On the species of the genus Selliporella SARTONI & CRESCENTI, 1962 from the Middle Jurassic of the coastal Dinarides of Croatia

Emended diagnosis of the genus Selliporella and its type-species, S. donzellii SARTONI & CRESCENTI is proposed, based on the definitely proven existence of non-ramified branches in the older (basal) part of thallus and their ramifying in its higher (younger) parts. Based on the differences in the morphological characteristics of branches in the upper thallus parts, the type-species has been split into two varieties: S. donzellii var. donzellii SARTONI & CRESCENTI and S. donzellii var. galaeformis n. comb. Selliporella cornutuformis n. sp. is proposed, characterized by distinctly articulated (segmented) and spiky thallus, with each primary branch bearing a bundle of several trichophorous secondaries. Generic attribution of species originally described as Diplopora johnsoni PRATURLON and Triploporella neocomiensis RADOIČIĆ has been reviewed, resulting in their being unified as the same species, which, according to its newly observed morphological characters, has been ascribed to the genus Pseudoclypeina. Because Diplopora johnsoni has been validly described, Triploporella neocomiensis becomes, taxonomically, the younger synonym of Pseudoclypeina johnsoni (PRATURLON) n. comb

On some Salpingoporella species from the Lower Cretaceous of Dinaric karst

In this paper a new species Salpingoporella tari n.sp. is established, found in a sample of Barremian intraclastic grainstone. It is similar to S. annulata (LORENZ) and S. grudii (RADOIČIĆ), but visibly more robust. It has few branches per whorl, and the whorls being spaced far apart. The branches are laterally compressed at their distal ends, therefore being vertically elongated. New fi nding of Salpingoporella cemi (RADOIČIĆ) gave the new data on the variability of the shape of its branches, and on the precise stratigraphic position of the investigated localities. Besides, Salpingoporella patruliusi BUCUR is illustrated, this being its first find outside Monti Apuseni (south Carpathians) and its geographic range thus encompassing also the Dinarides. Also, a large observed number of specimens of Salpingoporella muehlbergii (LORENZ) with ramifi ed thallus makes that feature both its species-specific and generic characteristic. Quite strongly varying values of various biometric parameters, depending on the position on the thallus in one and the same specimen, raises serious questions as to their reliability and usefulness as a distinguishing factor in comparing both the specimens of one and the same species and of species of the same genus

Montenegrella? gracilis n. sp., a new calcareous alga (Dasycladales) from the Upper Barremian of Mt. Biokovo (Dinarides Mts., Croatia)

Montegrella? gracilis n.sp. (Dasycladales) is characterized by thick calcareous envelope and narrow central cavity. Bipartite branches are arranged alternately in consecutive whorls. The primaries are visibly differentiated into a thin, tendril-like stalk in the proximal part and a club-shaped or ellipsoidal inflated swelling in the distal part. The secondaries are poorly visible, of unclear shape and number, with a supposedly common starting point. On the type-locality, the alga occurs within a rich, typically Upper Barremian, algal assemblage. The validity of the genus Montenegrella, being disputed by BARATTOLO (1983), is commented upon by showing the generic attribution of the same or different species either to Suppiluliumaella or to Montenegrella by different authors

Clypeina lagustensis n.sp., a new calcareous alga from the Lower Tithonian of the Lastovo Island (Croatia)

Clypeina lagustensis n.sp. has been found in the Lower Tithonian deposits of the Lastovo Island (Dalmatia, Croatia). It is visually similar, obviously related and in some sections appearing almost identical, to Clypeina jurassica FAVRE, from which it differs by visible swellings and thinning of the central cavity, more pronounced distance between neighbouring whorls of fertile branches, and shape and structure of the interverticillate thallus parts, characterized by having well developed, hairy, sterile branches. These, after emerging from the exit pore, divide into several bundles which form a common turf with a calcareous envelope in the proximal part. Normal 0 21 false false false HR X-NONE X-NONE <!--[endif] --

The coralline flora of a Miocene maërl: the Croatian “Litavac”

The fossil coralline fl ora of the Badenian bioclastic limestone outcropping in Northern Croatia is known by the name “Litavac”, shortened from “Lithothamnium Limestone”. The name was given to indicate that unidentified coralline algae are the major component. In this first contribution to the knowledge of the coralline flora of the Litavac, Lithothamnion valens seems to be the most common species, with an unattached, branched growth-form. Small rhodoliths composed of Phymatolithon calcareum and Mesophyllum roveretoi also occur. The Badenian benthic association is dominated by melobesioid corallines, thus it can be compared with the modern maërl facies of the Atlantic Ocean and Mediterranean Sea. Since L. valens still survives in the present-day Mediterranean, an analogy between the Badenian Litavac and the living L. valens facies of the Mediterranean is suggested

