The geology of Croatia has some Precambrian rocks mostly covered by younger sedimentary rocks and deformed or superimposed by tectonic activity. [1]
The country is split into two main onshore provinces, a smaller part of the Pannonian Basin and the larger Dinarides. These areas are very different.
The carbonate platform karst landscape of Croatia helped to create the weathering conditions to form bauxite, gypsum, clay, spilite, and limestone. [2]
The territory covers 56,594 square kilometres (21,851 square miles), consisting of 56,414 square kilometres (21,782 square miles) of land and 128 square kilometres (49 square miles) of water. [3] Elevation ranges from the mountains of the Dinaric Alps with the highest point of the Dinara peak at 1,831 metres (6,007 feet) near the border with Bosnia and Herzegovina in the south [3] to the shore of the Adriatic Sea which makes up its entire southwest border. Insular Croatia consists of over a thousand islands and islets varying in size, 48 of which permanently inhabited. The largest islands are Cres and Krk, [3] each of them having an area of around 405 square kilometres (156 square miles). [3] Karst topography makes up about half of Croatia and is especially prominent in the Dinaric Alps. [4] There are several deep caves in Croatia, 49 of which deeper than 250 m (820.21 ft), 14 of them deeper than 500 m (1,640.42 ft) and three deeper than 1,000 m (3,280.84 ft). Croatia's most famous lakes are the Plitvice lakes, a system of 16 lakes with waterfalls connecting them over dolomite and limestone cascades. The lakes are renowned for their distinctive colours, ranging from turquoise to mint green, grey or blue. [5]
The Pannonian Basin, or Carpathian Basin, is a large basin in Central Europe. The basin mostly is centered on the territory of modern Hungary, but also covers regions of western Slovakia, southeastern Poland, western Ukraine, western Romania, northern Serbia , the tip of northeast Croatia (Slavonia), northeastern Slovenia (Prekmurje), and eastern Austria. The Pannonian Basin is located within the arcuate Carpathian mountain chain that encircles the basin; this chain joins the Alpine mountain system to the west and the Dinaric mountain system to the southwest. [6] The basin is bounded by the intra-Carpathian mountain ranges and basement uplifts. [6] The Croatian sector of the basin has an area of 26,000 square kilometres (10,000 sq mi) and is broken into 4 main sub-basins – Sava, Drava, Northwest Croatia and Slavonija. [6] Evidence of the Carboniferous Variscan orogeny remains in Mt. Papuk in the east. [2] The basement is pre-Permian and is made of igneous, metamorphic and sedimentary rocks, with granites, gneisses, schists, and various low-grade metamorphic rocks and seem[ weasel words ] to have been affected by the Caledonian and Variscan orogenies. In the Pannonian area, Neogene material lies on top of older bedrock, emplaced on the periphery of the Paratethys Ocean. Neogene rocks include marl, conglomerate and sandstone as well as andesite and tuff. In the Drava River valley, the Neogene is seven kilometres thick. Many units contain lignite, and oil is found in lower units.
Croatia is mostly formed as a part of the Dinarides. The Dinaride region lies outside of the Pannonian Basin to the Southwest. The Dinarides is a mountain range in Southern and Southeastern Europe, separating the continental Balkan Peninsula from the Adriatic Sea. They stretch from Italy in the northwest through Slovenia, Croatia, Bosnia and Herzegovina, Serbia, Montenegro. [7] [8] The Dinaric Alps extend for approximately 645 kilometres (401 mi) along the western Balkan peninsula from the Julian Alps to the northwest in Italy, downwards to the Šar and Korab massif, where their direction changes. The Dinarides are a wide NW-SE fold-and-thrust belt stretching from southwestern Slovenia to Montenegro along the Adriatic coast of Croatia and inland.
