ABSTRACT

This article shows the results of a detailed mineralogical investigation of the Recent bottom sediment of the Arabian Gulf bordering Kuwait. The main objective of this study is to determine the sediment sources of the study area and to define their relative importance. Heavy and light minerals in the very fine sand and coarse silt fractions were estimated microscopically. These size fractions were selected for heavy mineral analysis because they represent a large proportion of the total sediment budget and their results will be readily comparable with the published results of the potential sources (wind-bore and river-bore sediments). X-ray diffraction was utilized to determine the mineralogical composition of the "whole sediment" and the mineral constituents of the clay-size fraction

The light minerals are chiefly composed of carbonates, quartz, and feldspars with lesser quantities of chert, gypsum, and mica. Dolomite was found to be the most common heavy mineral followed by amphiboles, pyroxenes, mica, opaques, and epidotes. Aragonite, garnet, zircon, and tourmaline were recorded in lesser quantities.

The gross mineralogy is biased toward carbonates, clay minerals, and a small amount of quartz and feldspars. Carbonates are represented by low-Mg calcite, dolomite, high-Mg calcite, and aragonite. Low-Mg calcite and dolomite were found to be the most common carbonate species. They are thought to be of detrital origin carried into the study area primarily as dust fallout. Clay minerals are composed of illite, palygorskite, an illite-montmorillonite mixed layer, kaolinite, and chlorite. Illite and palygorskite are the most important clay minerals, forming more than 70% of the clay-size fraction. It is suggested the palygorskite is most probably developed as a diagenetic mineral in the lower Mesopotamian plain and transported to the study area by eolian processes. Other clay minerals are thought to be of detrital origin derived from many sources.

The results show that the dust storms which originate in southern Iraq and Kuwait by the prevailing northwestern wind are a major contributor to the total sediment budget, particularly with respect to dolomite, palygorskite, and low-Mg calcite. Other sources which have impact upon the study area are local coastal sediment, direct precipitation from Gulf water, Shatt-al-'Arab river sediments, and the submerged ancient sediment off Kuwait.