Resumen de Transformación de coladas básicas alcalinas subaéreas en lavas almohadilladas en ambiente litoral: un ejemplo del Plioceno, Norte de la isla de Gran Canaria
Domingo Gimeno Torrente, Francisco José Pérez Torrado, J.-L. Schneider, P. Wassmer
This note descrites the transition of a basic lava flow (4.3-4.15 m.y.) belonging to initial events of Roque Nublo volcanic group to submarine pillow lava flows in the northeastern shoreline of Cran Canaria island. The host littoral environment is characterized by a flat shallow shelf covered by a decimeter to meter thick level of white even laminated marine sediments. The lava rivers flowed some 20 km from the center of Cran Canaria island towards the sea, and 3 km inside of the shallow shelf. The bottom of the pillows level crops out in the range of 75-140 m above present sea level, and is constituted by a 20 m thick level of dominant pillow lava flows, and minor pillow breccia and hyaloclastite. It is characteristic the absence of hyaloclastite delta, and the pillow tubes are intrusive in the underlying white marine sediments. A number of lithofacies (peperitization, in situ hyaloclastite formation, fluidification of sediment, erosion and bulldozing of sediment) are characteristic of this lower section of pillow pile. The pillow shows evidence of shallow water column (multiple rind structure), fast flow (hollow pillows) and moderate degasification of the magma (segregation of phenocrystals towards the glassy rinds).
The upper transition of the pillow pile to pahoehoe flows shows a characteristic lithofacies constituted by metric feeder tubes filled with hyaloclastites generated in situ.
