Page 1 - TonarelliTurgutcan1992

SHALLOW SEDIMENT COMPOSITION AT FOUR LOCALITIES
ON THE SICILIAN-TUNISIAN PLATFORM

B. TONARELLI , Ferda TURGUTCAN, Michael D. MAX. Tuncay AKA L , SACLANT Undersea
Research Centre, 1-19138 La Spezia, ltafy

Abstract
Analyses from 44 grab samples and 21 core samples illustrate the strong resemblance between
the physically separated recent sediment carbonate platform of the Adventure Bank and the Lampedusa
shelf and their contrast to recent sediment in the west-central Malta Channel and the deep seafloor
southwest of Pantelleria lsland. Carbonate sediments, which are formed from active shelly and alga! debris
sources, are confined to water depths shallower !han about 75 metres. In deeper water, at least on the
centrai Malta Plateau, pelagìc, hemìpelagic and terrìgenous materia! probably of aeolean derivation,
dominate sediment clastic constituents.

lntroduction Sample Analyses

Modern sediments on the Platform are Samples were returned to SACLANTCEN

strongly influenced by the local production of for in-house analysis immediately following each

calcareous alga! and shelly materia! in shallower cruise. Cores (Tables) were carefu lly handled. to

water. These materials often find their way into minimize disruption of sediment character, and

deeper waters because of current activity and except far initial extraction of the core and liner

sediment mass movements, where they can have from the barre!, cores were maintained in a vertical

a strong impact upon overall sedime nt posìtion unti! after acoustic velocity analysis. Ali

composition. Volcanics are most common around grab samples were bagged with sea water,

volcanic sites and terrigenous detritus has been allowing some analyses lo be carried out on
generated from both the African and Sicilian land naturally wet specimens. Al least 2-15 cm of free

masses. Pelagic and hemipelagic debris water over the top of each core was sealed in

constitute the main part of the sediments where trimmed core liners to maintain moisture and in-situ

they have a more characteristically marine aspect. salinity. A bulk samples of about 80g was taken

Since the early 1970's SACLANT from each grab sample. In cores, samples were

Undersea Aesearch Center has cond ucted taken al the surface and at about every 10 cm

research into the physical properties of the water downward in the core.

mass and seafloor in the Sicilian-Tunisian Platform. Analytical elements fall into two generai

Three ma in areas of the sea bottorn on the Sicilian- groupings; those which directly reflect sea floor
Tunisian Platform have been core and grab character and those that may not be exactly the

sampled (Fig. 1). This compilation includes ali same as the sea floo r properties. Grain size

specimens and analyses from the area . (Shepard, 1954 ; Folk, 1974), color, chemieal

SACLANTCEN sedimentological and oth er composition of particles, and stratigraphy are likely

geologica! and geophysical research is continuing to be the same on the sea floor and in undisrupted

in the area of the Sicilian-Tunisian Platform. cores and grab samples that have not suffered

particle loss upon

cl L recovery . Cores are

generally more reliable

1 37o than grab samples
because the core is not

exposed to sea water

flushing during recovery

and fine grained fraction

will not be lost. Other

physical properties such as

36o porosity, water content,
wet and dry density, and

void ratio may vary. When

the specimen is removed

from th e sea floor

conditions, dissolved gas

can usually decompress,

causing fluid movement

and small-scale changes in

11° 12° 13° 14° 15° sediment micro-fabric. lt is
likely that changes of

Figure 1. Location map and detailed areas of study. A, Adventure Sani<; 8, porosity wi ll also affect

Lampedusa Sani<; C, Centrai Malta Plateau . measurements of water

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