Hasil untuk "Stratigraphy"

Georgina M. Virgo, Alan S. Collins, Morgan L. Blades et al.

The Tonian to Cryogenian (ca. 1000–635 Ma) marks a crucial turning point in Earth’s history, where tectonic reorganisation and fluctuating oceanic and atmospheric geochemistry plunged the globe into icehouse conditions. This was followed by a postglacial warming period that delivered large volumes of nutrients to the oceans and stimulated eukaryotic evolution. The Adelaide Superbasin in South Australia hosts a thick repository of Neoproterozoic and lower Cambrian sedimentary successions that preserve the depositional conditions during this unique time. In this study, detailed sedimentological data were collected from over 8,350 m of measured section at seven locations across the northern Flinders Ranges. Tonian deposits reveal a carbonate platform setting, where deposition was controlled by basin geometry and proximity to uplifted source areas. In the early Cryogenian, sedimentary successions were affected by the Sturtian glaciation, characterised by two glacial advance-retreat phases that coincide with climatically driven regression. The end of the Sturtian glaciation was marked by basin subsidence and widespread transgression into a more distal subaqueous environment. Despite the lithostratigraphic and sequence stratigraphic similarity between Tonian–Cryogenian successions globally, their correlation remains contentious. The influence of local tectonic regimes during the Tonian created a potential oceanic restriction between developing basins, which challenges the chemostratigraphic correlation between these deposits. Further, limited geochronological ages and opposing interpretations of glacial cyclicity puts into question the timing and extent of the Sturtian glaciation. Conversely, the post glacial transgression appears to be the most globally consistent as it results from climatically controlled sea level rise that was driven by melting ice sheets.

J. Ren, L. Song, L. Song et al.

<p>To study the relationship between rock mechanical properties and resistivity under deep-underground environmental conditions, a rock resistivity test system, which can realize the simultaneous control of temperature, pressure, seepage, and the chemical environment, was developed; further, a corresponding specimen-sealing method was explored. The system primarily comprises a triaxial system, chemical permeation system, temperature control system, and test control system. The reliability of the system was verified through tests and preliminary experiments. The resistivity of fractured granite specimens under coupling of seepage and temperature and the resistivity of unfrozen and freeze–thawed coals during triaxial compression were tested with this test system. The test results show that the temperature-induced resistivity change is greater at low seepage pressures for fractured granites, and the effect of seepage on rock resistivity is greater at lower temperatures. The resistivity change patterns of unfrozen and freeze–thawed coals during triaxial compression differ quite significantly. The resistivity of unfrozen coal specimens exhibits a decreasing trend in the initial compression stage and then gradually increases with rises in the deviatoric stress. After freezing and thawing, the electrical resistivity of coal decreases during the entire compression process.</p>

Tommaso Pomilio

Un approccio alla dominante cinematografica, in atto nella testualità fenogliana: non solo per alcune delle sue strutture narrative, o per la stratigrafia di rimandi citazionali (espliciti oppure impliciti, casomai anche mediati), e dunque per il “romanzo di formazione” di un immaginario (anche) generazionale, ma soprattutto per l'avventura-movimento dello sguardo, nell’intensità del suo frammentare, ricomporre, nella dinamica d’una “inquadratura” indissolubilmente oculare e linguistica, ipnotica e sempre in processo.  An approach to the cinematographic dominant, active in Fenoglio’s textuality: that is, not only the narrative structures, or the stratigraphy of citational references (explicit or implicit), and thus the ‘Bildungsroman’ of a (also) generational imaginary, but above all the adventure-movement of the gaze, in the intensity of its fragmenting, recomposing, in the dynamics of a ‘framing’ that is indissolubly ocular and linguistic, hypnotic and always in process. 

