Evidence for a Paleoaquifer from Early Diagenetic Siderite of the Cardium Formation, Alberta, Canada

Abstract

ABSTRACT The sedimentology and stratigraphy of the Cretaceous Cardium Formation are generally interpreted as indicating an offshore, shallow-marine shelf environment of deposition; however, geochemical and isotopic data suggest that porewater salinity varied widely during early diagenesis for much of the Cardium. In cases with little or no evidence of subaerial exposure of the sediments, this apparent conflict can be resolved by postulating infiltration of early meteoric water into these nearshore sediments behind a mobile mixing zone. Infiltration of meteoric water and movement of the interface may have been possible during any phase of basin formation, whether transgression, regression, or stillstand. Evidence for the presence of this paleoaquifer is found in data from the early-diagenetic s derite cements of the Raven River Allomember and Carrot Creek Member of the Cardium Formation.