Four major Paleogene sedimentary belts—the Peralta, El Mamey, and Tavera Belts of Hispaniola, and the Cerrillos Belt of Puerto Rico—provide important constraints on the Eocene-Miocene tectonic evolution of the northern Caribbean. The southeastern half of the Peralta Belt consists of two basinal sequences, the lower to upper Eocene Peralta Group, and the middle(?) Eocene to lower Miocene Rio Ocoa Group, which were deposited along the southwest margin of the Greater Antilles island arc during, and after, the last stages of arc magmatism. Peralta Group strata are cut by thick, stratally disrupted thrust fault zones, and probably record development of an Eocene accretionary prism composed of offscraped trench deposits. Ocoa Group strata lack these stratally disrupted fault zones, and we interpret these rocks as fore-arc basin deposits. The Peralta underthrusting event was probably amagmatic and may have been related either to transpression associated with the earliest stages of the presently active left-lateral, strike-slip regime of the northern Caribbean; or to “back-arc” compression associated with the last stages of the arc-Bahamas collision along the northeast margin of the arc; or to a combination of both. The tectonic evolution of the northwestern half of the Peralta Belt, which contains only Upper Cretaceous rocks, remains relatively poorly understood.
Coincident with Eocene deposition of the Peralta Group, the middle Eocene epiclastic, volcaniclastic, and volcanic rocks of the Cerrillos Belt of Puerto Rico were deposited in two short-lived intra-arc basins. In contrast to coeval Peralta Group deposits, the Cerrillos Belt rocks were associated with active arc magmatism, possibly along both margins of the belt. Late Eocene, northeast-verging thrust faults and folds that cut the Cerrillos Belt may record closure of the basins during the last stages of the Greater Antilles-Bahamas collision. Alternatively, basin opening and closure may reflect periods of transtension and transpression in an intra-arc, strike-slip fault zone associated with an obliquely convergent margin.
Paleocurrents indicate that the basinal rocks of the El Mamey Belt of northern Hispaniola were deposited in an elongate, arc-parallel basin(s) active from late Eocene to early Miocene time. A basal, middle Eocene angular unconformity probably records deformation of island-arc basement during collision between the Greater Antilles arc and the Bahamas Platform. Paleoflow within the El Mamey basin apparently reversed during late Oligocene time, from an early period of southeasl-directed paleoflow to later northwest-directed paleoflow. An angular unconformity separates folded El Mamey Belt rocks from upper Miocene, flat-lying marls of the overlying Villa Trina Formation, reflecting an early(?)-middle Miocene period of folding, uplift, and erosion. This deformation may be related to the development of a restraining bend within the northern Hispaniola portion of the left-lateral northern Caribbean Plate boundary zone.
The Tavera Belt of north-central Hispaniola underwent two distinct periods of basin development during early Oligocene (Velazquitos and Inoa Formations) and late Oligocene to early Miocene (Represa and Janico Formations) time, interrupted by a middle Oligocene period of folding and erosion. Complex paleocurrent patterns from the Represa and Janico Formations suggest that sediment may have been derived from at least three sides of the Tavera basin during late Oligocene-early Miocene time. Basinal sedimentation ended during the early Miocene, when Tavera Belt rocks were gently folded, eroded, and covered by shallow-marine conglomerates of the Cercado Formation. We tentatively interpret both the El Mamey and Tavera Belts as developing within a broad “California-type” strike-slip borderland.
