THE GEOLOGICAL SIGNIFICANCE OF MAJSTORSKA CESTA – A HISTORICAL ROAD ON VELEBIT MT. WITH A SPECIAL REVIEW OF JURASSIC CARBONATE ROCKS

Kao povijesna velebitska prometnica Majstorska cesta uvrštena je na popis kulturnih dobara Republike Hrvatske 2007. godine, ponajprije stoga što je od izgradnje i puštanja u promet 1832. godine do danas očuvana u izvornoj trasi od Obrovca do lokaliteta Paljenik na sjeverozapadnome kraju mjesta Sveti Rok. Cesta leži na sedimentnim stijenama stratigrafskoga raspona od gornjega karbona do gornjega paleogena ili od 315 milijuna godina do oko 25 milijuna godina prije današnjice. To je raspon od 290 milijuna godina. Uglavnom su to izvrsno otkriveni vapnenci i dolomiti, a dijelom i klastične naslage. Spomenuti izdanci čine jedinstvenu reprezentativnu i znanstveno važnu prirodnu vrijednost u Hrvatskoj i na svjetskoj razini. Izgrađuju ne samo Velebit nego i sve karbonatne stijene krških Dinarida i kao takve jedinstven su prirodni geološki muzej važan kako za hrvatsko ozemlje, tako i za područja izgrađena od plitkomorskih karbonatnih stijena Sredozemlja u širemu geološkom smislu, tj. od Meksika i Kariba preko gorskih lanaca Atlasa, Pireneja, Alpa, Karpata, Dinarida, Helenida, Pontida, Taurida, Iranida do Himalaja. Najvažnija geološka znamenitost jest profil od prijevoja Mali Alan do Tulovih greda. Radi se o kontinuiranome profilu kroz jurske karbonatne stijene, tipskome za čitave krške Dinaride, u stratigrafskome rasponu od hetangija do sredine titona (raspon geološke starosti od 201,3 do oko 148 milijuna godina prije sadašnjosti), uključujući provodne fosile i kompletan stratigrafski slijed naslaga (stijena) te uvid u dodir jurskih sa starijim, trijaskim naslagama. Kao višedesetljetni istraživači Velebita (od 1962. godine do danas) željeli bismo upozoriti na potrebu zaštite spomenutih izdanaka stijena i jurske starosti. Geologija Majstorske ceste opisana je smjerom od Svetoga Roka prema Obrovcu.Majstorska Cesta is a historical road along Velebit Mt., NW of Sveti Rok, preserved in its original state since opening in 1832 and therefore added to the cultural heritage list of the Republic of Croatia in 2007. The road passes through sedimentary rocks ranging in age from Upper Carboniferous to Upper Paleogene, i.e. from 315 Ma until approx. 25 Ma old rocks (a time span of 290 Ma). These are mostly well exposed limestones and dolomites, sporadically clastics. Such rocks build up not only Velebit Mt., but also the entire Karst Dinarides. As such, they represent a unique natural museum important not only for the Croatian landscape, but also for all countries with shallow marine carbonates in the Mediterranean Region and wider, i.e. areas of Mexico, the Caribbean, along mountains like the Atlas, the Pyreneans, the Alps, the Carpathians, the Dinarides, the Helenides, the Pontides, the Taurides, the Iranides and the Himalayas. The most important geological feature is a section from Mali Alan Saddle to Tulove Grede Ridge. It is a continuous section along the Jurassic carbonates, typical for the Karst Dinarides, of stratigraphic period from Hettangian to Middle Tithonian (201.3-148 Ma), comprising the typical (index) fossils and complete geological rock sections, including contact between Jurassic and Triassic rocks. The authors have researched Velebit Mt. since 1962 until recent times, and thus recognize the necessity to preserve the described Jurassic rock outcrops. They describe the geology of Majstorska Cesta from Sv. Rok to Obrovac

Geoloy of the cave Park Grabovača and surrounding terrains proposed for its widening

