IL CONTESTO GEODINAMICO DELL’AREA DI ACI

Carmelo Monaco

Dipartimento di Scienze Biologiche, Geologiche e Ambientali, Sezione di Scienze della Terra, Università di Catania

Geological studies and morphological analysis, compared with geodetic data, suggested that shallow thrusting and folding occur at the front of the chain, south of Mt. Etna

A flight of coastal-fluvial

terraces evidences

middle-late Pleistocene

deformation at the front

of the chain

Ristuccia,… Monaco… et al., 2013

Terreforti AnticlineB

C

Terreforti Anticline

Morphotectonic analysis

For each order of terrace:

- Elevation of inner edge

- OSL dating

- Correlated MIS

- Sea level correction

- Uplift rates

Ristuccia,… Monaco… et al., 2013

Velocity diagram showing the short-term

variations of the uplift rates (~1.2 mm/year)

Uplift rates have been calculated

for the last 240 ka by fitting the

elevations of the distinct

palaeoshorelines corrected for sea-

level changes.

The geometry of terraces indicates

that local tectonic processes,

related to the migration of the front

of the Sicilian orogen, coupled with

sea-level changes during the

Middle Pleistocene.

The two oldest terraces are in fact

deformed, suggesting activity of

the fold between 240 and 200 ka.

OSL age determinations and

topographic data allowed us to

determine a growth rate of 1.4

mm/year for the Terreforti anticline,

along its hinge.

Terreforti Anticline

Ristuccia,… Monaco… et al., 2013

Thrusting and folding are still

active in the area even

though, according to SAR

data, current deformation has

migrated slightly to the north

(Catania Anticline, uplifting at

a rate of ~10 mm/yr).

1995-2000 ground velocity map

(Bonforte et al., 2011)

Catania Anticline

Terreforti Anticline

Ground deformation measured from 2003 to 2011 by ENVISAT

Catania Anticline

Holocene deformation along the Catania Anticline is difficult to observe since it occurs in a volcanic and strongly populated area

..

1. University Campus

2. Underground excavations

1

2

yellow circles indicate sampling sites

(Branca…Monaco… et al., 2014)

Holocene vertical deformation along

the coastal sector of Mt. Etna

A detailed survey of morphological and

biological markers of paleo-shorelines

has been carried out along the coastal

sector of Mt. Etna volcano in order to

verify if folding extends seawards.

We have mapped markers of raised Holocene shorelines, which are represented by beach rocks,

wave-cut platforms, balanid, vermetid and algal rims. The

timing of coastal uplift has been determined by radiocarbon dating of shells collected from the raised

paleo-shorelines.

Branca…Monaco… et al., 2014

a) Aci Trezza, Holocene serpulid and algal reef encrusting 500 ka old basalts.

b) Wave-cut platforms on the 500 ka old pillow lavas forming the Aci Castello rock.

To correctly assess the total amount of tectonic uplift of

the coast during the Late Holocene, we have compared

the elevation-age data of sampled shells to the local curve of Holocene sea-level rise (according to the model

of Lambeck et al., 2004)

Branca…Monaco… et al., 2014

Structural sketch map of Etna volcano showing:

1) the vertical velocities, expressed in mm/yr obtained by interferometric data of Bonforte et al. (2011) in the period 1995-2000

2) the last 20 ka uplift/subsidence rates observed both along the coast (PSL=paleo-shoreline; DHA=docks and other manmade structures) and in the offshore (LGM= last glacialmaximum platform)

Branca…Monaco… et al., 2014

Recent subsidence at the hanging wall of the San Leonardello Fault

1995 2010 Stazzo harbour

San Leonardello graben

A network of approximately

400 km of high resolution

seismic reflection profiles

(sparker single channel)

was recorded along the

continental shelf between

Capo Sant'Alessio and-Castelluccio Agnone.

ESAT (Eastern Sicily Active Tectonic) cruise

The last step: acquisition of sparker profiles in the Mt. Etna offshore

Neptune 1

Power supplyand mini trace

Streamer and wire

Sparker

- The shallow layers have been investigated using Sparker

profiles that have clearly defined the tectonic structures with

vertical resolution of up to 1 m in the vicinity of the sea floor.

- The acoustic sources for seismic prospecting was a 1 kJ

Sparker power supply (frequency 1 KHz). Positioning was

controlled by a Differential GPS. Data were recorded using a

single-channel streamer with an active section of 2.8 m,

containing seven high-resolution hydrophones, for 1.0 s two

way time (t.w.t.) at 10000 Hz (0.1 ms) sampling rate.

Location, geometry, kinematics of the structures of the sedimentary substratum

a) Geometry and distribution of detected seismic units along the sparker line L1; b) A seismo-stratigraphic model reconstructed from seismic facies analysis; c) correlation of the seismic units with age-constrained volcanics and sedimentary deposits outcropping on-land (age of volcanics from Branca et alii, 2011). S1, S2 and S3 are erosional surfaces; SBM: sea bottom multiple.

It was performed

using the Geo-Suite

software package

that offers a

comprehensive

series of advanced 2

and 3-D tools using

all types of domain

information plus

geological and

geophysical

knowledge in one

single software

environment.

Data processing and interpretation (Barreca, Corradino, Monaco, Pepe, 2018)

Barreca,…Monaco… et al., 2018

Acireale fault

Timpefault

system(SE slope)

(a) Un-interpreted; and (b) interpreted line L2 showing reverse faulting, extending from the seafloor into the basement Unit A . Along the SW sector, Pleistocene-Holocene sediments are tilted toward the Catania Canyon, with a displacement of ~28 m. Mud/fluid intrusions (1 and 2), deforming the units C and D, are evident. ACR: Acireale; ACT: Aci Trezza; S1 and S3, erosional surfaces; sbm, sea bottom multiple

(Barreca et al., 2018)

(a) interpreted line L3 showing a set of normal faults controlling the seafloor morphology; (b) Recent sediments within the wedge-shaped basin suggest syn-sedimentary activity on these faults .ACR: Acireale; ACT: Aci Trezza; S1: erosional surface; sbm: sea bottom multiple.

(Barreca et al., 2018)

Interpreted NNE-SSW trending L4 line showing the offshore prolongation of the NW-SE-trending, mainly NNE-dipping normal faults, also recognized on line L3. Faults displacedMiddle Pleistocene to Holocene deposits also affecting the seafloor; ACR: Acireale; ACT: Aci Trezza; S1: erosional surface; sbm: sea bottom multiple.

(Barreca et al., 2018)

Gutscher,…Barreca …et al., 2016; Polonia…Monaco… et al., 2016Barreca…et al., 2018)

Tectonicinterpretation