Small-scale shallow-water carbonate sequences of Resolution Guyot (Sites 866, 867, and 868)

Abstract

The Hauterivian to upper Albian carbonate sediments drilled on Resolution Guyot are all of shallow-water origin. The volcanic basement is covered by dolomitized oolitic and oncolitic grainstones of an inner-ramp setting. At 1400 m below seafloor (mbsf), they pass into peritidal facies punctuated by small coral and rudist bioherms and by beach sediments. The upper part of the guyot is composed of lagoonal carbonates exhibiting some calcrete horizons. The material collected from Holes 867B and 868A implies that the platform was rimmed by barrier islands and storm beaches, and that reefs were of minor importance. This is in contrast to modern atolls, where reefs are the major rim builders. In the late Albian, the platform was subaerially exposed and karstified, then drowned. -from Authors