A brief insight into the Upper Triassic to Miocene sedimentary succession of the External Dinarides SE of Dubrovnik (southern Croatia)
Croatia, 1 day, trip leaders: Igor Vlahović, Antun Husinec, Božo Prtoljan
starts & ends: 12.06.2023., Dubrovnik
This field trip focuses on selected intervals of the ~5-km-thick Upper Triassic–Miocene predominantly carbonate sedimentary succession of the External Dinarides, spectacularly exposed in the Konavle area near Dubrovnik in southern Croatia. The oldest deposits cropping out in the area are Norian–Rhaetian laminated dolomites (regionally known as Hauptdolomit or Main Dolomite) overlain by Hettangian and Pliensbachian shallow-marine limestones, the latter with common lithiotid bivalves. These carbonates formed on a huge semi-isolated carbonate platform of the southern Tethys, which in the late Early Jurassic disintegrated into a set of smaller isolated platforms, separated by oceanic basins. A major part of the External Dinarides is therefore composed of the relatively well-preserved Adriatic Carbonate Platform deposits, predominantly typical shallow-marine carbonates ranging from Toarcian to Maastrichtian, covered by Eocene or in places younger foreland deposits formed due to the collision with the Eurasian Plate.
The trip will emphasize the tectonic, eustatic, and environmental controls that shaped the varied depositional environments, from tidal flats with subaerial exposure breccias and carbonate platform oolite shoals to foreland basins with mixed siliciclastic-carbonate deposits, showing more than 180 MY of a complex geological history in a single day. There will be a focus on Toarcian, Fleckenkalk-equivalent oncolitic and oolitic grain-supported limestones, Middle and Upper Jurassic carbonate parasequence/sequence development and disconformities, Upper Cretaceous to Paleogene carbonate deposits, and, in this area younger, Oligocene–Miocene flysch. In addition, we will provide some amazing viewpoints and a touch of local cuisine, as well as offer a glimpse into the contribution of terroir to the flavour of red wines in southern Croatia.
Deep-water Triassic to Cretaceous sedimentary succession of the Budva Zone (Montenegro)
Croatia, Montenegro, 2 days, trip leaders: Duje Kukoč, Martin Đaković, Špela Goričan
starts: 11.06.2023., Dubrovnik; ends: 12.06.2023., Dubrovnik
This excursion will examine the complete Middle Triassic to the end of Cretaceous succession of the Budva Basin, exposed in costal Montenegro (SW of Dubrovnik). Interpreted as a deep-water intraplatform basin in the External Dinarides, the Budva Basin succession is today exposed in several thrust sheets. The Upper Triassic part of the succession consists of cherty limestones overlain by Lower Jurassic alteration of cherts and shales, with Triassic-Jurassic boundary exceptionally well exposed. The Jurassic deep-water sedimentation in the basin was influenced by the dynamic of surrounding carbonate platforms. Carbonate gravity-flow deposits/sediments are deposited together with radiolarites and pelagic limestones. Pelagic limestones are also present in the Lower Cretaceous followed again by radiolarites and Globotruncana limestones at the top.
This fieldtrip will be held in the touristic coastal region of Montenegro and presents a chance to visit world-wide known historic coastal towns of Montenegro.
The Dinarides fold and thrust belt of Croatia and Bosnia and Herzegovina is positioned between the foreland Adriatic and the backarc Pannonian Basin. Gradual switch from contraction to extension during the Late Oligocene resulted in formation of the first lacustrine intramontane basins along the reactivated thrusts in the internal Dinarides. The extension reached the external Dinarides in the Early Miocene, when the combined effects of tectonic subsidence and the extended humid and warm climate of the Miocene Climate Optimum initiated the formation of the Dinaride Lake System. At the same time, the rifting in the Pannonian Basin and the related tectonic collapse of the internal Dinarides culminated in the Middle Miocene in their marine flooding by the Paratethys Sea. The present excursion will provide an overview on the Late Oligocene to Pliocene sedimentary evolution on different structural units along the transect from the southern Pannonian Basin to the external Dinarides. The first day of the excursion will be dedicated to the southern Pannonian Basin Neogene megasequence in Hrvatsko Zagorje and the Slavonian Mountains region, the second day to the Oligocene-Miocene sediments of the Ugljevik and Zenica-Sarajevo basins, and, finally, the third day to the Miocene-Pliocene successions of the Bugojno and Livno-Tomislavgrad basins.
