A global radiolarian dataset of 167 Pliensbachian and Toarcian species was analysed. An extinction interval was recognized through the Late Pliensbachian and Early Toarcian. The predominance of extinctions over originations was caused by a series of climate and environmental changes related to intensified magmatic activity. The diversity trends were in line with other marine faunas (ammonites and also benthos) but opposed to phytoplankton. A distinct provincialism between low-latitude and mid- to high-latitude assemblages has been established. The paper is the first report on the global response of radiolarian faunas to the environmental deterioration around the Pliensbachian-Toarcian boundary, and will be of interest to the broader research community focusing on this and other extinction intervals.
COBISS.SI-ID: 35815213
The Guevgueli Ophiolite Complex near Demir Kapija (Eastern Vardar Ophiolitic Unit) was studied for the age and facies of the overlying sediments. Cherts in direct contact with basalts are dated to late Bathonian–early Callovian with radiolarians. The post-obduction sequence, here informally named the Demir Kapija group, is composed of polymictic conglomerate, probably Kimmeridgian in age, and a more than 350 m thick carbonate succession. The carbonate succession consists of hemipelagic, slope and platform-margin facies, and contains algae and benthic foraminifers indicative of the Tithonian age. The Demir Kapija group is an exceptionally well preserved example of platform evolution on top of obducted ophiolites and may serve for better understanding of other genetically similar carbonate platforms that characterized the closing Meliata-Maliac-Vardar branch of the Neotethys. The first author Duje Kukoč was a PhD student in our research group until February 2015.
COBISS.SI-ID: 37759021
The research into the fossil population structure of the cave bear from the Mokrica cave provided new data concerning the behaviour and mortality of this extinct species. Age at death was estimated for 128 different individuals by analysing cementum increments, root formation and crown wear of left M1 teeth. After the frequency distribution of specimens through one-year intervals, the mortality trends can be estimated for various lifetime periods, and interpreted in accordance with data for present-day bears. Extremely fragile molars of less than 6 month old cubs did not get preserved. Yearlings are the most numerous age class in the fossil population from the Mokrica cave. Mortality drastically dropped after cave bears survived their first hibernation in the second winter. The lowest mortality rate was observed in the 9-15 years age group, when cave bears would be expected to be in their prime. The oldest age recorded by cementum analysis is approximately 30 years, which indicates that the maximum life span was similar to present-day bears. Previous hypotheses that were not based on objective methods of age determination, suggested for one third shorter longevity of the cave bear. Study of dental tissues shows that the mortality in the cave was seasonally restricted – the majority of deaths in the cave occured during winter and in early spring. Sex structure of the fossil population has been studied on the sample of 750 canines. The significantly higher proportion of males in the group of older juveniles and subadults could be explained by the fact that the weaning period is more critical for males also in present-day bears. In young adults and prime adults the mortality was presumably higher in females. The sex structure of adult bears, especially in the sample of older individuals, indicates that the Mokrica cave was used as winter den mostly by solitary males.
COBISS.SI-ID: 27555629
The age of 28 cave bears individuals that died in Križna jama has been determined by the analysis of all lower left specimens of d4 milk teeth and M1 permanent teeth. Results show a relatively low proportion of juveniles and a large proportion of old individuals. The presence of cubs younger than 3 months indicates that females at least occasionally hibernated in Križna jama and gave birth during that time. The oldest age was reached by a particularly large male that lived for about 28 years. The life span of the cave bear was therefore similar to that of present-day brown bears. Season at the time of death has been determined for 10 individuals by the analysis of dentine thickness and examination of the last cementum increment. The majority of deaths occurred in winter, during hibernation. It is possible that some bears died in the cave shortly after the hibernation period. Sex structure has been studied on the sample of 67 canines of individuals older than 18 months. Almost 3/4 of them belonged to males, with male to female ratio of 2.72. It can be assumed that Križna jama was used as a winter den mostly by prime adult and old male bears.
COBISS.SI-ID: 35154477
This review paper on evolution of Miocene sedimentary sequences in Slovenia is part of the monograph The Geology of Slovenia. Miocene sedimentary rocks are found prevailingly in areas of eastern Slovenia in narrow synclines of a general east-west strike. Beginning of sedimentation of Neogene beds in eastern Slovenia is associated with geodynamic processes resulting from back-arc rifting and extrusion of the ALCAPA block (Eastern Alps, Carpathians, Pannonian basin) owing to compression and rotation of Adria-Apulia microplate with respect to Eurasian plate. As a result of lithospheric extension and syn-rift subsidence narrow, elongated sedimentation basins (half-grabens) formed, each with its own temporal dynamics, depending upon the distance from the Carpathian arc, respectively subduction zone. The system of basins was formed by rapid Miocene subsidence of pre-Miocene basement as a consequence of Lower Miocene extension. The latter lasted to near the end of Middle Miocene, when it was replaced by a compressional tectonic regime. This resulted in interruption of communication with surrounding seas (Mediterranean and Indo-Pacific), the basins subsided owing to lithosphere cooling, and they get filled by thick sequences of terrestrial deposits. Start of the extensional tectonic regime resulted in opening of marine passages that connected the arisen syn-rift basins with surrounding seas and enabled flooding of the sedimentation basins. The sedimentation was then controlled next to tectonics also by global changes of sea-level which resulted in distinct and characteristic paleoecological evolutions in individual sedimentation basins. Consequently occur in the region of Slovenia sediments of prevailing marine origin from Karpatian all to Middle Sarmatian. At that time marine communication became interrupted, and marine sedimentation was replaced first by brackish and limnic sedimentation, and in terminal phase by thick fluvial deposits. Further the detail sedimentary succession of different basins and their stratigraphic and paleoecologic correlation are described.
