Cyclic growth and mass wasting of submarine Los Frailes lava flow and dome complex in Cabo de Gata, SE Spain.

The Los Frailes Formation lava-flow and dome complex is a Miocene succession that is part of the Cabo de Gata volcanic zone of SE Spain. The complex comprises dominantly dacitic, subaqueous domerocks and interstratified sedimentary horizons emplaced over a fewtens of thousands of years. Facies of the Los Frailes Formation include coherent lava, in-situ hyaloclastite, locally with microfossil-bearing siltstone matrix, pumiceous and block-rich tuff, and massive monomict breccia and megabreccia, in which clasts are locally several metres in diameter. The monomict megabreccias display both “block facies” and “matrix facies” architecture and show internal deformation at the block-matrix contacts. They are inferred to have derived from debris avalanches. Facies are divided into four volcanic units separated by fossiliferous marine sedimentary units emplaced during hiatuses in volcanism. The Los Frailes Formation lava-flow and dome complex were emplaced in a shallow setting that may have included emergent areas. Lava flows and the margins of dome edifices interacted with sea water to form hyaloclastite, and pyroclastic currents deposited pumiceous materials. Sector collapse of marine domes fed small-volume debris avalanches with generally the same facies and distribution of facies as the larger-scale equivalents on which traditional models are built.