Geologica Balcanica

Abstracts, Volume 27 (1997)

27. 1-2. Sofia 1997

Editorial

Geologica Balcanica dedicates the present volume 27 to the 50th Anniversary of the Geological Institute of the Bulgarian Academy of Sciences.

Human society changed dramatically over these fifty years, and the last eight years brought also fundamental changes on the Balkan Peninsula and in Bulgaria. The approaching 21st century augurs new challenges, and they are particularly important for Earth scientists.

Geologists are accustomed with the slow invisible changes that last for millions of years. Human history exhibits an acceleration that becomes critical at the eve of the new century. The total number of human beings upon Earth doubled in fourty years, and it is expected to double again in the first half of next century. Fast urbanization is another feature of our days that changes drastically the face of the Earth. New materials and technologies bring revolutionary changes in life and science. New problems arise or/and will arise in the search for a sustainable development of modern society. Some of the most important ones are closely related to Earth sciences, and namely:

- shortage of energy resources;

- shortage of water resources;

- shortage of some mineral raw materials, and needs for restructuring the mining industry in view of sustainable development;

- degradating and insufficient soils, mostly in the Third world;

- enormous increase of waste, radioactive waste included;

- natural hazards of geologic character, as earthquakes, volcanic eruptions, landslides, and their consequences in overpopulated regions.

The Balkan Peninsula is particularly vulnerable to some of the natural geologic processes. Our society seems to be unaware of the importance of geological sciences in this perspective. Our governments give some attention to Earth sciences only when the consequences of natural geologic processes combined with neglect from the part of the authorities result in suffering of thousands of citizens, and in irreparable loss of human beings and expensive constructions. One of the most important duties of geologists as an educated part of society is to draw the attention towards the crucial problems of today that will multiply tomorrow, and to fight for the place of geology and geologists in the modern society.

The Chief Editor

Nikolov, T., Tzankov, Tz. 1997. The Bulgarian Early Cretaceous basin in the Tethys panorama. - Geologica Balc., 27, 1-2; 3-6.

The Bulgarian Early Cretaceous basin developed within the northern periphery of the Tethyan Ocean adjacent to the European fragment of the Eurasian lithospheric plate. The basin was of a back-arc type, and formed over the Moesian microplate. It had an arc configuration convex to the North. An avolcanic island arc was situated South of it. Further South, a comparatively narrow interarc basin developed that was bounded to the South by a well-expressed volcanic island arc. The mid-ocean zone of the Tethys Ocean passed through the Aegean.

Maslarevi L., Krsti, B. 1997. Paleozoic continental slope deposits in the Stara Planina Mountains, Eastern Serbia. - Geologica Balc., 27, 1-2; 7-18.

Paleozoic (Devonian) marine sediments of the Inovo Formation in the Stara Planina Mountain consist of various metaclastic rock varieties: from conglomerates to siltstones and shales, composed of quartz, feldspar, rarely mica and abundant fragments of magmatic acid and basic rocks and intraclasts. On the basis of numerous typical sedimentary structures and textures, the clastics are interpreted as continental (lower or base of) slope deposits, resulting from a variety of mass gravity transports, viz.: debris flow, turbidity current, density-modified grain-flow, and grain flow, intermittently combined with traction currents or laminar flows. In some intervals of its history, the continental slope became unstable due to tectonic movements which led to massive submarine sliding, slumping and tearing away of extrabasinal and intrabasinal blocks and olistoliths which slipped down the slope and mostly, by the debris flow mechanism, deposited with normal hemipelagic sediments.

Budurov, K., Zagorchev, I., Trifonova, E., Petrounova, L. 1997. The Triassic in Southwest Bulgaria. Contribution to the stratigraphy of the Iskur Carbonate Group in the Vlahina Mountain. - Geologica Balc., 27, 1-2; 19-26

The section of the Iskur Carbonate Group (Spathian - Norian) in the Vlahina Mountains is the southernmost section of the peri-Tethyan (Balkanide type) Triassic in Southwest Bulgaria. Considerable lateral facies differences are recorded. A new Boychovtsi Member of the Lyubash Formation is introduced here for the first time. It is based upon the interbedding of limestones and marls with shales, and covers the uppermost parts of the Spathian Stage and lower parts of the Anisian Stage. The Boychovtsi Member of the Lyubash Formation covers the thin variegated interbedding of the Svidol Formation, and is covered either by the Mogila Formation (section Boychovtsi) or directly by dolomites of the Bosnek Formation.

