Precession-related sapropelites of the Messinian Sorbas Basin (South Spain): paleoenvironmental significance

Autor: María Angeles Bárcena, Antonio Vázquez, Rosa Utrilla, F. J. Sierro, Guillermo Francés, I. Zamarreño, José-Abel Flores
Přispěvatelé: Fundación Ramón Areces
Rok vydání: 2000
Předmět:
Zdroj: Digital.CSIC. Repositorio Institucional del CSIC
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ISSN: 0031-0182
DOI: 10.1016/s0031-0182(00)00058-4
Popis: The Sorbas Basin (Southern Spain) is a narrow and elongated basin located in the Betic Corridor that formed the northern connection between the Atlantic and the Paleomediterranean during the late Miocene. In the centre of the basin, about 120 m of well-preserved cyclic marine sediments crop out, ranging in age from 7.2 to 6 Myr. These cycles make up the Abad Member and are an excellent example of precession control over sedimentation. In the upper part of the sequence (Upper Abad Member), the cycles include organic-rich laminated brown marls (sapropelites) alternating with homogeneous marls displaying diatomite layers. The OM-rich laminated marls are the westernmost sapropelites of the Mediterranean. This paper is a geochemical, mineralogical, sedimentological, and micropaleontological analysis of three cycles with sapropelites. The data enable us to distinguish two main climatic scenarios. The climate, which dominated each of these scenarios, regulated the sedimentology and the physico-chemistry of the water column, resulting in the sapropelite/homogeneous marl cyclic alternations. The sapropelites developed during a climate characterised by a long period of temperate and humid conditions that occur at times of precession minima. These climatic conditions changed progressively to a subarid and drier weather, during which homogeneous sediments were deposited. The changes between these scenarios were gradual, as expected from precession dynamics. Our data suggest that the change from the subarid to the humid climate (transition from homogeneous marls to laminated sapropelites) took place at a faster rate or, at least, was recorded more rapidly by the sediments than the transition from the humid interval to the sub-arid period.
This study was supported by research grants of the Fundación Ramón Areces and DGCYT Projects PB95-0927-CO2, PB 98-0288-CO2.
Databáze: OpenAIRE
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