Geološki anali Balkanskoga poluostrva

From shallow-water carbonate ramp to hemipelagic deep-marine carbonate deposition: Part 1. General characteristics, microfacies and depositional history of the Middle to Late Anisian Bulog sedimentary succession in the Inner Dinarides (SW Serbia)

2024-02-04T10:17:32+00:00

The opening of the Neo-Tethys started in the Middle Anisian and is recorded in the drowning sequence of the shallow-water Ravni/Steinalm Carbonate Ramp and the subsequent deposition of deep-marine limestones, e.g., the red nodular limestones of the Bulog Group. In the Inner Dinarides of southwest Serbia the continental break-up of the Neo-Tethys Ocean is characterized by the formation of a horst-and-graben topography. The change from deposition of shallow-water carbonates formed in an epicontinental sea (graben stage of the Neo-Tethys Wilson Cycle) to red nodular deep-marine limestones (Bulog Limestone) in the late Pelsonian (Middle Anisian) is relatively abrupt due to the rapid decrease of carbonate production. The deeper-water Bulog Limestone, deposited in the early stage of the passive continental margin evolution of the western Neo-Tethys can be dated by conodonts and in rare cases also by ammonoids quite exactly, and therefore it is possible to reconstruct the Pelsonian to Illyrian sedimentological evolution precisely: 1) The late Pelsonian is characterized by the drowning of the shallow-water Ravni Carbonate Ramp and a rapid deepening of the depositional realm. Extension led to the formation of neptunian dykes in the shallow-water Ravni Formation, filled with deeper-marine red micrite, and the formation of a horst-and graben morphology. Whereas some of the horsts uplifted and emerged in the grabens near to the newly formed escarpments thick breccia successions were deposited with a fining-upward trend during the early-middle Illyrian. On top of other horsts or newly formed gentle slopes red nodular limestones were deposited. In cases layers with enriched ammonoids formed (Fossillagerstätten). 2) The early-middle Illyrian ongoing subsidence resulted in the deposition of more and more condensed red nodular limestones with hard ground formation. 3) Around the middle/late Illyrian boundary a new pulse of tectonic motions resulted in the tilting of blocks, the formation of new escarpments and again mobilization of mass transport deposits. In addition, a second generation of neptunian dykes was formed. They crosscut the late Pelsonian to middle Illyrian Bulog Limestone, the Pelsonian Ravni Formation, and the older generation of neptunian dykes in the shallow-water Ravni Formation. All formerly emerged horsts flooded and red nodular limestones were deposited on the karstified shallow-water Ravni Formation after a gap. This second pulse of tectonic motions is related to the widespread volcanism in the Dinarides as visible in the appearance of mm-sized biotite clasts in the late Illyrian Bulog Limestone. In contrast to the Outer Dinarides, where thick volcanics are intercalated in the Illyrian sedimentary succession, in the Bulog Limestone successions of the Inner Dinarides volcanics are missing. In general the Pelsonian-Illyrian sedimentary succession is characterized by a stepwise deepening of the depositional realm.

From shallow-water carbonate ramp to hemipelagic deep-marine carbonate deposition: Part 2. Sirogojno (Klisura quarry) – the reference section of the Middle to Late Anisian Bulog sedimentary succession in the Inner Dinarides (SW Serbia)

