Morphoneotectonics and Lithology of the Eastern Sector of the Gulf of Trieste (NE Italy)
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Journal of Maps ISSN: (Print) 1744-5647 (Online) Journal homepage: http://www.tandfonline.com/loi/tjom20 Morphoneotectonics and lithology of the eastern sector of the Gulf of Trieste (NE Italy) Sara Biolchi, Stefano Furlani, Stefano Covelli, Martina Busetti & Franco Cucchi To cite this article: Sara Biolchi, Stefano Furlani, Stefano Covelli, Martina Busetti & Franco Cucchi (2016) Morphoneotectonics and lithology of the eastern sector of the Gulf of Trieste (NE Italy), Journal of Maps, 12:5, 936-946, DOI: 10.1080/17445647.2015.1099572 To link to this article: http://dx.doi.org/10.1080/17445647.2015.1099572 © 2015 Sara Biolchi View supplementary material Published online: 21 Oct 2015. Submit your article to this journal Article views: 104 View related articles View Crossmark data Citing articles: 1 View citing articles Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=tjom20 Download by: [University of Trieste] Date: 04 May 2017, At: 07:22 JOURNAL OF MAPS, 2016 VOL. 12, NO. 5, 936–946 http://dx.doi.org/10.1080/17445647.2015.1099572 SCIENCE Morphoneotectonics and lithology of the eastern sector of the Gulf of Trieste (NE Italy) Sara Biolchia, Stefano Furlania, Stefano Covellia, Martina Busettib and Franco Cucchia aDipartimento di Matematica e Geoscienze, Università degli Studi di Trieste, Trieste, Italy; bIstituto Nazionale di Oceanografia e di Geofisica Sperimentale – OGS, Borgo Grotta Gigante 42/c – 34010 Sgonico, Trieste, Italy ABSTRACT ARTICLE HISTORY The paper aims to describe and map the geomorphological and lithological features of the Gulf Received 29 May 2015 of Trieste and its eastern coasts and to define its neotectonic behaviour by means of the analysis Revised 8 September 2015 of the morphoneotectonic evidence. The final map, produced at a scale of 1:30,000, shows the Accepted 21 September 2015 outcome of field investigations carried out along the coast and the sea bottom and a detailed fi KEYWORDS geomorphological classi cation of the coastline. Published and new data coming from the Coastal geomorphology; analysis of archaeological remains, geomorphological and sedimentological sea-level geomorphotypes; indicators and geophysical researches are discussed in order to provide a complete overview neotectonic; NE Adriatic of the study area. 1. Introduction provided the distribution of the main fault systems and the activity in the gulf during the Quaternary. The Gulf of Trieste is an epicontinental semi-enclosed This paper aims to present a 1:30,000 morphoneo- shallow marine basin in the NE Adriatic Sea, with a tectonic map (Main map) of the rocky coasts of the maximum depth of 25 m. Marine sedimentation is eastern sector of the Gulf of Trieste together with the strongly affected by local inputs of freshwater, fed by lithological features of the sea bottom. The map the Isonzo and Timavo rivers in the north and some extends up to 1000 m inland in order to represent land- minor rivers in the southeastern sector (Covelli, fl forms and deposits derived from marine, karst, uvial Fontolan, Faganeli, & Ogrinc, 2006). The eastern side and gravitational processes. Moreover, a detailed classi- of the gulf is bordered by rocky coasts and dominated fication of the coastal landscape is provided. by plunging cliffs and shore platforms (Furlani, Pappalardo, Gomez-Pujol, & Chelli, 2014). The surface area of the gulf is about 600 km2, with the water depth 2. Study area generally shallow, reaching a maximum of about 25 m in the central part of the gulf. The Gulf of Trieste constitutes the northeastern end of The neotectonic behaviour of the Gulf was first the Adriatic Sea and is bordered to the north by the highlighted during the 1980s by many authors, includ- Friuli Plain, to the east by the Classical Karst plateau, ing Cucchi, Forti, and Semeraro (1979), Carulli et al. and to the south by the Istrian peninsula. In the (1980), Carobene and Carulli (1981), Zanferrari et al. Karst and in Istria, a thick carbonate platform sequence (1982), Cucchi, Forti, and Forti (1983), Slejko et al. outcrops. It spans the time from the early Cretaceous to (1987), Carulli and Cucchi (1991), Del Ben, Finetti, the early Eocene and is followed by the Eocene flysch Rebez, and Slejko (1991). (Cucchi, Biolchi, Zini, Jurkovšek, & Kolar-Jurkovšek, Over the last decade, the neotectonic behaviour of 2015; Cucchi, Pirini Radrizzani, & Pugliese, 1987; this area has been investigated using new instrumental Jurkovšek, Cvetko Tešović, & Kolar-Jurkovšek, 2013). data as well as sea-level markers. Braitenberg, Nagy, This carbonate sequence is composed of Monte Coste Romeo, and Taccetti (2005) described the SE–NW tilt- Limestone (350–400 m thick, Aptian-Albian in age), ing of the Karst plateau; Antonioli, Carulli, Furlani, composed of bedded, foraminiferal, dark limestones Auriemma, and Marocco (2004), Antonioli et al. and layers of breccia. It is overlain by the Monrupino (2007, 2009), Furlani et al. (2011), Melis et al. (2012) fm. (300–700 m, middle-upper