Zahra Khaloasgari, Mahnaz Amirshahkarami, Koorosh Rashidi Sharifabad

Abstract The biostratigraphy of the marly-limestone Pabdeh Formation has been studied in a section located in the Interior Fars (folded Zagros). Five assemblage biozones of plankton foraminifera with Early Eocene to Late Eocene age were identified in the studied section. Biozone 1 with a thickness of two meters has been identified at the base of the studied succession and includes Morozovellavela scoensis and Morozovella conicotruncata species defining the Early Eocene age. Biozone 2 with a thickness of 59 meters is the Early Eocene in age and is associated with the first occurrence of Morozovella aragonensis at the base and the last occurrence of Chiloguembelina wilcoxensis at the top. Biozone 3 with a thickness of 66 meters is defined by the first occurrence of Globigerinatheka kugleri at the base and the occurrence of Guembelitrioides nuttalli at the top and represents the beginning of the part of the Middle Eocene. The presence of Orbulinoides beckmanni indicates the Middle Eocene for biozone 4 with a thickness 88 meters. Biozone 5 with a thickness of 163 meters indicates the Middle–Late Eocene for the top of studied succession according to the first and last occurrence of Hantkenina alabamensis. Keywords: Pabdeh Formation, Planktonic foraminifera, Early Eocene–Late Eocene, Biostratigraphy     Introduction The Laramide orogeny event is one of the tectonic events affecting the geology of Iran, which played a significant role in the formation of independent Cenozoic sedimentary basins of Iran (Aghanabati 2004). The subduction of Neotethys under the Iranian Plate began in the Upper Jurassic–Lower Cretaceous and was accompanied by the evolution of the present-day tectonic structure of Zagros in the Upper Paleocene–Lower Eocene (Heidari 2008). The Zagros sedimentary basin has three sedimentary units: Khuzestan Plain, folded Zagros or external Zagros, high Zagros or internal Zagros (Darvishzadeh 1991). After the Late Cretaceous movements, in the Early Paleogene, the whole Zagros was covered by an progressive sea. In the coastal areas of this sea the Sachun Formation, in shallow areas the Jahrom Formation and in deep areas the Pabdeh Formation  have been deposited (Aghanabati 2004). The Pabdeh Formation is limited to the shales layers of the Gurpi Formation with the Maastrichtian age (in Fars and Khuzestan) to the Paleocene age (in Lorestan) at the lower boundary, and is limited to the limestones layers of the Asmari Formation with Oligocene–Miocene age at the upper boundary. The studied section is located in the Tang-e-Chogan area 35 km of northeast of Kazeron in the Interior Fars Basin in the folded Zagros. This section is on the axial line of the Dashtak anticline in the geographical position 51° 36′ 48/22′′ to 51° 36′ 58/09′′ East and 29° 47′ 28/52′′ to 29° 47′ 69/59′′ North. The lithology of the Pabdeh Formation in the Tang-e-Chogan section with a thickness of 378 meters is composed of marls, marly limestones, and medium to thick bedded limestones. In its lower boundary, there are gray shales of the Gurpi Formation (Upper Cretaceous) with disconformities (Moghaddasi et al. 2020) and the upper boundary is overlain by the limestones of the Asmari Formation (Oligocene–Miocene). Considering the special position of the Pabdeh Formation in the petroleum system of the Zagros Basin, it is important to study this formation. For this reason, in this research, the stratigraphy and biostratigraphy of this formation based on plankton foraminifera have been investigated.   Discussion of Results & Conclusions The biostratigraphy of the Pabdeh Formation in the studied section is according to the biozonation of planktonic foraminifera by Toumarkine and Luterbacher (1985), Bolli et al. (1985), Berggren and Pearson (2005), Wade et al. (2011), and Bown et al. (2020). Five assemblage biozones of plankton foraminifera with the Early Eocene to Late Eocene age were identified in the studied section. Biozone 1 with a thickness of two meters has been identified at the base of the studied succession and includes Morozovella velascoensis and Morozovella conicotruncata species defining the Early Eocene age. Biozone 2 with a thickness of 59 meters is Early Eocene in age and is associated with the first occurrence of Morozovella aragonensis at the base and the last occurrence of Chiloguembelina wilcoxensis at the top and is consistent to the base of the biozone E5 of Berggren and Pearson (2005), Wade et al. (2011). Assemblage biozone 2 includes Morozovellaaequa, Morozovella formosa, Morozovella gracilis, Chiloguembelina wilcoxensis, Morozovella aragonensis, Morozovella caucasica, Morozovella subbotinae, Alicantinasp., Subbotinasp., Subbotinacf. eocanea, Pseudohastigerinamicra, Planorotalite pseudoscitula, Clavigerinella akersi, Parasubbotina pseudowilsoni, Hantkenina sp. Biozone 3 with a thickness 66 meters includes assemblage of Guembelitrioides nuttalli, Globigerina sp., Hantkenina sp., Uvigerina havanensis, Hantkenina mexicana, Globigerinatheka kugleri, Acarinina bullbrooki, Morozovella cf. aragonensis, Planorotalites pseudoscitula, Globorotalia renzi, Globorotalia sp. ,Hantkenina longispina, Morozovelloides cf. crassatus, Hantkenina alabamensis, Pseudohastigerina cf. micra, Turborotalia cerroazulensis, Globigerina velascoensis, Subbotina eocaena. It is defined by the first occurrence of Globigerinatheka kugleri at the base and the occurrence of Guembelitrioides nuttalli at the top and represents the beginning of the part of the Middle Eocene and is in accordance of the base of the biozone E8 of Wade et al. (2011). Biozone 4 with a thickness 88 meters includes Globigerina sp., Hantkenina sp., Hantkenina mexicana, Acarinina bullbrooki, Hantkenina longispina, Hantkenina alabamensis, Turborotalia cerroazulensis, Subbotina eocaena, Orbulinoides beckmanni, Pseudohastegina cf. micra, Globigerina pseudoeocaena, Pseudohastegrina micra, Hantkenina aff. Dumblei. According to biozone P13 of Berggren and Van Couvering (1974) and Berggren and Pearson (2005) and biozone E12 of Wade et al. (2011) the presence of Orbulinoides beckmanni indicates the Middle Eocene for biozone 4. Biozone 5 indicates the Middle–Late Eocene for the top of the studied section according to the first and last occurrence of Hantkenina alabamensis. Biozone 5 with a thickness of 163 meters Globigerina sp., Hantkenina sp., Hantkenina mexicana, Acarinina bullbrooki, Hantkenina longispina, Hantkenina alabamensis, Turborotalia cerroazulensis, Globigerina pseudoeocaena, Globigerina sp., Planorotalites pseudoscitula The biostratigraphy of the Pabdeh Formation in the Tang-e-Chogan section indicates five assemblage biozones of plankton foraminifera with the Early Eocene to Late Eocene age. These biozones include 21 genera and 24 species of the following planktonic and benthic foraminifera: Acarinina bullbrooki, Alicantina sp., Chiloguembelina wilcoxensis, Clavigerinella akersi, Globorotalia renzi, Globigerina pseudoeocaena, Globigerina sp., Globigerinatheka kugleri, Guembelitrioides nuttalli, Hantkenina alabamensis, Hantkenina longispina, Hantkenina mexicana, Hantkenina sp., Kathina sp., Lenticulina sp., Morozovella aequa, Morozovella aragonensis, Morozovella caucasica, Morozovella conicotruncata, Morozovella formosa, Morozovella gracilis, Morozovella subbotinae, Morozovellavela scoensis, Morozovelloides cf. crassatus, Orbulinoides beckmanni, Parasubbotina pseudowilsoni, Planorotalites pseudoscitula, Pseudohastegrina micra, Streptochilus sp., Subbotina eocaena, Subbotina sp., Turborotalia cerroazulensis, Uvigerina havanensis.

