The Heavy Mineral Population Within the Beach Sand Facies of the Meridian Sand Exposed in Mississippi

Abstract

ABSTRACT The Meridian Sand outcrop exposed across Neshoba, Newton, Lauderdale and Clarke counties, Mississippi, contains sedimentary characteristics which indicate deposition within a mainland or barrier beach setting. Based on the standard deviation of sample means and the sample coefficient of samples from 17 localities, the Meridian Sand can be considered a moderate to well sorted, medium- to fine-grained quartz sand. Sedimentary structures such as bidirectional cross stratification, tabular cross stratification alternating with plane beds, and a dominant Skolithos ichnofacies suggest shoreface to foreshore deposition. The heavy mineral population of the Meridian Sand in this area of Mississippi is 1.43% of the total sand population and occurs within the Wentworth interval of 0.5 mm to 0.125 mm. Opaque minerals, mainly ilmenite and leucoxene, comprise 43.5% of the total heavy mineral population. The dominant nonopaque minerals are staurolite and kyanite, which comprise 22% and 13% of the heavy mineral population respectively. Other nonopaque species include zircon (8.9%), rutile (4.0%), tourmaline (3.6%), sillimanite (0.8%), hornblende (0.4%), and anatase (0.35%). Nonopaque species, found only in trace amounts (<0.1%), include garnet, spinel, andalusite, monazite, fluorite, chloritoid, and mica. The heavy mineral content of the Meridian Sand is mainly concentrated in what appears, from field observation, to be foreshore and upper to middle shoreface placer deposits. High concentrations, up to 5%, occur as localized accumulations in what might be considered back beach or even washover deposits. Variation does occur in the quantity of individual heavy mineral species throughout the exposed Meridian Sand. There is no indication, however, of stratigraphic or lateral variation of the total heavy mineral population.