Istraživano područje Pećinskoga parka Grabovača kod Peušića u Lici i njegovoga planiranog proširenja izgrađeno je pretežito od krednih karbonatnih stijena – vapnenaca, dolomita i dolomitnih breča te paleogensko-neogenskih vapnenačkih breča, razvrstani prema starosti u stratigrafske jedinice. Utvrđene su i izdvojene u donjoj kredi donjoaptski palorbitolinski i baćinelski vapnenci, gornjoaptske emerzijske breče i vapnenci, albske emerzijske breče, gornjoalbski vapnenci, prijelazni gornjoalbsko-donjocenomanski dolomiti i dolomitne breče, gornjokredni vapnenci raspona stariji cenoman – konijak, paleogensko-neogenske karbonatne breče i holocenske naplavine. U tektonskom pogledu to je blago borano područje sa strukturama dinarske orijentacije poremećenima kasnijim normalnim i reverznim rasjedima.Investigated area of the Cave Park Grabovača, near Perušić town in the Lika region, Croatia, is composed predominatly of Cretaceous carbonate rocks – limestones, dolomites and dolomte breccia, as well as of Paleogene-Neogene calcareous breccia. According to their facies characteristics the rocks are separated and described in following stratigraphic units: the Lower Aptian palorbitolina and bacinella limestones, the Upper Aptian emerged breccia and limestones, the Lower Albian emerged breccia, the Upper Albian limestones, transitional Upper Albian to the Lower Cenomanian dolomites and dolomite breccia, the Upper Cretaceous limestones, the Paleogene-Neogene calcareous breccia and the Holocene deposits. With regard to tectonic structures this terrain is composed of several anticlines and syclines of the Dinaric orientation i.e. with northwest to southeast striking. After folding during the Neogene those structures were disturbed by several reversed and numerous normal faults

Correlation of Quaternary Sediments and Tectonic Activity of the Eastern Part of the Drava River Depression

The Holocene, Upper Pleistocene and Middle Pleistocene sediments in the eastern part of the Drava depression the substratum of which is determined by the conditional EK marker Q\u27, are composed in the lower part mainly of silts and clays and in the upper part of sands. The thickest parts are about 400m. The composition of the transparent heavy minerals and the result of the paleontological treatment show that the sedimentation was in the lake or swamp with the origin of detritus from the metamorphic rocks and smaller quantity of older clastic sediments.The collected data show the quaternary tectonic activity after the sedimentation of the marker horizon Q\u27. In the area between the boundary faults of the valley, the faults of the system E.N.E. - W.S.W. (N.E. - S.W.) influenced directly the sedimentation and the folding . They were the consequence of the regional movements and stress strain behaviour of rock masses, which built the structures of the valley.As a result, the horizontal component of the left wing movement is visible along the diagonal system of faults. The vertical movements have also been determined. The greatest amplitudes were along the boundary South fault of the Drava valley, up to 350 m for the period of Middle and Upper Pleistocene, or 90 m for Upper Pleistocene only

Sedimentary bodies, forms and occurrences in the Tudorevo and Mirovo glacial deposits of northern Velebit (Croatia)

A small glacier of cirque-valley type existed during the Late Pleistocene Würm Glacial in the Tudorevo and Mirovo karst valleys of Northern Velebit. Its source was in Tudorevo, and it moved through Dundović Mirovo and Bilensko Mirovo to Baričević Dolac, shaping U-valleys around 4 km in length. After melting, glacial deposits remained, composed of chaotic and unsorted till, composed of carbonate sand, debris and sub-rounded clasts, cobbles and blocks of predominantly Middle Jurassic and subordinately Lower Jurassic carbonate rocks. In Dundović Mirovo and Bilensko Mirovo, where the largest masses of glacial deposits occur, terminal and recessional moraines can be found over the ground moraine, as well as some other features, mostly drumlins (drumlin field), eskers, erratic blocks, kettle holes and striations. Some erratics have been transported for more than 4 km from their primary outcrops, e.g. clasts of Lower Jurassic Toarcian Spotty limestone. A terminal moraine was deposited between Bilensko Mirovo and Baričević Dolac, perpendicular to the glaciated U-valley and it forms the Bilo hill, the northern and southern foothills of which are composed partly of glaciofluvial deposits. Between Tudorevo and Mirovo, a recessional moraine occurs above the ground moraine. The glacier was subject to polyphase melting and freezing, and the youngest freezing events may be related to cirques in Tudorevo. During melting events, glacier lakes are supposed to have existed, initially in the Baričević Dolac, later in Mirovo area and finally in Tudorevo. These discharged into the karst underground by percolation through till and by erosion to the karstified underlying Middle Jurassic carbonates