S. Hellmann, S. Hellmann, M. Grab et al.

<p>Cross-borehole seismic tomography is a powerful tool to investigate the subsurface with a very high spatial resolution. In a set of boreholes, comprehensive three-dimensional investigations at different depths can be conducted to analyse velocity anisotropy effects due to local changes within the medium. Especially in glaciological applications, the drilling of boreholes with hot water is cost-efficient and provides rapid access to the internal structure of the ice. In turn, movements of the subsurface such as the continuous flow of ice masses cause deformations of the boreholes and complicate a precise determination of the source and receiver positions along the borehole trajectories. Here, we present a three-dimensional inversion scheme that considers the deviations of the boreholes as additional model parameters next to the common velocity inversion parameters. Instead of introducing individual parameters for each source and receiver position, we describe the borehole trajectory with two orthogonal polynomials and only invert for the polynomial coefficients. This significantly reduces the number of additional model parameters and leads to much more stable inversion results. In addition, we also discuss whether the inversion of the borehole parameters can be separated from the velocity inversion, which would enhance the flexibility of our inversion scheme. In that case, updates of the borehole trajectories are only performed if this further reduces the overall error in the data sets. We apply this sequential inversion scheme to a synthetic data set and a field data set from a temperate Alpine glacier. With the sequential inversion, the number of artefacts in the velocity model decreases compared to a velocity inversion without borehole adjustments. In combination with a rough approximation of the borehole trajectories, for example, from additional a priori information, heterogeneities in the velocity model can be imaged similarly to an inversion with fully correct borehole coordinates. Furthermore, we discuss the advantages and limitations of our approach in the context of an inherent seismic anisotropy of the medium and extend our algorithm to consider an elliptic velocity anisotropy. With this extended version of the algorithm, we analyse the interference between a seismic anisotropy in the medium and the borehole coordinate adjustment. Our analysis indicates that the borehole inversion interferes with seismic velocity anisotropy. The inversion can compensate for such a velocity anisotropy. Based on the modelling results, we propose considering polynomials up to degree 3. For such a borehole trajectory inversion, third-order polynomials are a good compromise between a good representation of the true borehole trajectories and minimising compensation for velocity anisotropy.</p>

