Jožica Zupanič

Borings in Mobile Clasts from Eocene Conglomerates of Northern Dalmatia (Coastal Dinarides, Croatia)

SummaryBored clasts occur in Eocene conglomerates deposited in the upper shoreface and beachface settings of the Dinaric foreland basin. The trace fossil assemblage consists ofGastrochaenolites, Trypanites, and possibly some other ichnotaxa and may be compared to theTrypanites Ichnofacies. The preservation characteristics of the borings reflect many stages of colonisation/boring and abrasion. The removal of shells of the boring bivalves, the different depths of the abrasional truncation of borings, and the predominant preservation of the largest excavations (Gastrochaenolites) in the ichnocoenosis are related to repeated phases of abrasion, caused by the mobility of clasts. Coastal gravel is a specific variant of hard substrates, whose mobility controls the colonisation of borers, the type of assemblage and its preservation potential.

Impressions of the Biota Associated With Waterfalls and Cascades from a Holocene Tufa in the Zrmanja River Canyon, Croatia

The following types of calcified deposits characterize Holocene waterfall tufas in the Zrmanja river: mossy deposits, algally laminated crusts and algally coated grains. Petrological examination revealed, that abundant organic remains belonging to mosses and algae provide supporting material, over which tufa accretion takes place, leaving well-defined impressions of the biota. Postgenetic features like meniscus, isopachous and drusy mosaic calcite spar cementation, as well as aggradational neomorphism are only rarely present.

Sharply-Topped Alluvial Gravel Sheets in the Palaeogene Promina Basin (Dinarides, Croatia)

The upper part of the Promina Beds at their western extent is represented by two alluvial units: the Kunovac Beds and the Upper Alluvial Unit. The Kunovac Beds contain a high proportion of fine-grained sediments, and generally lacks debris flow deposits. The principal architectural components of the Kunovac Beds are (1) complex (multilateral, multi-storey) gravel-dominated sheets, which originated by the advance of mobile-channel belts, and were terminated by sudden abandonment, (2) smaller heterogeneous gravelly-sandy sheets, which originated in fluvial belts from a combination of sheet flows and channelized flows, (3) small isolated ribbons reflecting the filling of small channels, and (4) floodplain mudstones and sandstones. The basic style by which the Kunovac Beds, as well as the most part of the Promina alluvium were built up are the repeated advances and abandonments of the alluvial belts, and related stacking of coarse-grained sheets and floodplain deposits. The most important factors responsible for the dominance of this sheet-like geometry are high sediment supply and high aggradation and subsidence rates. Deposition of the Kunovac Beds occurred on alluvial plains, situated between the basin-margin proximal alluvium (including fans) and marginal-marine zone of the Promina Basin. The alluvial Promina Beds represent a transverse type of basin-fill pattern, whereas the deepest portion of the basin experienced longitudinal palaeotransport.

An Association of Marine Tractive and Gravity Flow Sandy Deposits in the Eocene of the NW Part of the Island of Pag (Outer Dinarides, Croatia)

The Eocene clastics of the NW part of the island of Pag overlie carbonate platform deposits and are dominantly sandy. Besides minor components, they include cross-laminated and cross-bedded sandstones produced by marine tractive flows, mostly directed toward E, and ESE, and dominantly massive sandstones probably deposited by gravity flows. The area was situated close to sand-rich sources and river mouth(s). Possible settings include a delta-related shallow-marine area, and a sea strait. Structural deformation intervened very early in the history of a complex outer dinaric foreland realm and governed its subsequent evolution, in contrast to a simple foreland trough envisaged before.

The youngest stage in the evolution of the Dinaric carbonate platform: the Upper Nummulitic Limestones in the North Dalmatian foreland, Middle Eocene, Croatia

The paper provides a description of the poorly known Upper Nummulitic Limestones exposed in the North Dalmatian foreland basin of the Outer Dinarides in Croatia. This formation originated on a land-attached ramp-type platform with a temperate sediment production. It transgressively overlies older platform limestones and includes limestones deposited in very shallow, restricted settings, which subsequently evolved into carbonate platform environments typified by diversified biota. The succession terminated at a drowning unconformity, which is intra-Bartonian (Middle Eocene) in age based on biostratigraphic interpretations of the larger foraminifera present. This study demonstrates that the history of the carbonate platform of the Outer Dinarides extends into the Bartonian and that the studied limestones document the youngest, hitherto unknown stage in the platform development. The SW margin of the Upper Nummulitic platform was dissected by faults and prone to collapse, which represented the source for megabreccias deposited in an adjacent basin. This platform-basin system represents a new element in the sedimentary and tectonic evolution of the Dinaric foreland.