Linkages between the Aptian-Albian marine facies in Chihuahua and Sonora, Mexico

©xico. The sections studied in the Sierra Banco de Lucero in Chihuahua and Sierra Las Azules in Sonora, are mainly made of micritic limestone and sandy limestone, with some intervals of interbedded shales. Both sections have very similar faunal associations. Both sections display some environmental differences resulting from fluctuation of the sea level, the direct lateral continuity of the two successions remains unresolved, these variations are reflected in the microfacies and also in minor differences in taxonomic diversity of microfossils. The microfacies shows that, the dominant environments in both sections range from pelagic open ocean, to slope and to basin, upper platform and lagoonal environments were identified only in the upper part of the Chihuahua succession. However, the Sierra Las Azules succession, represents deeper conditions with respect to the Banco de Lucero section. Both successions represent the interval comprised between the upper Aptian and the lower Albian, however, they are slightly diacronous; it is likely that the section in Sonora is slightly older than the Banco de Lucero section. Our field and lab data demonstrate the lithostratigraphic and chonostratigraphic affinities between both successions. © 2019, Instituto de Geologã-a, Universidad Nacional Autã3noma de Mã