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Investigating the Middle Triassic volcanic and volcaniclastic rocks in the External Dinarides (Croatia and Bosnia and Herzegovina) an undeveloped rift system has been determined. This rift system was formed as a back-arc extension in the north-western edge of Palaeotethys Ocean (Stampfli & Borel, 2002 ; Schmidt et al., 2008). Geochemical data (whole rock REE and trace element composition and EMP analysis on pyroxene and feldspar crystals and crystaloclasts of different volcanic and volcaniclastic facies) indicates calc-alkaline magma composition, characteristic for subduction zones and contamination by the crustal material. Therefore we interpret the development of Middle Triassic rift in the Dinarides as a back-arc rift area that was strongly influenced by the subduction of the Palaeotethys toward north that stared in Early Permian and lasted throughout the whole Triassic. The geotectonic history of this part of Tethys is described as follows: In the Upper Permian and Early Triassic the Dinarides were located in the western Palaeotethys. According to the palinspastic reconstructions (Haas et al., 1995 ; Scotese, 2002 ; Stampfli & Borel, 2002 ; Schmidt et al., 2008 ; Stampfli et al., 2013) this Palaeotethyan area represented a shallow bay resembling a vast epicontinental sea, in the Dinarides, interpreted as a broad epeiric ramp (Aljinović et al., 2015). In the southern part of this ocean rifting started in the Permian between the Cimmerian block and the southwest coast of Pangea. This rift system (Neotethys) advanced to the north and finally formed the Tethyan Ocean in the Jurassic. From afore mentioned palaeogeographic reconstructions it is notable that the subduction of Pelaeotethys persisted throughout the Triassic. This subduction process could have influenced the magma formation in the Middle Triassic. The former subduction, which caused the formation of Pangea could have also left the imprint on the Middle Triassic magma composition (Crisci et al., 1984). Palinspastic reconstructions place the area of the External Dinarides, and surrounding areas in the vicinity of earlier Gondwana and Laurasia suture line, the similar direction of the newly formed Tethyan rift. This caused the subduction of the Gondwana crustal material, and its partial melting that had great influence on the Middle Triassic magma in the western Tethys. Except the primary rifting direction there were additional extensional/rift systems in the continental part of Pangea. There were three recorded back-arc rift zones in the Middle Triassic: Meliata and Meliac Oceans, and the rift system directed across the Dinaridic and Alpine area. The area of the External Dinarides was bordered by the opening of the Tethyan Ocean from the southwest and opening of the Meliata and Meliac Oceans in the north. The External Dinaridic aborted rifting direction did not evolve because of these two compressive movements that forced its closure.

The crust of weathering is developed in marginal parts of the small Žepče ultramafic body which is disconformably overlain by fresh-water sediments of the Žepče Neogene intramontane basin. 1.) Moderately serpentinized lherzolite make up the fresh zone; 2.) The transitional zone is composed of strongly serpentinized lherzolites crosscut by veinlets filled by magnesite, breunnerite, dolomite, ankerite, calcite, quartz and opal; 3.) The uppermost zone, overlain by Neogene fresh-water sediments, is composed of desintegrated ultramafic and mafic rocks mixed with nontronite-bearing soil. Sample from the all the three zones are constrained by optical method, X-ray difraction, electron-mmicroprobe and major and trace elements.

The Croatian coastal region is a part of Maritime Dinaric Alps which and coincides with the Adriatic Carbonate Platform (AdCP). The some of the coastal karst depressions developed into larger lakes, although not numerous (

