Petrological characteristics of Gröden sandstones : master’s thesis

U diplomskom radu analiziran je petrografski sastav 6 uzoraka gredenskih pješčenjaka (stratigrafska starost - srednji perm) od kojih je pet iz doline Pikovačkog potoka (okolica Brušana, Velebit) te jedan uzorak pješčenjaka s tipskog lokaliteta Gröden (Italija). Na osnovi mikropetrografske analize, modalne analize sastava te analiza sastava teške mineralne frakcije bilo je moguće interpretirati porijeklo materijala, indekse trošenja, klimu i reljef u vrijeme taloženja pješčenjaka ova dva lokaliteta. Četiri uzorka iz Pikovačkog potoka determinirani su kao litične grauvake, jedan kao gusto pakirani litični arenit dok uzorak Gröden pš. locus typicus predstavlja feldspatsku grauvaku. Litične grauvake/arenit iz Pikovačkog potoka svjedoče o nezrelim pješčenjacima koji ukazuju na blizinu izvorišnog područja i vjerojatno aktivnu tektoniku u zaleđu. Provenijencijski dijagrami ukazuju da je materijal bio deriviran iz područja recikliranog orogena. Sastav teške mineralne frakcije u kojem dominiraju dobro zaobljena stabilna zrna cirkona, turmalina i rutila ukazuju na porijeklo iz pretaloženih sedimentnih stijena. Prisustvo distena i klorita u sastavu teške mineralne frakcije sugerira porijeklo iz metamorfnih stijena. Stoga se pretpostavlja taloženje gredenskih pješčenjaka Pikovačkog potoka u okolišu lepezne delte ili delte prepletenog rječnog sustava unutar riftnog tektonskog sklopa (recikliranog orogena). Sastav uzorka Gröden pš. locus typicus projicira se u područje na granicu izdignutog kontinentalnog bloka (sustav riftnih dolina) i magmatskog luka što ukazuje da su se u blizini nalazila moguća izvorišta magmatskih stijena. Crvena boja svih analiziranih uzoraka kao i relativno veliki postotak tzv. limonitiziranih zrna u sastavu teške mineralne frakcije ukazuju na aridnu klimu u vrijeme taloženja. Projekcije sastava prema dijagramu indeksa trošenja upućuju također na aridnu/semiaridnu klimu i visoki reljef izvorišnog područja u kojem dominiraju metamorfne ili sedimentne stijene za sve uzorke Pikovačkog potoka te na aridnu/semiaridnu klimu visokog reljefa, ali plutonskog izvorišnog područja za uzorak Gröden pš. locus typicus. Ovaj je podatak u skladu s analizama teške frakcije koja se razlikuje za locus typicus i gredenske pješčenjake iz Pikovačkog potoka.Abstract: Six samples of Gröden sandstones (Middle Permian) were analysed: Five of them were from Pikovac creek (vicinity of Brušane, Mts. Velebit) and one was from the locus typicus Gröden (Italy). Based on micropetrographical characteristics of sandstones, as well as on modal analysis of mineral composition and heavy mineral association, origin of material, weathering index of source rocks, climate and relief in period of deposition have been suggested. Four samples from Pikovac creek were determined as lithic greywackes, one as densly packed lithic arenite, while the sample from Gröden sandstone locus typicus represent feldspar greywacke. Lithic graywackes/arenite imply very low maturity and suggest close proximity of source rocks as well as the active tectonic in the hinterland of depositional basin. Heavy mineral association with large amount of fairly rounded stabile grains – zircon, turmaline, rutile points to recycled sedimentary origin. Presence of dystene and chlorite in the heavy mineral assemblage suggest metamorphic origin. These data assume that Gröden sandstones from Pikovac creek were possibly deposited in fan delta and briaded delta depositional environment as a part of rift system (recycled orogen). Composition of Gröden locus typicus has been plotted on the boundary area between basement uplift block (rift valley system) and magmatic arc, which suggests vicinity of magmatic rocks in the source area. All analysed samples are red colored and have a large amount of limonitized grains in the heavy mineral assemblage which point to the arid climate in time of deposition. Weathering index diagram for Pikovac sandstones implies arid/semiarid climate and high relief of source area where metamorphic or sedimentary rocks dominate, while arid/semiarid climate and high relief with plutonic source rocks were supposed for provenance of Gröden sandstone locus typicus

