coast of Telde and, specifically, in Salinetas, Aguadulce and Ámbar beaches. The beachrocks are calcarenites and, in minor amounts, conglomerate formed in the Present Interglacial stage. The beachrocks appear in intertidal and subtidal zones, and they show up to 2.2 m thick, attain some tens of metres in width and consist of one or several decimetric-thick horizons (less 50 cm), dipping below 15º seaward. The calcarenites are formed by bioclasts (red algae, molluscs and, minor amounts, of echinoderms, foraminifera, and bryozoan) and lithoclasts (mafic and felsic volcanic rock fragments and, felsic and ferromagnesian minerals, and intraclasts). The porosity is intergranular and the isopachous cement of high-magnesian calcite (HMC). The CO3Mg concentration in these cements varies between 9.1 and 14.6% (<461 ppm of Sr and <1336 ppm of Na). Therefore, these carbonate cementation was formed by phreatic marine waters.