Structural analysis of Mesozoic and Cenozoic deformational structures in western part of Papuk Mt. : master's thesis

Strukturno-geološka istraživanja načinjena u okviru ovog diplomskog rada su obuhvatila područje zapadnog Papuka između naselja Voćin, Kamenska, Pakrac i Daruvar. To je područje izgrađeno većinom od predmezozojskih magmatskih i metamorfnih stijena. Permsko-mezozojski klastični i karbonatni sedimenati izgrađuju krajnje zapadne te djelomično sjeverne obronke ovog dijela Papuka, a neogenske naslage Panonskog bazena gotovo isključivo njegove rubne dijelove, uz manje lokalne pojave u središnjem djelu. Strukturna analiza mezozojskih i kenozojskih deformacijskih struktura provedena je s ciljem definiranja njihovih tipova, opisa njihovim morfoloških značajki, orijentacije i prostornog rasporeda te i njihova pridruživanja odgovarajućim deformacijskim događajima. Megaskopske prebačene bore u permsko-mezozojskim naslagama determinirane su kao strukture nastale za vrijeme kasnokrednog do paleogenskog kompresijskog događaja (D1). Njihova izvorno sjeveroistočna vergencija interpretirana je kao posljedica deformacija nastalih na gornjoj ploči tijekom završnog stadija u fazi kolizije između Jadranske ploče (donja ploča) i Tisije (gornja ploča) u Savskoj suturnoj zoni. U kasnijem tektonskom razvoju za vrijeme miocena, tijekom lateralne ekstruzije i rotacije Tisija-Dacija tektonskog mega-bloka u smjeru kazaljke na satu, ove strukture su najvjerojatnije također zarotirane za oko 40° u smjeru kazaljke na satu pa su na taj način dovedene u približno današnji položaj s pružanjem S – J. Megaskopske bore i kogenetski reversni rasjedi sjeverne vergencije i pružanja I – Z kojim su deformirane neogenske naslage, u ovom su radu interpretirani kao deformacijske strukture nastale u kompresijskoj fazi bazenske inverzije (D2), a za koju se pretpostavlja da je započela na prijelazu neogena u pliocen i kvartar. Ova deformacijska faza zahvatila je i već ranije borane permsko-mezozojske stijene u zapadnom dijelu Papuka, tako da su one dvostruko borane. Interpretirani 2D refleksijski seizmički profili potvrđuju postojanje kasnomiocenske do recentne kompresijske tektonike koja se odražava u boranim i rasjednutim naslagama miocena i plio-kvartara na sjevernom i na zapadnom rubu Papuka, ali također i ukazuju na ekstenzijsku deformacijsku fazu aktivnu u vrijeme starijeg miocena.Structural-geological investigations of this diploma thesis cover the area of the western Papuk Mt. between Voćin, Kamenska, Pakrac and Daruvar settlements. This area is built mostly of pre-Mesozoic magmatic and metamorphic rocks. Permian-Mesozoic clastic and carbonate sediments cover the westernmost and partly the northern slope of this part of the Papuk Mt., while the Neogene deposits of the Pannonian Basin almost exclusively built up its marginal parts, with only minor and local occurrences in the central part. Structural analysis of Mesozoic and Cenozoic deformational structures was done with the aim of defining their types, describing their morphological features, orientation and spatial distribution, as well as to attribute their genesis with particular deformation events. Megascopic overturned folds in Permian-Mesozoic deposits were determined as structures formed during the Late Cretaceous to Paleogene compressional event (D1). Their original northeastern vergence was interpreted as related to the backthrust propagation within the Tisza mega-block (upper plate) during the final collision with the Adria (lower plate) in the Sava Suture Zone. During the Miocene lateral extrusion and clockwise rotation of Tisa-Dacia tectonic mega-block, these structures are most likely also rotated by c. 40° in a clockwise sense and thus brought to approximately present-day position and the N – S strike. Megascopic E – W striking folds and cogenetic reverse faults with the northern vergence that are documented to deform Neogene deposits were interpreted in this thesis as deformational structures formed during the compression phase of the Pannonian basin inversion (D2), assumed to start in latest Neogene to earliest Pliocene time. This deformation phase also affected previously folded Permian-Mesozoic rocks in the westernmost part of the Papuk Mt., which resulted in superposed folding in these rocks. Interpreted 2D reflection seismic sections confirm the existence of the Late Miocene to recent compressional tectonics, which is reflected in folded and faulted upper Miocene and Quaternary deposits at the northern and western margins of the Papuk Mt., but also indicate the extensional deformation phase active during the Early Miocene

