Page 19 - Maldonado_Stanley_1976

16 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES

725-735, km 750-762 in Figure 12, and km 770- ure l 0). This depression extends north of Linosa
780 in Figure 13Bv B 2 ). The transition between Island and forms the northwest end of the Pantel-
some of these depressions and the Neritic-Bathyal leria Trough (Zarudzki, 1972:20). The Pliocene-
platform is subtle. These depressions are differ- Quaternary strata are truncated by faults at the
entiated from the adjacent platform surfaces on edge of the depression.
the basìs of a thicker sedimentary cover (range The small northwestern basin (km 770-780, Fig-
from 0.5-0.8 seconds, 450-720 m), broad basinal ure 13Bv B 2 ) is characterized by intense folding
morphology, and a marked tectonic pinching out and distortion of the sediment within the depres-
of the sedimentary sequences against the depres- sion, suggesting compression (cf. Zarudzki, 1972).
sion margins. This zone provides evidence of recent tectonic
The Malta-Linosa depression ìs wide (105 km) movement as indicated by the tilting and folding
and displays vertical tectonic structures analogous of the surficial reflectors visible in the 3.5 kHz
to those described o n the platform (Figures 3, l O, records (Figure 13B 2 ).
Il). Structurally, this depression is a genti e syn- The Gela Basin (Zarudzki, 1972), also called the
cline without major sea mounts or knolls; seismic South Sicily Basin (Finetti and Morelli, 1972), is
profiles show the faulted margin of the depression. located between the Malta Trough and Sicily and
The fault which has affected the most surficial re- may be assigned to this environment.
flectors displays a downthrow of over 100 m (Fig- Sediments in cores are characterized by their ap-

NORTHWEST SOUTHEAST

FIGURE 12.-Profiles north of Adventure Bank showing two distinct, small depressions on the
neritic-bathyal borderland. Note topographic high devoid of Pliocene-Quaternary sediment cover
between the depressions.