Climate and stratigraphic paleoindicators from the Canary Islands

Abstract

The last 5 million years are characterized by global climate changes and are reflected in three ancient fossiliferous marine deposits visible in the Canary Islands. In this work there are considered three main deposits which include characteristic groups of fossil fauna that are proposed to be paleoecological and paleoclimate indicators. The Mio-Pliocene transit is represented by the coral Siderastrea micoenica Osasco, 1897; the gastropods Rothpletzia rudista Simonelli, 1890; Ancilla glandiformis (Lamarck, 1822); Strombus coronatus De- france, 1827 and Nerita emiliana Mayer, 1872 and the bivalve Gryphaea virleti Deshayes, 1832. These are the most characteristic fossils and typical of a very warm climate and littoral zone. Associated lava flows have been radiometrically dated and provide a range between 8.9 and about 4.1 Ma. In the Middle Pleistocene a strong global warming caused a sea level rise (Marine Isotope Stage 11). Fossil remains of MIS 11 are preserved on the coast of Arucas (Gran Canaria Is.) and in a tsunami deposit at Piedra Alta (Lanzarote Is.). These fossiliferous deposits contain the bivalve Saccostrea cucullata (Born, 1780), the gastropod Purpurellus gambiensis (Reeve, 1845) and the corals Madracis pharensis (Heller, 1868) and Dendrophyllia cornigera (Lamarck, 1816). The former was dated by K-Ar method on pillow lavas (circa 420,000 years) and the latter by Uranium Series method on corals (circa 481,000 years). The Upper Pleistocene started with another strong global warming, known as the Last Interglacial or MIS 5.5, circa 125,000 years ago. Marine fossil deposits of this stage are present Igueste de San Andre´s (Tenerife Is.); El Altillo, Las Palmas de Gran Canaria downtown and Maspalomas (Gran Canaria Is.); Matas Blancas; Las Playitas and Morro Jable (Fuerteventura Is.) and in Playa Blanca and Punta Penedo (Lanzarote Is.). The main fauna of these sites are: the coral Siderastrea radians (Pallas, 1766), currently living in the Cape Verde archipelago, the Gulf of Guinea and the Caribbean. The gastropods Strombus bubonius Lamarck, 1822 and Harpa doris (Ro¨ding, 1798), currently living in the Gulf of Guinea. We also have study the present bio-oceanographic conditions of the areas where are currently living these species. We have managed variables such as the Sea Surface Temperature (SST) and the concen- tration of Chlorophyll-a pigment (Chl-a). These parameters have been collected by remote sensors and processed by the SEASCanarias. They have allowed us the estimation of the marine conditions during the Pleistocene interglacials.