Quaternary glaciations of the Alps-Dinarides junction
Slovenia,Croatia, Bosnia and Hercegovina, 4 days, trip leaders: Manja Žebre, Petra Jamšek Rupnik, Jernej Jež, Giovanni Monegato, Uroš Stepišnik
starts: 9.06.2023., Gorica (SLO); ends: 12.06.2023., Dubrovnik
Formerly glaciated mountain landscapes are important archives for the study of Quaternary climate change. This landscape type is widespread in the European Alps as well as in the mountains around the Mediterranean, where a lot of new geomorphological and geochronological data has been collected in the last decade. This field trip will provide an overview of the latest findings on glacial chronology, ice extent and past climate, with a focus on the transition area between the Alps and the Dinarides, stretching from Slovenia and Croatia to Bosnia and Herzegovina. The first day will be dedicated to the Soča valley and the Trnovski gozd plateau at the Alps-Dinarides junction, where deformed glacial deposits in a profile at Most na Soči, the sedimentary succession in the Renče clay pit with one of the best preserved LGM palaeovegetation records at the Alps-Dinarides, and the moraine chronology of Smrekova draga will be discussed in detail. The second day will focus on the northern part of the Dinarides (Snežnik and Velebit mountains) and will cover glacial geomorphology and chronology with two main stops in Gomance and Krasno. On the third and fourth day, the glacial chronology of the Čvrsnica, Velež and Crvanj mountains in the central part of the Dinarides will be presented.
Beaches and cliffs - uncommon coastal forms along the Croatian Adriatic (Dugi Otok, Split, Brač)
Croatia, 4 days, trip leaders: Kristina Pikelj, Maja Martinuš, Blanka Cvetko Tešović
starts: 9.06.2023., Zadar; ends: 12.06.2023., Dubrovnik
Over 6000 km long Croatian coast is primarily an erosive coast, formed after the Pleistocene-Holocene sea-level rise when previously deeply karstified terrain was submerged. As a result, this coast is mainly rocky and steep, where beaches and cliffs are not common coastal forms. This field trip will focus on coastal segments where gravel beaches and true cliffs were formed. The first segment of the field trip includes the Dugi Otok Island with the famous wide Sakarun beach where gravel, sand, and Posidonia banquette participate in unique biogeomorphological processes. In contrast, tectonically predisposed plunging cliffs formed in carbonates in the Telašćica Nature Park will also be visited. The second location is a true cliff developed in flysch within the Split urban zone. This coastal form undergoes rapid erosion, where its slope processes are endangering a part of the urban area. The third location is Brač Island and its unique gravel spit Zlatni Rat. The other carbonate segments of the Brač Island coast will be visited as well, including Pučišća quarry.
Geology of the old town of Dubrovnik
Croatia, 4 days, self-guided (Google Earth .kmz file)trip leader: Tvrtko Korbar
starts and ends: any time
Southern and northern elevated parts of the Old town of Dubrovnik are built on Mesozoic carbonate rocks deposited on the Adriatic Carbonate Platform. The carbonate bedrock is heavily faulted and fractured since strong tectonic deformations of the once buried carbonates began in Eocene with the formation of the External Dinarides, and are still ongoing because of the proximity of regional active faults. The deformed packages of stratified limestones and dolomites resemble lithostratigraphical units established in the wider region of southern Dalmatia, and show sedimentological features typical for peritidal subtropical sedimentation while rare key microfossils allow age determination. The central part of the town is built on anthropogenic deposits filling a narrow late Holocene embayment characterized by superficial Quaternary sediments that cover the heavily fractured and dissected carbonate bedrock. The southern rocky shore is in patches covered by thin (sub)recent supratidal aragonitic encrustations known as pelagosite.
Volcano-sedimentary-evaporitic rocks from aborted Triassic rift and Cretaceous to Paleogene Adriatic carbonate platform successions: OAEs, K–Pg boundary and Pc platform top (central Dalmatian islands, Croatia)
Croatia, 4 days, trip leaders: Tvrtko Korbar, Mirko Belak, Ladislav Fuček, Thomas Steuber
starts: 16.06.2023., Dubrovnik; ends: 19.06.2023., Split
Vis archipelago is located in the central part of the Adriatic Sea and was recognized as UNESCO Global Geopark in 2019. The islands emerged during the Quaternary because of the salt tectonics that characterizes the area. The Adriatic Carbonate Platform (ACP) existed during most of the Mesozoic in the central part of the then more spacious subtropical Adriatic microplate (Adria). The NE part of the platform has been incorporated into the Dinarides fold-and-thrust belt during the Paleogene while the SW part remained relatively undeformed within the Adriatic foreland that is now mostly covered by the sea. Salt diapirs are the most prominent subsurface tectonic structures in the central part of the Adriatic, and are built of once deeply buried volcano-sedimentary-evaporitic rocks deposited during the middle Triassic rifting stage of the Adria. Diapirs uplifted overlying carbonates and in places pierce a few kilometres thick ACP succession (e.g., Komiža Bay, Vis island). Thus, up to 1500 m thick succession of Cretaceous shallow-water carbonates is exposed on the flanks of the Komiža diapir. While pre- and post-Aptian successions are characterised by monotonous peritidal cycles, the Aptian is marked by prominent facies diversification because of the perturbations caused by the Ocean Anoxic Event 1 (OAE 1). The OAE 2 is not completely recorded within the Cenomanian-Turonian succession on the islands of Vis and Biševo, because of a local emergence of the platform during the event, which is followed by a relatively short period of deposition until the Coniacian. In the NE part of the platform, the deposition continued until the Maastrichtian, and in places even into the Paleocene. Thus, the Cretaceous–Paleogene (K-Pg) boundary event is recorded within rare successions deposited on tidal flats (Hvar island) or in inner-platform lagoons (Brač island), but there is still debate on the origin of the specific boundary layer. The Palaeocene platform top is characterized by a major subaerial exposure during which distinct discontinuity surfaces have been formed. The ACP top is unconformably overlain by diachronous Eocene Foraminiferal limestones that are deposited on the distal ramp of migrating Dinaric foreland basin.
