Ryan Ramsook

ryan.ramsook@uwimona.edu.jm

• Cretaceous-Paleocene sedimentation patterns and geological evolution of basin-platform successions, Blue Mountains, Jamaica.

Thesis Abstract

Detailed mapping and logging of the Campanian-Paleocene succession in the northern Blue Mountains, eastern Jamaica , has produced a revised geological map and tectonic evolution for the area. A review of the correlation of this Volcanic Back Arc and Post Arc Succession with analogous successions elsewhere in Jamaica , Puerto Rico and Hispaniola is given.

The region underwent NW-SE directed extension and rifting related to a change from north-eastward to eastwards motion of the Caribbean Plate following collision between the Nicaragua Rise and the Yucat à n Block in the Late Campanian/early Maastrichtian. The geologic history is divided into pre-rift, syn-rift and post-rift stages.

The Campanian to Early? Maastrichtian pre-rift sequence consists of andesitic volcanics and associated marine limestones and clastics. In the northern part of the study area, the succession consists of the Bonnie View Andesite (Campanian? porphyritic pyroxene and plagioclase andesite) with pillow structures and the fault bounded Providence Formation (calcareous poorly sorted conglomerates and graded sandstones, siltstones, shales and mudstones with Campanian ammonites). In the central study area the succession was deposited closer to an active island arc volcano and consists of a thick andesitic pile (including the Bellevue Formation) with a thin early Middle Campanian marine incursion (Back Rio Grande Formation) and is overlain by ?Early Maastrichtian rudist-bearing limestones and associated proximal volcaniclastics (Rio Grande Formation).

The Bowden Pen Formation (latest Maastrichtian?) represents the base of the syn-rift sequence by poorly sorted conglomerates and sandstones deposited in alluvial fans and proximal submarine fans as the rift system developed. This is succeeded by a coarsening upwards (rift-filling) sequence of abyssal turbiditic sandstones and shales passing up into thick sandstones (Moore Town Formation).

Post-rift deposition is marked by a change to carbonate deposition in the late Paleocene, and cessation of uplift on the rift's margins and westward migration of rifting to the Wagwater Trough.

Selected Publications

• Mitchell, S.F., and Ramsook, R . (2007). Rudist bivalve assemblages from the Back Rio Grande Formation (Campanian, Cretaceous) of Jamaica and their stratigraphical significance. Cretaceous Research .
• Mitchell, S.F., Gunter, G.C and Ramsook. R . (2007) Paleoecology of the rudist Biradiolites in the Maastrichtian of Jamaica. SEPM Special Publication No.87 .
• Ramsook. R . (in press). Ichnology and Sedimentology of a deep water Paleocene rift deposit, Blue Mountain Inlier, eastern Jamaica .
• Ramsook , R . and Hastie, A. (work in progress). Geochemistry and sedimentological significance of an accretionary lapilli unit within the Cretaceous Rio Grande Formation, northeast Blue Mountains, Jamaica
• Ramsook. R . (2006). The Paleocene larger foraminifer, Ranikothalia catenula, within limestone units of the Southern Wagwater Belt , Eastern Jamaica . - Caribbean Journal of Earth Science volume 40 .
• Ramsook. R . (2005). Geology of the Blue and John Crow Mountains , eastern Jamaica . A Guide to the Blue Mountains . Natural History Society of Jamaica .
• Robinson, E., Miller, D., Khan, S., Ramsook, R ., & Rowe, D-A. (2005). The sediment budget study of the Rio Grande Watershed Portland Parish, Jamaica . Prepared for the Government of Jamaica's National Environment and Planning Agency and the United States Agency for International Development Ridge to Reef Project under USAID Contract # 532-C-00-00-00235-00.