ABSTRACT

The three main sources of sediment in the Straits of Florida are, (i) the Florida Current contributing a low-magnesian calcitic biogenic ooze; (ii) the Bahama Banks, where the highly aragonitic sediments arise; and (iii) the "relict" sediments which are the source for the detrital silicates and phosphates. A possible fourth source is the Miami Terrace Reef which has a relatively large high-magnesian calcite content. Off-shore currents carry the detritals southward along the coast of Florida until they are blocked by the Florida Current. Aragonitic sediments move westerly from the Bahama Banks, but to the west the Florida Current strongly curtails their cross channel movement. The mineral suite of the Straits of Florida sediments is composed principally of biogenic carbonates except to file northwest where quartz comprises more than half of the sediment, and reflects the strong faunal control of sediment mineralogy.

Trace elements found in the carbonate fraction of the sediments of the Straits of Florida are divided into three groups. The first group, strontium and chromium, has a positive correlation with aragonite and similar quadratic trend surfaces east of the axis of the Florida Current. West of the axis chromium behaves differently than does strontium and correlates with the insolubles to the northwest. Statistical evidence indicates that strontium is not significantly enriched in the carbonate sediments after deposition. Manganese and cobalt, the second group, vary directly with each other and statistical analysis shows that they are present in the same phase. From the trend surfaces and linear statistical treatment of manganese and cobalt with respect to the carbonate minerals and insolub es, these two elements occur in low magnesium calcite. Therefore, the Florida Current is a principal source for the distribution of manganese and cobalt in the Straits of Florida. The third group of elements, iron, zinc and chromium, are correlated with the "relict" sediments to the northwest where their most probable source is the carbonate-fluorapatite.