Pleistocene facies of Belize barrier and atoll reefs

Abstract

The knowledge of Pleistocene reef facies of Belize, Central America, is largely limited to outcrops in the northernmost part of the country. Otherwise, Pleistocene limestone, which forms the basement of the modern barrier and atoll reefs, occurs in the subsurface and is to a major extent unstudied. Based on the study of 40 m of core from 25 rotary core holes collected on central and southern Belize barrier and on atoll reefs, five Pleistocene reef facies are distinguished in the present study. They include (1) Acropora palmata grainstone, (2) Acropora cervicornis grainstone, (3) biogenic grainstone, (4) mollusk packstone, and (5) mollusk-foram wackestone. Facies 1 and 3 occur on marginal reefs, facies 2 is found on marginal and lagoonal reefs, and facies 4 and 5 mark lagoon shoals and lagoons, respectively. Most of the facies have equivalents in the Pleistocene of the wider Caribbean and also in the modern of the study area. Diagenetic features include dissolution, caliche formation, laminated blocky low-magnesium-calcite and dogtooth spars. Age data from Pleistocene corals obtained during earlier studies are discussed, and indicate deposition during marine isotope stage 5, between 140-80 ka bp.

Sedimentology, palaeoenvironments and biostratigraphy of the Pliocene–Pleistocene carbonate platform of Grande‐Terre (Guadeloupe, Lesser Antilles forearc)

“…Buildups are dominated by dome‐shaped colonies of Montastraea , associated with Diploria , Porites and rare Acropora colonies. This association suggests a water depth of 5 to 25 m in fore‐reef position (Gischler, 2007). Bioclastic deposits are composed of grainstones with larger benthonic foraminifera.…”

Mixed carbonates and siliciclastics in the Quaternary of southern Belize: Pleistocene turning points in reef development controlled by sea-level change

“…Pleistocene reef and shelf facies recovered during this project (Table 4) with abundant coral packstone and grainstone, mollusc‐rich wackestone, marls and clays have both fossil and modern counterparts in the study area (Tebbutt, 1975; Macintyre & Toscano, 2004; Mazzullo, 2006; Gischler, 2007).…”

“…because of die‐out by white band disease (Aronson & Precht, 1997). In addition, A. cervicornis is quite abundant in latest Pleistocene (MIS 5) sections of the barrier reef and the offshore atolls (Tebbutt, 1975; Gischler, 2007). On the other hand, the species is known to appear and disappear over short time intervals on Holocene Caribbean reefs (Davis, 1982; Shinn et al.…”

“…On the central and southern Belize Barrier Reef and on the offshore atolls, the upper few metres of Pleistocene limestone were recovered in shallow coreholes (Purdy, 1974a,b; Gischler & Hudson, 1998, 2004). Gischler (2007) distinguished five facies including: marginal (i) A. palmata ; (ii) A. cervicornis ; and (iii) biogenic grainstone facies. In atoll lagoons: (iv) mollusc packstone; and (v) mollusc–foraminifera wackestone facies are found below Holocene sediment.…”

Reef development at high-latitudes during multiple interglacial cycles: New evidence from Lord Howe Island, southwestern Pacific

“…Application of an open-system correction (Thompson and Goldstein 2005) on this sample yields an open-system 230Th age of~120 ka. Unlike Last Interglacial corals from marine isotope stages 5 and 7 in the Bahamas (Kindler et al 2006), Belize (Gischler 2006) and New Caledonia (Frank et al 2006) where enough UI Th is present to calculate open-series ages, this correction cannot be applied to the other two corals from the core which have suffered serious U-leaching. The occurrence of serious U-leaching in these samples (as compared to LH-II-350C) suggests that these stratigraphically lower corals may have undergone several cycles of both marine and subaerial diagenesis, with conversion of aragonite to calcite.…”