Publication: Estratigrafía y sedimentologia del Triásico en el sector Medinaceli-Somaen (Soria)
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Publication Date
1987
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Editorial Complutense
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Abstract
Se estudian los caracteres estratigráficos y sedimentológicos del Triásico que aflora en el sector Medinaceli-Somaén (prov. Soria). Se establecen cuatro unidades littoestratigráficas de carácter informal. El hallazgo de tres asociaciones palinológicas hacen posible una mayor precisión en las atribuciones de edad. El análisis sedimentológico permite reconocer, dentro de la unidad inferior «Areniscas y Lutitas de Jubera», un ambiente fluvial con algunos canales de alta sinuosidad que evolucionan en la vertical a un ambiente fluvial con canales de baja sinuosidad; la parte superior correspondería a depósitos de carácter intermareal terrígeno. Las unidades en facies carbonáticas de tipo Muschelkalk que se suceden, «Capas Dolomíticas» y «Capas de Royuela», se depositaron en un ambiente mareal carbonatado, mientras que «Lutitas y Yesos de El Puente» podrían corresponder en este área a depósitos típicos de una llanura evaporítica tipo «sebkha».
Triassic sequence from the Medinaceli-Somaén area-Central Spain (fig. 1) can be divided into four well differenciated lithostratigraphic units: «Jubera sandstones and siltstoneso, «Dolostones beds», «Royuela beds» and «El Puente Siltstones and Gypsum». Three palynological assemblages has been founded. One of them in «Dolostones beds» and two low in the «Royuela beds». Alí of them are Ladinian in age, moreover the Triassic sequence in the Medinaceli- Somaen area whould range from Anisian to Norian (fig. 2). On the sedimentological point of view, several environment have been distinguished. «Jubera sandstones and siltstones» are mainly fluviatile sediments, that passed up into a tidal siliciclastic environment. There is evidence that the lower part of this unit represent lateral accretion deposits in a high sinuosity stream (fig. 3). Abandoned channels, crevasse splays and levee deposits, Lave been also reconnaised (figs. 3, 4 y 5). The overlying «Dolostones beds» and «Royuela beds» units were deposited in a carbonatic intertidal-flat environment. Main facies assemblages, including shallowing upward sequences, are represented in figs. 8 and 9. The «El Puente siltstones and gypsum» unit, were probably formed in a coastal sabkha environment.
Triassic sequence from the Medinaceli-Somaén area-Central Spain (fig. 1) can be divided into four well differenciated lithostratigraphic units: «Jubera sandstones and siltstoneso, «Dolostones beds», «Royuela beds» and «El Puente Siltstones and Gypsum». Three palynological assemblages has been founded. One of them in «Dolostones beds» and two low in the «Royuela beds». Alí of them are Ladinian in age, moreover the Triassic sequence in the Medinaceli- Somaen area whould range from Anisian to Norian (fig. 2). On the sedimentological point of view, several environment have been distinguished. «Jubera sandstones and siltstones» are mainly fluviatile sediments, that passed up into a tidal siliciclastic environment. There is evidence that the lower part of this unit represent lateral accretion deposits in a high sinuosity stream (fig. 3). Abandoned channels, crevasse splays and levee deposits, Lave been also reconnaised (figs. 3, 4 y 5). The overlying «Dolostones beds» and «Royuela beds» units were deposited in a carbonatic intertidal-flat environment. Main facies assemblages, including shallowing upward sequences, are represented in figs. 8 and 9. The «El Puente siltstones and gypsum» unit, were probably formed in a coastal sabkha environment.