Belivanova, V. 1997. Diagenesis of the Triassic carbonate rocks from the Golo Bardo Mountain, Southwestern Bulgaria. - Geologica Balc., 27, 1-2; 27-35

The Golo Bardo mountain is located to the Southeast of the town of Pernik (south-western Bulgaria). It is built up completely of Triassic sediments. Limestones and dolomites predominate.

The diagenesis of the Triassic carbonate rocks from the Golo Bardo mountain is studied for the first time. Six sections are investigated. The spectrum of diagenetic events includes textural changes and authigenic mineral formation. They are represented by transformation of bioskeletal aragonite into calcite, compaction, cementation, recrystallization, dolomitization, silicification, albitization, pyritization.

Transformation of bioskeletal aragonite into calcite is established both in non-washed allochemic sediments and washed high-energy sediments. Cementation, dolomitization and recrystallization are the most common processes and are typical of the whole Triassic section.

Calcite cements occluded the original pore space, filled secondary voids and post-lithification fractures in those rocks. Fibrous, bladed, syntaxial and blocky cements are established.

Planar-S to nonplanar textures are characteristic for the Triassic dolomites in the mentioned region. Nonplanar boundaries are characteristic of growth at elevated temperature (> 50 C) and/or high supersaturation.

Recrystallization concerns matrix, cement and some bioclasts. Full recrystallization without traces of any primary textural elements is very rarely observed.

Formation of authigenic albite is of local significance. The chemical composition of the mineral obtained by three electron microprobe analyses is: Na2O - 11,66%; Al2O3 - 20,67%; SiO2 - 67,67%. Chemically it is defined as pure albite (Na0,99 Al1,06 Si2,95 O8 ).

Silicification is not a common process. It concerns both matrix and allochems, usually in low-energy non-washed sediments. The type of bioskeletal fragments probably is of no importance for that process.

Pyrite is present almost every where in the Triassic carbonates but in unimportant amounts. Fine grained aggregates, pseudomorphs on bioclasts (mainly foraminifers) and single cubic crystals are observed. Pyrite is established both in micritic carbonate matrix and in recrystallized sparitic parts of the same matrix.

Lakova, I. 1997. Additional palynological data on the age of the Razhcha Formation, Osogovo Mts., West Bulgaria. - Geologica Balc., 27, 1-2; 36.

The occurrence of the miospore species E. zavallatus indicates that the age of the Rashcha Formation in the locality Rasovo is Late Lochkovian. The presence of representatives of the open sea microplankton (acritarchs) in the palynological preparations, although co-occurring with miospores and tubular stuctures, shows that the Rashcha Formation was deposited in marine environment with some supply of terrestrial plant debris from the neighbouring land.

Benatov, S. 1997. Costirhynchopsis vidlicis (Urosevic, 1981) - a new brachiopod species for the Bulgarian Middle Triassic . - Geologica Balc., 27, 1-2; 37-43.

The new Triassic species for Bulgaria - Costirhynchopsis vidlicis (Urosevic, 1981) is studied by statistical methods, to determine the external morphology of the shell and by serial sections, for internal shell structure. By comparing descriptions of Costirhynchopsis Dagis, 1977 and Fissirhynchia Pearson, 1977 it is accepted that the two genera are separate taxa, even though they are very close.

Dimitrova, T. 1997. Palynological results. Pollen analysis of the deposit San Faustino, Central Italy. - Geologica Balc., 27, 1-2; 44.

Zelilidis, A., Kontopoulos, N., Avramidis, P. Bouzos, D. 1997. Late Eocene to Early Miocene depositional environments of the Mesohellenic Basin, North-Central Greece: Implications for hydrocarbon potential. - Geologica Balc., 27, 1-2; 45-56.

Late Eocene to Early Miocene Mesohellenic Basin deposits accumulated in a tectonically controlled basin with irregular and narrow shelves. The boundaries between the Eocene-Oligocene Krania-Eptachori Formations and the Oligocene-Miocene Eptachori-Pentalophos Formations record the global sea-level falling during the corresponding time intervals. The sediments of the Mesohellenic Basin have characteristics of lowstand fan deposits without coastal onlap. It is suggested that the concept of the hydrocarbon habitat is applicable to the Mesohellenic Basin due to the following characteristics of the studied deposits: (a) The outer fan sandstones lobes, classified in this work as suprafan lobes, are characterized by stacked channel sand bodies with good lateral and vertical communications. These features constitute excellent reservoir facies. (b) The fine-grained, lobe-fringe and basin-plain deposits of the studied marine turbidites may have operated as either fertile source rocks or topseals. (c) The geometry of the lobes (stacked channel sand bodies) and the internal unconformities (between the four formations) present excellent stratigraphic traps. (d) The synchronous evolution of these deposits assures the timely relationship among all factors listed above. Since the studied sediments correspond mostly to the western margin deposits it is very possible that basinwards, in the direction of the progradation, he interchannel deposits must laterally pass into, the outer fan sandstone lobe, lobe fringe and basin plain deposits. Therefore, sediments of the basin interior not presently exposed are very likely to support favorable conditions for petroleum play.