The Dinarides formed by subduction and collision processes in the border zone between Europe and Adria tectonic plates. The Adria plate is still pushing the Cenozoic carbonate rocks up on top of the Adriatic lithosphere. Ultramafic ophiolite formed with the opening of a branch of the Tethys Ocean in the Cretaceous, followed by a magmatic activity. With continued continental subduction in the Paleogene, uplift began. The Adriatic Sea is a carbonate platform structural belt with Mesozoic-Paleogene flysch, chert, and limestone superimposed on it. Cenozoic Paleogene rocks unconformably overlie Cretaceous rocks with bauxite, coal and freshwater limestone, overlain by marine limestone from the Eocene and flysch formed in a trough between two carbonate platforms. Sandstone, marl, and limestone deposited in basins now beneath the Adriatic Sea during the Neogene.
The Adriatic Sea and the Po Valley are associated with a tectonic microplate—identified as the Apulian or Adriatic Plate that separated from the African Plate during the Mesozoic era. This separation began in the Middle and Late Triassic, when limestone began to be deposited in the area. Between the Norian and Late Cretaceous, the Adriatic and Apulia Carbonate Platforms formed as a thick series of carbonate sediments (dolomites and limestones), up to 8,000 metres (26,000 ft) deep. [9] Remnants of the former are found in the Adriatic Sea, as well as in the southern Alps and the Dinaric Alps, and remnants of the latter are seen as the Gargano Promontory and the Maiella mountain. In the Eocene and early Oligocene, the plate moved north and north-east, contributing to the Alpine orogeny (along with the African and Eurasian Plates' movements) via the tectonic uplift of the Dinarides and Alps. In the Late Oligocene, the motion was reversed and the Apennine Mountains' orogeny took place. [10] An unbroken zone of increased seismic activity borders the Adriatic Sea, with a belt of thrust faults generally oriented in the northeast–southwest direction on the east coast and the northeast–southwest normal faults in the Apennines, indicating an Adriatic counterclockwise rotation. [11]
An active 200-kilometre (120 mi) fault has been identified to the northwest of Dubrovnik, adding to the Dalmatian islands as the Eurasian Plate slides over the Adriatic microplate. Furthermore, the fault causes the Apennine peninsula's southern tip to move towards the opposite shore by about 0.4 centimetres (0.16 in) per year. If this movement continues, the seafloor will be completely consumed and the Adriatic Sea closed off in 50–70 million years. [12] In the Northern Adriatic, the coast of the Gulf of Trieste and western Istria is gradually subsiding, having sunk about 1.5 metres (4 ft 11 in) in the past two thousand years. [13] In the Middle Adriatic Basin, there is evidence of Permian volcanism in the area of Komiža on the island of Vis and the volcanic islands of Jabuka and Brusnik. [14] Earthquakes have been observed in the region since the earliest historical records. [11] A recent strong earthquake in the region was the 1979 Montenegro earthquake, measuring 7.0 on the Richter scale. [15] Historical earthquakes in the area include the 1627 Gargano peninsula and the 1667 Dubrovnik earthquakes, both followed by strong tsunamis. [16] In the last 600 years, fifteen tsunamis have occurred in the Adriatic Sea. [17]
Coal, oil, gas, and water are the leading natural resources in Croatia.
The geography of Croatia is defined by its location—it is described as a part of Central Europe and Southeast Europe, a part of the Balkans and Southern Europe. Croatia's territory covers 56,594 km2 (21,851 sq mi), making it the 127th largest country in the world. Bordered by Bosnia and Herzegovina and Serbia in the east, Slovenia in the west, Hungary in the north and Montenegro and the Adriatic Sea in the south, it lies mostly between latitudes 42° and 47° N and longitudes 13° and 20° E. Croatia's territorial waters encompass 18,981 square kilometres (7,329 sq mi) in a 12 nautical miles wide zone, and its internal waters located within the baseline cover an additional 12,498 square kilometres (4,826 sq mi).
The Alps form part of a Cenozoic orogenic belt of mountain chains, called the Alpide belt, that stretches through southern Europe and Asia from the Atlantic all the way to the Himalayas. This belt of mountain chains was formed during the Alpine orogeny. A gap in these mountain chains in central Europe separates the Alps from the Carpathians to the east. Orogeny took place continuously and tectonic subsidence has produced the gaps in between.