Selection of the most appropriate interpolation method for sandstone reservoirs in the Kloštar oil and gas field

The distribution of porosity data collected at the Kloštar field is analysed. This field is located in the north-western part of the Sava depression, and represents one of the most long-standing fields with respect to oil production in Croatia, where production has been on going for mo re than 50 years. Several reservoirs of very diverse lithology and stratigraphic age have been discovered. The oldest reservoirs (with minor oil re serves) occur in basement rocks of the Tertiary system (in formally named the »temeljno gorje«), then in Badenian coarse-grained clastics, as well as sandstones of Panonian and Pontian ages. Major reservoirs, with respect to size, number and volume, are located in sediments of the Upper Pannonian and Lower Pontian. These are medium-grained sandstones, mostly quartz-mica grains, mutually separated by mar ls. Reservoirs of Lower Pontian age occur within whole structures (anticlines) at Kloštar, while the Upper Pannonian has been developed only in the south–west part. Earlier studies on the reservoirs have included only several measured values of reservoir porosity. These values have not been mapped, but only a unique average value, characteristic for the whole reservoir was calculated. Reinterpretation of e-logs in creased the number of in put values to 20 points of data. Rules are determined for the distribution of porosities in the largest reservoir of the Lower Pontian named »T«. These re ularities can be translated to the other sandstone reservoirs. Several interpolation methods were selected (inverse distance, nearest neighbourhood and moving average), with special emphasis on kriging. The interpolated maps are different. Based on a comparison of iso porosity, lines, sha es, and cross-validation results, kriging was evaluated as the most appropriate method for porosity interpolation

Depositional conditions during Pliocene and Pleistocene in Northern Adriatic and possible lithostratigraphic division of these rocks

Na području Sjevernog Jadrana nalaze se neogenske i kvartarne naslage razmjerno velikih debljina. Odlagane su u nekoliko depresija unutar Jadranskoga bazena, od kojih je najveća Padska. Današnje granice te depresije pružaju se unutar talijanskog i hrvatskog podmorja Jadrana gdje su pliocenske i pleistocenske sekvencije hemipelagičkog taloženja prekidane progradacijama delte rijeke Po, a u manjoj mjeri i rijeka Adige i Piave. Ti sedimenti sadrže važna ležišta značajnih količina prirodnog plina, te su dobro istraženi na području više talijanskih i hrvatskih plinskih polja dubokim bušotinama, kao i nizom različitih metoda snimanja podzemlja, uglavnom refleksijskom seizmikom. Slijed pliocenskih i pleistocenskih sedimenata može debljinom doseći i 6 000 m, a podijeljen je u odgovarajući sustav litostratigrafskih jedinica ranga formacija. Dok su na talijanskoj strani kenozojske naslage do mezozojske podine razrađene na dvanaest formacija, na hrvatskoj strani do sada je izdvojena samo jedna. To je formacija Susak koja obuhvaća sve stijene unutar kenozoika. Stoga se u hrvatskom dijelu Sjevernoga Jadrana predlaže uvođenje sljedećih litostratigrafskih jedinica u rangu formacija: formacija Dinaridi (mezozojske stijene), formacija Susak (paleocenske-miocenske stijene), formacija Istra (pliocenske naslage) i formacija Ivana (pleistocenske i holocenske naslage).In the area of Northern Adriatic Neogene and Quaternary sediments have relatively large thicknesses. Those are deposited in some depressions located inside Adriatic Basin, where is the largest Po Depression. Recent borders of Po Depression are located in Italian and Croatian offshore where hemipelagic sequences of Pliocene and Pleistocene were interrupted by Po palaeodelta progradations, and to a lesser extent of Adige and Piave Rivers. These sediments include important reservoirs with significant quantities of hydrocarbon gas, and it is why they are well explored in areas of Italian and Croatian gas fields by deep wells as well as different methods for subsurface imaging, mostly by reflective seismic. Sequence of Pliocene and Pleistocene sediments can reach thickness of 6 000 m, and it is divided in lithostratigraphic system with units in rank of formation. On Italian side Cenozoic sediments up to Mesozoic basement are divided in twelve formations, but on Croatian side has been described only one formation. It is Susak Formation that encompasses all Cenozoic rocks. It is why in Croatian part of Northern Adriatic in proposed introducing of the following lithostratigraphic units 8in rank of formation): Dinaridi Formation (Mesozoic rocks), Susak Formation (Palaeocene-Miocene rocks), Istra Formation (Pliocene sediments) and Ivana Formation (Pleistocene and Holocene sediments)