Temniskova-Topalova, D., Ognjanova-Rumenova, N. 1997. Description, comparison and biostratigraphy of the non-marine Neogene diatom floras from Southern Bulgaria. - Geologica Balc., 27, 1-2; 57-82.

Spassov, N. 1997. Varshets and Slivnitsa - new localities of Villafranchian vertebrate fauna from Bulgaria (taxonomic composition, biostratigraphy and climatochronology). - Geologica Balc., 27, 1-2; 83-90.

Two recently discovered rich Bulgarian localities have been studied and described as localities of Villafranchian fauna - Varshets and Slivnitsa. They represent two faunistic complexes immediately succeeding one another in time.

Varshets is a Late Pliocene locality. After its fauna it ought to be referred to the biochronological zone MNQ17, that may be subdivided into two successive subzones. It seems that the fauna of this locality is earlier than that of the marker locality St.-Vallier. The fauna of Varshets numbers more than 110 taxa of vertebrates, including 17 species of Macromammalia. The faunistic complex presupposes a mosaic landscape of open spaces and forests or an open ("park") type of forests. After the climatistratographic subdivision, the fauna falls at SCT12, or even more probably, at the beginning of SCT11.

The locality of Slivnitsa refers to the the very end of the Pliocene and the Late Villafranchian. The fauna consisting of 19 species of Macromammalia too, times it to the beginning of the zone MNQ18, which probably ought to be also divided into subzones - MNQ18a = Seneze Unit (Final Pliocene) and MNQ18b = Olivoa Unit (probably Earliest Pleistocene) . The time of this fauna corresponds to the intermediate cooling during the Beregovka warming that falls on the superclimatheme SCT10. The predominance of Bovidae, that are typical of the open spaces, indicates more aridic climate than Varshets. Slivnitsa and Seneze are the earliest localities where the first migration wave of Canis s.str. has appeared from the east. This wave having been spread in most regions of Europe at the beginning of the Pleistocene. It seems that Slivnitsa is the earliest locality reflecting the appearance of the genus Panthera on the continent.

Kontopoulos, N., Zelilidis, A. 1997. Depositional processes in outer arc marginal sub-basins during the Messinian time; Messinian crisis: An example from western Crete Island, Greece. - Geologica Balc., 27, 1-2; 91-100.

The ratio of sea-level falling rate to subsidence/uplift rate was the master factor controlling the evolution of three adjacent marginal sub-basins, the Platanos, Kastelli and Maleme Sub-Basins. During the Messinian, the Platanos Sub-Basin was characterized by a constant shelf environment with a water depth of deposition not more than 50 m; a sabkha environment which changed during the latest Messinian to a shelf environment characterized the Kastelli Basin, representing a water depth of deposition changing from 0 m to less than 50 m; finally, a terrestrial environment which changed during the latest Messinian to a shallow marine environment, characterized the Maleme Basin, representing a sea-level rise of no more than 50 m. The evolution of the depositional environments in the three adjacent basins suggests: a. A total sea-level fall of >250 m from latest Tortonian to latest Messinian time in the western Crete (>200 m during latest Tortonian and 50 m during Early Messinian). b. When the ratio of sea-level falling rate to subsidence/uplift rate is >1, lake or shallow marine environments (shelf) changed to terrestrial, and outer slope environments changed to shelf environment. When the ratio is slightly >1 a shelf environment changes to a sabkha; and when it equals 1, the depositional environment changes from a sabkha or terrestrial to shelf environment. c. Depositional environments characterized by lowstand conditions during the Messinian time.

Dimitrova, T. 1997. Palynological analysis of the deposit Fosso Bianco, Central Italy. - Geologica Balc., 27, 1-2; 101-104.

The palynological analysis of the Fosso Bianco section is based on the data obtained from 23 samples. Most of the samples contain polydominant and very rarely monodominant forest components. The palynological documentation is based on a classification of some well known paleoflora groups. The comparative characteristics of the pollen spectra is based mainly on the data of the boundary Pliocene/Pleistocene in Central Italy.

K. Markova, S. Valceva, S. Lefterova, V. Vuchev - Molecular-structural study of oxygen in coals. 1. Geochemical bonds of oxygen in Paleogene coals. - Geologica Balc., 27, 1-2; 105-110.

