Tephra event stratigraphy and emplacement of volcaniclastic sediments, Mogán and Fataga stratigraphic intervals, Part II: origin and emplacement of volcaniclastic layers

We subdivided volcaniclastic layers drilled during Leg 157 around Gran Canaria at distances up to 70 km from the shore of the island at Hole 953C, 955A, and 956B deposited between 14 and ~11.5 Ma into >100 volcaniclastic units at each site. Most volcaniclastic layers are <20 cm thick, but complex turbidite units up to 1.5 m thick make up 10% to 20% of all volcaniclastic units in Holes 953C and 956B. We distinguish several types of clasts: felsic vitroclasts, (1) bubble-wall/junction shards, (2) brown nonvesicular felsic shards, (3) welded tuff clasts, (4) pumice shards, and (5) sideromelane shards. Mineral phases comprise anorthoclase and lesser amounts of plagioclase, calcic and sodic amphibole (kaersutite, richterite, and edenite), clinopyroxene (titanaugite to aegirine), hypersthene, minor enstatite, phlogopite, Fe/Ti oxides, sphene, chevkinite, apatite, and zircon. Xenocrysts are dominantly titanaugite derived from the subaerial and submarine shield basalts. Lithoclasts are mainly tachylitic and crystalline basalt, the latter most common in Hole 953C, and fragments of felsic lava and ignimbrite. Bioclasts consist of open planktonic foraminifers and nannofossil ooze in the highly vitric layers, while filled planktonic foraminifers, benthic foraminifers, and a variety of shallow water calcareous and siliceous fossils and littoral skeletal debris are common in the basal coarser grained parts of turbidites.