Structural analysis of Mesozoic and Cenozoic deformational structures in western part of Papuk Mt. : master's thesis

Strukturno-geološka istraživanja načinjena u okviru ovog diplomskog rada su obuhvatila područje zapadnog Papuka između naselja Voćin, Kamenska, Pakrac i Daruvar. To je područje izgrađeno većinom od predmezozojskih magmatskih i metamorfnih stijena. Permsko-mezozojski klastični i karbonatni sedimenati izgrađuju krajnje zapadne te djelomično sjeverne obronke ovog dijela Papuka, a neogenske naslage Panonskog bazena gotovo isključivo njegove rubne dijelove, uz manje lokalne pojave u središnjem djelu. Strukturna analiza mezozojskih i kenozojskih deformacijskih struktura provedena je s ciljem definiranja njihovih tipova, opisa njihovim morfoloških značajki, orijentacije i prostornog rasporeda te i njihova pridruživanja odgovarajućim deformacijskim događajima. Megaskopske prebačene bore u permsko-mezozojskim naslagama determinirane su kao strukture nastale za vrijeme kasnokrednog do paleogenskog kompresijskog događaja (D1). Njihova izvorno sjeveroistočna vergencija interpretirana je kao posljedica deformacija nastalih na gornjoj ploči tijekom završnog stadija u fazi kolizije između Jadranske ploče (donja ploča) i Tisije (gornja ploča) u Savskoj suturnoj zoni. U kasnijem tektonskom razvoju za vrijeme miocena, tijekom lateralne ekstruzije i rotacije Tisija-Dacija tektonskog mega-bloka u smjeru kazaljke na satu, ove strukture su najvjerojatnije također zarotirane za oko 40° u smjeru kazaljke na satu pa su na taj način dovedene u približno današnji položaj s pružanjem S – J. Megaskopske bore i kogenetski reversni rasjedi sjeverne vergencije i pružanja I – Z kojim su deformirane neogenske naslage, u ovom su radu interpretirani kao deformacijske strukture nastale u kompresijskoj fazi bazenske inverzije (D2), a za koju se pretpostavlja da je započela na prijelazu neogena u pliocen i kvartar. Ova deformacijska faza zahvatila je i već ranije borane permsko-mezozojske stijene u zapadnom dijelu Papuka, tako da su one dvostruko borane. Interpretirani 2D refleksijski seizmički profili potvrđuju postojanje kasnomiocenske do recentne kompresijske tektonike koja se odražava u boranim i rasjednutim naslagama miocena i plio-kvartara na sjevernom i na zapadnom rubu Papuka, ali također i ukazuju na ekstenzijsku deformacijsku fazu aktivnu u vrijeme starijeg miocena.Structural-geological investigations of this diploma thesis cover the area of the western Papuk Mt. between Voćin, Kamenska, Pakrac and Daruvar settlements. This area is built mostly of pre-Mesozoic magmatic and metamorphic rocks. Permian-Mesozoic clastic and carbonate sediments cover the westernmost and partly the northern slope of this part of the Papuk Mt., while the Neogene deposits of the Pannonian Basin almost exclusively built up its marginal parts, with only minor and local occurrences in the central part. Structural analysis of Mesozoic and Cenozoic deformational structures was done with the aim of defining their types, describing their morphological features, orientation and spatial distribution, as well as to attribute their genesis with particular deformation events. Megascopic overturned folds in Permian-Mesozoic deposits were determined as structures formed during the Late Cretaceous to Paleogene compressional event (D1). Their original northeastern vergence was interpreted as related to the backthrust propagation within the Tisza mega-block (upper plate) during the final collision with the Adria (lower plate) in the Sava Suture Zone. During the Miocene lateral extrusion and clockwise rotation of Tisa-Dacia tectonic mega-block, these structures are most likely also rotated by c. 40° in a clockwise sense and thus brought to approximately present-day position and the N – S strike. Megascopic E – W striking folds and cogenetic reverse faults with the northern vergence that are documented to deform Neogene deposits were interpreted in this thesis as deformational structures formed during the compression phase of the Pannonian basin inversion (D2), assumed to start in latest Neogene to earliest Pliocene time. This deformation phase also affected previously folded Permian-Mesozoic rocks in the westernmost part of the Papuk Mt., which resulted in superposed folding in these rocks. Interpreted 2D reflection seismic sections confirm the existence of the Late Miocene to recent compressional tectonics, which is reflected in folded and faulted upper Miocene and Quaternary deposits at the northern and western margins of the Papuk Mt., but also indicate the extensional deformation phase active during the Early Miocene