Petrological characteristics of Gröden sandstones : master’s thesis

U diplomskom radu analiziran je petrografski sastav 6 uzoraka gredenskih pješčenjaka (stratigrafska starost - srednji perm) od kojih je pet iz doline Pikovačkog potoka (okolica Brušana, Velebit) te jedan uzorak pješčenjaka s tipskog lokaliteta Gröden (Italija). Na osnovi mikropetrografske analize, modalne analize sastava te analiza sastava teške mineralne frakcije bilo je moguće interpretirati porijeklo materijala, indekse trošenja, klimu i reljef u vrijeme taloženja pješčenjaka ova dva lokaliteta. Četiri uzorka iz Pikovačkog potoka determinirani su kao litične grauvake, jedan kao gusto pakirani litični arenit dok uzorak Gröden pš. locus typicus predstavlja feldspatsku grauvaku. Litične grauvake/arenit iz Pikovačkog potoka svjedoče o nezrelim pješčenjacima koji ukazuju na blizinu izvorišnog područja i vjerojatno aktivnu tektoniku u zaleđu. Provenijencijski dijagrami ukazuju da je materijal bio deriviran iz područja recikliranog orogena. Sastav teške mineralne frakcije u kojem dominiraju dobro zaobljena stabilna zrna cirkona, turmalina i rutila ukazuju na porijeklo iz pretaloženih sedimentnih stijena. Prisustvo distena i klorita u sastavu teške mineralne frakcije sugerira porijeklo iz metamorfnih stijena. Stoga se pretpostavlja taloženje gredenskih pješčenjaka Pikovačkog potoka u okolišu lepezne delte ili delte prepletenog rječnog sustava unutar riftnog tektonskog sklopa (recikliranog orogena). Sastav uzorka Gröden pš. locus typicus projicira se u područje na granicu izdignutog kontinentalnog bloka (sustav riftnih dolina) i magmatskog luka što ukazuje da su se u blizini nalazila moguća izvorišta magmatskih stijena. Crvena boja svih analiziranih uzoraka kao i relativno veliki postotak tzv. limonitiziranih zrna u sastavu teške mineralne frakcije ukazuju na aridnu klimu u vrijeme taloženja. Projekcije sastava prema dijagramu indeksa trošenja upućuju također na aridnu/semiaridnu klimu i visoki reljef izvorišnog područja u kojem dominiraju metamorfne ili sedimentne stijene za sve uzorke Pikovačkog potoka te na aridnu/semiaridnu klimu visokog reljefa, ali plutonskog izvorišnog područja za uzorak Gröden pš. locus typicus. Ovaj je podatak u skladu s analizama teške frakcije koja se razlikuje za locus typicus i gredenske pješčenjake iz Pikovačkog potoka.Abstract: Six samples of Gröden sandstones (Middle Permian) were analysed: Five of them were from Pikovac creek (vicinity of Brušane, Mts. Velebit) and one was from the locus typicus Gröden (Italy). Based on micropetrographical characteristics of sandstones, as well as on modal analysis of mineral composition and heavy mineral association, origin of material, weathering index of source rocks, climate and relief in period of deposition have been suggested. Four samples from Pikovac creek were determined as lithic greywackes, one as densly packed lithic arenite, while the sample from Gröden sandstone locus typicus represent feldspar greywacke. Lithic graywackes/arenite imply very low maturity and suggest close proximity of source rocks as well as the active tectonic in the hinterland of depositional basin. Heavy mineral association with large amount of fairly rounded stabile grains – zircon, turmaline, rutile points to recycled sedimentary origin. Presence of dystene and chlorite in the heavy mineral assemblage suggest metamorphic origin. These data assume that Gröden sandstones from Pikovac creek were possibly deposited in fan delta and briaded delta depositional environment as a part of rift system (recycled orogen). Composition of Gröden locus typicus has been plotted on the boundary area between basement uplift block (rift valley system) and magmatic arc, which suggests vicinity of magmatic rocks in the source area. All analysed samples are red colored and have a large amount of limonitized grains in the heavy mineral assemblage which point to the arid climate in time of deposition. Weathering index diagram for Pikovac sandstones implies arid/semiarid climate and high relief of source area where metamorphic or sedimentary rocks dominate, while arid/semiarid climate and high relief with plutonic source rocks were supposed for provenance of Gröden sandstone locus typicus