Mesozoic-Cenozoic Dinaric foreland basins
Bosnia and Hercegovina, Croatia, 4 days, trip leaders: Borna Lužar Oberiter, Katarina Gobo, Duje Kukoč
starts: 16.06.2023., Dubrovnik; ends: 19.06.2023., Zadar/Zagreb
Synorogenic basins record the long-lasting evolution of the Dinarides mountain chain which developed along the Adria margin through multiple tectonic phases involving large-scale ophiolite obduction and nappe stacking events. From rugged mountain landscapes in the hinterland to the clear blue waters of the Adriatic seaside the field trip will explore basin deposits ranging from the Jurassic to the Paleogene, displaying a variety of sedimentary facies from deep-water pelagics, various types of gravity deposits to shallow-marine and continental environments. Visited outcrops will cover the Late Jurassic-Cretaceous deep-water “Bosnian flysch" which initially formed in response to ophiolite nappe emplacement. The field trip will further follow outcrops recording later phases of flexural foreland basin advancement towards the Adriatic foreland during Cretaceous to Cenozoic orogeny. This involved major composite nappe stacking including thick sequences of Mesozoic and Paleogene carbonates giving rise to the calciclastic Promina beds which record syn-tectonic sedimentation in thrust wedge-top "piggyback” basins.
Mass wasting deposits: From ancient catastrophic submarine collapses to recent alluvial fans; Julian Alps, Soča Valley and Adriatic coast
Slovenia, Croatia, 4 days, trip leaders: Andrej Šmuc, Boštjan Rožič, Luka Gale, David Gerčar, Andrej Novak, Krešimir Petrinjak, Željko Pogačnik, Timotej Verbovšek,Tomislav Popit
starts: 16.06.2023., Dubrovnik; ends: 19.06.2023., Koper/Ljubljana (SLO)
Mass movements represent important processes that shape the surface of the Earth. This trip will present an overview of recent and ancient mass movements in a variety of different settings: from recent slope processes to Mesozoic massive submarine platform collapses. Holocene: Tamar and Soča valleys are alpine valleys filled with Holocene rock falls, landslides, debris-flows, mudflows and fluvial deposits. They are forming talus slopes, alluvial and debris-flow fans, each of them with a complex history of sedimentation and erosion. Quaternary: Vipava valley represents a ‘’tectonic’’ topography with steeply deeping Mesozoic carbonates thrusted over gently-sloping Palaeogene flysch. This facilitated the formation of a complex Quaternary sedimentary slope system (debris-flows, scree, mud-flows, rock avalanches, rotational and translational landslide). At the Adriatic coast, ongoing cliff evolution will be observed along with Eocene carbonate megabeds. Mesozoic-Cenozoic: In the middle Soča Valley we will observe three ancient mass movement deposits. Carnian extensional blocky breccia with up to 300m large blocks was deposited in the toe-of-slope. Middle Jurassic basinal blocky limestone breccia that documents the transition to the compressional regime. Paleogene up to 250m thick massive blocky breccias related to thrusting and foreland basin formation.
Quaternary deposited of the island on Mljet
Croatia, 1 day, trip leaders: Ivan Razum, Petra Bajo
starts and ends: 16.06.2023., Dubrovnik
Formation of Quaternary sediments of the South Dalmatian Archipelago is tightly connected to the sea level oscillations. In one case sea level rise enabled lake formation in sinkholes and dolinas which were eventually submerged. The best examples of such sedimentary environments are Veliko and Malo jezero, situated in the Mljet national park. In this field trip, evolution and palaeoclimate records derived from the needle-like aragonites, of these submerged Marine lakes, will be shown. Furthermore, the areal distribution of some well-known Holocene eruptions will be discussed since in Veliko jezero are the northernmost findings of Avellino and Mercato eruptions. In the other case, during low sea level, the shelf was emerged which enabled aeolian transport of shelf sediments onto the Islands forming the aeolian sand deposits. In this field trip provenance and time of formation of Aeolian sands will be discussed, again with the emphasis on the tephra occurrence, which enabled high precision dating of the deposits.