Structural analysis of Mesozoic and Cenozoic deformational structures in western part of Papuk Mt. : master's thesis

Strukturno-geološka istraživanja načinjena u okviru ovog diplomskog rada su obuhvatila područje zapadnog Papuka između naselja Voćin, Kamenska, Pakrac i Daruvar. To je područje izgrađeno većinom od predmezozojskih magmatskih i metamorfnih stijena. Permsko-mezozojski klastični i karbonatni sedimenati izgrađuju krajnje zapadne te djelomično sjeverne obronke ovog dijela Papuka, a neogenske naslage Panonskog bazena gotovo isključivo njegove rubne dijelove, uz manje lokalne pojave u središnjem djelu. Strukturna analiza mezozojskih i kenozojskih deformacijskih struktura provedena je s ciljem definiranja njihovih tipova, opisa njihovim morfoloških značajki, orijentacije i prostornog rasporeda te i njihova pridruživanja odgovarajućim deformacijskim događajima. Megaskopske prebačene bore u permsko-mezozojskim naslagama determinirane su kao strukture nastale za vrijeme kasnokrednog do paleogenskog kompresijskog događaja (D1). Njihova izvorno sjeveroistočna vergencija interpretirana je kao posljedica deformacija nastalih na gornjoj ploči tijekom završnog stadija u fazi kolizije između Jadranske ploče (donja ploča) i Tisije (gornja ploča) u Savskoj suturnoj zoni. U kasnijem tektonskom razvoju za vrijeme miocena, tijekom lateralne ekstruzije i rotacije Tisija-Dacija tektonskog mega-bloka u smjeru kazaljke na satu, ove strukture su najvjerojatnije također zarotirane za oko 40° u smjeru kazaljke na satu pa su na taj način dovedene u približno današnji položaj s pružanjem S – J. Megaskopske bore i kogenetski reversni rasjedi sjeverne vergencije i pružanja I – Z kojim su deformirane neogenske naslage, u ovom su radu interpretirani kao deformacijske strukture nastale u kompresijskoj fazi bazenske inverzije (D2), a za koju se pretpostavlja da je započela na prijelazu neogena u pliocen i kvartar. Ova deformacijska faza zahvatila je i već ranije borane permsko-mezozojske stijene u zapadnom dijelu Papuka, tako da su one dvostruko borane. Interpretirani 2D refleksijski seizmički profili potvrđuju postojanje kasnomiocenske do recentne kompresijske tektonike koja se odražava u boranim i rasjednutim naslagama miocena i plio-kvartara na sjevernom i na zapadnom rubu Papuka, ali također i ukazuju na ekstenzijsku deformacijsku fazu aktivnu u vrijeme starijeg miocena.Structural-geological investigations of this diploma thesis cover the area of the western Papuk Mt. between Voćin, Kamenska, Pakrac and Daruvar settlements. This area is built mostly of pre-Mesozoic magmatic and metamorphic rocks. Permian-Mesozoic clastic and carbonate sediments cover the westernmost and partly the northern slope of this part of the Papuk Mt., while the Neogene deposits of the Pannonian Basin almost exclusively built up its marginal parts, with only minor and local occurrences in the central part. Structural analysis of Mesozoic and Cenozoic deformational structures was done with the aim of defining their types, describing their morphological features, orientation and spatial distribution, as well as to attribute their genesis with particular deformation events. Megascopic overturned folds in Permian-Mesozoic deposits were determined as structures formed during the Late Cretaceous to Paleogene compressional event (D1). Their original northeastern vergence was interpreted as related to the backthrust propagation within the Tisza mega-block (upper plate) during the final collision with the Adria (lower plate) in the Sava Suture Zone. During the Miocene lateral extrusion and clockwise rotation of Tisa-Dacia tectonic mega-block, these structures are most likely also rotated by c. 40° in a clockwise sense and thus brought to approximately present-day position and the N – S strike. Megascopic E – W striking folds and cogenetic reverse faults with the northern vergence that are documented to deform Neogene deposits were interpreted in this thesis as deformational structures formed during the compression phase of the Pannonian basin inversion (D2), assumed to start in latest Neogene to earliest Pliocene time. This deformation phase also affected previously folded Permian-Mesozoic rocks in the westernmost part of the Papuk Mt., which resulted in superposed folding in these rocks. Interpreted 2D reflection seismic sections confirm the existence of the Late Miocene to recent compressional tectonics, which is reflected in folded and faulted upper Miocene and Quaternary deposits at the northern and western margins of the Papuk Mt., but also indicate the extensional deformation phase active during the Early Miocene

