Miocene-Pliocene bathyal benthic foraminifera and the uplift of Buff Bay, Jamaica

Abstract

We sampled lowermost middle Miocene to Pliocene sections exposed in roadcuts east of Buff Bay, Jamaica, for quantitative benthic foraminiferal studies. Our analyses document paleobathymetric changes and sediment sources. The Spring Garden Member of the Montpelier Formation and the Buff Bay Formation (middle to upper Miocene) were deposited at lower bathyal paleodepths (1,000 to 2,000 m) that probably exceeded 1,300 m, while the overlying Bowden Formation (Pliocene) was deposited within the upper bathal zone (200 to 500 m). A significant portion of the benthic foraminifera found in Buff Bay sections consists of transported shallow-water reefal elements (.Amphistegina spp./Asterigerina spp.) occurring in otherwise in situ deep-water bathyal biofacies. The lower part of the Spring Garden Member (middle Miocene) contains a typical cosmopolitan lower bathyal biofacies dominated by Globocassidulina subglobosa, Cibicidoides mundulus, Stilostomella aculeata, and Oridorsalis spp. A biofacies change that occurs within the Spring Garden Member may reflect the well-documented global benthic foraminiferal taxonomic turnover that occurred throughout the deep sea from early to middle Miocene Biochrons N8 to Nil. The upper Spring Garden Member and portions of the Buff Bay Formation (middle Miocene) faunas are characterized by the apparently endemic species Compressigerina coartata and Siphouvigerina porrecta; we interpret this as an in situ lower bathyal biofacies. Much of the Buff Bay Formation (middle-upper Miocene) is dominated by Reusella spinulosa var. pulchra, Uvigerina proboscidea, Rosalina sp. 1, and Siphouvigerina porrecta', although this assemblage may be an in situ lower bathyal biofacies, there is evidence to suggest that it may be a transported thanatofacies. The Bowden Formation (Pliocene) is characterized by an upper bathyal (200 to 600 m) biofacies dominated by Butimina aculeata, Globobulimima spp., Planulina foveolata (lower depth limit is 500 m), and Uvigerina sp. 1. The change in benthic foraminiferal biofacies between the Buff Bay and Bowden Formations reflects the tectonic uplift of the north coast of Jamaica. We estimate that at least 800 m of shallowing occurred between the late Miocene (ca. 8 Ma) and Pliocene (ca. 4 to 3 Ma) during the hiatus that separated deposition of the Buff Bay and Bowden Formations. A subsequent shallowing occurred from the Pliocene (bathyal paleodepths >200 m) to the Pleistocene (neritic depths <60 m; Robinson, 1969).

Ecostratigaphic Regime Shift During Late Quaternary Marine Isotope Stages 8-9 in Santaren Channel, Western Tropical Atlantic Ocean: Benthonic Foraminiferal Evidence From Odp Hole 1006a

“…An attempt to pick benthonic foraminifera from the entire .63 mm fraction yielded many juvenile miliolids that could not be readily assigned to species; so picking was restricted to the .105-mm fraction (cf. Katz, 2000, who examined the .150-mm fraction). This fraction was split to give an aliquot of ,300-400 specimens/sample.…”

“…Species were identified using Cushman (1921Cushman ( , 1922aCushman ( , b, 1923Cushman ( , 1929Cushman ( , 1930Cushman ( , 1931Cushman ( , 1944, Phleger and Parker (1951), Phleger and others (1953), Barker (1960), Schnitker (1971), Todd and Low (1971), Brooks (1973), Buzas and others (1977), Rose and Lidz (1977), Poag (1981), Poag and Tresslar (1981), van Morkhoven and others (1986), Bornmalm (1997), and Mohan and others (2011). These publications, along with Bermudez (1952), Bandy (1964), Hofker (1956Hofker ( , 1964Hofker ( , 1976Hofker ( , 1980, Katz (2000), Wilson and Ramsook (2007), Walker and others (2011), Wilson and Wilson (2011), and Wilson and others (2012), were used to assign species to presumed bathyal and shallow-water (especially reefal) habitats. Some of the species recovered (Brizalina goessi, Bulimina alazanensis, Gyroidinoides altiformis, Planulina ariminensis, Pullenia bulloides, Sigmoilopsis schlumbergeri) are capable of living not only at the middle bathyal ODP Site 1006, but at neritic or abyssal depths also (Parker, 1954).…”

“…from the dataset to identify patterns in what she considered to be an in situ benthonic foraminiferal fauna. From this she concluded that in situ pelagic sedimentation at Site 1006 was punctuated by periods of increased downslope transport of shallow-water material (a phenomenon also noted in the Miocene of Jamaica by Katz and Miller, 1993). Katz (2000) used changes in the in situ benthonic foraminiferal fauna to assess changes in paleocirculation.…”

“…From this she concluded that in situ pelagic sedimentation at Site 1006 was punctuated by periods of increased downslope transport of shallow-water material (a phenomenon also noted in the Miocene of Jamaica by Katz and Miller, 1993). Katz (2000) used changes in the in situ benthonic foraminiferal fauna to assess changes in paleocirculation. She concluded that these changes were unrelated to sequence stratigraphy and may instead have resulted from changing circulation patterns only indirectly related to sea-level fluctuations.…”

“…Wilson (2012b) concluded that the points of change in Kp across MIS 9 and 8 mark species-level regime shifts and suggested they have potential for ecostratigraphic correlation. Katz (2000) examined the Miocene benthonic foraminifera in this same ODP Hole. Based on multivariate analyses and documented depth distributions, she deleted transported, shallow-water taxa [Amphistegina/Asterigerina spp., Baculogypsinoides sp., Elphidium spp., Planorbulina spp., Reusella spinulosa (Reuss), and Tretomphalus spp.]…”