Danian (Lower Paleocene) shallow carbonates from the Urbasa-Andia plateau (W Pyrenees): Contrasting models of facies architecture and early diagenesis across a greenhouse ramp to reef-rimmed shelf system

Abstract

The Urbasa-Andia plateau, in the western Pyrenees (North Spain), provides the opportunity to asses in detail the facies types and architecture of a Danian (lower Paleocene) greenhouse ramp to rimmed shelf system, from the slope to the coralgal reefal margin, through to highly restricted evaporitic inner shelf areas, all integrated with a range of porosity forming diagenetic phases associated with highstand and lowstand of sea-level. The detailed nature of the stratal architecture of this greenhouse platform provides an understanding of potential reservoir layering, lateral facies changes and early dolomitization. Significantly, the Danian platform system also allows a whole macroporosity system related to a third order lowstand to be accessed in relative continuity, illustrating how eogenetic karstic porosity can change drastically across a carbonate platform, from the near-massive margin to a layered shelf interior. The outcrops to visit serve as potential analogues for fields in North Africa.