2024-02-04T09:58:33+00:00

The Middle to Late Anisian sedimentary succession preserved in the Klisura quarry in Sirogojno (Zlatibor Mt., SW Serbia) preserves the most complete deepening depositional history in the Inner Dinarides of Serbia. In this section tectonic motions in the frame of the Neo-Tethys break-up are mirrored in the depositional history with exceptional well preserved details. The Pelsonian Ravni Formation at the base of the section is dissected by two age different generations of neptunian dykes formed in A) the late Pelsonian, and B) the late Illyrian. Above the late Pelsonian drowning unconformity a deeping trend of the depositional environment is mirrored by the litho- and microfacies characteristics of the more than 21 meter thick red nodular limestones of the Bulog Formation. Time spans of starvation with deposition of Fossillagerstätten beds and hardgrounds mark characteristic changes in deposition. Two phases of distinct tectonic motions result in unconformities and a stepwise deepening of the depositional realm. The first and major unconformity is the drowning of the Ravni Carbonate Ramp and the nearly total demise of shallow-water carbonate production, i.e. the change in deposition from shallow- to deep-water limestones. The second phase of tectonic motions is expressed by the formation of an angular unconformity after a phase of starvation in the basin. No Bulog Limestone section in the Dinarides, even not in the type region near Sarajevo, preserves all these characteristic sedimentological features as preseverd in the Klisura quarry section in Sirogojno. Therefore the Klisura quarry section in Sirogojno is assigned as reference section for the sedimentological evolution and depositional environment reconstruction of the Bulog Formation in the Inner Dinarides, located in SW Serbia.

From shallow-water carbonate ramp to hemipelagic deep-marine carbonate deposition: Part 3. Lithostratigraphy and Formations of the Middle to Late Anisian Bulog sedimentary successions (Bulog Group) in the Dinarides (Bosnia&Herzegovina, Serbia, Montenegro)

2024-02-05T10:14:40+00:00

In the Middle Anisian the opening of the Neo‐Tethys started and this is characterized by a significant change in deposition in the whole Western Tethys Realm. In the Dinarides the Middle to Late Anisian tectonostratigraphic and basin evolution is mirrored by their sedimentary successions. In the Middle Anisian, the evolution of the shallow‐water Ravni Carbonate Ramp ended relatively abrupt in the late Pelsonian: a rapid decrease of carbonate production is accompanied by formation of a horst‐and‐graben topography. This change is expressed by the change in deposition from shallow‐water carbonates to deep‐ water sedimentary rocks, i.e. the Ravni Carbonate Ramp experienced a drowning. Contemporaneously neptunian dikes were formed in the underlying Ravni Formation, filled with deep‐water limestones. In the grabens, near to the newly formed escarpments mass transport deposits accumulated. During the time span late Pelsonian to middle Illyrian a general deepening trend is mirrored in the sedimentological trend and the microfacies characteristics. Fossilla ‐ gerstätten (mainly cephalopods) and hardgrounds occur widespread in the deeper‐water red nodular limestones formed widespread above the Ravni Carbonate Ramp. Around the middle/late Illyrian boundary a second intense pulse of tectonic motions, related to the onset of volcanic activity, resulted in a crosscut of the older horst‐and‐graben topo graphy. A second generation of neptunian dikes was formed, the blocks tilted, and again mass transport deposits accumulated near to escarpments. The late Illyrian is characterized by an overall deepening trend expressed also in a change in the microfacies characteristics to radiolarian‐rich wacke‐ to packstones. In cases even radio larites or silicified limestones are characteristic sedimentary rocks in late Illyrian to Ladinian times beside silicified volcano‐sedimentary rocks. This paper will define the late Middle‐Late Anisian red nodular limestones and related sedimentary rocks with mass transport deposits overlying the Ravni Carbonate Ramp on base of new sedimen tological, stratigraphic and micro facies data following the international rules and standards. The palaeo geographic position together with characteristic litho‐ and microfacies features cause the lithostratigraphic definition of thedifferent units. Included in the newly introduced Bulog Group are: 1) the emended and formalized Bulog Formation and 2) the newly introduced and defined Komarani Formation. The type‐section of the Bulog Formation east of Sarajevo (Han Vidović, central Bosnia and Herzegovina) is revisited. The Komarani Formation is introduced with the type‐section in Komarani village (Zlatar Mt. in SW Serbia). The reference sections for the Bulog Formation in SW Serbia (Klisura quarry on Zlatibor Mt.), Bosnia and Herzegovina (Pridvorica locality at Romanija Mt.) and in Montenegro (Boljevići near Virpazar), are defined. In the reference sections some characteristic lithological and microfacies features are better preserved as in the type‐section and included in the emendation and formalization of the Bulog Formation. The Bulog Formation at the type‐section and all reference sections are in the Late Triassic overlain by the shallow‐water carbonates of the Wetterstein and Dachstein Carbonate Platforms. Age and facies equivalent red nodular limestones deposited in the outer shelf region are part of the Middle to Late Triassic Hallstatt Limestone succession. In the type‐region of the Hallstatt Limestones these late Middle to Late Anisian red nodular limestones are named Schreyeralm Limestones. The name Schreyeralm Limestone was introduced earlier as the name Bulog Limestone. It is discussed if also in the Dinarides the name Schreyeralm Limestone should be used for such Anisian red nodular limestones deposited in the outer shelf region, for priority reasons, or if they should be included into the Bulog Formation to avoid confusion, for historical reasons.