Od grebena do bazena – progradacija plitkovodnih karbonata preko srednjetrijaskog riftnog bazena sjeverozapadne Hrvatske (Ivanščica, SZ Hrvatska)

The NW part of Croatia represents a tectonically complex area at the junction of the Dinarides and the Southern Alps. In Očura Quarry on Ivanščica Mt. there is 34 m thick section composed of volcanic, volcaniclastic and carbonate rocks that can be divided into three parts. The lower interval (7 m) is composed of dominantly basaltic rocks (SiO2 = 43–51 wt%). In the basal part glomeroporpyric basalt is followed by basaltic autoclastic breccia. The second interval (7–19 m) is composed of cm–dm irregularly and wavy bedded calcarenites, occasionally coarsening upward, with lithoclasts varying in size from fine sand up to fine breccia. Carbonate lithoclasts are mostly micritic limestones – biomicrite, pelmicrite, pelsparite, intrasparite, also bioclasts of bivalves, crinoids, ammonoids, brachiopods, and gastropods. Two types of basaltic lithoclasts are present in the dominantly calcarenite interval, one with the porphyric to glomeroporphyric texture, similar to the basalts of the lower part; and the other type completely hyaline. Lithoclasts are cemented by sparry calcite. In the coarser varieties lithoclasts are the same, with the only difference in the matrix found between the clasts, that is composed of fine calcarenites with basaltic lithoclasts. Calcarenites are interlayered by thin layers of biomicrites with filaments and radiolarians, and thin layers of fine to coarse ash vitriclastic tuffs. In the middle of this interval around 1.5 m thick matrix supported breccia occurs with limestone and basaltic lithoclasts. Third interval of the section (19–34 m) is composed of extremely unsorted breccia with slump texture. Clasts of limestones, calcarenites, and subordinary basalts are supported by fine grained matrix of carbonate and basaltic particles. Abundant framestone clasts are present in the breccia, containing complex reef community, dominating of sponge Celyphia zoldana, with other microorganisms of uncertain taxonomy Plexoramea cerebriformis and Olangocoelia otti, and others. Generally in this interval carbonate material is predominant over basaltic lithoclasts. The investigated section represents sedimentation in the deeper marine environment near the steep edge of the carbonate platform and reef. Basalts found at the base of the section present effusions in the marine areas, and their fragmentation and reworking. A thick interval of calcarenites with basaltic lithoclasts is formed by shedding of the carbonate material from the nearby platform to the pelagic/basinal areas, indicated by the pelagic limestone interlayers. Chaotic breccia with meter sized fragments of reefal limestones indicates a more proximal position to the shallow marine area from which these clasts were derived. Slump texture emphasizes gravitational processes. The general trend of coarsening upward, as well as the predominance of the framestone clasts in the breccias imply the progradation of the platform over the basinal areas. Therefore, indicating a relatively rapid closure of the basinal/pelagic areas and cessation of the extensional tectonics related to the Neotethyan rifting. One sample (OD-15A) bears conodonts Gladigondolella tethydis (Huckriede), Paragondolella trammeri (Kozur), that indicate Illyrian to Lower Longobardian age of this section. That age is in the accordance with the regional cessation of the volcanic activity in the Ladinian, and progradation of the platforms over the basinal areas that were filled with various clastic, volcaniclastic, silicious and pelagic sediments

