The Cretaceous History of Jamaica: a time of volcanoes & carbonate platforms with rudist bivalves
by Simon F. Mitchell | Department of Geography & Geology, University of West Indies, Mona, Kingston, Jamaica
Halberstadt lavas - photo copyright Simon F. Mitchell
The Cretaceous rocks of Jamaica differ significantly from the Cretaceous rocks of Yorkshire, although occasionally a fossil occurs that is common to both areas. Different parts of Jamaica have very different Cretaceous geological histories, with eastern parts of the island forming over the Galapagos hotspot in the Pacific Ocean and central and western parts of the island forming in a volcanic island arc probably associated with Mexican and Central American arcs.
The Cretaceous rocks of Jamaica consist of volcanic and plutonic rocks together with thick sedimentary successions including deep-water turbidite units derived from the volcanoes and shallow-water carbonate platforms. The carbonate platforms were the home to the rudists, a group of sessile bivalves that grew to enormous sizes, sometimes reaching a diameter of 2 m. The evolutionary history of the rudists is well represented in Jamaica, with the Lower Cretaceous showing a progression from small primitive forms to larger complex forms with shells bearing extensive canal systems.
But it is in the Upper Cretaceous where the largest and most bizarre forms are found, ranging from the giant barrel-shaped Barrettia in the Campanian to the massive croissant-shaped Titanosarcolites in the Maastrichtian. This talk will give a brief overview of the tectonic history of Jamaica and then explore the fascinating world of the rudists.
Speaker Bio:
Professor Simon Mitchell received a B.Sc. in Geology from the University of Hull (where he received the Moore Medal from the YGS for his mapping on Raasay) and a Ph.D. in Geology from the University of Liverpool (where his work concentrated on the Cretaceous rocks of Yorkshire). He has spent the last 25 years teaching at the University of the West indies, where he has trained students from across the Caribbean and researches into the geology of Jamaica, the rudists and larger foraminifers of the Americas and occasionally works on projects in the UK and elsewhere.