COBISS.SI-ID: 38854701
The Palaeolithic of southern Central Europe has a long history of archaeological research. Particularly the presence of numerous osseous projectile points in many early Upper Palaeolithic (EUP) assemblages in this region has attracted the attention of the international research community. The scarcity of properly identified and well-dated Aurignacian contexts represents an obstacle for investigation of the nature and timing of the Middle to Upper Palaeolithic transition. In this context, the question of whether Neandertals made Aurignacian osseous projectile points, either on their own or as a consequence of cultural interaction with anatomically modern humans, still remains an open issue. Here we reassess the EUP record of Slovenia by evaluating the Aurignacian character of the assemblages from Potočka zijalka, Mokriška jama and Divje babe I in the light of their suggested roots in the local Mousterian. We provide a comprehensive description of the lithic industry from Potočka zijalka, which represents one of the rare EUP assemblages of southern Central Europe with a representative number of lithic artefacts to be analysed from the perspective of lithic technology and raw material economy. Our re-analysis of the Slovenian assemblages is backed by a series of 11 new ultrafiltered collagen 14C dates obtained directly on associated osseous projectile points from the studied assemblages. The Aurignacian of Potočka zijalka underlines the remarkable consistency of the Early Aurignacian with low typotechnological variability across Europe, resulting from a marked dependence on transported toolkits and raw material conservation. The new radiocarbon determinations for the Aurignacian of Slovenia appear to post-date the 34-32 ka BP threshold for the last Neandertals in the region. Although not falsified, the hypothesis of Aurignacian bone tools in southern Central Europe as a product of late Neandertals is not supported by our re-examination of the EUP record of Slovenia.
COBISS.SI-ID: 37760045
In Snežna Jama cave, Slovenia, extensive speleothems composed of dolomite, aragonite and hydromagnesite have been found, occurring as 5 cm thick globular crusts coating the host rock. Dissolution of the dolostone host rock has provided Mg, which is the main control on the precipitation of aragonite, dolomite and hydromagnesite. Dolomite precipitation could be promoted by increased Mg/Ca ratios due to the prior precipitation of calcite and aragonite and by forced degassing due to ventilation caused by the existence of shafts cutting the main cave passage and a former entrance to the cave. However, in many caves such conditions do not lead to the formation of dolomite and so we discuss other mechanisms which might promote dolomite precipitation, like the possible contribution of microbes, or the transformation of precursor phases such as amorphous Ca-Mg carbonates, or hydromagnesite.
COBISS.SI-ID: 38627629
The mechanisms of formation of a speleothem and the diagenetic processes that affected it have been analyzed performing a detailed petrographical study. The correct interpretation of these processes is crucial for the understanding of changes in the chemistry of waters, temperature, or pCO2 and is critical to the correct interpretation of the paleoenvironmental significance of speleothems. The paper has been cited 10 times (WoS).
COBISS.SI-ID: 34672941
In spite of equal lithology, the local climate can affect soils’ geochemical characteristics. We examined the heavy metal content in soils developed on the Upper Triassic dolomite at six locations situated at increasing distances from the Adriatic Sea towards inland. An initial increase in annual precipitation towards inland is followed by a steady decrease. We tested the influence of the locations’ position, i.e. climate, vegetation cover, small- scale variability and analytical error. Very high small- scale variability prevented statistically significant differences from being established at the locations level. However, the simpler one-way and non-parametric varieties of ANOVA confirmed significant differences in Co, Cr and Ni among locations. The differences are more pronounced in grassland soils where the Cu and Pb contents also differ between locations. There is a positive correlation among annual precipitation, Co, Cr and Ni, and it seems that the prevailing winds can also influence their content in soils. The Co, Cr, Cu, and Ni values are readily highest in those locations with the greatest precipitation, possibly due to their resistance to leaching. The soils could be additionally enriched by an eolian contribution from the SW located outcropping flysch rocks. The established variability could be due to somewhat different dolomite composition. The reasons for the observed geochemical variability are complex and only partly due to climate.
COBISS.SI-ID: 1309534
Micro-scale observations in karst caves help to identify different processes that shaped local morphology. SEM/EDS inspection of speleothems from two karst caves in Slovenia, Predjama and Črna Jama, confirmed the presence of sub-angular to sub-rounded detrital fragments of clay minerals, feldspars, quartz, Fe-oxides/hydroxides, rutile and Nb-rutile, xenotime, kassite, allanite, fluorapatite, epidote, ilmenite, monazite, sphene and zircon. It is likely that they are derived from the weathered rocks of the Eocene flysch. Probably they were first transported into the caves by floodwaters forming cave sediments. Later, depending upon the climate conditions, they were moved by air currents or by water to the surface of active speleothems. They might also be redeposited from overlying soils enriched with wind-transported minerals from the flysch, or from higher passages filled with weathered flysch sediment, by drip-water percolating through the fissured limestone. As some of the identified minerals are carriers of REEs, Ti and Zr, their presence could affect any palaeoclimatic interpretations that are based upon the geochemical composition of the speleothems.
COBISS.SI-ID: 1253982