SASTAV I PROVENIJENCIJA GREDENSKIH PJEŠČENJAKA VELEBITA

Six samples of Gröden sandstones (Middle Permian) were analysed: Five of them were from Pikovac Creek valley (in the vicinity of Brušane village at Velebit Mts., Croatia) and one was from the locus typicus Gröden/Val Gardena (Italy). Based on the micropetrographical characteristics of sandstones, as well as on the modal composition and heavy mineral association, origin of material, weathering index of source rocks, climate and relief in the period of deposition have been supposed. Four samples from Pikovac Creek were petrographicaly determined as lithic greywackes, one as densely packed lithic arenite, while a specimen from Gröden locus typicus represents feldspar greywacke. Lithic greywackes/arenites imply very low maturity and suggest a close proximity of source rocks as well as the active tectonics in the hinterland of the depositional basin. Heavy mineral association in the samples from Pikovac Creek valley, with a large amount of fairly rounded stable grains (zircon, tourmaline and rutile), indicate that clastic material was derived from recycled orogen, and probably from reworked sedimentary rocks. The presence of kyanite and chlorite in the heavy mineral assemblage suggest their origin is from metamorphic rocks. This data assumes that Gröden sandstones from Pikovac Creek were possibly deposited in the fan delta or braided delta depositional environment as a part of a rift system (recycled orogen). The composition of the sample Gröden s. locus typicus (light and heavy mineral fractions) suggests the vicinity of magmatic rocks in the source area. All analysed samples are red coloured and have a large amount of limonitized grains in the heavy mineral assemblage, that point to the arid climate at the time of deposition. A weathering index diagram for Pikovac sandstones implies an arid/semiarid climate and high relief of the source area where metamorphic or sedimentary rocks dominate, while an arid/semiarid climate and high relief with plutonic source rocks were supposed for the provenance of Gröden s. locus typicus.Analizirano je šest uzoraka srednjopermskih gredenskih pješčenjaka: pet uzoraka iz doline Pikovačkoga potoka u okolici Brušana na Velebitu i jedan uzorak s locus typicus lokaliteta Gröden/Val Gardena u Italiji. Na temelju mikropetrografskih karakteristika pješčenjaka, njihova mineralnog sastava te sastava teške i lake mineralne frakcije, interpretirano je podrijetlo materijala, indeks trošenja matičnih stijena te klima i reljef u vrijeme taloženja. Četiri uzorka pješčenjaka iz Pikovačkoga potoka petrografski su određena kao litične grauvake, a jedan uzorak kao gusto pakirani litični arenit, dok je uzorak pješčenjaka s locus typicus lokaliteta Gröden određen kao feldspatska grauvaka. Litične grauvake/areniti podrazumijevaju vrlo nisku zrelost i sugeriraju blizinu matičnih stijena, kao i aktivnu tektoniku u zaleđu sedimentacijskoga bazena. Asocijacija teških minerala u uzorcima iz Pikovačkoga potoka, s velikom količinom dobro zaobljenih stabilnih zrna (cirkon, turmalin i rutil), upućuje na to da klastični materijal potječe iz recikliranoga orogena, i to vjerojatno od pretaloženih sedimentnih stijena. Prisutnost distena i klorita u teškoj mineralnoj frakciji sugerira podrijetlo iz metamorfnih stijena. Rezultati upućuju na to da su gredenski pješčenjaci iz doline Pikovačkoga potoka možda taloženi u okolišu lepezne delte koja je dio riftnoga sustava (reciklirani orogen). Sastav lake i teške mineralne frakcije uzorka Gröden s. locus typicus sugerira podrijetlo iz magmatskih stijena. Svi analizirani uzorci crvene su boje i imaju veliku količinu limonitiziranih zrna u teškoj mineralnoj frakciji, što upućuje na aridnu klimu u vrijeme taloženja. Dijagram indeksa trošenja pješčenjaka iz Pikovačkoga potoka upućuje na aridnu/semiaridnu klimu i visoki reljef izvorišnoga područja koji je izgrađen od sedimentnih i metamorfnih stijena, dok uzorak Gröden s. locus typicus pješčenjaka ukazuje na aridnu/semiaridnu klimu i visoki reljef, s magmatskim matičnim stijenama i izvorišno područje magmatskoga luka

Composition and provenance of Gröden sandstone from the Velebit Mts.