Od grebena do bazena – progradacija plitkovodnih karbonata preko srednjetrijaskog riftnog bazena sjeverozapadne Hrvatske (Ivanščica, SZ Hrvatska)

The NW part of Croatia represents a tectonically complex area at the junction of the Dinarides and the Southern Alps. In Očura Quarry on Ivanščica Mt. there is 34 m thick section composed of volcanic, volcaniclastic and carbonate rocks that can be divided into three parts. The lower interval (7 m) is composed of dominantly basaltic rocks (SiO2 = 43–51 wt%). In the basal part glomeroporpyric basalt is followed by basaltic autoclastic breccia. The second interval (7–19 m) is composed of cm–dm irregularly and wavy bedded calcarenites, occasionally coarsening upward, with lithoclasts varying in size from fine sand up to fine breccia. Carbonate lithoclasts are mostly micritic limestones – biomicrite, pelmicrite, pelsparite, intrasparite, also bioclasts of bivalves, crinoids, ammonoids, brachiopods, and gastropods. Two types of basaltic lithoclasts are present in the dominantly calcarenite interval, one with the porphyric to glomeroporphyric texture, similar to the basalts of the lower part; and the other type completely hyaline. Lithoclasts are cemented by sparry calcite. In the coarser varieties lithoclasts are the same, with the only difference in the matrix found between the clasts, that is composed of fine calcarenites with basaltic lithoclasts. Calcarenites are interlayered by thin layers of biomicrites with filaments and radiolarians, and thin layers of fine to coarse ash vitriclastic tuffs. In the middle of this interval around 1.5 m thick matrix supported breccia occurs with limestone and basaltic lithoclasts. Third interval of the section (19–34 m) is composed of extremely unsorted breccia with slump texture. Clasts of limestones, calcarenites, and subordinary basalts are supported by fine grained matrix of carbonate and basaltic particles. Abundant framestone clasts are present in the breccia, containing complex reef community, dominating of sponge Celyphia zoldana, with other microorganisms of uncertain taxonomy Plexoramea cerebriformis and Olangocoelia otti, and others. Generally in this interval carbonate material is predominant over basaltic lithoclasts. The investigated section represents sedimentation in the deeper marine environment near the steep edge of the carbonate platform and reef. Basalts found at the base of the section present effusions in the marine areas, and their fragmentation and reworking. A thick interval of calcarenites with basaltic lithoclasts is formed by shedding of the carbonate material from the nearby platform to the pelagic/basinal areas, indicated by the pelagic limestone interlayers. Chaotic breccia with meter sized fragments of reefal limestones indicates a more proximal position to the shallow marine area from which these clasts were derived. Slump texture emphasizes gravitational processes. The general trend of coarsening upward, as well as the predominance of the framestone clasts in the breccias imply the progradation of the platform over the basinal areas. Therefore, indicating a relatively rapid closure of the basinal/pelagic areas and cessation of the extensional tectonics related to the Neotethyan rifting. One sample (OD-15A) bears conodonts Gladigondolella tethydis (Huckriede), Paragondolella trammeri (Kozur), that indicate Illyrian to Lower Longobardian age of this section. That age is in the accordance with the regional cessation of the volcanic activity in the Ladinian, and progradation of the platforms over the basinal areas that were filled with various clastic, volcaniclastic, silicious and pelagic sediments

Middle Triassic syn-rift rhyolites and rhyolitic ignimbrites on the north-east margin of Adria (NE Slovenia, NW Croatia): possible source of rhyolitic tuffs (Pietra Verde) in the wider Dinaride area

