64 research outputs found

    MORPHOMETRIC APPROACH TO DETERMINATION OF LOWER JURASSIC SIPHOVALVULINID FORAMINIFERA

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    Siphovalvulina is among the first foraminifera that appear on carbonate platforms of the Lower Jurassic, forming a conspicuous element of low-diversity assemblages prior to recovery after the end-Triassic biotic crisis. The high morphologic variability of species of this genus is usually not documented, which makes the determination of species difficult and subjective. We demonstrate the variability in five morphotypes of Siphovalvulina in Sinemurian and Pliensbachian carbonate rocks from the Dinarides and the Southern Apennines. Due to the different interpretation of its architecture, an emendation of the genus Siphovalvulina is proposed. One morphotype has been left in open nomenclature and could belong to either S. variabilis Septfontaine or to S. beydouni BouDagher- Fadel & Noujaim Clark. Three morphotypes, differing in apical angle and/or size belong to S. ex gr. gibraltarensis BouDagher-Fadel, Rose, Bosence & Lord. We also describe a new genus and species, Radoicicina ciarapicae gen. n., n. sp. from the lower Sinemurian of the Southern Apennines. We suggest a close phylogenetic relationship between the two genera and introduce a new family, Siphovalvulinidae fam. n. of the superfamily Eggerelloidea

    Critical review of Pseudocucurbitidae (Miliolina, Foraminiferea) from the Late Triassic reef environments of the Tethyan area

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    Abstract. The Late Triassic foraminiferal genera Amphorella, Spiriamphorella, Urnulinella, Pseudocucurbita, Paratintinnina, Costifera and Siculocosta are considered junior synonyms of the genus Cucurbita. Consequently, the number of families of the Milioliporacea (Miliolina) is significantly reduced. The valid species of the genus Cucurbita are considered to be Cucurbita infundibuliforme Jablonský, 1973, C. subsphaerica (Borza & Samuel, 1977a) comb. nov., C. longicollum Senowbari-Daryan, 1983, C. battagliensis (Senowbari-Daryan, 1983) comb. nov., C. cylindrica (Senowbari-Daryan, 1983) comb. nov. and C. floriformis (Altiner et al., 1992) comb. nov.

    Rock analysis of Roman tombstones from Podkraj and Ig near Ljubljana

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    Naravni kamen so v okolici Ljubljane (Emona) izkoriščali in uporabljali že v rimskem obdobju. Na tem območju so ohranjeni številni kamniti spomeniki iz tistega časa. V članku je predstavljena analiza kamnine dveh nagrobnih stel, najdenih na južnem obrobju Ljubljanskega barja, na Ižanskem: nagrobnik za Kviemonija in njegovo družino iz cerkve sv. Janeza Krstnika v Podkraju pri Tomišlju in nagrobnik za Petona z Marofa na Igu (sekundarni najdišči). Na podlagi makroskopskega in mikroskopskega opisa sklepamo, da je spomenik iz Podkraja izklesan iz litiotidnega apnenca spodnjejurske starosti, spomenik z Iga pa iz ooidnega apnenca, ki po starosti sodi v vrhnji del spodnje jure ali v srednjo juro. Oba litološka različka najdemo na južnem obrobju Ljubljanskega barja, pri čemer je najbolj verjetno nahajališče litiotidnega apnenca okolica Podpeči.Natural stone around Ljubljana (Emona) was exploited and used at the time of the Roman Empire. Numerous stone monuments from this time remain in the area. The article provides rock analysis of two tombstones that have been found on the southern outskirts of Ljubljansko barje: the tombstone of Quiemonis and his family from the St. John the Baptist Church in Podkraj near Tomišelj and the Petto tombstone from Marof at Ig (both in secondary position). Based on the macroscopic and microscopic descriptions, the rock of the tombstone from Podkraj is considered to be Lower Jurassic lithiotid limestone, and the rock of the tombstone from Ig is made of ooidal limestone which is upper Lower and Middle Jurassic in age. Considering the spatial distribution of identified rocks on the southern outskirts of Ljubljansko barje and the potential sites of Roman quarries, the source of both rocks is local, and both tombstones most likely originated from the surrounding of Podpeč

