Abstract
The upper Albian Caniego carbonate platform consists of a 20-m-thick unit of rudist- and coral-bearing limestones that crops out at the northern margin of the Mena diapir in northern Spain. The limestones were deposited on top of a slowly subsiding area, the Mena paleohigh, a diapiric-induced horst bounded by synsedimentary faults. The Caniego limestones originated in shallow warm tropical waters following a widespread marine transgression at the base of the foraminifera Rotalipora appenninica zone (ammonite Stoliczkaia dispar zone). Around the middle part of the appenninica zone the Caniego limestones underwent subaerial exposure and karst development. Fibrous calcite cements filled the bulk of the fissure-dike and dissolution cavities. Field, petrological, and geochemical data indicate that the fibrous calcites are meteoric flowstones. δ18O values in these cements range from −3‰ to −4.5‰ and δ13C values range from −7‰ to −14‰ (relative to the Peedee belemnite [PDB] standard). Thick wedges of nearshore shallow-marine siliciclastic sediments were deposited in paleotrough areas surrounding the Caniego paleohigh while the platform was subaerially exposed. The carbonate platform was drowned in early Cenomanian time and hardground-condensed facies developed during this period (Rotalipora brotzeni zone). Deeper water noncondensed marly sedimentation was reestablished in the mid-Cenomanian (Rotalipora reicheli zone). Comparison of the Iberian Caniego limestones with worldwide successions suggests a coincidence in the timing of platform formation emergence and drowning in several basins of different lithospheric plates. Nevertheless, an overall lack of coordination of sea-level histories from different basins may be related to tectonic movements of the lithospheric plates. Plate rearrangement is invoked as the primary control on relative sea-level changes and sequence development.
