Late Miocene and Early Pliocene coastal deposits from the Canary Islands: New records and paleoclimatic significance

Abstract

The Canary Islands offer an outstanding context for paleoclimatic studies because their volcanic nature and the presence of datable lava flows, their antiquity, the existence of marine deposits and their location in the NE Atlantic. New records of Miocene and Pliocene coastal deposits are registered in the eastern Canary Islands, 100 km off the NW African coast. Late Miocene marine deposits are conglomerates and sandstones assigned to the Tortonian through a new 40 Ar/ 39 Ar age (9.60 ± 0.05 Ma) of an overlying lava flow at the Janubio site in Lanzarote Island. These deposits contain littoral-intertidal and intertropical genera of fossils, e.g. the gastropod Nerita and the coral Siderastrea, they are almost horizontal and were elevated up to 36 m in height by regional or local tectonics, yielding a relatively low rate of uplift of~3.75 m/Ma. Furthermore, Early Pliocene coastal deposits studied, are mainly marine conglomerates and sandstones and derived aeolianites that are spread over the south of Lanzarote and the west of the Jandía peninsula of Fuerteventura Island. No associated lava flow permits their dating, but they contain marine fossils of littoral and intertropical genera, as the gastropods Nerita and Persististrombus and the coral Siderastrea. They are all inclined toward the coast in the form of a large layer elevated up to 70 m a.s.l., in a surrounding geological environment with gypsum and aeolianites that indicate a eustatic sea-level fall with a regressive effect in the area. These deposits, previously attributed to the Quaternary, are now assigned to the Zanclean because of its similarity in lithology, appearance and fossil content with deposits in western Fuerteventura and NE Gran Canaria. The nearby existence of paleosols with particular structures indicates the start of climatic seasonality in the region; and the only possible time interval in a global context (record of deep-sea oxygen isotopes and sea-level history) fits in the most notable Pliocene global climatic change (~4 Ma) that is registered in the Canary Islands by mean of these coastal and aeolian deposits.

Earth-Moon Barycentre Excursions and Anomalous Quaternary Sea Level Highstands

“…But, the existence of other much older Strombus from the Early Pliocene has misled some studies. This confusion was confirmed with the first K/Ar ages [2] [3] and 40 Ar/ 39 Ar ages [4] [5] of associated lavas and with the study of these fossils, and consequently the deposits that contained them, confirming that they were not Quaternary. Subsequently, attention was focused on the list of other elements of the Quaternary fauna, confirming the mix of cold and warm faunas and dating corals by Uranium-series [6].…”

“…These Canarian late Miocene marine deposits correspond to an old intertidal zone and are directly covered by lava flow on the western coast of Lanzarote, in Janubio. The lava has an age of ca 9.6 My, using 40 Ar/ 39 Ar dating, and the height of the deposits is ca 36 m above sea level (ASL) [5]. As the sea level was close to the present level during the formation of Miocene marine deposits [18], we can consider them coincident, with an approximate rate of 3.75 m•My −1 [5].…”

“…The lava has an age of ca 9.6 My, using 40 Ar/ 39 Ar dating, and the height of the deposits is ca 36 m above sea level (ASL) [5]. As the sea level was close to the present level during the formation of Miocene marine deposits [18], we can consider them coincident, with an approximate rate of 3.75 m•My −1 [5]. In the case of the Upper Pleistocene (starting about 130 ky ago), the deposits have a height of a few centimetres (<5 cm) and for the upper Holocene (the last 5 ky) a few millimetres (<4 mm).…”

Estudios en Homenaje a Emigdia Repetto Jiménez: La investigación acompañando a la vida

“…En Lanzarote, en las Salinas del Janubio, hay un depósito marino íntimamente asociado a una colada de lavas. Obtuvimos una edad Argon/Argon de la colada (Meco et al, 2020) que resultó próxima a los 10 millones de años (Ma). Como el depósito en la actualidad se encuentra a unos 40 m de altura sobre el nivel del mar y éste era igual al de ahora, ello quiere decir que la isla de Lanzarote ha sufrido desde entonces una elevación de 40 m. Pero, en la zona de Los Ajaches, hay otros depósitos marinos, de unos 5 Ma, que están a 70 m. de altura.…”

“…ESTUDIOS EN HOMENAJE A EMIGDIA REPETTO JIMÉNEZ Fuente: Meco et al, 2020. Con el cese del clima constantemente cálido que acompañaba a las Janthina aparece la estacionalidad mostrada por las protecciones de la puesta de huevos de insectos para superar las estaciones desfavorables. Estas cámaras protectoras son propias de las regiones templadas (Figura 5) y aparecen por millones en los paleosuelos de las islas.…”