Radiolarian assemblage from radiolarites of the Krš Gradac section (SW Serbia): on the way to a better reconstruction of the Middle-Late Jurassic geodynamic history of the Inner Dinarides

2024-02-13T09:21:41+00:00

The type section of the Gonje Formation (Krš Gradac, Sjenica area) is characterized by an abundance of radiolarian tests, which, however, are generally recrystallized and poorly preserved. This paper focuses on the age of radiolarite sequence below the series with intercalated turbidites and mass transport deposits. The Callovian/Oxfordian (?early Oxfordian) moderately preserved radiolarian assemblage was determined from the higher part of the radiolaritic sequence without mass transport deposits. The new biostratigraphic age is consistent with the previously published data of the authors and reveals that the radiolaritic sequence without mass transport deposits of the Gonje Formation was deposited between the Bathonian and Oxfordian. The biostratigraphic age of this part of the Gonje Formation evidence that the Ljubiš Basin underwent in Late Oxfordian to earliest Tithonian times a phase of starvation with reduced sediment supply or production. The reasons for this starvation are discussed.

Paleoseismological features and tectonic setting of the Fethiye-Burdur Fault Zone (SW Turkey)

2024-02-05T10:14:27+00:00

The Fethiye-Burdur fault zone is not a single line. Still, it consists of discontinuous northeasterly trending fault segments developed parallel to each other between the Gulf of Fethiye and Burdur Lake. The NE-trending and left-lateral oblique-slip Fethiye-Burdur fault zone bounds the Isparta Angle to the west and is probably a continuation of the Pliny fault zone of the Hellenic arc. 1914, 1957, and 1971 earthquakes occurred in the Fethiye-Burdur fault zone, with magnitudes of 7.1, 7.0, and 6.1, respectively. The epicenter distribution of the last century of earthquakes indicates the continuation of the Fethiye- Burdur fault zone under the Gulf of Fethiye, probably to Rhodos Island.

According to GPS measurements, the Fethiye-Burdur fault zone is the southern limit of the Aegean extensional region. The Aegean region is characterized by coherent motion toward the SW at 30 mm/yr relative to the Eurasian plate. Field observations and fault plane solutions of recent earthquakes in and around the Burdur Lake region reflect normal and left-lateral oblique faulting considering the NE extension of the fault zone.

According to the proposed kinematic model, the different seismotectonic behaviors of the Burdur fault zone originate in the rigid influence of Yeşilova peridotite massif of the Lycian nappes that occur to the SW of Burdur Lake. The kinematic interactions between the mainly NE- trending en-echelon fault constituents of the Fethiye-Burdur fault zone result in different seismotectonic characteristics.

Evolution of the southeastern part of the Pannonian Basin and its implications

2024-02-05T10:13:33+00:00

The southeastern part of the Pannonian Basin System probably represents the most important area for determining its origin and evolution. The geodynamics also influenced the way that sediments fill the basin and therefore the economic resources that can be found in these sediments. All this led to the fact that the Pannonian Basin is the most developed part of our country. The great scientific value of this area is found in the fact that it represents an excellent training ground for the demonstration of the opening of the Pannonian basin system as well as the progradation of sediments from the southern and southeastern direction. In addition to the already confirmed economic importance through the exploitation of hydrocarbons, geothermal and hydrothermal waters, coal and construction materials, there is great potential in geoheritage and geotourism.