Blanka Cvetko Tešović

Planktonic foraminiferal biostratigraphy and paleoecology of Upper Cretaceous deposits from the Palmyride Region, Syria

This study represents a detailed micropaleontological investigation of the composition and diversity of planktonic foraminiferal assemblages from the Upper Turonian to Maastrichtian interval of two deep exploration wells (Al Mahr-1 and Palmyra-1) in the Palmyride area of Syria. In combination with a litostratigraphic analysis, this detailed biostratigraphic study provided important new paleoecological and paleoclimatic interpretations and insights into the nature of deposition along the northern passive margin of Gondwana during the Late Cretaceous. The investigated strata belong to three lithostratigraphic units (from base to top): the upper part of the Judea Formation (Upper Turonian–Earliest Santonian), the Soukhne Formation (Santonian–Lower Campanian), and the Shiranish Formation (Upper Campanian–Maastrichtian). The results represent the first detailed determination of planktonic foraminifera from the Palmyidra region. The presence of rich and diverse foraminiferal associations enabled the establishment of the following nine late Turonian to Maastrichtian biostratigraphic zones based on documented index-taxa and/or the entire microfossil assemblages: I) Dicarinella concavata Zone; II) Dicarinella asymetrica Zone; III) Globotruncanita elevaata Zone; IV) Contusotruncana plummerae Zone; V) Radotruncana calcarata Zone; VI) Globotruncanella havanensis Zone;VII) Pseudoguembelina palpebra Zone; VIII) Racemiguembelina fructicosa Zone; and IX) Abathomphalus mayaroensis Zone. The late Turonian to early Campanian foraminiferal assemblages (biozones I-IV) are highly dominated by opportunistic taxa (r-strategists) and suggest a generally fluctuating subtropical climate and deposition in outer shelf environments. The well-preserved and highly diversified late Campanian to Maastrichtian foraminiferal assemblages (biozones V-IX) imply the presence of a well-stratified water column, tropical to subtropical climate, and deposition in outer shelf to upper bathyal environments. A decrease in the number of planktonic species during the late Maastrichtian indicates cooling and deterioration of paleoceanographic conditions. Common occurrence of phosphate grains in the Soukhne Formation (Santonian–Lower Campanian) present an important indicator of specific geological and paleoenvironmental conditions, such as oxygen deficiency, upwelling and transgression. These conditions support the interpretations of high speciation and domination of opportunistic planktonic foraminiferal taxa (heterohelicids and muricohedbergelids) in Biozone II Dicarinella asymetrica Zone.

FIRST RECORD OF DINOSAURS IN THE LATE JURASSIC OF THE ADRIATIC-DINARIDIC CARBONATE PLATFORM (CROATIA)

Abstract All previously known dinosaur remains on the Adriatic-Dinaridic carbonate platform (ADCP) were described from Cretaceous deposits. A new trackbearing locality is late Tithonian in age and represents the oldest evidence of dinosaurs on the ADCP. The site is in an active quarry near the village of Kirmenjak in western Istria. Almost a thousand sauropod footprints including 23 single trackways have been found on the outcrop. Oval impressions represent pes prints, and horseshoe-shaped impressions represent manus prints; pes prints are 23 to 52 cm long. Calculated heights at the hip range from 153 to 306 cm. The main direction of dinosaur movement was toward the northeast, and some of the individuals were moving together. The trackways show a characteristic narrow gauge, and pace and stride lengths indicate a slow walk. The footprints are similar to Parabrontopodus ichnogenus, and the ichnocoenosis could be assigned to the Brontopodus ichnofacies. The presence of the sauropods on the Adriatic-Dinaridic carbonate platform during the Late Jurassic could be explained by connection with the African continent via its southern margins during emersion.

Facies Variability in Lower Liassic Carbonate Successions of the Western Dinarides (Croatia)

SummaryIn the Western Dinarides the Lower Liassic carbonates are underlain by Upper Triassic “Hauptdolomit”, whereas the first appearance of the foraminiferOrbitopsella praecursor (Gümbel) marks the beginning of the Middle Liassic. Their composition, observed at several localities in Western Croatia, shows a correlation of sedimentation events, which took place during Early Liassic on the Adriatic-Dinaridic carbonate platform. Facies variability is interpreted as result of autocyclic sedimentary processes on which the carbonate platform reacted by periodical oscillations of sea-bottom near the fair-weather wavebase. As a consequence, the Lower Liassic carbonate successions in the Dinarides is characterized by stacking of two main types of coarsening-upward parasequences: (1) the basal part of the Lower Liassic succession is represented by parasequences composed of mudstones or pelletal-bioclastic wackestones as their lower members, and peloidal-bioclastic wackestone/packstones to grain-stones as their upper members; and (2) the upper part of the Lower Liassic succession with parasequences consisting of mudstones or pelletal-bioclastic wackestones overlain by ooid grainstones. Judging from the composition of parasequences and thickness relations of their members, the first type is interpreted to comprise late transgressive system tract (ITST) and/or early highstand system tract (eHST), while the second type corresponds to a late highstand system tract (1HST) and/or early lowstand system tract (eLST) of a third-order sequence.

