Caracterização mineralógica da sequência sedimentar Ha7 do Cretácico Inferior do Guincho (Bacia Lusitaniana) (*)

Mineralogical assemblages, specially clay mineral assemblages, have been widely used in multidisciplinary stratigraphical studies. This paper presents the results obtained in the study of a Lower Cretaceous depositional sequence from the Lusitanian Basin (Portugal). The Upper Hauterivian – Lower Barremian section at Guincho Fort pertains mostly to the Ha7 3rd order depositional sequence defined by J. REY & al. (2003) and has been studied in a detailed bed-by-bed sampling corresponding to a total of 85 samples. The analysis of the obtained clay mineral assemblages has contributed to the paleoenvironmental and paleogeographical reconstruction of the studied interval and has improved the sequence stratigraphic interpretation and positioning of sequence boundaries and other sequential surfaces (transgressive and flooding surfaces).