    USE OF X-RAY MICRO-COMPUTED TOMOGRAPHY ON SELECTED UPPER TRIASSIC (RHAETIAN) FORAMINIFERA FROM THE WESTERN BLACK SEA SHELF, OFFSHORE ROMANIA

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    Upper Triassic (Rhaetian) foraminifera belonging to the species Glomospira charoides (Jones & Parker), Gaudryinopsis kelleri (Tappan), G. triadica (Kristan-Tollmann), Ammobaculites zlambachensis Kristan-Tollmann, Verneuilinoides racema (Trifonova), and Trochammina cf. jaunensis Brönnimann & Page were investigated using X-ray micro-computed tomography. Foraminifera were recovered from the drill core CM31 of the 817 Lebăda Vest borehole, located off the coast of Romania on the western Black Sea shelf, from depths of 2623 m to 2625 m. Tomographic data was used to generate digital models, which were then virtually sectioned in desirable ways. The acquired transects can be used for comparison with specimens viewed in thin sections, providing a better connection between specimens recovered from residues and those observed in thin sections using transmitted light microscopy

    Sediment infill of the Middle Triassic half-graben below Mt. Vernar in the Julian Alps, Slovenia

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    A sediment infill of a small, late Anisian–earliest Ladinian half-graben, sealed by massive limestone of the Schlern Formation is exposed on the northeastern slopes of Mt. Vernar in the eastern Julian Alps, Slovenia. The pre-rift base of the succession is formed by a chaotic mixture of massive limestone and limestone breccia of the Anisian platform. Sedimentation in the half-graben started with a 20 m thick thinly bedded pink nodular limestone which is informally named here as the Vernar member. It consists of microbial carbonate and was probably deposited within the photic zone. The Vernar member is overlain by poorly sorted polymict breccias of the Uggowitz Breccia Formation which reaches a thickness of at least 150 m, but pinches out rapidly towards the SE graben margin, reflecting the highly asymmetric basin geometry. Individual beds of breccia represent successive debris flow deposits. The Uggowitz Breccia Formation is followed by a few metres of sandstone and sandy limestone of the Buchenstein Formation. The limestone contains abundant grains of shallow marine origin and terrestrial plant fragments. The overlying post-rift Schlern Formation consists of crudely bedded and massive limestone, covering the graben. The consistent NE-SW strike of the graben-bounding faults and of the smallscale conjugate normal faults observed in the Uggowitz Breccia Formation suggests that the half-graben originated from NW-SE directed extension

    Origin of the Jezero v Ledvicah lake; a depression in a gutter-shaped karstic aquifer (Julian Alps, NW Slovenia)