The distribution of total oxygen, its forms of binding and geochemical bonds have been studied in Bulgarian Paleogene coals. Various petrographical and chemical analyses have been carried out. The analytical data are quantitatively evaluated by means of statisical, regressional and cluster analyses. The quantitative distribution of the oxygen forms in the coal macromolecule enables the estimation of the coalification processes development. The good correlation between oxygen-containing functional groups and the different macerals suggets that the hydroxyl (phenol), carbonyl and carboxyl groups can be used as genetic indicators. The dependences established between the carbon content, respectively, the reflectance and >CO and -COOH content points that these groups are coalification indicators.

27. 3-4. Sofia 1997

Metodiev, L. 1997. Toarcian and Aalenian ammonites in a part of the Western Stara Planina Mts., Bulgaria (taxonomy, stratigraphy). - Geologica Balc., 27, 3-4

This paper presents biostratigraphic data on the Toarcian and Aalenian ammonites in the clayey-calcareous and marly sediments of the Boukorovtsi Member of the Ozirovo Formation and Etropole Formation in a part of the Western Stara Planina Mts. Harpoceras falciferum, Hildoceras bifrons, Haugia variabilis, Grammoceras thouarsense, Dumortieria levesquei, Dumortieria moorei, Pleydellia aalensis, Ludwigia murchisonae and Graphoceras concavum Zones have been established and described. That zonal scheme has been correlated to the zonations of different authors in the North-west Europe. About 40 species of 18 genera, refereed to the families Phylloceratidae, Dactylioceratidae, Hildoceratidae and Graphoceratidae have been determined and 24 of them have been established or described at first in Bulgaria. The boundary between the Toarcian and Aalenian has been biostratigraphically traced.

Ivanova, D. 1998. Upper Jurassic zonation on cadosinids, stomiospherids and calpionellids of the Central Forebalkan, Bulgaria. - Geologica Balc., 27, 3-4.

Eleftheriadis, G., Staikopoulos, G. 1998. Upper Miocene volcanic rocks at Neo Petritsi, central Macedonia (N. Greece). - Geologica Balc., 27, 3-4.

Pavlopoulos, K., Maroukian, H. 1998. Geomorphic and morphotectonic observations in the drainage network of Kakotopia Stream, North East Attica, Greece. - Geologica Balc., 27, 3-4.

Evlogiev, J., Glazek, A. Sulimski, A., Czyzewska, T. 1998. New localities of vertebrate fauna in the Quaternary sediments in the vicinity of Rouse (North-East Bulgaria). - Geologica Balc., 27, 3-4.

Boev, Z. 1997. Chauvireria balcanica - gen. n., sp. n. (Phasianidae - Galliformes) from the Middle Villafranchian of Western Bulgaria - Geologica Balcanica, 27, 3-4

Since 1987 over of 120 vertebrate taxa (51 species of birds) were established in the Middle Villafranchian (MN17 zone) site near Varshets (43, 13 N, 23 ,17 E). The site is type-locality of Lagopus balcanicus Boev, 1995 and provides the second record of Apus baranensis Janossy 1977. Chauvireria balcanica is described by 1160 bone finds (MNI = 49) - over 85 % of the total amount of the collected avian material. Diagnosis: A small phasianid of Perdicinae subfamily with almost parallel os matacarpalis majus and os m. minus, sharper and smaller processus pisiformis, more erected processus extensorius, narrower spatium intermetacarpalis, well developed processus intermetacarpalis, which reaches os metacarpalis minus and which cranial edge forms an almost right angle. Osteometrically Chauvireria balcanica was of the same size as recent Ammoperdix griseogularis and A. heyi. The means of the total lengths (in mm) of some long bones are: coracoid - 27,2 (n=14); humerus - 40,4 (n=9); ulna - 36,8; (n=8) radius - 33,4 (n=4); carpometacarpus - 21,8 (n=27), and tarsometatarsus - 28,4 (n=6). Palaeocryptonyx donnezani from West Europe is taxonomically the closest Galliform to Chauvireria balcanica.

Koleva-Rekalova, E. 1997. Climate evolution during the Sarmatian of North-Eastern Bulgaria (according to sedimentological data). - Geologica Balc., 27, 3-4.

