Publication: Palinología del Turoniense en el sinclinorio de Campisábalos : aportaciones al análisis estratigráfico secuencial (Sistema Central-Cordillera Ibérica; Guadalajara-Segovia, España)
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2013
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Sociedad Geológica de España
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Abstract
El análisis palinológico de niveles arcillosos y margosos de la parte superior de la Formación Picofrentes, Capa de Alcorlo y tramo inferior de la Formación Embalse de la Tranquera en dos secciones (Somolinos y Grado de Pico) del sinclinorio de Campisábalos (Cordillera Ibérica-Sistema
Central) permite reconocer una tendencia general regresiva en toda la sucesión sedimentaria. Dicha tendencia se extiende desde ambientes neríticos de plataforma a ambientes costeros y lacustres muy próximos a la línea de costa, mostrando hacia techo episodios claramente continentales (con ausencia total de palinomorfos marinos y de aguas salobres). En la parte alta de la sucesión analizada se observa un cambio de tendencia a escenarios nuevamente marinos muy proximales. A lo largo de la sucesión analizada, se reconoce la presencia de tres conjuntos de parasecuencias de 4º orden, las dos inferiores presentarían una tendencia general regresiva y, en conjunto, formarían una secuencia deposicional de 3er orden, que tendría una edad Turoniense medio, confirmada por la presencia de granos de polen del
género forma Trudopollis. Por encima, la presencia de un cuerpo arenoso en relación con pólenes de carácter continental, permite diferenciar un tercer conjunto de parasecuencias de 4º orden que pertenecería ya a la secuencia de 3er orden suprayacente. Dicho litosoma arenoso y sus asociaciones palinológicas, reflejan una caída importante del nivel del mar asociado a un límite mayor de megasecuencia de 2º orden en la Cuenca Ibérica. La edad de este tercer conjunto de parasecuencias sería Turoniense
superior, confirmada por la presencia de polen de Vacuopollis.
The palynological analysis of several clayey and marly levels in the upper part of Picofrentes Formation, Alcorlo Bed and the lower part of the Embalse de la Tranquera Formation in two stratigraphic sections (Somolinos and Grado de Pico) in the synclinorium of Campisábalos (Iberian Range - Central System) allows to recognize the general sedimentary trend of the studied succession from neritic, platform environments to coastal and lagoonal ones, grading further upwards to clear continental events (complete absence of marine and brackish-water palynomorphs). Finally, at the top of the succession a major change in the sedimentary trend to proximal marine environments is again observed. The presence of three 4th order parasequence sets is observed. The two basal ones with an overall regressive trend, belonging to a 3rd order sequence and having a mid Turonian age according to the presence of the form genus Trudopollis. The existence of a lowstand sand body with pollen mainly continental, corresponds to a third 4th order parasequence set that is linked to the base of the overlying 3rd order sequence. That sandy lowstand body represents a major drop in the relative sea-level, developing a 2nd order megasequence boundary in the Iberian Basin; the age of this upper 4th order parasequence set is upper Turonian due to the presence of Vacuopollis pollen grains.
The palynological analysis of several clayey and marly levels in the upper part of Picofrentes Formation, Alcorlo Bed and the lower part of the Embalse de la Tranquera Formation in two stratigraphic sections (Somolinos and Grado de Pico) in the synclinorium of Campisábalos (Iberian Range - Central System) allows to recognize the general sedimentary trend of the studied succession from neritic, platform environments to coastal and lagoonal ones, grading further upwards to clear continental events (complete absence of marine and brackish-water palynomorphs). Finally, at the top of the succession a major change in the sedimentary trend to proximal marine environments is again observed. The presence of three 4th order parasequence sets is observed. The two basal ones with an overall regressive trend, belonging to a 3rd order sequence and having a mid Turonian age according to the presence of the form genus Trudopollis. The existence of a lowstand sand body with pollen mainly continental, corresponds to a third 4th order parasequence set that is linked to the base of the overlying 3rd order sequence. That sandy lowstand body represents a major drop in the relative sea-level, developing a 2nd order megasequence boundary in the Iberian Basin; the age of this upper 4th order parasequence set is upper Turonian due to the presence of Vacuopollis pollen grains.