The seabed of the northernmost part of Adriatic Sea is a key area to understand the processes related to Holocene sea-level and climatic variations. This zone, which lies between Istria Peninsula, Karst and the Friulian Plain, is divided between Italian, Slovenian and Croatian territorial waters and this administrative fragmentation has strongly limited international cooperation in the past. In May 2012 a team of Italian and Slovenian researchers, on-board of the research vessel “Urania”, surveyed the shelf between Italian and Slovenian coasts. During cruise, named NAD2012, about 400 NM of CHIRP-sonar seismo-acoustic profiles were acquired in the whole area and 10 gravity cores were collected in the Italian waters. The new data gathered during NAD2012 cruise allowed for the first time to observe in continuity the stratigraphic transition from the alluvial plain of Friuli to the rocky coast of Istria. A robust chrono-stratigraphical framework of the general setting of the Northern Adriatic shelf is supported by the geophysical, bathymetric and stratigraphic data collected during cruises VE2004 and VE2005, that led to the production of the geological map of the Italian seabed, northern of Po river mouth (Trincardi et al., 2011). In the last years Harpha Sea carried out a multibeam bathymetric survey of the Slovenian Waters, leading to the production of a very high-definition DEM. This is revealed as a fundamental tool for understanding the sea-floor morphologies and to plan the acquisition of the new seismo-acoustic profiles during NAD2012. The area between Monfalcone and Piran Bay is characterized by a mud-dominated body consisting of Holocene marine deposits, with a maximum thickness of about 25 m in Piran Bay and that thins toward the Friulian coast, where the delta system of Isonzo (Soča) River is present. The marine sedimentary body seals the alluvial plain that occupied the area until ca. 7.5 ka BC, when sea-level rise led the Adriatic to re-occupy the Gulf of Trieste (Ogorelec, 1981; Covelli et al., 2006; Trincardi et al., 2011). The evolution of the investigated area is constrained by a main threshold corresponding to the deep morpho-structural depression existing in front of Savudrija Promontory. Connected to the first depression, some very large submarine dunes characterize the NW corner of Slovenian boundary, and their origin seem to be related to main stream entering in the northernmost Adriatic sector with a counterclockwise direction. Another shallower but important erosional scour is present in front of Piran Promontory. The ancient alluvial plain is characterized by a complex network of fluvial ridges, with a general ENE-WSW direction, fed by the valleys draining Karst and Istria; moreover the DEM highlight an incised meandering paleochannel, recognizable from the Italian shelf to Koper Bay, partly sealed by the deltaic progradation of the Isonzo River. References S. Covelli, G. Fontolan, J. Faganeli, N. Ogrinc, 2006. Anthropogenic markers in the Holocene stratigraphic sequence of the Gulf of Trieste (northern Adriatic Sea). Marine Geology, 230, 29-51. B. Ogorelec, M. Mišič, M., A. Šercelj, F. Cimerman, J. Faganeli, P. Stegnar, 1981. The sediment of the saltmarsh of Sečovlje. Geologija 24, 179–216. F. Trincardi, A. Argnani, A. Correggiari, 2011. Note illustrative della Carta Geologica dei Mari Italiani alla scala 1:250.000 – Foglio NL 33-7 Venezia.S.EL.CA., Firenze, 151 pp.

Stratigraphic and morphologic evidence of the Holocene evolution of the Italian and Slovenian waters (northern Adriatic)

FONTANA, ALESSANDRO;
2012

Abstract

The seabed of the northernmost part of Adriatic Sea is a key area to understand the processes related to Holocene sea-level and climatic variations. This zone, which lies between Istria Peninsula, Karst and the Friulian Plain, is divided between Italian, Slovenian and Croatian territorial waters and this administrative fragmentation has strongly limited international cooperation in the past. In May 2012 a team of Italian and Slovenian researchers, on-board of the research vessel “Urania”, surveyed the shelf between Italian and Slovenian coasts. During cruise, named NAD2012, about 400 NM of CHIRP-sonar seismo-acoustic profiles were acquired in the whole area and 10 gravity cores were collected in the Italian waters. The new data gathered during NAD2012 cruise allowed for the first time to observe in continuity the stratigraphic transition from the alluvial plain of Friuli to the rocky coast of Istria. A robust chrono-stratigraphical framework of the general setting of the Northern Adriatic shelf is supported by the geophysical, bathymetric and stratigraphic data collected during cruises VE2004 and VE2005, that led to the production of the geological map of the Italian seabed, northern of Po river mouth (Trincardi et al., 2011). In the last years Harpha Sea carried out a multibeam bathymetric survey of the Slovenian Waters, leading to the production of a very high-definition DEM. This is revealed as a fundamental tool for understanding the sea-floor morphologies and to plan the acquisition of the new seismo-acoustic profiles during NAD2012. The area between Monfalcone and Piran Bay is characterized by a mud-dominated body consisting of Holocene marine deposits, with a maximum thickness of about 25 m in Piran Bay and that thins toward the Friulian coast, where the delta system of Isonzo (Soča) River is present. The marine sedimentary body seals the alluvial plain that occupied the area until ca. 7.5 ka BC, when sea-level rise led the Adriatic to re-occupy the Gulf of Trieste (Ogorelec, 1981; Covelli et al., 2006; Trincardi et al., 2011). The evolution of the investigated area is constrained by a main threshold corresponding to the deep morpho-structural depression existing in front of Savudrija Promontory. Connected to the first depression, some very large submarine dunes characterize the NW corner of Slovenian boundary, and their origin seem to be related to main stream entering in the northernmost Adriatic sector with a counterclockwise direction. Another shallower but important erosional scour is present in front of Piran Promontory. The ancient alluvial plain is characterized by a complex network of fluvial ridges, with a general ENE-WSW direction, fed by the valleys draining Karst and Istria; moreover the DEM highlight an incised meandering paleochannel, recognizable from the Italian shelf to Koper Bay, partly sealed by the deltaic progradation of the Isonzo River. References S. Covelli, G. Fontolan, J. Faganeli, N. Ogrinc, 2006. Anthropogenic markers in the Holocene stratigraphic sequence of the Gulf of Trieste (northern Adriatic Sea). Marine Geology, 230, 29-51. B. Ogorelec, M. Mišič, M., A. Šercelj, F. Cimerman, J. Faganeli, P. Stegnar, 1981. The sediment of the saltmarsh of Sečovlje. Geologija 24, 179–216. F. Trincardi, A. Argnani, A. Correggiari, 2011. Note illustrative della Carta Geologica dei Mari Italiani alla scala 1:250.000 – Foglio NL 33-7 Venezia.S.EL.CA., Firenze, 151 pp.
2012
AT THE EDGE OF THE SEA: SEDIMENTS, GEOMORPHOLOGY, TECTONICS, AND STRATIGRAPHY IN QUATERNARY STUDIES
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11577/3040831
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