Page 11 - Maldonado_Stanley_1976

8 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES

made with satellite and radar navigation. Seven T ABLE 2.-Position and water depth of camera stations in the
Strait of Sicily
Ewing piston cores were retrieved along a transect
between the Ionian and Balearic basins crossing CRUISE CAMERA STATION LATITUDE LON:;ITUDE WATER DEPTH
(in m)
different environments of the Strait. Continuous
(3.5 kHz) echo-sounding and sparker (30,000 Verna 14 J<-53 36°29'N 13°23 'E 1588
Joules) records were obtained along the ship track Atlantis 151 56 36°25'N 1P43'E 119
(Figure 3). These subbottom profiles have been 58 37°12 'N 11°34 'E 567
reduced photographically to the same horizontal 59 37°18'N 11°33'E 88
scale (Figures 5-15). 60 37°18'N 11°07'E 106
Additional core data have been obtained from 61 38°22 'N 1P23'E 381
the following organizations (Figure l, Table l): 62 38°14 'N 11°31'E 134
United States Naval Marine Geophysical Survey
Program 1965-1967, Area 6, cores AS 6-7 and AS
to 45 cm of core section) were sieved and the frac-
6-8 (U.S. Naval Oceanographic Office, 1967); Uni-
tion coarser than 63 microns extracted for radio-
versity of Miami cores P 6510-G33 and P 6510-
carbon dating. Carbon-14 age determinations also
G34; Groupe des Géologues Marins Mediterra-
have been made on bulk samples of about 15
néens, Campagne "Gesite"-1973, cores KS 12, KS
cm-long sections of cores. Our tests have shown
23, KS 33, KS 53, KS 63, KS 69, KS 76, KS 78, KS
that dates obtained with the total (or bulk) core
100, KS 104, KS 105, KS 109, KS IlO, KS ll8, KS
samples provide comparable dates to those ob-
120 and KS 125; Lamont-Doherty Geologica! Ob-
tained with the coarse fraction. We favor dating
servatory, cores Verna 14~ 138, 139, and 140, and
with bulk samples inasmuch as it allows us to use
San Pablo 8j 7; Woods Hole Oceanographic Insti-
much less core for dating. A total of 40 samples
tution, core C hai n 61 ~ 19. A t o tal of 32 cores ha ve
were age-dated (R. Stuckenrath, Smithsonian Ra-
been analyzed by us for this study (Figure I). A
diocarbon Laboratory, pers. comm.).
set of deep-sea camera station photographs (Fig-
In calculating sediment thicknesses on subbut-
ure I) was provided by the Lamont-Doherty Geo-
tom profiles we have assumed an average velocity
logica! Observatory (station Verna 14~ K 53) and
of 1800 m per second (Finetti and Morelli, 1972a,
six camera stations from Woods Hole Oceano-
b); the scales in the fìgures are given in two-way
graphic Institution (stations Atlantis 151~ 56, 58,
travel time.
59, 60, 61, an d 62). The camera station positions
are listed in Table 2.
The Gesite cores were X-radiographed before
Defìning the Major Strait Environments
splitting, while Lynch and Pillsbury cores were
radiographed (half cores) after splitting and be-
GENERAL
fore sampling. Detailed core logs record texture,
sedimentary and biogenic structures, color, and In this study "Strait of Sicily" is the generai geo-
other characteristics observed visually and on X- graphic term applicable to the entire region be-
radiographs. Gross texture and composition of the tween Tunisia and Sicily. The term "Strait Nar-
sand and lutite fraction of over 200 selected sam- rows" is applied to the narrowest passage (about
ples have been processed for mineralogica! analy- 160 km in width) between Cape Bon (Tunisia)
sis. The relative percentages of 14 compositional and Punta Stagnone or Marsala (southwest coast
components of the sand fraction in 48 of these of Sicily). The Strait trends in a northeast-
samples have been calculated. The lutite fraction southwest direction and is approximately 450 to
(silt plus day) was examined by means of the 700 km in length. It is broadest (over 500 km)
Scanning Electron Microscope; samples prepared along a north-south transect between southeast
for SEM analysis were soaked in 30% hydrogen Sicily and Libya. Recent charts (Carter et al.,
peroxide for at least 24 hours to destroy organic 1972; Finetti and Morelli, 1972a) of the centrai
matter. The core thickness sampled ranged from 4 Mediterranean show that the total area exceeds
2
to 12 mm. 175,000 km , and that over one-third of this sur-
Large samples of mud (comprising between 15 face (approximately 80,000 km2) is shallower than