Age of the Jurassic hemipelagic sediments from the Ljubiš area (Zlatibor Mt., SW Serbia)

The type section of the Ljubiš Formation, (Djokov Potok, Zlatibor area, western Serbia) is characterized by abundant poorly-to-moderately preserved radiolarians. The lower part of the type section is characterized by Middle Jurassic (?Bajocian to Bathonian) radiolarian assemblages with Japonocapsa fusiformis (YAO), Takemuraella weghae (GRILL & KOZUR), Eoxitus hungaricus KOZUR, E. baloghi KOZUR, Helvetocapsa matsuokai (SASHIDA), Quarkus japonicus (YAO), Hexasaturnalis suboblongus (YAO), H. tetraspinus (YAO). Taking into account previous data from the upper part of the Ljubiš Formation, the age of the formation can be estimated to be in the interval from the ?Bajocian to Bathonian-Oxfordian. The new biostratigraphic data clearly show the onset of tectonic motion in the Middle Jurassic, documented by the presence of mass transport deposits intercalated in the radiolarite successions. This suggests a Middle Jurassic onset of ophiolite obduction which triggered the rapid deepening of the Adria margin, documented by the abrupt change from carbonate to radiolarite deposition.</p

New data on the age of an Upper Cretaceous sediments in Brežđe (NW Serbia)

Radiolarian assemblages of Late Cretaceous age were studied in a carbonate-clastic section from the Cretaceous sedimentary cover that unconformably overlies Triassic sediments of the Jadar Block. According to the identified radiolarian associations, the studied limestone is of Santonian age. Considering the fact that these sediments belong to a broadly defined Turonian-Senonian geologic mapped unit, the obtained data are important for further more detailed biostratigraphic assignment of Late Cretaceous rocks in Western Serbia. Moreover, the obtained data are very important for interregional correlations

EVIDENCE FOR LADINIAN (MIDDLE TRIASSIC) PLATFORM PROGRADATION IN THE GYULAKESZI AREA, TAPOLCA BASIN, WESTERN HUNGARY: MICROFACIES ANALYSIS AND BIOSTRATIGRAPHY

A shallowing-upward carbonate sequence was studied from the outcrop at Gyulakeszi, Tapolca Basin (western Hungary), and it is interpreted as a Middle Triassic (Curionii&nbsp;or younger) platform progradation. Two lithostratigraphic units are distinguished. Microfacies analysis and micropaleontological investigation conducted on the red nodular, cherty limestone (Vászoly and Buchenstein formations) suggest that the lower unit was deposited during the&nbsp;Reitzi&nbsp;and the&nbsp;Secedensis&nbsp;ammonoid zones. The overlying white platform limestone (upper unit) is typical of a prograding platform and includes gravity-driven deposits at the base followed by periplatform facies deposited in shallow marine warm waters around the fair-weather wave base. The section at Gyulakeszi was unaffected by fabric-destructive dolomitization, which is uncharacteristic of similar platform facies in the Balaton Highland. Isopachous and radiaxial fibrous calcite cement found in the grainstone and boundstone facies are indicative of early lithification and diagenesis in the marine phreatic zone. “Evinospongiae”-type cement is described for the first time from the Balaton Highland and it is similar to the outer platform cements published previously from the Alps (Italy and Austria). The progradation could have advanced over the pelagic limestones as early as the&nbsp;Curionii&nbsp;zone, which is an undocumented event in the Veszprém Plateau. Similar event, however, is well known from the Western Dolomites, where aggradation was followed by intense progradation during the&nbsp;Gredleri&nbsp;and&nbsp;Archelaus&nbsp;ammonoid zones. The length of this progradation event at Gyulakeszi, however, is ambiguous since proven Ladinian (Longobardian) rocks are not exposed in the study area and were not penetrated by boreholes in the Tapolca Basin