Srednjotrijaske magmatske i piroklastične stijene u području Adrie, odnosno šireg područja Dinarida i Južnih Alpa su česta pojava. To su uglavnom bazične magmatske stijene: bazalti, andezit-bazalti, rjeđe andeziti te riolitne piroklastične stijene (Pietra Verde). Izvorište riolitnog piroklastičnog detritusa u širem području Dinarida do sada nije jasno određeno. Trijaske kisele magmatske stijene poznate su samo na SZ rubu Adrie. U okviru projekta GOST istraživane su ove stijene na uzvisini Sv. Junger u SI Sloveniji, koje su determinirane kao rioliti, te na području Margečana na uzvisinama Gradišće, Hamec, Oštra Gorica i Sv. Duh u SZ Hrvatskoj, koje su određene kao riolitni ignimbriti. Rioliti imaju porfirnu strukturu i homogenu teksturu. Fenokristali su plagioklas i K-feldspat, a osnova je leukokratna, devitrificirana u sitnozrnati kvarc, feldspat i bijeli tinjac. Fenokristali plagioklasa su alterirani u sitnolistićavi bijeli tinjac i minerale glina. K-feldspat je svijež s alteriranim inkluzijama. Riolitni ignimbriti imaju debljinu veću od 100 m. Izdvajaju se (1) čvrsti laminirani folijativni tok riolitnih ignimbrita i (2) čvrsti masivni riolitni ignimbriti. Folijativne trake su debljine od 1–10 cm. Izmjenjuju se vrlo tanki slojevi vitrofirnog, lapilno vitrofirnog i kristaloklastičnog riolitnog piroklastičnog toka. Lamine vitrofirnog riolitnog piroklastičnog toka izgrađene su od izmijenjenog matriks-potpornog piroklastičnog detritusa manjeg od 2 mm i devitrificirane staklaste osnove. Vitrofirni riolitni lapilni ignimbrit sadržava izmijenjene matriks-potporne do klast-potporne plovučce veće od 2 mm i kristaloklaste u devitrificiranoj staklastoj osnovi. Kristaloklastični riolitni piroklastični tok izgrađen je od kristaloklasta kvarca, albita (An0.0-4.5Ab95.1-99.9Or0.1-0.6) i K-feldspata (An0.0- 1.0Ab1.8-4.2Or95.0-98.4), kao i vrlo rijetkih čestica lapilnog plovučca, dok je matriks izmijenjen u fengit. Masivni čvrsti riolitni lapilni ignimbriti izgrađeni su od klast-potpornih do matriks-potpornih alteriranih lapilnih plovučaca, a rjeđe od kristaloklasta izmijenjenih feldspata i kvarca u devitrificiranoj staklastoj osnovi. Produkti izmjene u svim varijetetima su sitnozrnati kvarc i listići filosilikata. Alteracijski procesi su dvofazni: tijekom dijagenetskih procesa i postdijagenetskih tektonskih procesa kao što su dinamo-termalne metamorfne promjene, koje se očituju u klivažu uškriljavanja po kojem se razvija folijativni bijeli tinjac. Bijeli tinjac je fengit sa sadržajem 3.4 SiT a.p.f.u. Izvorište riolitnih tufova (Pietra Verde) na području Strahinjščice, Žumberačke gore i šireg područja Dinarida (Lika, Knin, Svilaja i dr.) mogu biti navedene istraživane eksplozivne riolitne vulkanske stijene SI ruba Adrie

Middle Triassic syn-rift rhyolites and rhyolitic ignimbrites on the north-east margin of Adria (NE Slovenia, NW Croatia): possible source of rhyolitic tuffs (Pietra Verde) in the wider Dinaride area