Six samples of Gröden sandstones (Middle Permian) were analysed: Five of them were from Pikovac Creek valley (in the vicinity of Brušane village at Velebit Mts., Croatia) and one was from the locus typicus Gröden/Val Gardena (Italy). Based on the micropetrographical characteristics of sandstones, as well as on the modal composition and heavy mineral association, origin of material, weathering index of source rocks, climate and relief in the period of deposition have been supposed. Four samples from Pikovac Creek were petrographicaly determined as lithic greywackes, one as densely packed lithic arenite, while a specimen from Gröden locus typicus represents feldspar greywacke. Lithic greywackes/arenites imply very low maturity and suggest a close proximity of source rocks as well as the active tectonics in the hinterland of the depositional basin. Heavy mineral association in the samples from Pikovac Creek valley, with a large amount of fairly rounded stable grains (zircon, tourmaline and rutile), indicate that clastic material was derived from recycled orogen, and probably from reworked sedimentary rocks. The presence of kyanite and chlorite in the heavy mineral assemblage suggest their origin is from metamorphic rocks. This data assumes that Gröden sandstones from Pikovac Creek were possibly deposited in the fan delta or braided delta depositional environment as a part of a rift system (recycled orogen). The composition of the sample Gröden s. locus typicus (light and heavy mineral fractions) suggests the vicinity of magmatic rocks in the source area. All analysed samples are red coloured and have a large amount of limonitized grains in the heavy mineral assemblage, that point to the arid climate at the time of deposition. A weathering index diagram for Pikovac sandstones implies an arid/semiarid climate and high relief of the source area where metamorphic or sedimentary rocks dominate, while an arid/semiarid climate and high relief with plutonic source rocks were supposed for the provenance of Gröden s. locus typicus

1st Biospeleological Expedition - Biokovo 2017

Pretpostavlja se da na Biokovu postoji preko 1 000 speleoloških objekata od kojih je nešto više od 400 do sada zabilježeno, a više od 115 je biospeleološki istraženo. Prijašnja istraživanja podzemne faune pokazala su da je Biokovo jedno od najbogatijih područja podzemnom faunom u Hrvatskoj. Navedeni podaci su ukazali na potrebu za dodatnim biospeleološkim istraživanjem speleoloških objekata Biokova. Prvu biospeleološku ekspediciju – Biokovo 2017 je organiziralo Hrvatsko biospeleološko društvo u suradnji s udrugom Breganja i Speleološkim odsjekom Planinarskog društva Imber. Ekspedicija je početno imala dva glavna cilja: biospeleološki istražiti 8 dubokih jama na području Parka prirode Biokovo i ponoviti nacrt Vilimove jame (A-2). Glavni termin ekspedicije je bio od 17. do 25. lipnja 2017. Prije same ekspedicije su napravljena dva terenska izlaska u svibnju i lipnju kada su označeni pristupi do dubokih jama i glavnina objekata se opremila, te jedan teren u listopadu nakon ekspedicije. Na ekspediciji je prema preliminarnim rezultatima pronađeno 10-ak novih vrsta za znanost. Topografski su snimljene 2 duboke jame (Jama pod Kamenitim vratima i Nova velika), Vilimova jama (A-2) do 101 m dubine, A-1 do 110 m dubine i 4 manja speleološka objekta. Biospeleološka istraživanja su provedena u ukupno 26 speleoloških objekata, među kojima je bilo 8 dubokih jama. Ekspedicija je brojila ukupno 52 sudionika među kojima 43 biospeleologa i/ili speleologa iz 20 speleoloških i bioloških udruga i organizacija. Među sudionicima je bilo i 6 stranaca.It is conjectured that there are over 1000 caves on the Biokovo Mountain of which more than 400 have been found so far and 115 have been biologically surveyed. Earlier research suggested that the Biokovo Mountain is home to the richest subterranean fauna in Croatia and that further understanding of the cave biology was necessary. The “1st Biospeleological Expedition - Biokovo 2017” was organised by the Croatian Biospeleological Society in cooperation with the Breganja Association and Imber Speleological Section.  The two main goals of the expedition were to biologically survey eight deep caves in the Biokovo Nature Park and to update the survey of Vilimova Jama (A-2). The main part of the expedition took place from 17th to 25th June 2017 but it took two other visits in May and June to mark the approaches to the deep caves and to equip most of them. More work was also done in October after the expedition. According to preliminary results, around 10 new species have been found, two deep caves (Jama Pod Kamenitim Vratima and Nova Velika) and four shallower caves were completely surveyed, and Vilimova Jama (A-2) Cave and A-1 Cave were mapped to depths of 101 m and 110 m, respectively.  Biospeleological research was carried out in 26 caves of which eight are deep caves. Altogether 52 people participated in the expedition of which 43 were speleologists or biospeleologists from twenty different speleological and biological associations. Among the participants, six people were from other countries

