Heav) minerals are present in trace quantities in type A sands. No studies of the heav}^ 

 mineral fraction were conducted as part of this investigation. Previous analyses of the 

 Florida shelf in heavy mineral assemblage are contained in Tyler (1934), Pilkey (1963), 

 Gorsline (1963), Pilkey and Field (1972), and Milliman, Pilkey, and Ross (1972). 



The calcareous fraction of type A sand comprises less tlian 15 percent of the sand and is 

 composed principally of mollusk fragments, with lesser amounts of echinoid fragments, 

 barnacles, bryozoa, worm tubes and benthic foraminifera. Calcareous ooids, characteristic 

 grain-types off Cape Canaveral, are absent from cores collected in this study, although they 

 have been reported in deeper deposits seaward of the survey area by Terlecky (1967). Other 

 calcareous grains reported farther to tlie south by Meisburger and Duane (1971) and Field 

 and Duane (1974), wliich are absent or occur only in small quantities in the survey area, are 

 barnacles, calcarenite lithoclasts and algal clasts. 



It is principally tlie difference in total carbonate content and in composition of the 

 carbonate fraction that distinguisiies type A surficial shelf sands of the north Florida region 

 from those adjacent and south of Cape Canaveral. 



The moUusk assemblage in type A sands is quite diverse and includes forms judged to 

 have been reworked from the substrata or introduced as a detrital element as well as forms 

 presently inhabiting the area. 



The most important mollusks in type A sediment are species of Aequipecten, Anadara, 

 Anomia, Lucina, Mulinia, and Ostrea, all pelecypods. Gastropods are scarce in this sediment 

 type as they are in general througliout the study area. 



Foraminiferal fauna in type A sediment ranges from sparse to abundant. The assemblage 

 is dominated by species of Quinqueloculina and Elphidium with Hanzawaia spp. of equal 

 importance south of Marineland (20°40'N.). The assemblage is diverse in some places witli 

 30 or more species represented in a count of 300 specimens, and comparatively restricted in 

 other places. 



(2) Type F Sediments. Type F sediment is a very fine to fine, poorly sorted silty 

 quartz sand (Fig. 23) characterized in particular by its distinctive faunal assemblage and 

 close relationship to siielf morpholog). Tliis saYid is tlie cliaracteristic sediment of the 

 shoreface and contiguous innermost ramp along the length of the survey area from Cape 

 Canaveral to Georgia. About 70 percent of cores containing t} pe F sediment are within 4 

 nautical miles of shore; only 10 percent of cores within 4 nautical miles does not contain 

 this sediment. 



Accessory detrital minerals comprise several percent of the sediment, and biogenic 

 carbonates account for about 20 percent of the sediment. Quartz grains are polished, clear 

 and subrounded to angular. Accessory minerals include phosphorite, feldspar, mica, and 

 heavy minerals. Mineralogic properties of type F sand are similar to those of type A with 

 the exception of high mica content in some samples. Phosphorite grains are also locally 

 abundant. 



48 