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    The Julian Alps are composed almost exclusively of Triassic to Lower Jurassic carbonates, which results in a karstified high-al­pine landscape. In such settings, large water accumulations are not expected and precipitated water drains vertically, gathers in deep, large-scale aquifers, and outflows in large karstic springs located in deeply incised valleys. Some small lakes, however, exist in high alpine areas. Most commonly, they formed above impermeable glacial sediments and are generally characterized by stagnant waters. Jezero v Ledvicah lake, which is one of the seven lakes in the Triglav Lakes Valley, is an exception, because it shows high subaqueous water inflow and outflow and occurs among highly karstified and permeable carbonates. Combining previous research with our new, detailed geological mapping of the lake surroundings and sedimentary research on the Lower Jurassic strata, we propose a hydrogeological model with the aim of explaining the extraordinary behaviour of the lake. We propose that Jezero v Ledvicah lake: A) is part of the “gutter-shaped” aquifer with perched groundwater that is situated below the floor of the Triglav Lakes Valley; B) barriers of the aquifer are structural (faults and thrust) and stratigraphic (clay interlayers in Lower Jurassic limestone); C) the lake formed in a structural, hydrogeological and morphological depression within this aquifer; D) the groundwater of the aquifer is re­charged not solely from the surface directly above the aquifer but additionally by subterraneous inflow from the overlying Slatna Nappe aquifer; and E) groundwater outflows from the aquifer at the southern end of the Triglav Lakes Valley, where the Lower Jurassic limestone pinches out.Key words: high-alpine lake, karstic aquifer, Julian Alps, Triglav Lakes Valley, Jurassic limestone, Southern Alps.Nastanek Jezera v Ledvicah – globel v žlebu podobnem kraškem vodonosniku (Julijske Alpe, SZ Slovenija)Julijske Alpe skoraj v celoti sestavljajo triasni in jurski karbonati, kar se odraža v morfologiji kraške visokogorske pokrajine. V tovrstnih razmerah ni pričakovati večjih površinskih pojavov vode, saj padavinska voda pronica vertikalno in se akumulira v obsežnih globokih vodonosnikih, iz teh pa izteka v izdatnih kraških izvirih, ki so v globoko vrezanih dolinah. Kljub temu v alpskem visokogorju obstaja nekaj manjših jezer. Večina jih je nastala nad neprepustnimi ledeniškimi sedimenti in jih lahko opredelimo kot stoječe vode. Jezero v Ledvicah, ki je eno izmed sedmih jezer v dolini Triglavskih jezer, je izjema, saj ima močno podzemno napajanje in iztok (je pretočno) ter se pojavlja med močno zakraselimi in prepustnimi karbonati. Na podlagi predhodnih raziskav, izdelave nove geološke karte okolice jezera in sedimentoloških raziskav spodnjejurskih plasti predlagamo strukturno-geološki in hidrogeološki model, da bi razložili nastanek in lokacijo jezera. Naše ugotovitve kažejo, da je A) Jezero v Ledvicah del žlebu podobnega vodonosnika z visečo podzemno vodo, ki se pojavlja v jurskih plasteh pod dnom doline Triglavskih jezer, B) da so hidrogeološke bariere vodonosnika strukturne (prelomi in nariv) in stratigrafske (plasti gline v spodnjejurskem apnencu), C) da je jezero nastalo v strukturni, hidrogeološki in morfološki depresiji znotraj vodonosnika, D) da se podzemna voda ne napaja izključno iz padavin, ki padejo neposredno na površino vodonosnika, ampak dodatno s podzemnim napajanjem iz višje ležečega vodonosnika Slatenske tektonske krpe in E) da podzemna voda izteka iz vodonosnika na južnem delu doline Triglavskih jezer, kjer se plastnati spodnjejurski apnenci (in s tem vodonosnik) izklinjajo.Ključne besede: visokogorsko jezero, kraški vodonosnik, Julijske Alpe, dolina Triglavskih jezer, jurski apnenec, Južne Alpe

    Microfossils from Middle Triassic beds near Mišji Dol, central Slovenia

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    Middle Triassic beds exposed along the road between Mišji Dol and Poljane pri Primskovem (Posavje Hills) comprise marlstone, tuff, volcaniclastic sandstone, and thin- to medium-bedded limestone and dolostone. The succession was logged and sampled for conodonts. A relatively rich conodont assemblage was determined, consisting of Budurovignathus gabrielae Kozur, Budurovignathus sp., Cratognathodus kochi (Huckriede), Gladigondolella malayensis Nogami, Gladigondolella tethydis Huckriede, Gladigondolella sp., Neogondolella balkanica Budurov & Stefanov, Neogondolella cf. excentrica Budurov & Stefanov, Neogondolella constricta (Mosher & Clark), Neogondolella cornuta Budurov & Stefanov, Neogondolella sp., Paragondolella excelsa Mosher, Paragondolella liebermani (Kovacs & Kozur), Paragondolella trammeri (Kozur), Paragondolella cf. alpina (Kozur & Mostler), and Paragondolella sp. The assemblage correlates with the upper Anisian and lowermost Ladinian assemblages from the Global Boundary Stratotype Section and Point (GSSP) of the Ladinian at Bagolino in the Southern Alps in northern Italy. Along with conodonts, numerous specimens of benthic foraminifera Nodobacularia? vujisici Urošević & Gaździcki were recovered from the lowermost part of the succession. Previous research on this taxon is critically evaluated