Srednjotrijaske magmatske i piroklastične stijene u području Adrie, odnosno šireg područja Dinarida i Južnih Alpa su česta pojava. To su uglavnom bazične magmatske stijene: bazalti, andezit-bazalti, rjeđe andeziti te riolitne piroklastične stijene (Pietra Verde). Izvorište riolitnog piroklastičnog detritusa u širem području Dinarida do sada nije jasno određeno. Trijaske kisele magmatske stijene poznate su samo na SZ rubu Adrie. U okviru projekta GOST istraživane su ove stijene na uzvisini Sv. Junger u SI Sloveniji, koje su determinirane kao rioliti, te na području Margečana na uzvisinama Gradišće, Hamec, Oštra Gorica i Sv. Duh u SZ Hrvatskoj, koje su određene kao riolitni ignimbriti. Rioliti imaju porfirnu strukturu i homogenu teksturu. Fenokristali su plagioklas i K-feldspat, a osnova je leukokratna, devitrificirana u sitnozrnati kvarc, feldspat i bijeli tinjac. Fenokristali plagioklasa su alterirani u sitnolistićavi bijeli tinjac i minerale glina. K-feldspat je svijež s alteriranim inkluzijama. Riolitni ignimbriti imaju debljinu veću od 100 m. Izdvajaju se (1) čvrsti laminirani folijativni tok riolitnih ignimbrita i (2) čvrsti masivni riolitni ignimbriti. Folijativne trake su debljine od 1–10 cm. Izmjenjuju se vrlo tanki slojevi vitrofirnog, lapilno vitrofirnog i kristaloklastičnog riolitnog piroklastičnog toka. Lamine vitrofirnog riolitnog piroklastičnog toka izgrađene su od izmijenjenog matriks-potpornog piroklastičnog detritusa manjeg od 2 mm i devitrificirane staklaste osnove. Vitrofirni riolitni lapilni ignimbrit sadržava izmijenjene matriks-potporne do klast-potporne plovučce veće od 2 mm i kristaloklaste u devitrificiranoj staklastoj osnovi. Kristaloklastični riolitni piroklastični tok izgrađen je od kristaloklasta kvarca, albita (An0.0-4.5Ab95.1-99.9Or0.1-0.6) i K-feldspata (An0.0- 1.0Ab1.8-4.2Or95.0-98.4), kao i vrlo rijetkih čestica lapilnog plovučca, dok je matriks izmijenjen u fengit. Masivni čvrsti riolitni lapilni ignimbriti izgrađeni su od klast-potpornih do matriks-potpornih alteriranih lapilnih plovučaca, a rjeđe od kristaloklasta izmijenjenih feldspata i kvarca u devitrificiranoj staklastoj osnovi. Produkti izmjene u svim varijetetima su sitnozrnati kvarc i listići filosilikata. Alteracijski procesi su dvofazni: tijekom dijagenetskih procesa i postdijagenetskih tektonskih procesa kao što su dinamo-termalne metamorfne promjene, koje se očituju u klivažu uškriljavanja po kojem se razvija folijativni bijeli tinjac. Bijeli tinjac je fengit sa sadržajem 3.4 SiT a.p.f.u. Izvorište riolitnih tufova (Pietra Verde) na području Strahinjščice, Žumberačke gore i šireg područja Dinarida (Lika, Knin, Svilaja i dr.) mogu biti navedene istraživane eksplozivne riolitne vulkanske stijene SI ruba Adrie

Basin to reef transition in the Middle Triassic Northwestern Croatian rift related basin (NCTRB)

In NW Croatia Middle Triassic volcano-sedimentary successions were deposited on the passive continental margin during a period of extensional tectonic related to the Neotethyan rifting. The studied succession in Očura Quarry on Ivanščica Mt is 34 m thick section, divided into three parts. The lower part is composed of dominantly basaltic rocks. In the basal part glomeroporpyric basalt is overlaid by basaltic autoclastite and peperite. The middle part is composed of cm–dm thick irregularly and wavy bedded calcarenites, in places coarsening upward. Carbonate lithoclasts are mostly micritic limestones with bioclasts. Basaltic lithoclasts are less common, one with the porphyric to glomeroporphiric texture, similar to basalt from the lower part; and the other type completely hyaline. There are also thin layers of biomicrites with filaments and radiolarians, thin layers of volcaniclastics, and a thick breccia interval. The upper part is composed of extremely unsorted breccia with slump-texture. Clasts of limestones, calcarenites, and subordinary basalts are supported by fine grained matrix of carbonate and basaltic particles. Within breccia there are abundant framestone clasts containing complex reef community, dominating of sponge Celyphia zoldana, with other microorganisms of uncertain taxonomy Plexoramea cerebriformis and Olangocoelia otti, and others. The investigated section represents sedimentation in the deeper marine environment near the steep edge of the carbonate platform that prograde over it. Basalts found at the base of the section represent submarine effusions, and their fragmentation and reworking. A thick interval of calcarenites with basaltic lithoclasts is formed by shedding of the carbonate material from the nearby platform to the pelagic/basinal areas, indicated by the pelagic limestone interlayers. Chaotic breccia with meter sized fragments of reefal limestones indicates a more proximal position regarding to the shallow marine area from which these clasts were derived. Slump texture emphasizes gravitational processes. The general trend of coarsening upward, as well as the predominance of the framestone clasts in the breccias imply the progradation of the platform over the basinal areas. Similar successions have been described from the neighbouring area

