Page 5 - TonarelliTurgutcan1992

The bases of the silt horizons often show Tyrrhenian margin of Sicily and the Sardinian
small-scale irregularities produced by compaction.
These have a relief no greater than 0.7 cm and cha nnel.
show no directional or slope component. They The sediments of the west-central Matta

appear to have been produced by in-situ Plateau have a more pelagic character, remarkably
similar to that of the deep water Pantelleria basin.
compaction rather than by bed traction. Thus we There is only a hint of local shelly sediments along
find no direct evidence of sediment mass
movements along the seabed causing erosive or the eastern, more shallow and rocky ridge of the
traction features. lt is possible that because of the eastern Malta Plateau that forms a bathymetric
high salinity of the Mediterranean bottom water, high between southern Sicily and Malta (Max et al.,
that sediment slumps derived from the basin this vo l.), but the African carbonate shelf
marg ins form sediment sheets for substantial environment does not seem to be fully developed
d istances within the water column, before settling
out. Th e presence of common non-directional on the Malta Plateau, even where water depths
convolution within the more fine-grained fraction
indicates that these sediments had a very surface- are shallow.
layer high porosity al th eir initial deposition, and Sediments of the centrai Pantelleria Basin
have largely compacted without substantial lateral
movement. appear to be typical ot deep water sediments in

Conclusions the incised basins of the Sicilian-Tunisian Platform
The shallow water Adventure and (Colantoni et al., this vol.). They are characterized
Lampedusa Banks occupy the same sedimentary
province, even though they are separated by the by fine-gra ined sediments of a pelagic detrital
deeper water channel of the Strait of Sicily. The character, and have been largely redeposited in
Adventure Bank thus comprises the northernmost the basins owing to local slump activity along basin
part of the true African carbonate shelf margin margins. Even though they are very dose to
(IBCM, 1987, 1990). The shelf immediately to the
north of the Adventure Bank between the Egadi active sediment provinces, only a very small
ls!an.d.s. and western Sicily has more rocky texture fraction of their total sediment budget has been
(Colantoni et al., this vol.) and a different range of derived from shallow water sources.
sediments, that form a transitional depositional
zone with the less calca reous sediments of the Thus, fine-grained carbonate detritus
either entering the water by a eolean means or
settling from dead carbonate-skeletal micro-
organisms ...:ithin the water mass, appear to

contribute to about the same proportion of clay·

size particles irrespective of water depth. In the

much more deep basins, where ca rbonate
solubility is higher than anywhere on the Sicilian-
Tunisian Plat!orm, this relationship may not hold.

Area Type n GRAVEL SANO SILT CL/,Y ..MEAN phi CaC03
A grab 18 ·;. .sQ •;. .sQ ~ SQ
~ so 12.5 17.3 SQ..!.!}. .% ~
76.3 20.0 5.6 4.3
5.6 7.6 2 .81 1.86 97.0 0.9

131 3 24 .5 2 .4 49.4 0,3 5.9 2 .8 20.2 0.4 2.71 0.21 87.2 2.6 .

132 7 12 .0 7.3 78.2 18.7 l .5 1.3 8.3 10.7 2.00 0.88 93 .3 3.8

247 2 1 10.2 9.4 67.0 17.8 11 .6 7.6 11.2 60 2 .27 1.33 90.8 3 .4

248 20 8.3 6.0 74.1 16.0 8.0 5.6 9.6 5.5 2.08 0.90 92.9 4.0 .

249 18 9 .4 9.9 73.6 22.8 9.8 8 .6 7.2 6 .2 2.04 0.88 92.6 3 .1 .

250 7 55.1 29.7 31.9 20.6 9.3 8.2 3 .7 1.7 1.25 2.53 93.2 1.3 t

251 16 12.9 7.6 70.4 15.2 6.9 4.3 9.8 5 .7 l .73 1.00 91.2 4.0 :
o
PB grab l 3 .2 l 5.0 81.8 1.00

139 14 o 7.5 9.4 19.5 7 .4 72.9 16.0 9.31 1.21 35.6 5.4 :

B grab 24 4.9 6.2 88.4 9.7 3.4 3.5 3.4 3 .7 1.86 0.57 96.2 1.9 :

133 5 7.6 2.8 82.6 4.7 4.9 1.4 4.9 2.1 1.96 0.21 91.3 2.4 ;

134 6 8.4 6.1 76.8 6 .5 5.4 1.9 9.4 3.1 2.38 0.39 91.8 1.§_ j

141 25 2.9 2.0 73.1 14.1 11.1 5.6 13.0 9.9 3.15 1.14 86.9 7.2 ;
252 ·-. •-j
253
12 12.8 19.3 77.4 18.0 4.5 1.4 5.4 1.5 1.05 1.02 96.0 0.8 :
c 254 ... ·1· ·.·_~~
23 6.9 6.4 61.2 8 .8 15.0 4.7 16.9 5.3 3 .45 1.04
255 90._4 .
256
257 17 3. l 6.5 28.0 4.2 58.7 12.8 10.2 7.3 4. 54 0 .90 34:9 :. 5 :~.j
258
25 1.4 2.5 30.5 19.9 ' 48. l 12.2 18 .3 14.2 5.84 1.29 . 38.6 . ?4·..0~-·lir
20 0.6 2.0 68.7 ; 18.9 • 21.3 7.3 9.9 11.7 4.64 1.10 30.1
.

12 12.0 5.7 28.8 · 10:5 · 26.9 4.9 32.4 8, 1 5.31 0.96 ~~·?. . ~...~.j
31 1. 2 3.4 9.6 : .12.4 44.9 10.9 44.3 10.7 7.94 1.18 29.6 . 5 .9

Table 7. Generalized grain size analyses for grab and core (numbered) samples. n: number of samples. A,
Adven!ure Bank; B. Lampedusa Bank; C, Malta Plateau; PB, Pantelleria.

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