Depositional conditions during Pliocene and Pleistocene in Northern Adriatic and possible lithostratigraphic division of these rocks

Na području Sjevernog Jadrana nalaze se neogenske i kvartarne naslage razmjerno velikih debljina. Odlagane su u nekoliko depresija unutar Jadranskoga bazena, od kojih je najveća Padska. Današnje granice te depresije pružaju se unutar talijanskog i hrvatskog podmorja Jadrana gdje su pliocenske i pleistocenske sekvencije hemipelagičkog taloženja prekidane progradacijama delte rijeke Po, a u manjoj mjeri i rijeka Adige i Piave. Ti sedimenti sadrže važna ležišta značajnih količina prirodnog plina, te su dobro istraženi na području više talijanskih i hrvatskih plinskih polja dubokim bušotinama, kao i nizom različitih metoda snimanja podzemlja, uglavnom refleksijskom seizmikom. Slijed pliocenskih i pleistocenskih sedimenata može debljinom doseći i 6 000 m, a podijeljen je u odgovarajući sustav litostratigrafskih jedinica ranga formacija. Dok su na talijanskoj strani kenozojske naslage do mezozojske podine razrađene na dvanaest formacija, na hrvatskoj strani do sada je izdvojena samo jedna. To je formacija Susak koja obuhvaća sve stijene unutar kenozoika. Stoga se u hrvatskom dijelu Sjevernoga Jadrana predlaže uvođenje sljedećih litostratigrafskih jedinica u rangu formacija: formacija Dinaridi (mezozojske stijene), formacija Susak (paleocenske-miocenske stijene), formacija Istra (pliocenske naslage) i formacija Ivana (pleistocenske i holocenske naslage).In the area of Northern Adriatic Neogene and Quaternary sediments have relatively large thicknesses. Those are deposited in some depressions located inside Adriatic Basin, where is the largest Po Depression. Recent borders of Po Depression are located in Italian and Croatian offshore where hemipelagic sequences of Pliocene and Pleistocene were interrupted by Po palaeodelta progradations, and to a lesser extent of Adige and Piave Rivers. These sediments include important reservoirs with significant quantities of hydrocarbon gas, and it is why they are well explored in areas of Italian and Croatian gas fields by deep wells as well as different methods for subsurface imaging, mostly by reflective seismic. Sequence of Pliocene and Pleistocene sediments can reach thickness of 6 000 m, and it is divided in lithostratigraphic system with units in rank of formation. On Italian side Cenozoic sediments up to Mesozoic basement are divided in twelve formations, but on Croatian side has been described only one formation. It is Susak Formation that encompasses all Cenozoic rocks. It is why in Croatian part of Northern Adriatic in proposed introducing of the following lithostratigraphic units 8in rank of formation): Dinaridi Formation (Mesozoic rocks), Susak Formation (Palaeocene-Miocene rocks), Istra Formation (Pliocene sediments) and Ivana Formation (Pleistocene and Holocene sediments)