Basin to reef transition in the Middle Triassic Northwestern Croatian rift related basin (NCTRB)

In NW Croatia Middle Triassic volcano-sedimentary successions were deposited on the passive continental margin during a period of extensional tectonic related to the Neotethyan rifting. The studied succession in Očura Quarry on Ivanščica Mt is 34 m thick section, divided into three parts. The lower part is composed of dominantly basaltic rocks. In the basal part glomeroporpyric basalt is overlaid by basaltic autoclastite and peperite. The middle part is composed of cm–dm thick irregularly and wavy bedded calcarenites, in places coarsening upward. Carbonate lithoclasts are mostly micritic limestones with bioclasts. Basaltic lithoclasts are less common, one with the porphyric to glomeroporphiric texture, similar to basalt from the lower part; and the other type completely hyaline. There are also thin layers of biomicrites with filaments and radiolarians, thin layers of volcaniclastics, and a thick breccia interval. The upper part is composed of extremely unsorted breccia with slump-texture. Clasts of limestones, calcarenites, and subordinary basalts are supported by fine grained matrix of carbonate and basaltic particles. Within breccia there are abundant framestone clasts containing complex reef community, dominating of sponge Celyphia zoldana, with other microorganisms of uncertain taxonomy Plexoramea cerebriformis and Olangocoelia otti, and others. The investigated section represents sedimentation in the deeper marine environment near the steep edge of the carbonate platform that prograde over it. Basalts found at the base of the section represent submarine effusions, and their fragmentation and reworking. A thick interval of calcarenites with basaltic lithoclasts is formed by shedding of the carbonate material from the nearby platform to the pelagic/basinal areas, indicated by the pelagic limestone interlayers. Chaotic breccia with meter sized fragments of reefal limestones indicates a more proximal position regarding to the shallow marine area from which these clasts were derived. Slump texture emphasizes gravitational processes. The general trend of coarsening upward, as well as the predominance of the framestone clasts in the breccias imply the progradation of the platform over the basinal areas. Similar successions have been described from the neighbouring area

Deposition of volcaniclastites in pelagic environment on rifted continental margin during the Middle Triassic

The Middle Triassic volcano-sedimentary successions related to the opening of the Neotethys Ocean in NW Croatia were investigated for their age and facies interpretation. Stratigraphically stacked volcanic and volcaniclastic lithologies, ranging from basaltic to rhyolitic, are interlayered with pelagic sedimentary rocks in the studied sections. These successions were deposited on a passive continental margin with dynamics set by intense rift-related tectonic movements and volcanic activity. Following disintegration of stable shallow-marine environment newly formed lithospheric blocks gave rise to a complex pelagic depositional environment as extension progressed. Pelagic limestones and radiolarian cherts were deposited on drowned blocks with episodic intercalations of volcanic and pyroclastic deposits from the early Illyrian to possibly late Ladinian. Shallow-water carbonate environment still existed laterally as suggested by resedimented carbonate detritus. Deep-rooted normal faults created by extension provided paths for submarine basaltic extrusions. Magma quenched in contact with sea water creating basaltic hyaloclastites that were redeposited in deeper parts of the basin. Acidic volcaniclastics, commonly known as “pietra verde”, were produced by explosive volcanic eruptions, and deposited in pelagic environment by different gravitational mechanisms, including pyroclastic density currents. Variations in thickness of these deposits indicate different sedimentation mechanisms and reflect complex topography of the depositional environment. Water-settled air fall deposits produced thinner layers, while thicker layers indicate redeposition of material from topographic heights to more subsided parts. Unconsolidated pyroclastic detritus was partly reworked soon after deposition and redistributed gradually filing the basin. Medium- to fine-grade turbidite sedimentation is inferred for these deposits based on grain size, normal grading, horizontal lamination and mixing of volcanic and pelagic material. Presumed stratigraphic gaps in investigated successions, and possibly condensed sedimentation, can be explained by complex basin topography and prevailing sedimentation mechanisms, which resulted with sediment erosion and its subsequent redistribution