Geochemical Evidence of Saharan Dust Parent Material for Soils Developed on Quaternary Limestones of Caribbean and Western Atlantic Islands

Abstract

Most previous workers have regarded the insoluble residues of high-purity Quaternary limestones (coral reefs and oolites) as the most important parent material for well-developed, clay-rich soils on Caribbean and western Atlantic islands, but this genetic mechanism requires unreasonable amounts of limestone solution in Quaternary time. Other possible parent materials from external sources are volcanic ash from the Lesser Antilles island arc and Saharan dust carried across the Atlantic Ocean on the northeast trade winds. Soils on Quaternary coral terraces and carbonate eolianites on Barbados, Jamaica, the Florida Keys (United States), and New Providence Island (Bahamas) were studied to determine which, if either, external source was important. Caribbean volcanic ashes and Saharan dust can be clearly distinguished using ratios of relatively immobile elements (Al2O3/TiO2, Ti/Y, Ti/Zr, and Ti/Th). Comparison of these ratios in 25 soils, where estimated ages range from 125,000 to about 870,000 yr, shows that Saharan dust is the most important parent material for soils on all islands. These results indicate that the northeast trade winds have been an important component of the regional climatology for much of the Quaterary. Saharan dust may also be an important parent material for Caribbean island bauxites of much greater age.

Geochemical evidence for African dust and volcanic ash inputs to terra rossa soils on carbonate reef terraces, northern Jamaica, West Indies

“…Pye (1988) suggests, on the basis of work in Australia by Brimhall et al (1988), that African dust could be the source of aluminum enrichment in Jamaican bauxites. Muhs et al (1990) report the same possibility for younger soils on Jamaican limestones, which we reexamine in the present paper.…”

Aeolian dust in Colorado Plateau soils: Nutrient inputs and recent change in source

“…MS and Zr are correlated at all depths combined (R 2 ϭ 0.62; P Ͻ 0.05). Zr and Ti usually vary together in sediments, because they are chemically immobile proxies for detrital-heavy minerals (32,33). We observed a difference in the relative abundance of Zr and Ti when the BSC was compared with underlying sediment (Fig.…”

Biogeochemical effects of iron availability on primary producers in a shallow marine carbonate environment

“…), possibly derived from transport through the Everglades. The more patchy distribution of iron in sediments from the southwest Florida shelf may be indicative of a nonuniform source of iron or sediment redistribution by water currents, eolian transport, or other physical process (e.g., Muhs et al 1990;Duce and Tindale 1991).…”