Tectonic blocks and basin evolution from the late Cretaceous to Paleogene in eastern Jamaica

Abstract

Jamaica records a 150 million year record of Caribbean-North American Plate interaction. The Cretaceous rocks can be divided into three broad blocks: the Western Jamaica Block (WJB) contains arc rocks associated with sedimentary rocks deposited adjacent to the arc; the Western Blue Mountains Block (WBMB) contains Campanian arc rocks with extensive granitoid intrusions and various subduction-zone related metamorphic rocks (schists and serpentinites); and the Eastern Blue Mountains Block (EBMB) contains typical Caribbean Large Igneous Complex (CLIP) volcanic rocks of late Turonian to early Coniacian age and mid Campanian volcanic rocks derived from a depleted mantle plume source region. Thus the WJB and WBMB contain a typical arc rock basement, whereas the EBMB has a CLIP basement with an affinity for the centre of the Caribbean Plate. Amongst the metamorphic rocks in the WBMB are glaucophane schists, which have a CLIP protolith and record peak metamorphic ages in the mid Campanian, demonstrating the existence of a Pacific-facing arc at this time. Taking account of the position of Jamaica in the mid-Eocene (south of the Yucatan Block), Jamaica can be assembled by left-lateral strike-slip faulting, with two slab tears, as the Cuban arc migrates to the NE past the Yucatan Block. Transtension across this fault zone is seen as the main driving force for the generation of basins (John Crow and Wagwater rifts) during the late Maastrichtian to early Eocene, with separate sedimentary-volcanic successions deposited in each basin. Volcanism in the Wagwater Basin is consistent with decompressional melting of under-plated CLIP rocks at this time. Following the collision of Cuba with the Bahamas Platform, Caribbean Plate movement shifted from north-eastwards to eastwards, and at this time the assembly of the Cretaceous Blocks of Jamaica was completed. The previous NE-SW orientated strike-slip fault zone was now transformed into a normal fault and records movements from the Eocene through to the present day. Notably basement uplift, with preserved onlap (or demonstrable onlap based on derived clasts) onto the Cretaceous arc ‘basement’ is recorded in the northern Blue Mountains (Port Antonio area) during the late Campanian, early Paleocene, early Eocene, mid Eocene, late Oligocene and early Pliocene. This demonstrates continued tectonic activity throughout the Cenozoic, with the likelihood of at least transitory land areas throughout this time interval. Previous models for the evolution of Jamaica are far too simplistic, and the new model adequately explains the geology of Jamaica in a Caribbean Plate context.

AAPG Datapages/Search and Discovery Article #90330©2018 AAPG Hedberg: Geology of Middle America – the Gulf of Mexico, Yucatan, Caribbean, Grenada and Tobago Basins and Their Margins “Integration of the geology of the area from the southern onshore of North America to the northern onshore of South America”, Siguenza, Guadalajara, Spain, July 2-5, 2018