The Neogene to Quaternary Lake Pannon sedimentary successions of the SW part of the Pannonian Basin are characterized by three 2nd order megacycles divided by major regional unconformities. In here described sediments are related to the transtensional post-rift thermal basin subsidence and belong to the second megacycle between the Base Pannonian to the Base Pliocene unconformity For the interpretation of the genesis and evolu-tion of the wider depositional area around the recent gas field Legrad in the NW Croatia inter- disciplinary approach were used. Information on lithology, ichnology, sedimentary structures and structural elements were obtained from complete macroscopic examination of cores. Petrophysical and calcimetry measurements, detailed petrographical (and microporosity) and palynological analyses were done. Geochemical evaluations were considered. All available well data were correlated and calibrated with well log and seismic data. Paleorelief features (like channel position and their direction) are visible on coherency time-slices.Investigated deposits and related cores are presented by alteration of sandstone, siltstone and marls. Sandstones, generally lithic arenites, are very well cemented with intergranular porosity. They are moderately sorted, with grains in the range from very fine to medium sand size. Sandstones are sporadically rich in organic matter. Siltstone is also well cemented. Marls occasionally contain smaller amount of siliciclastic component and pyrite occurrences. Open and reduced microfractures are sometimes visible. Sandstones are largely homogenous and thick to several meters. Horizontal and cross- lamination are detected only in uppermost part of the studied sedimentary succession (Lower Pontian deposits). Soft sediment deformation structures like load casts, ball-and-pillow and flame structures are relatively frequent. Rip- up marl clasts are sporadically observed suggesting channel sedimentation. Subvertical bioturbation is common. Terrigenous organic matter (phytoclast debris) are ubiquitous. Palynological macerals of the cored sedi-ments in the lower part of the investigated interval are rich in organic contents. Most of the palynofacies (70–80 %) is amorphous matter. Liptinite kerogene, generally made of weakly diverse dinocyst assemblage, some pollen grains (mostly bisaccate) and a few green algae remnants (Botryococcus brauni), completed the organic residue (10–20 %). Lignohumine clasts are scarce. Macerates are biodegraded. Pyrite inclusions in palynomorphs are frequent. Index fossils Spiniferites bentorii and S. bentorii oblongus specify the Upper Pannonian age. By the biostratigraphical classification of the organic walled microphytoplankton, samples belong to Spiniferites bentorii main zone, to the Spiniferites bentorii oblongus subzone. Younger sediments, although somewhat different, are also rich in organic matter. Lignohumine clasts of variable sorts and size make 30–60 %, while amorphous matter makes 30–40 % of total organic matter content. Liptinite component, composed of dinocysts, some freshwater alga (Pediastrum simplex, Spirogyra sp.), various polled grains (chiefly bisaccate) and a few spores, make 10–20 % of palynofacies. The Lower Pontian age is confirmed by Spiniferites balcanica, S. bentorii coniunctus and S. validus. According to the dinocyst palynozonation, samples belong to Spiniferites balcanica main zone, to the Spiniferites bentorii coniunctus subzone. Sediments originate in lacustrine environment as channel (and interchannel) deposits and subaquatic fans caused by gravity flow mechanisms (mostly turbidites). The Late Pannonian sedimentation took place in slightly deeper environment of decreased salinity, moderately distant to shore and terrigenous influx. The Early Pontian sediments were created in also somewhat distal and deeper freshwater environment but in the zone of the significant terrigenous influence.

Lake sedimentary record was used to reconstruct paleoenvironmental changes during Late Pleistocene and Holocene along the Croatian karst region on the Eastern Adriatic. Lake sediments were studied using multidisciplinary approach, combining sedimentological, mineralogical and geochemical analysis with paleontological proxies like pollen, ostracods or diatoms and dated using radiocarbon absolute dating. The most of the lakes cover the end of Pleistocene and beginning of the Holocene and show the evolution of the lakes and environmental changes during the last 12.000 years. Paleolimnological research was conducted on lake sediments on the eastern Adriatic coast (Lake Vrana on the Island Cres, Bokanjačko blato, Lake Vrana near Biograd and Lake Baćina- Crniševo) and they enabled reconstruction paleoenvironmental conditions from the late Pleistocene until present. Due to the proximity of the sea and permeable karst, the lake levels are influenced significantly by the sea level rise during the Holocene. Lakes represent typical karst lakes dominated by carbonate sedimentation, with periodic siliciclastic input. In every lake, three periods can be distinguished, the beginning of the Holocene with increased erosion and higher concentrations of siliciclastic material, middle Holocene with formation of deeper lakes and carbonate sedimentation, and Late Holocene characterised by erosion of siliciclastic material as a result of deforestation and human impact. Deposition of the siliciclastic material in Lake Vrana near Biograd lasted until 9.1 ka BP, when carbonate lake sedimentation started and the lake was formed. At the end of the period from 9.6 to 9.1 ka BP the dark organic rich sediment was deposited. The marine influence on the Lake Vrana sediments is evident after 6.1 ka BP. The present lake water conditions (alternating seasonal changes in the salinity, freshwater- brackish) were established at 3.8 ka BP. Deposition of homogenous carbonate mud (lake marl) started at 3 ka BP. In Lake Baćina deposition of the siliciclastic material was very intense from 11.7 to 10 ka BP, and then gradually decline until 7.5 ka BP. Dominant carbonate deposition lasted from 7.5 until 4.5 ka BP, when intensive changes in the sediments began, observed by the high sand fraction until 2.5 ka BP, and in between the alternate intervals were developed with calcite and quartz and those in which only calcite is present. In Bokanjačko blato the deposition of siliciclastic material lasted from 10.3 to 6.1 ka BP and then gradually decreases until 5.2 ka BP, when carbonate deposition began. In Lake Vrana on the Island Cres, the beginning of the Holocene is characterized by the deposition of the siliciclastic material, but which continues to the middle Holocene, until 4.5 ka BP when the carbonates appear. During the Holocene contrasting climate pattern has been identified in the central Mediterranean. Paleoenvironmental reconstructions of investigated lakes on the Eastern Adriatic coast correlate well with the lakes situated north of around 40°N of latitude, which are characterised by a wetter early Holocene, followed by relatively drier conditions during the middle Holocene and gradually increased moisture in the Late Holocene. South of 40°N of latitude there is opposite trend, very dry conditions in the first half of the Holocene and wettest period during the Mid Holocene followed by a progressive aridification, evident in lakes Preola and Pergusa on Sicily.

