La unidad evaporítica del Messiniense en la Cuenca del Bajo Segura (Cordillera Bética oriental)facies, cronología y ciclos sedimentarios de control astronómico
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Universitat d'Alacant
info
ISSN: 0213-683X
Year of publication: 2018
Issue Title: Comunicaciones presentadas en la LXIII Sesión Científica / Elche, 25 de Noviembre de 2017
Issue: 63
Pages: 3-6
Type: Article
More publications in: Geogaceta
Abstract
The Messinian evaporitic unit in the Bajo Segura Basin is represented by the San Miguel Formation. In the outcroping reference section, the San Miguel de Salinas composite -SMdS(c)-, this formation is represented by seven selenitic gypsum beds forming bipartite cycles with intervals of sapropelitic laminated marls, including sandy facies related to storm ebb surges. In the SM1 and LM boreholes, nine and fifteen cycles are recognized, respectively. The temporal calibration of the gypsum beds presented in our study is based on the tuning with the precessional cycles. This results in ages ranging from 5.969 Ma for the first bed (G1) and 5.63 Ma for the last bed (G15). The lithological pairs of gypsum and laminated marl are genetically related to moments of insolation minima (precession maxima) and insolation maxima (precess ion minima), respectively. These oscillations generate repetitive changes in the conditions of the bottom of the marine basin, alternating moments of oxygenation (in phases with dry or arid climate) and of anoxia (in phases of humid climate).