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Analyses of Common Elements and Oxides in the Paleosols of the Bahamas and of the Northern Mariana Islands

Domenii publicaţii > Ştiinţele pământului şi planetare + Tipuri publicaţii > Tezã de masterat (nepublicatã)

Autori: Ersek, V.

Editorial: Mississippi State University, 2004.

Rezumat:

Paleosols from the Bahamas and the Northern Mariana Islands (CNMI) are
closely related to past atmospheric circulation and dust load. In the Bahamas the sources of insoluble residue (IR) must be allogenic because the islands consist of almost pure carbonates. The Al2O3:TiO2 ratio was used to establish the provenance of the IR of the paleosols. Comparisons of this ratio from Bahamian paleosols, North African dust,Lesser Antilles ash and North American loess reveal that the African dust is the major contributor to the IR, with a potential minor volcanic input from the Lesser Antilles. The contribution of the North American loess to the IR was not determined because of geochemical similarities with the North African dust. The study of two outcrops in
Eleuthera indicate that paleosols can act as aquicludes. The Bahamian samples were collected on a roughly north-south transect in order to establish the climatic influence on paleosol properties. Even though there is a marked climatic gradient in the Bahamas, the paleosol geochemistry shows no trend that could be related to paleoclimate. While previous studies indicated that the source of insoluble
residues in the soils of CNMI is carbonate dissolution, the present study shows that atmospheric deposition of ash from the Mariana arc and dust from the Asian continent may play a significant role in paleosol formation.

Cuvinte cheie: paleosoluri, carbonati, Bahamas, Insulele Mariane, geologie, paleoclima // paleosols, carbonates, Bahamas, Northern Mariana Islands, geology, paleoclimate

URL: http://www.geo.oregonstate.edu/~ersekv/Ersek_Thesis.pdf