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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 63 (1979)

Issue: 9. (September)

First Page: 1604

Last Page: 1604

Title: Chemical Differentiation of Temperate and Tropical Limestone-Derived Soils: ABSTRACT

Author(s): W. C. Isphording

Article Type: Meeting abstract


Chemical analyses of soils formed by the weathering of limestone bedrock in the U.S. Gulf Coast, Missouri, Tennessee, Mexico, and Guatemala were used to determine whether any significant differences were present that would allow identification of soils of rocks weathered under tropical as contrasted with temperate climatic conditions. Over 100 samples were analyzed for their major oxides (SiO2, Al2O3, Fe2O3, CaO, MgO, K2O, Na2O, and TiO2) and, for selected samples, certain trace elements were determined as well (Ba, Zn, Sc, La, Ce, Eu, Lu, Rb, Hf, Cr, and Co). X-ray diffraction analyses were also carried out on representative samples for each climatic zone.

Cluster analysis was then applied to the chemical and mineralogic data to determine the number of distinct limestone soils that could be identified and to compare soils from the two major climatic regions. Discriminant analysis was then used to test whether the tropical soils were, truly, different from their temperate-zone counterparts.

Variation in trace-element chemistry was not found to be particularly useful in differentiating samples from the two climatic zones but was useful in establishing depositional patterns within a given region. Variations in the major oxide chemistry were useful, however, as climatic-zone indicators and were also found to reflect tectonic conditions in the adjacent land areas at the time the carbonates were being deposited offshore and diagenetic changes that have occurred since deposition.

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