Tomina jama kod Krvavca u dolini rijeke Neretve

Tomina jama cave was explored and preliminary research conducted from 2015 to 2019. Tomina jama is currently the only known anchialine cave in the Neretva River area. At this time, the cave has been explored up to 58 m with the last 23 to 25 m submerged. Tomina jama is a typical anchialine cave system with a freshwater lens at the surface and seawater layer at the bottom. Salinity in the cave increased from 0 at the surface to 33 at a depth of 22 m, whereas dissolved oxygen concentrations decreased from 9.1 mg/L to anoxic conditions at depth. The hypoxic/anoxic zone extended for more than 10 m. Water temperature ranged from 14.8°C at the surface to 17.2°C at the bottom while pH decreased with depth from 7.74 to 6.86. Redox sensitive trace metals (i.e. Mo and U) deviated from salinity driven conservative mixing behavior. The upper freshwater layer was characterized by low Mo and U concentrations, 6.5 and 2.1 nmol/L, respectively. As salinity increased with depth, Mo and U concentration also increased (65.0 and 8.1 nmol/L, respectively). Of interest however, as depth continued to increase to the bottom salt layer (salinity 33) the Mo and U concentrations were significantly lower than for open ocean (~115 and ~13.5 nmol/L, respectively) implying removal process of Mo and U within the anoxic bottom waters. Further investigation of possible Mo and U enrichment within the cave sediment and porewaters is needed in order to establish possible linkages between the water and porewater chemistry (i.e. especially sulphide concentration, a trigger for Mo water column exhaustion) and the removal processes of Mo and U within the water column. Within the anoxic bottom waters, increased concentrations of Fe and Mn were observed indicating the formation of reduced Fe and Mn minerals within. Several stygobionts were discovered in the freshwater layer including serpulids Marifugia sp. and crustaceans of the genera Monolistra, Troglocaris and Niphargus. Most notable is the finding of the endemic serpulids, which is the first record of this animals for an anchialine cave. Prior to this discovery, Marifugia has only been found in freshwater caves from Dinaric karst region. Preliminary DNA results indicate that this specimen might not belong to Marifugia cavatica species and may be a new species. Below the halocline, the cave walls and bottom were covered with a significant bacterial mat. Samples were collected for future microbiome analyses