The Apennines or Apennine Mountains are a mountain range consisting of parallel smaller chains extending c. 1,200 km (750 mi) along the length of peninsular Italy. In the northwest they join with the Ligurian Alps at Altare. In the southwest they end at Reggio di Calabria, the coastal city at the tip of the peninsula. Since 2000 the Environment Ministry of Italy, following the recommendations of the Apennines Park of Europe Project, has been defining the Apennines System to include the mountains of north Sicily, for a total distance of 1,500 kilometres (930 mi). The system forms an arc enclosing the east side of the Ligurian and Tyrrhenian Seas.
The Dinaric Alps, also Dinarides, are a mountain range in Southern and Southcentral Europe, separating the continental Balkan Peninsula from the Adriatic Sea. They stretch from Italy in the northwest through Slovenia, Croatia, Bosnia and Herzegovina, Serbia, Montenegro, and Kosovo to Albania in the southeast.
The Alpine orogeny or Alpide orogeny is an orogenic phase in the Late Mesozoic (Eoalpine) and the current Cenozoic that has formed the mountain ranges of the Alpide belt.
Orjen is a transboundary Dinaric Mediterranean limestone mountain range, located between southernmost Bosnia and Herzegovina and southwestern Montenegro.
The Southern Alps are a geological subdivision of Alps that are found south of the Periadriatic Seam, a major geological faultzone across the Alps. The southern Alps contain almost the same area as the Southern Limestone Alps. The rocks of the southern Alps gradually go over in the Dinarides or Dinaric Alps to the south-east. In the south-west they disappear below recent sediments of the Po basin that are lying discordant on top of them.
A foreland basin is a structural basin that develops adjacent and parallel to a mountain belt. Foreland basins form because the immense mass created by crustal thickening associated with the evolution of a mountain belt causes the lithosphere to bend, by a process known as lithospheric flexure. The width and depth of the foreland basin is determined by the flexural rigidity of the underlying lithosphere, and the characteristics of the mountain belt. The foreland basin receives sediment that is eroded off the adjacent mountain belt, filling with thick sedimentary successions that thin away from the mountain belt. Foreland basins represent an endmember basin type, the other being rift basins. Space for sediments is provided by loading and downflexure to form foreland basins, in contrast to rift basins, where accommodation space is generated by lithospheric extension.
Croatia proper is one of the four historical regions of the Republic of Croatia, together with Dalmatia, Istria, and Slavonia. It is located between Slavonia in the east, the Adriatic Sea in the west, and Dalmatia to the south. The region is not officially defined, and its borders and extent are described differently by various sources. In contemporary geography, the terms Central Croatia and Mountainous Croatia are used to describe most of this area, the former referring to the northeastern part and the latter to the southwestern part; the far western part is known as the Croatian Littoral; likewise the terms 'Zagreb macroregion' and 'Rijeka macroregion' can be used instead. Croatia proper is the most significant economic area of the country, contributing well over 50% of Croatia's gross domestic product. The capital of the Republic of Croatia, Zagreb, is the largest city and most important economic centre in Croatia proper.
The Adriatic Sea is a body of water separating the Italian Peninsula from the Balkan Peninsula. The Adriatic is the northernmost arm of the Mediterranean Sea, extending from the Strait of Otranto to the northwest and the Po Valley. The countries with coasts on the Adriatic are Albania, Bosnia and Herzegovina, Croatia, Italy, Montenegro, and Slovenia.
The Western Carpathians are an arc-shaped mountain range, the northern branch of the Alpine-Himalayan fold and thrust system called the Alpide belt, which evolved during the Alpine orogeny. In particular, their pre-Cenozoic evolution is very similar to that of the Eastern Alps, and they constitute a transition between the Eastern Alps and the Eastern Carpathians.
