Neogene and Pleistocene fossil brachiopods of the Eastern Islands. Current appointments.

[EN] Numerous specimens of fossil brachiopods have been found in the different fossiliferous outcrops of the Canary Islands. These fossils have been found in the deposits of Mio-Pliocene age of the eastern Canary Islands, described and illustrated in the work of Meco et ali. 2005 and in the outcrops interpreted as a tsunami deposits  in Piedra Alta, Lanzarote, belonging to the Marine Isotope Stage 11 dated to circa 330 ka. 4 species of fossil brachiopods have been identificated: Terebratula sinuous Brocchi 1814, Lacazella mediterranea Risso 1826 Terebratulina caputserpentis (Zbyszewski, 1957) and Thecidium cf . digitatum (Sowerby 1823). These fossils provides stratigraphic and paleoclimatic taxonomic information. Furthermore, in order to compare the fossil brachiopods with present in the Canary Island, a reference collection is defined with specimens obtained from marine sediment surveys at Gran Canaria, La Palma and El Hierro, identifying 3 species: Argyrotheca barrettiatia (Davidson, 1866), Megerlia truncata (Linaeus 1767 ) and Pajaudina atlantica (Logan 1988).

The Acridian plagues, a new Holocene and Pleistocene palaeoclimatic indicator

[EN] Five palaeosols, intercalated within the Quaternary dune beds of Fuerteventura and Lanzarote (Canary Islands), off the Moroccan coast, mark wetter climatic episodes. In all of them, billions of calcified insect ootheca testify to past occurrences of Acridian plagues, such as those reaching the western Sahara following heavy rainfall events over the Sahel.

Characterisation of a pleistocene debris-avalanche deposit in the Tenteniguada Basin, Gran Canaria Island, Spain

[EN] We studied a large debris-avalanche deposit of Pleistocene age in the Tenteniguada Basin, Gran Canaria Island, Spain. This deposit, which is well preserved because it is mostly covered by basanite lava flows, has distinctive matrix and block facies, hummocky topography and internal structures typical of debris avalanches. However, neither syneruptive lavas nor some characteristic features of volcanic debris-avalanche deposits, such as a stratovolcano edifice or a horseshoe-shaped crater, are present. The occurrence of internal features characteristic of volcanic avalanche deposits could be attributed to the volcanic materials involved in the movement rather than to the triggering of the avalanche during a volcanic eruption.

El clima en el Atlántico norafricano durante los interglaciales MIS 5.5 y MIS 11.3 a partir de los paleoindicadores Harpa rosea Lamarck [1816] y Saccaostrea cucullata (Born, 1780) en el archipiélago canario

Universidad de Las Palmas de Gran Canaria. Departamento de Biología. Programa de doctorado de Gestión de recursos vivos marinos y medioambiente ; bienio 2006-2008

Los depósitos de ceniza volcánica del Pleistoceno Superior-Holoceno de la región de Tafí del Valle-Cafayate, noroeste de Argentina

VIII Congreso geológico de España, Oviedo, 17-19 julio 2012

Climatic and stratigraphic paleoindicators from the Canary Island

[EN] The last 5 Myr  are characterized by cliamatic variations globally and are reflected in ancient fossiliferous marine deposits visible in the Canary Islands. The fossils contained are identificated as paleoecological and paleoclimatic 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 Defrance, 1827 and Nerita emiliana Mayer, 1872 and the bivalve Gryphaea virleti Deshayes, 1832 as most characteristic fossils  and typical of a very warm climate and littoral zone. Associated  lava flows  have been dated radiometrically  and provides a range between  8.9 and about 4.2 Kyr. In the mid-Pleistocene, about 400,000 years ago, the called Marine Isotope Stage 11, a strong global warming that caused a sea level rise happens. Remains of the MIS 11  are preserved on the coast of Arucas (Gran Canaria), and associated with a tsunami in Piedra Alta (Lanzarote). These fossilifeorus  deposits contains the bivalve Saccostrea cucullata (Born, 1780), the gastropod Purpurellus gambiensis (Reeve, 1845) and the corals Madracis pharensis (Heller, 1868) and Dendrophyllia cornigera (Lamarck, 1816). Both sites have been dated by K-Ar on pillow lavas (approximately 420,000 years) and by Uranium Series on corals (about 481,000 years) respectively. The upper Pleistocene starts with another strong global warming known as the last interglacial or marine isotope  stage (MIS) 5.5, about 125,000 years ago, which also left marine  fossil deposits exposed in parallel to current in Igueste of San Andrés (Tenerife),  El Altillo, the  city of Las Palmas de Gran Canaria  and Maspalomas (Gran Canaria),  Matas Blancas, the Playitas and Morrojable (Fuerteventura ) and in Playa Blanca and Punta Penedo (Lanzarote ). The fossil coral Siderastrea radians (Pallas , 1766 ) currently living in the Cape Verde Islands , the Gulf of Guinea and the Caribbean has allowed Uranium series dating. The gastropods Strombus bubonius Lamarck, 1822 and Harpa doris (Röding , 1798 ) currently living in the Gulf of Guinea. Current biogeography using synoptic data obtained through satellites provided by the ISS Canary Seas provides data of Ocean Surface Temperature (SST) and Chlorophyll a (Chlor a) . This has allowed the estimation of these sea conditions during interglacials compared to today .

Las pardelas pleistocenas de Hueso del Caballo

[EN] Osseous remains of numerous shearwaters and of eggshells of the only egg laid and often undamaged appear in the sand dunes of Jandía Península and more specifically in "Hueso del Caballo" which was one of their breeding si tes. Toe bones also visible in the sandy walls of a quarry were uncovered by the present aeolian erosion and are found in a layerwith Hymmenoptera nests and terrestrial mollusc shells in a dune dated by radiocarbon as being more than 30.000 years old. This fact proves there was a halt in the aeolian processes during a humid interval, probably related to the African aterían pluvial in Upper Pleistocene and a fixation of the dunes by vegetation.