Analizirana je fosilna zajednica ostrakoda i palinomorfa iz sedimenata ispod i iznad sloja vulkanskog pepela na lokalitetu Sjeničak čija je starost određena na 16 Ma. Zajednica ostrakoda sugerira taloženje u relativno slonom vodenom tijelu, a zajednica palinomorfa subtropske klimatske uvijete.

Površinski kop Tomašica, smješten je u centralnom dijelu Ljubijskog rudonosnog bazena, unutar debelog paketa paleozojskih sedimenata Sansko-unske navlake (MAKSIMČEV i JURIĆ, 1964). Određen je stupanj vitrinitne refleksije na tamnim, metasomatskim sideritnim rudama, vapnencima i sedimentima iz sideritno-limonitnog člana flišne formacije Javorik. Najstarije stijene u području Ljubijskog rudonosnog bazena su devonski klastiti i karbonati. Na njima leže debeli paketi karbonskih fliševa predstavljeni klastičnim i vulkanogeno-sedimentnim naslagama, unutar kojih se nalaze olistoliti karbonatnih stijena. Diskordantno na gornjem karbonu nalaze se klastične formacije srednjeg perma (GRUBIĆ i dr., 2001). Unutar karbonske serije, debljine oko 600 m, nalazi se glavni dio metasomatskog i žilnog orudnjenja Ljubijskog bazena. Olistolitni blokovi karbonatnih stijena metasomatski su izmijenjeni, ankeritizirani i sideritizirani. Sideritna ruda u Tomašici javlja se unutar flišne formacije Javorik u sideritno-limonitnom članu, (donji do srednji karbon), i u olistolitnom članu, kao nepravilna metasomatska sideritna i ankeritna tijela i blokovi (gornji karbon ; GRUBIĆ i dr., 2001). Za analizu je korišten LEITZ - MPV3 mikroskop-fotometar pri povećanju od 500×, u imerzionom ulju, u laboratoriju za organsku geokemiju, INA. Za kalibraciju fotometra koristi se sintetski spinel (R = 0, 42%) i granat (R = 0, 82% i 1, 76%). Odabrani uzorci stijena smrvljeni su i usitnjeni u ahatnom tarioniku. Odvaga od 2 g tretirala se u konc. HCl, i u konc. HF te ispirala u destiliranoj vodi. Nakon sušenja, koncentrirana organska tvar miješala se s imerzionim uljem i prenosila na pokrovno stakalce. Stupanj termalne metasomatoze uzorka određen je iz stupnja vitrinitne refleksije korištenjem dijagrama odnosa efektivnog vremena zagrijavanja, maksimalne temperature stijene i vitrinitne refleksije (T-Ro-t) po postupku opisanom u BOSTICK i dr. (1979), i korištenjem jednadžbe prema BERKER i PAWLEWICZ (1994): T = (lnRo + 1, 68)/0, 0124, Ro = stupanj vitrinitne refleksije. Za vitrinitnu refleksiju odabrano je devet uzoraka, 6 vapnenaca, i po jedan uzorak alevrolita, siderita i sedimenta bogatog sulfidima, iz sideritno-limonitnog člana u Tomašici, unutar kojih je udio organskog ugljika bio >0.5%. Petrografskom analizom utvrđeno je da se sastoje uglavnom od amorfne organske tvari (100%). Izuzetak je uzorak alevrolita, unutar kojeg je analizom utvrđeno da se sastoji od 30% vitrinita i 70% amorfne organske tvari. Uslijed visokog stupnju termičke zrelosti liptiniti i inertiniti nisu identificirani, jer su njihova optička svojstva vrlo slična onima u vitrinita. Jedan uzorak vapnenca sadrži i tragove pirobitumena, na kojem je određen stupanj vitrinitne refleksije od Ro = 4, 60%. U svim uzorcima termički alteracijski indeks (Thermal Alteration Index, TAI) iznosi 4, što odgovara visokom stupnju zrelosti organske tvari. Također, u uzorcima je uočena veća količina pirita. Stupanj refleksije vitrinita, određen na uzorcima vapnenaca, alevrolita, siderita i sedimenta bogatog sulfidima kreće se od Ro = 3, 15 – 4, 80%. Prema dijagramu odnosa efektivnog vremena zagrijavanja, maksimalne temperature stijene i vitrinitne refleksije (T-Ro-t) procijenjena temperatura formiranja vitrinita iznosi 193 - 215&ordm ; ; C (BOSTICK i dr., 1979 ; Sl. 1), a prema jednadžbi BERKER i PAWLEWICZ (1994) iznosi 228 - 262&ordm ; ; C. Na jednom uzorku vapnenca, stupanj vitrinitne refleksije određen je na česticama pirobitumena i iznosi Ro = 4, 60%, što odgovara temperaturi formiranja vitrinita od 210&ordm ; ; C (BOSTICK i dr., 1979), odnosno 258&ordm ; ; C (BERKER i PAWLEWICZ, 1994). Dobiveni podaci podudaraju se s maksimalnim temperaturama homogenizacija fluidnih inluzija (L+V+SHal→ L = 201 - 259 C), kao i sa srednjim temperaturama dobivenim Na/K geotermometrom na izluževinama fluidnih inkluzija (Na/K = 149 - 284 C, srednja vrijednost iznosi 208 C ; CAN, 2002). Nema indikacija da je temperatura u ležištu prelazila 300&ordm ; ; C, kako sugeriraju neki autori (GRUBIĆ i dr., 2003), i vjerojatno se kretala oko 210 - 260&ordm ; ; C.

