Key features of mixed carbonate-siliciclastic shallow-marine systems ...

was characterized by a dominant extensional tectonic
regime, periodically interrupted by short compressional
or transpressional phases (VAN DIJK, 1991; MASSARI et
alii, 2002; ZECCHIN et alii, 2004a).
Since mid-Pleistocene time, the Calabrian Arc expe -
rienced strong uplift, and a staircase of marine terraces
developed (figs. 1A and 1B). The uplift was interpreted as
the result of either an isostatic rebound that followed the
breaking of the subducted Ionian Crust (SPAKMAN, 1986;
WESTAWAY, 1993; WORTEL & SPAKMAN, 2000), or a convective
removal of the deep root and a consequent decoupling
of the Calabrian Arc from the subducting plate
(DOGLIONI, 1991; GVIRTZMAN & NUR, 2001).
In the study area, marine terraces consist of a transgressive
erosional surface onto a Plio-Pleistocene slope
succession (the Cutro Clay), unconformably overlain by
shallow-marine sediments (GLIOZZI, 1987; PALMENTOLA
et alii, 1990; ZECCHIN et alii, 2004b; ZECCHIN et alii, 2010)
(fig. 1B). ZECCHIN et alii (2004b) identified five levels of
terraces in the Crotone area. The oldest and highest terrace,
named Cutro terrace, is up to ca. 200 m of elevation,
and it has been ascribed to marine isotope stage (MIS) 7
(ca. 200 kyr) (GLIOZZI, 1987; ZECCHIN et alii, 2004b;
NALIN et alii, 2007; ZECCHIN et alii, 2011) or 9 (ca. 330
kyr) (PALMENTOLA et alii, 1990). The younger terraces are
placed between 100 and 8 m, and their estimated ages
range from 125 to 50 kyr B.P. (ZECCHIN et alii, 2004b).
The uplift rate calculated for the Crotone area varies
between 0.4 and 1.8 m/kyr (COSENTINO et alii, 1989; PAL-
MENTOLA et alii, 1990; ZECCHIN et alii, 2004b).
INTRODUCTION
KEY FEATURES OF MIXED CARBONATE-SILICICLASTIC SHALLOW-MARINE SYSTEMS 371
Fig. 1 - A) Geologic sketch-map of the Crotone Basin with location of the Capo Colonna area, SE of Crotone (modified from MASSARI et alii,
2002); B) geologic map of the Capo Colonna promontory, with indication of the ten measured sections (modified from ZECCHIN et alii, 2009).
THE CAPO COLONNA TERRACE
The EW-elongated Capo Colonna promontory is
located a few km south-east of Crotone and extends
toward the Ionian Sea for 3 km, with an eastward dip of
ca. 1 degree (figs. 1A and 1B). The promontory is bordered
by a coastal cliff whose seaward margin is at 10 to
15 m a.s.l. Its landward edge is located at ca. 50 m a.s.l.
and terminates against a steep slope.
The Pleistocene Capo Colonna marine terrace lies on
top of the promontory, and consists of carbonate to siliciclastic
sediments (up to 10 m thick) unconformably overlying
the Plio-Pleistocene deep marine Cutro Clay Formation
(NALIN & MASSARI, 2009; ZECCHIN et alii, 2009) (fig. 1B).
Although all authors consider the terrace younger than
MIS 5e, there is no agreement in its precise age. In particular,
most of the terrace has been ascribed to MIS 5c (about
100 kyr B.P.) by PALMENTOLA et alii (1990) and ZECCHIN et
alii (2009), whereas GLIOZZI (1987) and NALIN & MASSARI
(2009) ascribed the terrace to MIS 5a (about 80 kyr B.P.).
STRATIGRAPHIC ARCHITECTURE
The Capo Colonna terrace is composed of two transgressive-regressive
cycles, 1 to 8m m thick, stacked to
form a retrograding pattern (fig. 2), which is inferred to
be the result of a generalized glacio-eustatic rise superimposed
on regional uplift (NALIN & MASSARI, 2009;
ZECCHIN et alii, 2009). The present study is focused on
the second cycle (CC2, figs. 2-4), that is that better deve -
loped and exposed, allowing an accurate analysis of
downdip facies changes.
A complete analysis of the stratal architecture of
cycles forming the Capo Colonna terrace was provided by
ZECCHIN et alii (2009). The basal surface of both cycles is
represented by a wave ravinement surface (WRS) cutting
into the Plio-Pleistocene Cutro Clay, and overlain by
coarse-grained lags and transgressive shell concentrations
(ZECCHIN et alii, 2009) (figs. 2-4). The WRS that marks
the base of the CC2 cycle may be picked for ca. 3 km
downdip (fig. 2) and has an average seaward gradient of
ca. 0.6°. The dip of the surface is thought to be close to