FRACTAL ANALYSIS OF FRACTURE SYSTEMS IN UPPER TRIASSIC DOLOMITES IN ŽUMBERAK MOUNTAIN, CROATIA

U ovome radu prikazani su rezultati fraktalne analize pukotinskih sustava u gornjotrijaskim dolomitima Žumberka. Mehanička svojstva stijena zajedno s dijagenetskim i strukturnim procesima rezultirali su pukotinskim sustavima koji se mogu opisati kao fraktali. Prirodni fraktali neovisni su o mjerilu u određenome intervalu mjerila u kojemu se pojavljuju. Raspodjela pukotina može se tada opisati raspodjelom power-law i fraktalnom dimenzijom. Fraktalna dimenzija mjera je kojom određeni objekt ispunjava prostor. Može se procjenjivati iz fotografi ja izdanaka koje su pretvorene u binarne fotografi je gdje bijela boja predstavlja pukotine/stijenu, a crna stijenu/pukotine. Fraktalna dimenzija pukotinskih sustava tada se može procjenjivati na temelju metode box-counting. U ovome radu prikazani su rezultati fraktalne analize triju izdanaka. Rezultati su vrlo slični dosad objavljenim rezultatima fraktalne analize sličnih dolomita iz Slovenije. Procijenjene fraktalne dimenzije kreću se u intervalu 2,69 – 2,78, a ovise o raspodjeli pukotinskih sustava na izdanku. Niže vrijednosti upućuju na veći utjecaj manjega broja velikih pukotina. Veće vrijednosti fraktalnih dimenzija upućuju na ujednačenu raspodjelu većega broja manjih pukotina. Fraktalna dimnezija vrlo je važan parametar u opisu pukotinskih sustava jer predstavlja mjeru kako su pukotine raspoređene na izdanku. Može se koristiti i pri izradi diskretnih modela pukotinskih sustava (engl. Discrete Fracture Network – DFN) ako se raspodjela pukotina modelira s raspodjelom power-lawThis paper presents results of fractal analysis of fracture systems in upper Triassic dolomites in Žumberak Mountain, Croatia. Mechanical rock characteristics together with structural and diagenetic processes results with fracture systems that can be considered as fractals. They are scale-invariant in specific range of scales. Distribution of fractures can be than described with power law distribution and fractal dimension. Fractal dimension is a measure of how fractures fill the space. Fractal dimension can be estimated form photographs of outcrops by converting photographs to binary photographs. In binary photo there is only black (rock or fractures) and white (fractures or rock). Fractal dimension is then estimated based on box-counting method. In this paper we present results of fractal analysis from three outcrops. Results are very similar to previous published results from outcrops of dolomites in Slovenia. Obtained fractal dimensions are in range 2,69-2,78 and it depends on how fracture systems are distributed in the outcrop. Lower values indicate smaller number of fractures and higher significance of larger fractures. Higher values indicate distribution of more similar sized fractures throughout whole outcrop. Fractal dimension is very significant parameter in rock fracture system characterisation sense it describes how fractures are distributed in the outcrop. It can be used in discrete fracture network modelling if spatial distribution of fractures is represented with power law distribution

History of investigations on fossil algae in Croatia

Investigations of fossil algae in Croatia began in 1907 with the very first description of the Permian dasyclad Mizzia velebitana from Mt. Velebit by Austrian geologist Richard Schubert. This was followed by Julius Pia’s investigations (1920, 1925), on material given to him by Schubert. The first Croatian researcher on fossil algae was Milan Herak, Pia’s PhD student, with his first paper on Ladinian dasyclads published in 1950. He cooperated with a colleague from the Faculty of Science, Vanda Kochansky-Devidé, who published her fi rst papers together with Herak on Permian and Carboniferous dasyclads in 1959 and 1960. While Herak focused on Triassic algae, Kochansky-Devidé investigated mostly Upper Palaeozoic algae and fusulinid oraminifera. Ivan Gušić comes from the same faculty, and his first paper was published in 1966. Momčilo Milanović, from the Institute of Geology (the present day Croatian Geological Survey), published his first paper in 1962, focusing mainly on Permian algae. The most prolific researcher Branko Sokač also came from the Institute of Geology; his first papers dated from 1964, and he is still an active researcher. Over time, papers originating from the “Zagreb Algological School” become distinguished by rich and well illustrated fossil material, making numerous contributions to the better understanding of fossil benthic algae from younger Palaeozoic and Mesozoic strata. This was possible not only because of the diligence of the authors, but was also the result of the very thick and well exposed carbonate sequence of the Croatian Dinarides Mts. Rajka Radoičić from Beograd (Serbia) also described some taxa from Croatia. Almost all the research refers to dasycladal algae, while other algae are only rarely investigated. Complete references to all papers are given