THE CHARACTERISTICS OF THE PRODUCTION AND PROCESSING OF OIL AND NATURAL GAS IN CROATIA FROM 2000 TO 2014

U radu su analizirane značajke pridobivanja i preradbe nafte, kondenzata i prirodnoga plina u Republici Hrvatskoj od 2000. do kraja 2014. godine. Iznos bilančnih (eksploatacijskih) rezervi nafte i kondenzata kreće se od 9330,92 × 103 m3 (2005. godina) do 13 471,08 × 103 m3 u 2013. godini, dok količine njihova pridobivanja postupno opadaju od 1332,61 × 103 m3 na 639,96 × 103 m3. Odnos pridobivanja i rezervi postupno opada, što znači da blagi porast rezervi uopće ne utječe na količine crpljenja. Eksploatacijske rezerve prirodnoga plina tijekom promatranoga razdoblja uvelike osciliraju. Najveće su bile 2007. godine (40 919,70 × 106 m3), a najmanje 2014. godine (17 932,98 × 106 m3). Za razliku od tekućih ugljikovodika, odnos pridobivenih i eksploatacijskih količina raste i najveći je 2014. godine. Svekolike potrebe u Hrvatskoj za naftom (prikazano kao ukupna potrošnja sirove nafte) u 2013. bile su 3032,8 × 103 m3 te plina 2809,90 × 106 m3. Zanimljiv je podatak da potrošnja nafte brzo opada, što je povoljan trend sa stajališta emisije stakleničkih plinova. Dio se podmiruje iz vlastite eksploatacije, međutim ovisnost o uvozu nafte i prirodnoga plina i dalje je evidentna i kreće se od 75 % do 84 % (nafta), odnosno od 28 % do 46 % (prirodni plin) i to se jače ne mijenja. Količine prerađenih ugljikovodika postupno opadaju, poglavito motornoga benzina i loživoga ulja, dok dizelskoga goriva ostaju približno jednake. Iznimno su važna daljnja istraživanja te razvoj eksploatacije nafte i plina, poglavito ulaganjem u educiranje kadrova i nove tehnologije.This research analyzes the characteristics of the production and processing of oil, condensates and natural gas in the Republic of Croatia starting from 2000, until the end of 2014. Amounts of balance sheet (exploitable) reserves of oil and condensates ranges from 9330,92 × 103 m3 in 2005, to 13 471,08 × 103 m3 in 2013, while extracted amounts are gradually declining from 1332,61 × 103 m3 to 639,96 × 103 m3. The ratio of extracted amounts and reserves is gradually declining, meaning that a slight increase in reserves does not affect the extracted amounts. Exploitable reserves of natural gas during the observed period fluctuate greatly. Being peaked in 2007, at 40,919.70 × 106 m3, they reached a low in 2014, at 17,932.98 × 106 m3. Unlike liquid hydrocarbons, the ratio of extracted and exploitable amounts is growing and peaked in 2014. Overall energy demands for oil in Croatia (shown as total consumption of crude oil) amounted to 3032,8 × 103 m3 in 2013, while demands for natural gas amounted to 2809,90 × 106 m3. It is interesting to note that the consumption of oil is rapidly declining, which is a favorable trend from the standpoint of reducing emissions of greenhouse gases. While needs are partly covered by domestic exploitation, the dependence on imports of oil and natural gas is still evident and ranges from 75% to 84% for oil and 28% to 46% for natural gas, without major changes to the trend. The amounts of processed hydrocarbons are declining gradually, especially motor gasoline and fuel oil, while diesel fuel amounts remain mostly the same. Further research as well as development of the exploitation of oil and natural gas is of paramount importance, especially by investing in cadre education and new technologies