Caracterización paleoclimática de la serie margosa Langhiense de Can Rosell (Barcelona)

Abstract

Distinct changes during the Langhian in the clay mineral composition of the Can Rosell section, in the VallCs-Penedts graben, allow the distinction of three intervals (basal, intermediate and upper intervals). The boundaries between these intervals coincide with changes in the aragonitelcalcite ratio and in the MgCO, molar percentage of Amussiopecten baranensis (ALMERA and BOFILL). The basal interval is characterized by relatively high amounts of kaolinite, smectite, and illite, while the MgCO, of LMC and the ratio LMCIARG oscillate. The intermediate interval shows an increase in kaolinite and a decrease in smectite content. The LMCI ARG decrease and the MgCO, of LMC increases. During the upper interval the amount of kaolinite and the MgCO, decreases while the amount in illite and the ratio LMCIARG increases. The synchronism of the changes in clay mineralogy and in the mollusca mineral composition seems to suggest paleoclimatic changes. The basal interval seems to correspond to a semi-humid climate, during the deposition of the intermediate interval the humidity and temperature increases, and the upper interval presumably corresponds to an arid climate and to a decrease of temperature.