The climate evolution during the Sarmatian of North-Eastern Bulgaria is inferred mainly on sedimentological data. They include detailed investigations on sedimentary rocks from the Euxinograd, Odurtsi, Topola and Karvuna Formations. It is proved that the climate during the Sarmatian was predominantly humid - from temperate to subtropical, with an exception of the Late Bessarabian, when it was arid. The temperatures and humidity gradually increased from the Volhynian to a considerable part of the Bessarabian. During the Late Bessarabian the temperatures remained high, but the himidity drastically decreased (climate aridization). In the beginning of the Chersonian the humidity again increased, whereas the temperatures gradually decreased, and during the Middle Chersonian they were considerably lowered.

Spassov, N. 1997. The Villafranchian mammalian fauna and its investigation in Europe, on the Balkans and in Bulgaria. - Geologica Balc., 27, 3-4

The mammalian fauna of the transition from Pliocene to Pleistocene (usually designated as Villafranchian fauna) is of considerable interest. The first signs of formation of the recent Palearctic fauna should be looked for namely among the Villafranchian one. Because of the fragmentariness of most of the finds and the uneven research degree of different regions, the Villafranchian "Stage" in the mammalian fauna's development remains still insufficiently clarified. The investigations of the Villafranchian fauna are more detailed in W Europe. Corresponding investigations in SE Europe are still more incomplete. Greece and Romania are the only countries of SE Europe with well studied Villafranchian localities. Almost no mammalian megafaunas of that time have been known in Bulgaria so far. Two Bulgarian localities have been recently discovered - Varshets and Slivnitsa. Their investigation has resulted a great richness of vertebrate fossils, so that now they could be placed among the marker localities of Villafranchian fauna within E Europe. Further investigation of the Villafranchian faunistic complexes on the Balkans would considerably contribute to clearing up the migratory routes, the forming and the evolution of this fauna throughout Europe. However, zoogeographical differences are quite probable, thus the biostratigraphic criteria created in W Europe should be applied with a certain attention for the Eastern regions of the continent and especially in the Palearctic areas to the East of Europe.

Eliopoulos, D., Laskou, M., Economou-Eliopoulos, M. 1998. Geochemical features of Ni-laterites from the western parts of the Balkan Peninsula. - Geologica Balc., 27, 3-4

Fe-Ni ore samples from the Sfikia (Veria), Alonakia, Stournari, Kria Vrissi and Mavrolivado (Vermio) and Edessa deposits, plus underlying hornstone and talc-schist, were analyzed for major, minor and trace elements, including REE, Pt, Pd and Au. Also, chromite grain-fragments in Ni-laterites, from northern Greece, Bitincka (Albania), Rzanovo (FYROM) and Sumadija (Yugoslavia) were analyzed by electron microprobe.

In general, there is a wide variation in the major, minor and trace element content since they cover a variety of Ni-laterite deposits. The Au, Pt and Pd contents are low, although higher than in bauxite ores from Greece, ranging between <5 and 20 ppb, <10 and 99 ppb, <1 and 22 ppb, respectively. The rare earth element (REE) content ranges from less than 10 ppm to 260 ppm. In the majority of the analyzed samples there is a preference of Ce over La. Thorium and U contents range from <0.5 to 36 ppm, and <0.5 to 12.5 ppm respectively. On the basis of factor analysis of the geochemical data of these ores there is a strong interelement correlation among REE as well as between them and Al, Ti, Th and U. Although more geochemical research is required to define the conditions of acidity and Eh during the laterites formation in the Balkan peninsula, the interelement positive correlation among REE, U and Th may indicate that they share a common genesis.

Ivanova, V., Gougov, L., Dimovski, S. 1998. Metallogenic prognostication of the Luki ore field (scale 1:50000) by use of computer-prognosticating system. - Geologica Balc., 27, 3-4.

Piperov, N. 1998. Hellium-3 evidence for a spot of thinned lithosphere in the eastern part of the Balkan Peninsula. - Geologica Balc., 27, 3-4

The presence of a mantle component in the crust-to-atmosphere volatile flux may be considered as evidence for increased crustal permeability. The air-corrected 3He/4He = R ratio, usually normalized to Rair, is well known as a starting point for such an evaluation. The relative abundance of 3He, however, may be underestimated especially in the case of helium-rich fluids. The 3He/20Ne ratio is proposed as an alternative geochemical tracer for mantle exhalation, normalizing the 3He abundance to a small and comparatively constant atmospheric component: neon.

The 3He/20Ne ratio for 21 mineral water sites from the eastern part of the Balkan peninsula are calculated on the bases of previous measurements. The regional distribution of the values found is compared with the data available on the depth of Moho discontinuity and lithosphere/asthenosphere boundary. An evident correlation between 3He/20Ne maximum values and an area with thin lithosphere is observed.

Varia

Stefan Bonev and Ekim Bonev - founders of Geologica Balcanica

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