Tomina jama kod Krvavca u dolini rijeke Neretve

Tomina jama cave was explored and preliminary research conducted from 2015 to 2019. Tomina jama is currently the only known anchialine cave in the Neretva River area. At this time, the cave has been explored up to 58 m with the last 23 to 25 m submerged. Tomina jama is a typical anchialine cave system with a freshwater lens at the surface and seawater layer at the bottom. Salinity in the cave increased from 0 at the surface to 33 at a depth of 22 m, whereas dissolved oxygen concentrations decreased from 9.1 mg/L to anoxic conditions at depth. The hypoxic/anoxic zone extended for more than 10 m. Water temperature ranged from 14.8°C at the surface to 17.2°C at the bottom while pH decreased with depth from 7.74 to 6.86. Redox sensitive trace metals (i.e. Mo and U) deviated from salinity driven conservative mixing behavior. The upper freshwater layer was characterized by low Mo and U concentrations, 6.5 and 2.1 nmol/L, respectively. As salinity increased with depth, Mo and U concentration also increased (65.0 and 8.1 nmol/L, respectively). Of interest however, as depth continued to increase to the bottom salt layer (salinity 33) the Mo and U concentrations were significantly lower than for open ocean (~115 and ~13.5 nmol/L, respectively) implying removal process of Mo and U within the anoxic bottom waters. Further investigation of possible Mo and U enrichment within the cave sediment and porewaters is needed in order to establish possible linkages between the water and porewater chemistry (i.e. especially sulphide concentration, a trigger for Mo water column exhaustion) and the removal processes of Mo and U within the water column. Within the anoxic bottom waters, increased concentrations of Fe and Mn were observed indicating the formation of reduced Fe and Mn minerals within. Several stygobionts were discovered in the freshwater layer including serpulids Marifugia sp. and crustaceans of the genera Monolistra, Troglocaris and Niphargus. Most notable is the finding of the endemic serpulids, which is the first record of this animals for an anchialine cave. Prior to this discovery, Marifugia has only been found in freshwater caves from Dinaric karst region. Preliminary DNA results indicate that this specimen might not belong to Marifugia cavatica species and may be a new species. Below the halocline, the cave walls and bottom were covered with a significant bacterial mat. Samples were collected for future microbiome analyses

Petrological characteristics of Gröden sandstones : master’s thesis

U diplomskom radu analiziran je petrografski sastav 6 uzoraka gredenskih pješčenjaka (stratigrafska starost - srednji perm) od kojih je pet iz doline Pikovačkog potoka (okolica Brušana, Velebit) te jedan uzorak pješčenjaka s tipskog lokaliteta Gröden (Italija). Na osnovi mikropetrografske analize, modalne analize sastava te analiza sastava teške mineralne frakcije bilo je moguće interpretirati porijeklo materijala, indekse trošenja, klimu i reljef u vrijeme taloženja pješčenjaka ova dva lokaliteta. Četiri uzorka iz Pikovačkog potoka determinirani su kao litične grauvake, jedan kao gusto pakirani litični arenit dok uzorak Gröden pš. locus typicus predstavlja feldspatsku grauvaku. Litične grauvake/arenit iz Pikovačkog potoka svjedoče o nezrelim pješčenjacima koji ukazuju na blizinu izvorišnog područja i vjerojatno aktivnu tektoniku u zaleđu. Provenijencijski dijagrami ukazuju da je materijal bio deriviran iz područja recikliranog orogena. Sastav teške mineralne frakcije u kojem dominiraju dobro zaobljena stabilna zrna cirkona, turmalina i rutila ukazuju na porijeklo iz pretaloženih sedimentnih stijena. Prisustvo distena i klorita u sastavu teške mineralne frakcije sugerira porijeklo iz metamorfnih stijena. Stoga se pretpostavlja taloženje gredenskih pješčenjaka Pikovačkog potoka u okolišu lepezne delte ili delte prepletenog rječnog sustava unutar riftnog tektonskog sklopa (recikliranog orogena). Sastav uzorka Gröden pš. locus typicus projicira se u područje na granicu izdignutog kontinentalnog bloka (sustav riftnih dolina) i magmatskog luka što ukazuje da su se u blizini nalazila moguća izvorišta magmatskih stijena. Crvena boja svih analiziranih uzoraka kao i relativno veliki postotak tzv. limonitiziranih zrna u sastavu teške mineralne frakcije ukazuju na aridnu klimu u vrijeme taloženja. Projekcije sastava prema dijagramu indeksa trošenja upućuju također na aridnu/semiaridnu klimu i visoki reljef izvorišnog područja u kojem dominiraju metamorfne ili sedimentne stijene za sve uzorke Pikovačkog potoka te na aridnu/semiaridnu klimu visokog reljefa, ali plutonskog izvorišnog područja za uzorak Gröden pš. locus typicus. Ovaj je podatak u skladu s analizama teške frakcije koja se razlikuje za locus typicus i gredenske pješčenjake iz Pikovačkog potoka.Abstract: Six samples of Gröden sandstones (Middle Permian) were analysed: Five of them were from Pikovac creek (vicinity of Brušane, Mts. Velebit) and one was from the locus typicus Gröden (Italy). Based on micropetrographical characteristics of sandstones, as well as on modal analysis of mineral composition and heavy mineral association, origin of material, weathering index of source rocks, climate and relief in period of deposition have been suggested. Four samples from Pikovac creek were determined as lithic greywackes, one as densly packed lithic arenite, while the sample from Gröden sandstone locus typicus represent feldspar greywacke. Lithic graywackes/arenite imply very low maturity and suggest close proximity of source rocks as well as the active tectonic in the hinterland of depositional basin. Heavy mineral association with large amount of fairly rounded stabile grains – zircon, turmaline, rutile points to recycled sedimentary origin. Presence of dystene and chlorite in the heavy mineral assemblage suggest metamorphic origin. These data assume that Gröden sandstones from Pikovac creek were possibly deposited in fan delta and briaded delta depositional environment as a part of rift system (recycled orogen). Composition of Gröden locus typicus has been plotted on the boundary area between basement uplift block (rift valley system) and magmatic arc, which suggests vicinity of magmatic rocks in the source area. All analysed samples are red colored and have a large amount of limonitized grains in the heavy mineral assemblage which point to the arid climate in time of deposition. Weathering index diagram for Pikovac sandstones implies arid/semiarid climate and high relief of source area where metamorphic or sedimentary rocks dominate, while arid/semiarid climate and high relief with plutonic source rocks were supposed for provenance of Gröden sandstone locus typicus