Cenomanian in age), and Evelpidou, Pirazzoli, and Spada (2015) studied ver- composed of light grey and dark grey dolomites, with tical tectonic rates using geomorphological, sedimento- frequent red-yellowish lenses of bedded dolomites, logical and archaeological markers. Busetti et al. micritic limestones and calcareous-dolomitic alterna- (2010a), employing multichannel seismic surveys, tions (Colizza, Cucchi, & Ulcigrai, 1989). The sequence CONTACT Sara Biolchi [email protected] © 2015 Sara Biolchi JOURNAL OF MAPS 937 continues with the Zolla Limestone (200 m, upper Cen- thrusts is displaced by tear-faults, which are strike- omanian-Turonian in age), which is composed of slip faults with NE–SW or ENE–SWS orientation bedded micritic limestones with pelagic fauna and (Cucchi & Piano, 2013)(Figure 1). very fossiliferous bioclastic limestones, and the In the gulf, a system of thrusts related to the inver- Aurisina Limestone (600–1400 m, Upper Campanian- sion of the Dinaric foredeep occurs (Busetti et al., upper Maastrichtian), which is composed of shallow 2010a, 2010b, 2013). water, fossiliferous limestones. The cretaceous sequence ends with the Liburnia fm. (upper Maastrichtian-Paleo- cene), 80–200 m thick, which includes the Cretaceous– 3. Materials and methods Paleogene boundary (Pirini Radrizzani, Pugliese, & The lithological and tectonic features represented on the Stocca, 1987; Tewari et al., 2007). The latter is subdi- map were partly derived from a revision of the Geologi- vided in two parts: Liburnia fm. A, composed of bedded cal Map of the Classical Karst (Cucchi & Piano, 2013; and medium dark-grey, bioclastic, micritic limestones Cucchi et al., 2015) and the models provided by Placer and Liburnia fm. B, composed of thin-bedded dark lime- (2008) and Placer, Vrabec, and Celarc (2010). In the off- stones, slightly marly and massive bioclastic and coral shore area, the tectonic features are derived from Busetti algal limestones. The carbonate sequence ends with et al. (2010a, 2010b 2013). The geomorphological – the Alveolinid and Nummulitid Limestone (70 300 m, characteristics of the coastal sector were provided by lower Eocene in age), which is composed of grey, very the CGT Project (RAFVG, 2008a) and were integrated fossiliferous limestones, rich in macroforaminifers. At by field surveys and air-photo interpretation that the top of the carbonate sequence, an alternation of allowed to refine the original data, in particular those limestones and marls, the Transitional Beds, 50 m regarding the coastal features. The map of the eastern thick and Middle Ypresian-Lower Cuisian in age part of the Gulf of Trieste was enhanced by the represen- (lower Eocene) occur (Burelli et al., 2008). The drowning tation of the sediments covering the sea bottom. of the carbonate platform is followed by the deposition Grain-size results from previous works (Brambati & of the turbidite sediments of the Flysch fm., which is Catani, 1988; Covelli & Fontolan, 1997; Covelli et al., composed of an alternation of silty marlstones and sand- 2006; Ogorolec, Misic, & Faganeli, 1991) were included stones, dated back to the middle Eocene (Bensi, Fanucci, in a comprehensive data-set along with those obtained š ć Pav i , Tunis, & Cucchi, 2007). from new sampling, where bottom sediments were col- Finally, Quaternary deposits are composed of allu- lected by means of a grab during fieldwork in 2006. vial deposits, sedimented by small temporary streams, Sedimentological results report the percentage of terra rossa in the karst area and cemented debris sand and pelite (mud) contents where the size limits fl which sometimes cover ysch cliffs. are from 2 to 0.050 mm (sand) and finer than 0.050 – In the gulf, the same lithologies occur, with the 3 4 mm (pelite) according to Nota (1958) classification: km of Cretaceous to Paleogene carbonates overlaid by a sand (pelite < 5%), pelitic sand (5% <pelite>30%), fl wedge of ysch up to several hundred metres thick, very sandy pelite (30% <pelite>70%), sandy pelite draped by Quaternary continental and marine sedi- (70% <pelite>95%), pelite (pelite >95%). ment, thickening westward from a few metres at the Field mapping and symbols convention have been – coast to 1 200 m in the central part of the gulf (Busetti performed according to the guidelines of the Geologi- et al., 2010a, 2010b). cal Survey of Italy (Gruppo di Lavoro per la Cartografia From a geodynamic viewpoint, the Karst belongs to Geomorfologica, 1994). The resulting map of the Gulf the External Dinarides (Figure 1). The latter are charac- of Trieste consists of two main sections: terised by thrusts, reverse faults and high-angle faults, (1) the main geomorphological map at a 1:30,000 – often with a strike-slip movement, NW SE oriented. scale. It includes the lithological map of the sea- The thrusts caused the development of a series of over- bottom and the related legend; laid tectonic units with a SW vergence, tending to the (2) a morphoneotectonic sketch map of the Gulf of superimposition of the Mesozoic carbonate sequence Trieste (upper right side of the map), draped on the Paleogene turbidite one.