Sequence stratigraphy of tidally influenced deposits in a salt-withdrawal minibasin:Upper sandstone member of the Potrerillos Formation(Paleocene),La Popa basin,Mexico

摘要

The Potrerillos minibasin of the La Popa basin,Mexico,is defined by the Carroza syncline and bounded by the El Gordo anticline and the La Popa salt weld.Stratigraphic geometries and facies distribution of the upper sandstone member of the Potrerillos Formation within the minibasin indicate that diapirism,shortening,and deposition were simultaneous and complexly interrelated during the Paleocene.The upper sandstone member is a regressive succession of marginal marine,siliciclastic deposits.Wave-dominated shore-face deposits consist of mudstone,siltstone,and sandstone and are interpreted to represent offshore to upper shoreface environments.Tide-dominated environments are heterogeneous and grouped into four broad classes based on the energy of the depositional environment.Lower delta-plain deposits range from mudstone to sandstone and are interpreted to represent channel,flood-plain,and lagoonal environments.Sedimentary structure orientations indicate asymmetrical,bidirectional paleocurrents with a dominant southeast trend parallel to regional structural trends.Unconformity-bounded strata onlap the El Gordo anticline,indicating syndeposi-tional folding and control of the depositional system by detachment fold trends in the basin.