Loess yesífero en el Cuaternario Superior de la cuenca del Ebro (España): características generales

IRIONDO, MARTIN; KROHLING, DANIELA

Zona Arqueológica Número 4. “Miscelánea en Homenaje a Emiliano Aguirre”- Volumen I: Geología.

Museo Arqueológico Regional. Comunidad de Madrid

Lugar: Alcalá de Henares. Madrid.; Año: 2004; p. 44 - 50

The Ebro basin is a large depression located in the norteastern sector of Spain. It is limited bythe Cordillera Ibérica, the Pirenees and the coastal Catalonian Ranges. A significantaccumulation of loess occurred in the basin between 12,000 and 7,000 years B.P. The mostinteresting point in this case is that the sediment is composed of anhidrite and gypsum, a veryrare occurrence in the World. The loess was registered in several localities, among thoseCarcar (Navarra) and Gandesa (Tarragona) were studied in detail. The gypsum is in form ofcolourless rounded to subrounded clasts, with perfect exfolliation. The anhidrite appears inthree varieties: a) colourless pseudocubic grains, b) colourless rounded clasts, and c) grainspartially altered to gypsum. The scenario proposed here for the loess sedimentation is adominance of the northwest wind named “cierzo” or “seré” under a desertic climate. Note thatsuch a meteorological system is originated in an enhancement of the Azores Anticycloneduring the Pleistocene-Holocene transition, not necessarily linked to glacial o periglacialconditions.