Topography of Croatia is defined through three major geomorphological parts of the country. Those are the Pannonian Basin, the Dinaric Alps, and the Adriatic Basin. The largest part of Croatia consists of lowlands, with elevations of less than 200 metres above sea level recorded in 53.42% of the country. Bulk of the lowlands are found in the northern regions of the country, especially in Slavonia, itself a part of the Pannonian Basin plain. The plains are interspersed by the horst and graben structures, believed to break the Pannonian Sea surface as islands. The greatest concentration of ground at relatively high elevations is found in Lika and Gorski Kotar areas in the Dinaric Alps, but such areas are found in all regions of Croatia to some extent. The Dinaric Alps contain the highest mountain in Croatia—1,831-metre (6,007 ft) Dinara, as well as all other mountains in Croatia higher than 1,500 metres. Croatia's Adriatic Sea mainland coast is 1,777.3 kilometres long, while its 1,246 islands and islets encompass further 4,058 kilometres of coastline—the most indented coastline in the Mediterranean. Karst topography makes up about half of Croatia and is especially prominent in the Dinaric Alps, as well as throughout the coastal areas and the islands.
The Ombla is a short river in Croatia, northeast of Dubrovnik. Its course is approximately 30 metres long, and it empties into the Rijeka Dubrovačka, ria formed by the Adriatic Sea near Komolac in Dubrovnik-Neretva County. Rijeka Dubrovačka is actually a ria, a flooded river valley formed through changes in sea surface elevation on a geologic time scale. The river rises as a karst spring fed by groundwater replenished by Trebišnjica, which is an influent stream flowing in Popovo Polje, in the immediate hinterland of the Ombla. The elevation difference between the river's source and its mouth is just over 2 metres. The average discharge of the river is 24.1 cubic metres per second. The drainage basin of the Ombla encompasses 600 square kilometres and, besides the short surface course, includes only groundwater flow.
The High Karst Unit is a tectonic unit in the Balkans region of Southeastern Europe, part of the Dinaric Alps or Dinarides, that is characterized by typical high-altitude karst features. It is found in Slovenia, Croatia, Italy, Bosnia and Herzegovina, Kosovo, Serbia, Montenegro and Albania.
The main points that are discussed in the geology of Iran include the study of the geological and structural units or zones; stratigraphy; magmatism and igneous rocks; ophiolite series and ultramafic rocks; and orogenic events in Iran.
Hungary is in the Pannonian Basin in Central Europe, is surrounded by the Carpathians, Alps and Dinarides, but for the most part dominated by lowlands. Sixty-eight percent of the country is lowlands below 200 meters altitude. Hilly terrain covers 30% of the country, while mountains cover only 2%. The entire Pannonian Basin is in the Danube watershed.
The geology of Bosnia & Herzegovina is the study of rocks, minerals, water, landforms and geologic history in the country. The oldest rocks exposed at or near the surface date to the Paleozoic and the Precambrian geologic history of the region remains poorly understood. Complex assemblages of flysch, ophiolite, mélange and igneous plutons together with thick sedimentary units are a defining characteristic of the Dinaric Alps, also known as the Dinaride Mountains, which dominate much of the country's landscape.
The geology of Austria consists of Precambrian rocks and minerals together with younger marine sedimentary rocks uplifted by the Alpine orogeny.
The geology of Italy includes mountain ranges such as the Alps and the Apennines formed from the uplift of igneous and primarily marine sedimentary rocks all formed since the Paleozoic. Some active volcanoes are located in Insular Italy.
The Budoš Limestone is a geological formation in Montenegro, dating to 180 million years ago, and covering the Toarcian stage of the Jurassic Period. It has been considered an important setting in Balkan paleontology, as it represents a unique terrestrial setting with abundant plant material, one of the few know from the Toarcian of Europe. It is the regional equivalent to the Toarcian units of Spain such as the Turmiel Formation, units like the Azilal Formation of Morocco and others from the Mediterranean such as the Posidonia Beds of Greece and the Marne di Monte Serrone of Italy. In the Adriatic section, this unit is an equivalent of the Calcare di Sogno of north Italy, as well represents almost the same type of ecosystem recovered in the older (Pliensbachian) Rotzo Formation of the Venetian region, know also for its rich floral record.