Naslov
Relationship between submerged tidal notches and recent tectonic movements in the Vinodol Channel (NE Adriatic Sea)

Autori
Juračić, Mladen ; Benac, Čedomir

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
ADRIA 2006. International Geological Congress on the Adriatic area. Abstracts / Colantoni, Paolo ; Mencucci, Daniela ; Menichetti, Marco ; Nesci, Olivia - Urbino : Universita degli studi di Urbino, 2006, 65-66

Skup
ADRIA 2006. International Geological Congress on the Adriatic area

Mjesto i datum
Urbino, Italija, 19.06.2006. - 20.06.2006

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Nije recenziran

Ključne riječi
neotectonics; tidal notch; Krk Island; Croatia

Sažetak
The Vinodol Channel, as a part of the Kvarner area (North Adriatic), is located between Vinodol coast (NE) and coast of the Krk Island (SW). Coasts of this channel have irregular triangle shape. Very narrow Tihi Channel is connection with Rijeka Bay on NE side. Toward SE the width of Vinodol Channel is more than 10 km. The coasts of Vinodol Channel are formed in Cretaceous and Paleogene carbonates (limestone, dolomite, and carbonate breccia) and Paleogene silicaclastic sedimentary rocks (flysch). Carbonate rocks predominate in the coastal area, whereas flysch outcrops are restricted. At shallow sea floor (up to 20 m depth) coarse-grained sandy and gravely sediment prevail, whereas in deeper zone the sea floor is covered by fine-grained muddy sediment (Juračić et al. 1999). Morphogenetic processes caused by tectonic movements and rapid sea level changes, as well as climatic changes during Quaternary, shaped the Vinodol Channel. In this semi-enclosed channel, weak to moderate winds prevail. There is relatively short wind fetch in the channel, and the wave heights are smaller than in offshore Adriatic. Although NE wind “ Bura” is the strongest along that part of the Adriatic coast, due to the limited fetch it does not generate the highest waves. Thus bioerosion prevails on the carbonate rocky coast. Near the eustatic peak of the Holocene sea-level rise, in the Northern Adriatic area there was a period of equilibrium between the regional tectonic subsidence and hydro-isostatic emergence, and the relative sea level has been stable for a few thousand years (Pirazzoli, 2005). This situation permitted the development of well expressed tidal notch at least until Roman times. Tidal notches are widespread on carbonate coasts in Kvarner area (Pirazzoli, 1980 ; Benac and Juračić, 1998 ; Fouache et al. 2000) and are considered to be one of the best indicators of the local sea-level change. Later, at date not yet exactly determined, very rapid subsidence occurred in North Adriatic area. Tidal notches are 45 to 65 cm below MSL in most places of Rijeka Bay, but in the Bakar Bay their positions is more then 100 cm below MSL (Benac et al. 2004). Pirazzoli (2005) suggested coseismic origin of this subsidence affected by displacement of Adriatic plate against Carnic and Julian Alps. On the coasts of Vinodol Channel, a well developed tidal notch below mean sea level (MSL) has been recognized. Only the tidal notches with horizontal extension larger than one meter were measured. The roof of tidal notches was always at least 45 cm below MSL. Tidal notches had asymmetric shape, height between 55 and 390 cm, and depth between 25 and 160 cm. The precision of measurements was &plusmn ; 2 cm. On the NE coast of Vinodol Channel the position of notches was 48 to 55 cm below MSL. On the SW coast of Vinodol Channel (NE coast of the island of Krk) the position of notches was 55 to 66 cm, but around Šilo peninsula the position was shallower: between 45 and 58 cm below MSL. Deeper positions of tidal notches on NE coast of Vinodol Channel and shallower position on its SW coast indicate enhanced subsidence on the footwall of the Vinodol thrust. This tectonic style is similar to one in the parallel Vinodol valley (Blašković, 1999). However, shallower position of of tidal notches at Šilo Peninsula requires revision of tectonic interpretation. Generally speaking, different position of tidal notches in the Vinodol Channel are clear indicator of active recent tectonic movements in NE part of Kvarner area. High seismicity supports the notion of distinctive recent tectonic activity in the NE part of Kvarner area (Herak et al, 1996).

Izvorni jezik
Engleski

Znanstvena područja
Geologija, Građevinarstvo

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