Estudio sedimentológíco del Saxoniense y del Buntsandstein entre Molina de Aragón y Albarracín (Cordillera Ibérica)

Abstract

The sedimentological analysis of the Saxonian unit «Lutitas y Aremscas de Tormón» and the five Buntsandstein units of this area provides several examples of alluvial sedimentation. Ihe unit «Lutitas y Areniscas de Tormón» reflects a flood-dominated, alluvial fan, complex system, which gradually evolved into the unit «Conglomerados de la Hoz del Gallo» (Lowest fluntsandstein) that can be interpreted as stream dominated, alluvial fan deposits passing basinward into a grave! dominated alluvial plain. Paleocurrent trends of tbís two clastic units are transversal to the main NW-SE fracture directions in the aren (Fig. 6). The red sandstones that overly the conglomerates, can be divided into three lithostratigraphic units (Fig. 1). This sandstones are interpreted as sandy dominated braided streams flowing aecording to the main NW-SE fault unes (Fig. 15). Ihe «Limos y Areniscas de Rillo» unit comprises mixed grave! sand fluviatile deposits evolving up into a more sandy fluvial system with low sinuosity braided channels and, finally, into a more distal alluvial plain. The complete unit sbows a fining-upward trend. Ihe sedimentary evolution of this area, together with the palaeogeographical distribution is interpreted as a interior fracture basin type, according to KINGSTON a al. (1983), reflecting a tensional tectonie environment. There is a very outstanding struetural feature in this area consisting on a horst, named «Umbral del Tremedal» by previous authors, where many of the clastic and sorne of the carbonatic units wedges out and some of them have a great thickness decrease. Buntsanóstein thickness is about 50 m on the horst avea, reaehing up to 800 m towards the northeast in the surrounding graben area.