Heavy-Mineral Distribution Along Coastline of Ghana, West Africa: ABSTRACT

Abstract

As part of a natural resource appraisal of beach and shelf sediments of Ghana, the mineralogy and texture of beach sands along the Ghana coastline was studied. Precambrian (Dahomeyan) rocks rich in heavy minerals are widely distributed throughout Ghana, providing varied mineral suites along the coast. Most of the beach sediments studied were moderately well-sorted medium sands. Opaque and micaceous minerals constitute between 19 and 17% of the total heavy mineral suite, which on average comprises 46% of the sand. Five mineral provinces, based on relative frequency of the most abundant nonopaque and nonmicaceous heavy minerals, are recognized. (1) Tano province (between Half Assini and Esiama) is characterized by high staurolite (26%) and the least amounts of garnet (0.3% s. an average of 8.3%) + amphibole (4.6%) + kyanite (1.6%) + epidote (1.8%) + pyroxene (1.3%). (2) Ankobra province (between Axim and Shama) is characterized by increased amphibole (15%) + staurolite (11%) + kyanite (2.7%) + epidote (2.6%). The marked increase in amphibole may be attributed to local outcrops of hornblende-rich Dixcove Granite. (3) Pra province (between the Pra and Densu Rivers) is characterized by increased staurolite (24%) + amphibole (11.3%) + kyanite (4.8%) + garnet (3.7%) + tourmaline (1.5%) + relatively high local occurrences of zircon. The Cape Coast Granite complex exerts a significant influence in this area. (4) Densu province (between the Densu River and Ada) is characterized by staurolite (26.8%) + garnet (16%) + amphibole (15.2%) + kyanite (3.5%) + epidote (3. %), whose sources are the acidic division of Lahomeyan epidote-bearing hornblende schist and kyanite-bearing marble exposed near Accra. (5) Volta province (between Anyanui and Aflao) is characterized by garnet (17.5%) + staurolite (11.7%) + amphibole (9%) + kyanite (5%) + epidote (4.5) + pyroxene (3.8%). Except for rutile and zircon, heavy mineral content of the area appears to be independent of sedimentary texture. However, the distribution patterns of the heavy minerals reflect the dynamic conditions of the littoral drift in the dispersal of sediments along the coastline of Ghana. End_of_Article - Last_Page 311------------