The Ljubija Fe carbonates-sulfide-barite ore field (44.55° N, 16.3° E) is located at the margin of Mesozoic carbonate platform, within Sana-Una river Paleozoic terrain, Inner Dinarides, 180 km NW from Sarajevo, Bosnia and Herzegovina. Fe carbonates occur as stratabound siderite and ankerite replacement in limestones and siderite-sulphide veins placed within shales. Mineralization is hosted by Middle Carboniferous sedimentary formation represented mainly by clastics (subgraywackes, graywackes, sandstones and organic-rich shales) and carbonate blocks placed within shales. Barite veins with fluorite are occurred within upper parts of ore deposit (Palinkaš, 1988). The main types of iron ore are (1) microcrystalline dark siderite and ankerite ; (2) sparry siderite veins within shales, contain sulfides and quartz ; (3) "zebra" siderite contains cavities infilled with sparry ankerite, quartz, sulfides and alteration phyllosilicates as tossudite and cookeite. Carbon and oxygen isotopic composition of mineralized and barren carbonates were determined in order to constrain the origin and nature of Fe-mineralization. The data have been obtained on the 54 carbonates from 32 hand samples. Based on textural and geochemical characteristics several generations of carbonates can be distinguished. The average d13C value of organic rich fine-grained limestone non-affected by mineralizing fluid of +1.6 +/- 0.4 ‰ V-PDB corresponds well to the world-wide Phanerozoic marine carbonates values. Affected limestones are slightly depleted on 13C. Light calcite veins which cut dark limestones affected by mineralizing fluid show δ 13C value of 0.2 +/- 0.16‰ . Microcrystalline dark ankerite with the average d13C and d18O values of -0.1 +/- 0.3 ‰ and +19.3 +/- 0.2 ‰ , respectively, has been identified to belong to the first Fe-carbonate generation. Microcrystalline dark siderite and dark siderite from zebra ore have the same average d13C. The next generation of Fe-carbonates is presented by light siderite from zebra ore with average d13C and d18O values of -2.3 +/- 0.8 ‰ and +19.7 +/- 0.6 ‰ , respectively. Ankerite sample isolated from zebra ore shows slightly depletion on 13C with average d13C value of -2.4 ‰ and d18O value of +15.9 ‰ . Sparry vein siderite is distinguished as the last generation of Fe-carbonates with average d13C and d18O values of -2.5 +/- 1.1 ‰ and +20.4 +/- 2.0 ‰ , respectively. Variations in d13C values of the host limestones and Fe carbonates point to progressive metasomatic replacement of calcite by siderite and can not be explain as a product of the synsedimentary event. The replacement of limestones by Fe-carbonates is a volume-for-volume process and result of two separate but coeval reactions - dissolution of the host mineral and precipitation of the replacing mineral (Garrels and Dreyer, 1952). Zebra ore was formed at the place where hot, acid fluid affected limestones. Volumetric rate of calcite dissolution was higher then volumetric rate of siderite precipitation. Dark fine grained (metasomatic) siderite was precipitated when fluid of lower temperature and acidity reacted with the host limestones. Volumetric rate of calcite dissolution was equal to volumetric rate of siderite precipitation i.e. primary texture was retained. Bicarbonate ions have been leached from limestones in reaction with mineralizing fluids. Fluids enriched on HCO3- deposited vein siderite within shales as the latter generation of Fe carbonates. Crystallization temperature of dark siderite was calculated from oxygen isotope fractionation between siderite and recrystallized calcite. Calcite-water and siderite-water equations by Zhang (1999) gave an apparent isotope equilibration temperature of 224°C. Fluid in isotopic equilibrium with both siderite and recrystallized calcite at the calculated temperature should have a d18O of 11.5‰ V-SMOW.