Springer Online Journal Archives 1860-2000
Abstract The Berriasian Huérteles Alloformation is the fourth alloformation in which the Tithonian-Berriasian Depositional Sequence is divided in Eastern Cameros Basin. This depositional sequence can be recognized in several basins East of The Iberian Plate. Huérteles Afm. was deposited in a trough with a NW-SE orientation and strong subsidence. In this trough the sedimentary record exceeds 1000 m in thickness for this alloformation. The Basin shows a marked asymmetry, with the highly subsident trough displaced to the NE. The sedimentary system consists of a playa complex, in which several subenvironments can be distinguished. The proximal or bajada environments were located to the west. The terrigenous materials, that constitute the sediments of these areas, come from the erosion of materials previously deposited in the Basin. To the East the environments were mainly saline lakes, that received siliciclastic materials from the Northeast, where the main border fault system was situated. The vertical sequence in the central part of the Basin (where a perennial saline lake was located) shows a marked cyclicity, with primary sequences about 10 m thick. These consist of laminated limestones in their lower part, and carbonate breccias at the top. These primary sequences represent the filling of a lake, with relatively dilute waters at first, passing gradually into a saline lake. This reflects a transition from humid to arid climatic periods. Additionally there is another cyclicity of a higher rank indicated by sequences about 300 m thick These major sequences are formed by primary sequences. The minor primary sequences are mainly composed of laminated limestones in the lower part of the major sequences, and the carbonate breccias dominate in the upper part of the major sequences. These major sequences may indicate longer periods of climatic variation, that varied from a relatively humid to an arid climate. This sequential arrangement was accentuated by the strong tectonic activity during sedimentation, that produced large slump structures where evaporites were more abundant.
Type of Medium: