Page 3 - Basin_formation_the Egadi

F . Gamberi. A. Argnuni / Tectonophysics 252 (19951285-294 287

38" 3. Seismic data
50'

The data set on which this study is based (Fig. 3)
consists of a grid of multichannel seismic reflection
profiles. Part of these profiles were acquired by the
Italian Board of Industry in 1982 with a 3000 c.i.
airgun array and a 96-channel streamer. In addition,
the Institute of Marine Geology of Bologna col-
lected, in 1989, a closely spaced grid of seismic
profiles over the southernmost one of the two basins
located offshore the Egadi Islands (basin INVO-2).
These profiles, acquired with a Sparker 30 kJ and a
24-channel streamer, total about 1000 km and have
been time-migrated.

36' 'JO'O 4. Basin INVO-2
00'
This basin has a NW-SE strike and is divided by
10'50' a structural high with the same trend into a western
(WS) and an eastern (ES) subbasin (Fig. 4). The
Fig. 2. Bathymetric map showing location of basins INVO-I and basin infill presents the typical seismic facies of
INVO-2. EFTB = Egadi Foreland Thrust Front; PT = Pantelleria Plio-Quaternary sediments in the basins surrounding
trough; BI = basin INVO- I ; 8 2 = basin INVO-2. Sicily (Fabbri et al., 1981; Argnani et ai., 1987), but
due .t the lack of well data we are not &le .t
construct a chronostratigraphic scheme for the sedi-

main thmst between the Sardinian and the CPK units ;;

was reactivated as an extensional detachment zone

which led to the tectonic denudation of the CPK unit

in Late Miocene time (Tricart et al., 1994)

More to the south, on top of the Egadi FTB, two

main basins of Plio-Quaternary age (basins INVO-1

and INVO-2) were formed during this extensional

phase (Fig. 2; Gamberi and Argnani, 1993). They

have a NW-SE trend and are located along the

northern prolongation of the Pantelleria valley, a

N-S-trending lineament which constitutes the west-

ern boundary of the Pantelleria trough, one of the

deep basins occurring in the centra1 Strait of Sicily

(Argnani, 1990; Gamberi and Argnani, 1993).

INVO-1 and INVO-2 basins have experienced

contractional episodes, subsequent to the extension 370

or altemating with it, and present a variety of con- 20 11.1n' 1~-~~

stnictures' of these stnictures Fig. 3. Seismic grid over basin INVO-2. Bold lines are seismic
profiles shown in this paper, ES = eastern subbasin; SH =
already been described in the literature (Catalano and stnictural high; WS = western subbasin.

Milia, 1990; Gamberi and Argnani, 1993).