Modeling of the geological probability procedure for the prediction of high flows in small streams, case study of Medvednica Mt., Croatia

Floods are defined by maximum water levels or flow of high-water waves. Here, we defined the deterministic method for the calculation of the probability of a high discharge event, named as the Probability Of Success (POS). The POS method previously developed for petroleum subsurface systems has been modified for the surface hydrological system with the purpose of flood prediction. The case study of this research is the small basin of Kašina Stream on Medvednica Mt. (NW Croatia). The data are obtained upstream from the hydrological station Gornja Kašina. The POS model is defined by four categories. Each geological category is described with accompanied events and probabilities. Floods are defined by four categories: total precipitation, total water flow, basement, and maximal water capacity in soil. The categories total precipitation and basement were divided into two sub-categories each: quantity and duration; porosity and soil depth. Data are collected for a hydrometeorological event, namely an intensive convective storm on 24–25 July 2020, when Zagreb was locally hit by heavy urban floods. The presented probability method yielded a probability of 1.76% that such an event could happen to the station. However, the flooding was not recorded. A comparison of the real event and the predicted probability supported the adequacy and applicability of the method, showing it has high reliability. The presented probability model could be easily applied, with small modifications, to the entire area of Northern Croatia for the prediction of small basin flooding events

1st Croatian Biospeleological expedition - Biokovo 2017

Biokovo Mountain in Croatia is a Dinaric hotspot of subterranean biodiversity and its area of 196 km 2 is protected as a nature park. Until now, more than 400 caves have been registered here, however, only in about 30% of them biospeleological research has been carried out. It is hypothesized that over 1000 caves exist in highly karstified Biokovo Mt. Biospeleological research of the area started at the beginning of 20th century and deep caves were infrequently explored after the year 1980. Previous research recorded more than 90 troglobiotic species in this area and most of them are endemic. The primary goal of the Expedition was a systematic survey of eight deep caves (depth over 250 m), one of which was never before biospeleologically surveyed. We also surveyed other caves from which material for detailed faunistic analysis was missing. The main part of the expedition took place from 17 th to 25 th June 2017, with 52 participants. Fauna was collected by hand and by pitfall traps with baits, in the total of 26 caves. Five deep caves were completely surveyed (depth up to 710 m), the topographic map was made when missing, and fauna was photographed. Microclimatic conditions were measured and in two caves data loggers were placed. According to preliminary results, around 10 new species for science have been found from following groups: leeches (Hirudinea), spiders (Araneae), harvestmen (Opiliones), woodlice (Isopoda), centipedes (Chilopoda), springtails (Collembola), two-pronged bristletails (Diplura) and beetles (Coleoptera). These results confirm that deep caves of Biokovo Mt are still underexplored and that detailed and systematic research is needed.