Mineralogía de arcillas y diagénesis en la Formación de Quintanaloma (Cretácico Superior, Norte de Burgos, España)

Abstract

The preliminary results of mineralogical analysis of 28 inner platform carbonate samples taken from the Quintanaloma Formation sediments (Upper Campanian-Lower Maastrichtian) at the Credilla de Sedano section (northern Burgos) are presented. Calcite is the most important mineral and is represented by both micritic matrix and «blocky» crystals derived from cementation and recrystallization of bioclasts. Ankerite is thought to have been formed under early diagenetic conditions. Its iron source was probably related to continental soils and further flocculation favoured by humic adds at low salinities into a gently dipping carbonate ramp. Detrital siliciclastic minerals indicate the influence of a deltaic system which became less active towards the upper half of the section. Clay minerals are clearly inherited in origin and confirm: a very low diagenetic degree. So it is suggested from the presence of kaolinite along the whole studied section and the less-transformed smectite (RO). Smectite is associated to siliciclastic inputs related jto distal but not necessarily deep areas of a possible deltaic apparatus. Kaolinite is persistent along the whole section and was probably formed under the humid and warm climatic conditions that largely dominated the Norcastilian Platform during the late Cretaceous. Finally, detrital illite is widely documented in the most part of the less-diagenetized sections of the Basque-Cantabrian Basin