    A glimpse of the lost Upper Triassic to Middle Jurassic architecture of the Dinaric Carbonate Platform margin and slope

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    In the southernmost outcrops of the Slovenian Basin the Middle Jurassic coarse-grained limestone breccia (mega)beds are interstratified within a succession that is otherwise dominated by hemipelagites and distal turbidites. In this paper, these beds are described as the Ponikve Breccia Member of the Tolmin Formation. We provide descriptions of the studied sections with detailed geological maps and analysis of the breccia lithoclasts. From the latter, a non-outcropping margin of the Dinaric Carbonate Platform is reconstructed. In the Late Triassic the platform margin was characterized by a Dachstein-type marginal reef. After the end-Triassic extinction event, the platform architecture remained, but the reefs were replaced by sand shoals characterized by ooids. In the late Early Jurassic and/or early Middle Jurassic a slope area might have been dissected by normal faults and a step-like paleotopography was formed. In the Bajocian, during a period of major regional geodynamic perturbations, extensional or transtensional tectonic activity intensified and triggered the large-scale collapses of the Dinaric Carbonate Platform margin producing the limestone breccias described herein. This may in turn have caused a backstepping of the platform margin, as is evident from the occurrence of Late Jurassic marginal reefs that are installed directly above the Upper Triassic and Lower Jurassic inner platform successions

    Parameters of Explosive Formed Projectiles

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    Kroz ovaj rad prikazani su tipovi i vrste eksplozivnih tvari, procesi koji su vezani uz njih te razna područja primjene. Prikazati će se o vojna primjena kumulativnih naboja, poglavito eksplozivno formiranim projektilima i utjecajnim čimbenicima učinka djelovanja projektila. Budući da se kumulativni naboji u svim oblicima koriste u području obrane, poznavanje karakteristika, sposobnosti djelovanja i mogućnost primjene pojedinih izvedbi je od osobite važnosti kako u kontekstu teoretske analize djelovanja tako i u praktičnoj primjeni. Na osnovi rezultata ispitivanja objašnjeno je kako pravilan izbor čimbenika može rezultirati optimalno konstruiranim eksplozivno formiranim projektilom. Cilj ovoga rada potvrđivanje formiranje i djelovanje projektila prema Hopkinsonovom i Misznay – Shardinovom efektu. Kako bi se mogla provesti ova studija učinkovitosti djelovanja provedeno je šest praktičnih ispitivanja na terenskom poligonu RGNF-a Ljubeščica.Through this scientific research work, the types and kinds of explosive substances, the processes related to them and various areas of application are presented. We will talk about the military application of cumulative charges, especially explosively formed projectiles and the influential factors of the effect of projectile. Since shaped charges in all forms are used in the field of defense, knowledge of the characteristics, performance and the possibility of applying individual types of charges is of particular importance both in the context of theoretical analysis of projectile performance and in the practical application itself. Based on the test results, the interdependencies of individual shaped charge factors were determined and it was explained how the correct choice of factors can result in an optimally constructed explosively formed projectile. The aim of this paper is to find the optimal parameters necessary to achieve the desired effect and performance of the explosively formed projectile, and to confirm the formation and action of the projectile according to the Hopkinson and Misznay - Shardin effect. In order to be able to conduct this performance study, six practical tests were conducted on the test field site of RGNF Ljubeščica
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