A new dinosaur tracksite in the Late Albian of Istria, Croatia

A new site with dinosaur footprints has been found in the upper Albian sediments of Istria, Croatia. The site was discovered near the city of Pula, at the Zlatne Stijene locality. The carbonate succession of the Zlatne Stijene locality is characterized by thin bedded limestones deposited in peritidal and foreshore environments. The microfossil assemblage found at the site indicates a late Albian age. One clearly distinguishable footprint and four indeterminate rounded tracks were discovered at the investigated outcrop. The footprint is tridactyl and belongs to a medium-sized bipedal theropod dinosaur of approximately 3 meter in length. Regarding dimensions and morphology it is closely related to the other late Albian theropod footprints from the Adriatic-Dinaridic carbonate platform (ADCP). The Zlatne Stijene locality fits with the Brontopodus ichnofacies concept.

Cretaciclavulina gusici n. gen., n. sp. (?family Valvulinidae BERTHELIN, 1880), a new larger benthic foraminifer from the lower Campanian of Brač Island, Croatia

The larger benthic foraminifera Cretaciclavulina gusici n. gen., n. sp. is described from the lower Campanian Pucisca Formation of the Island of Brac, Croatia. With its elongate test, trochospiral to uniserial coiling, simple chambers, paraporous wall structure, and areal aperture provided with a cribrate apertural plate, Cretaciclavulina is tentatively placed into the family Valvulinidae BERTHELIN, 1880. Besides Neobalkhania bignoti CHERCHI, RADOICIC & SCHROEDER, 1991, Fleuryana adriatica DE CASTRO, DROBNE & GUSIC, 1994, and Reticulinella fleuryi CVETKO, GUSIC & SCHROEDER, 1997, Cretaciclavulina gusici represents the fourth benthic foraminifera newly described from the Upper Cretaceous shallow-water carbonates of Brac Island.

Dinosaur footprints in the Upper Hauterivian deposits of the Palud Bay in Istria, Croatia

Sixteen dinosaur footprints are exposed along the upper-bedding plane of a single Upper Hauterivian limestone layer in the Palud bay (western Istria, Croatia). This distinct footprint-bearing horizon is part of the thick Mesozoic Adriatic-Dinaridic Carbonate Platform stratal succession. Strata at the Palud site are characterized by peritidal (shallow subtidal to intertidal) limestone with several shallowing-upward cycles composed of mudstone, peloidal wackestone/packstone, peloidal packstone/grainstone and fenestral mudstone/wackestone with common geopetal infill. The Late Hauterivian age of these deposits is determined from their microfossil assemblage, which is dominated by ostracods, benthic foraminifera and calcareous green algae Dasycladales. The Palud site dinosaur footprints are circular to elliptical in shape, with no clearly visible digit impressions (except for one questionable example), and are rather large with average length of 30 cm. Most footprints have a well-defined expulsion rim that represents displacement and compression of soft, waterlogged sediment substrate by the weight of the dinosaur. All of the footprints are of nearly same shape and size, which indicates that they were produced by the same kind of tracemaker – likely a sauropod dinosaur. These animals left their footprints on top of a shallowing-upward succession of an intertidal environment during a short subaerial exposure of fine-grained carbonate sediment.

High-frequency sea-level changes recorded in deep-water carbonates of the Upper Cretaceous Dol Formation (island of Brač, Croatia)

High-frequency sea-level changes recorded in deep-water carbonates of the Upper Cretaceous Dol Formation (island of Brač, Croatia) The upper part of the Middle Coniacian/Santonian-Middle Campanian deep-water Dol Formation of the island of Brač is composed of countless fine-grained allodapic intercalations deposited in an intraplatform trough. Within the studied section 13 beds can be distinguished, each defined by its lower part built up of dark grey limestone with abundance of branched, horizontally to subhorizontally oriented burrows, and the upper part, in which the light grey to white limestone contains larger burrows, rarely branched, showing no preferential orientation. The lower, dark grey, intensively bioturbated levels are interpreted as intervals formed during high-frequency sea-level highstands, while the upper, light grey-to-white levels are interpreted as intervals formed during the high-frequency sea-level lowstands. Cyclic alternation of these two intervals within the fine-grained allodapic beds is interpreted as the interaction between the amount of carbonate production on the platform margin and the periodicity and intensity of shedding and deposition in the distal part of toe-of-slope environment, which is governed by Milankovitch-band high frequency sea-level changes.

Stable isotope analysis of Upper Tithonian limestones with dinosaur footprints from Kirmenjak quarry (Istria, Croatia)

The Kirmenjak locality of western Istria, Croatia, represents the oldest evidence of a dinosaur presence on the Adriatic- Dinaridic Carbonate Platform (ADCP). In a quarry at this locality, almost a thousand sauropod footprints are recognized in one distinctive trackbearing horizon within the Upper Tithonian limestones. The stable isotopes of oxygen and carbon, in conjunction with microfacies analysis of carbonate rocks exposed in this quarry, unravel details about the marginal marine or coastal environments in which sauropods left their footprints. Rocks from the trackbearing horizon, and laterally adjacent area, represent intertidal fenestral mudstones that form the top of a shallowing- upward succession, capped with a thin peloidal packstone/grainstone layer and overlain by subtidal mudstone. The formation and preservation of footprints was favoured by short-duration exposure of muddy sediment and its rapid burial beneath more mud. The isotopic composition of the sample from the trackbearing horizon is not substantially different from those of an adjacent area without footprints and from the overlying mudstone. Stable isotope analysis supports petrographic observations that the conditions on the carbonate tidal fl at during formation of rocks with dinosaur footprints were not unique. Documented variations in stable isotope compositions refl ect minor differences in the depositional and diagenetic history of the Kirmenjak quarry succession.