Caribbean Journal of Earth Science, 36 (2002), 1-10.

 

 

The peri-Caribbean ophiolites: structure, tectono-magmatic significance and geodynamic implications

 

 

G. Giunta, L. Beccaluva, M. Coltorti, D. Mortellaro, F. Siena and D. Cutrupia

 

ABSTRACT. New geological and petrological data on ophiolitic complexes deformed and dismembered along the Caribbean Plate margins are presented in the framework of IGCP 433, in order to contribute to the debate on the origin and evolution of the Caribbean Plate. A “near Mid-America” original location of the Jurassic-Cretaceous Caribbean oceanic realm (proto-Caribbean phase) is suggested. Generation of oceanic crust can be initially referred to multiple spreading centres (LREE depleted MORB, in Venezuela, Costa Rica, Cuba, Guatemala, Hispaniola), evolving, into a thickened oceanic plateau (REE-flat MORB locally associated with picrites, in Costa Rica, Hispaniola, Venezuela, Dutch and Venezuelan Islands). At the same time, both the South and North American continental margins were affected by rifting and within-plate tholeiitic magmatism (Venezuela and Cuba). From Early to Late Cretaceous (eo-Caribbean phases), one subcontinental subduction zone, with melange formation (recorded only in Venezuela), and two main stages of intraoceanic subduction may be recognised: 1) an initial NE- and SE-dipping sinking of unthickened proto-Caribbean lithosphere, recorded by deformed and HP/LT metamorphosed ophiolitic melanges and volcano plutonic sequences with island-arc tholeiitic affinity (IAT) in Venezuela, calc-alkaline affinity (CA) in Cuba and both IAT and CA affinity in Guatemala and Puerto Rico; 2) followed by intraoceanic subduction, with reverse polarity, responsible for the first tectonic arrangement of the Caribbean margins, recorded by unmetamorphosed tonalitic intrusives, and related to the onset of the Aves-Lesser Antilles arc system and its eastward migration. In the Late Cretaceous, the undeformed interior of the Caribbean Plate, i.e. the Colombian and Venezuelan Basins, was restricted by subduction of the Pacific plate, building the Central American Isthmus. The Tertiary to Present eastward displacement of the Caribbean Plate led to the progressive dismembering of the deformed ophiolitic belts and their obduction at its margins. Presented at IGC-BRAZIL/2000.

 

 

Two very fossiliferous rudist sites from the Marchmont Inlier, northwestern Jamaica

 

Gavin C. Gunter

 

ABSTRACT. The Marchmont Inlier of north-western Jamaica exposes Upper Cretaceous rudist bearing limestones and intervening clastics. The purpose of this note is to document the presence of two localities in this inlier that yield abundant, well-preserved rudist specimens belonging to the Titanosarcolites fauna. Collections from these sites have significantly increased our knowledge of the rudist assemblages present within the inlier, and may prove invaluable in future studies on the biostratigraphy and palaeoecology of Jamaican rudists.

 

 

Field guide to the geological evolution of the Maastrichtian rocks of the Central Inlier, Jamaica

 

Simon F. Mitchell

 

ABSTRACT. This field guide describes the geology found in the central part of the Central Inlier. The oldest rocks present, the Arthurs Seat Formation represent the deposits of a volcanic arc. These are succeeded unconformably by a Maastrichtian (Upper Cretaceous) transgressive-regressive cycle consisting of the Slippery Rock, Thomas River and Guinea Corn formations, and the Summerfield Group. The various stops show how this transgressive-regressive cycle developed.

 

 

The trace fossil Schaubcylindrichnus coronus Frey and Howard, 1981, from the White Limestone Group of northeast Jamaica

 

Donovan J. Blissett and Ron K. Pickerill

 

ABSTRACT. The upper Lower-Middle Miocene Pelleu Island Formation of the Middle Eocene to Middle Miocene White Limestone Group, northeast Jamaica, has yielded the trace fossil Schaubcylindrichnus coronus Frey and Howard, 1981. The documentation of this bundled trace fossil is important because it is the first report of this ichnotaxon from Jamaica and indeed the Caribbean region. As a corollary it therefore adds to the geographical distribution of the trace fossil, and it is the first record that extends its palaeoenvironmental range to a deep-water setting.

 

 

Field guide to the geology of the Eocene Chapelton Formation (Yellow Limestone Group), western Central Inlier

 

Stephen K. Donovan

 

ABSTRACT. This field guide provides details of an excursion that demonstrates the faunas and sedimentary facies of the Yellow Limestone Group in the western part of the Central Inlier, between Dump (near Christiana), parish of Manchester, and Stettin, parish of Trelawny. Units examined include the Freemans Hall beds, Stettin Member, Guys Hill Member and Dump Limestone, representing a range of shallow water, near shore palaeoenvironments.

 

© Geological Society of Jamaica.