Shore Normal Distribution of Heavy Minerals on Ocean Beaches: Southeast Atlantic Coast

Abstract

Source: https://erdc-library.erdc.dren.mil/jspui/Cross-shore beach sample sets from 102 locations along the barrier-dominated Atlantic coast from Kitty Hawk, North Carolina, to Palm Beach, Florida, were studied to determine if there were systematic differences in heavy mineral abundance and species frequency distribution between sampling stations on each transect line and between barrier and mainland segments. Only the more commonly occurring heavy minerals species were counted, including rutile, garnet, staurolite, epidote, amphibole, and tourmaline. On each transect, samples were taken at the step, the existing limit of uprush, berm crest, midberm, and inland limit of the beach. The weight percent of the heavy mineral fraction was found to be consistently and substantially higher in backshore and berm crest samples than in the foreshore samples from the same transect. A comparison of the frequency distribution of heavy mineral species showed that mineral species having the higher specific gravity, i. e., rutile, garnet, and staurolite, are much more abundant in backshore samples than in foreshore samples from the same transect and that the amount of difference generally increases with increasing specific gravity. Amphiboles occurred in much greater abundance in foreshore samples, while epidote and tourmaline show less pronounced and consistent differences between backshore and foreshore samples