S. Yeung, M. Forster, E. Skourtsos et al.

<p>The Late Cretaceous Asteroussia event as recorded in the Cyclades is a potential key to the tectonic evolution of Western Tethys. Microstructural analysis and <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M1" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msup><mi/><mn mathvariant="normal">40</mn></msup><mi mathvariant="normal">Ar</mi><msup><mo>/</mo><mn mathvariant="normal">39</mn></msup><mi mathvariant="normal">Ar</mi></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="49pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="1b3028ccc4b469916ef2e4ca2dcca302"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="se-12-2255-2021-ie00001.svg" width="49pt" height="15pt" src="se-12-2255-2021-ie00001.png"/></svg:svg></span></span> geochronology on garnet–mica schists and the underlying granitoid basement terrane on the island of Ios demonstrates evidence of a Late Cretaceous high-pressure, medium-temperature (HP–MT) metamorphic event. This suggests that the Asteroussia crystalline nappe on Crete extended northward to include these Gondwanan tectonic slices. In this case, the northern part of the Asteroussia nappe (on Ios) is overlain by the terrane stack defined by the individual slices of the Cycladic Eclogite–Blueschist Unit, whereas in the south (in Crete) the Asteroussia slices are near the top of a nappe stack defined by the individual tectonic units of the external Hellenides. This geometry implies that accretion of the Ios basement terrane involved a significant leap of the subduction megathrust (250–300 <span class="inline-formula">km</span>) southward. Accretion needs to have commenced at or about <span class="inline-formula">∼38</span> <span class="inline-formula">Ma</span>, when the already partially exhumed slices of the Cycladic Eclogite–Blueschist Unit began to thrust over the Ios basement. By <span class="inline-formula">∼35</span>–34 <span class="inline-formula">Ma</span>, the subduction jump had been accomplished, and renewed rollback began the extreme extension that led to the exhumation of the Ios metamorphic core complex.</p>

R. Benjakul, C. Hollis, H. A. Robertson et al.

<p>The dominant paradigm for petrogenesis of high-temperature fault-controlled dolomite, widely known as “hydrothermal dolomite” (HTD), invokes upwelling of hot fluid along faulted and fractured conduits from a deep over-pressured aquifer. However, this model has several inherent ambiguities with respect to fluid sources and their dolomitisation potential, as well as mechanisms for delivering enough of these reactive fluids to form substantial volumes of dolomite. Here, we use generic 2D and 3D reactive transport simulations of a single transmissive fault system to evaluate an alternative conceptual model whereby dolomitisation is driven by seawater being drawn down into the subsurface and heated. We examine the evolution of fluid chemistry and the distribution of diagenetic alteration, including predictions of the rate, distribution, and temperature of HTD formation, and consider the possible contribution of this process to the Mg budget of the world's oceans.</p> <p>The simulations suggest that it is possible for convection of seawater along the fault damage zone to form massive dolomite bodies that extend hundreds of metres vertically and along the fault within a timescale of a few tens of thousands of years, with no significant alteration of the country rock. Dolomitisation occurs as a gradient reaction by replacement of host limestones and minor dolomite cementation, and it results in the discharge of Mg<span class="inline-formula">²⁺</span>-poor, Ca<span class="inline-formula">²⁺</span>-rich fluids to the sea floor. Fluids sourced from the basement contribute to the transport of heat that is key for overcoming kinetic limitations to dolomitisation, but the entrained seawater provides the Mg<span class="inline-formula">²⁺</span> to drive the reaction. Dolomite fronts are sharper on the “up-flow” margin where Mg<span class="inline-formula">²⁺</span>-rich fluids first reach the threshold temperature for dolomitisation, and the “down-flow” dolomite front tends to be broader as the fluid is depleted in Mg<span class="inline-formula">²⁺</span> by prior dolomitisation. The model demonstrates spatial contrasts in the temperature of dolomitisation and the relative contribution of seawater and basement-derived fluids which are also commonly observed in natural fault-controlled dolomites. In the past, such variations have been interpreted in terms of major shifts in the system driving dolomitisation. Our simulations demonstrate that such changes may also be a product of emergent behaviour within a relatively stable system, with areas that are dolomitised more slowly recording the effect of changes in fluid flow, heat, and solute transport that occur in response to diagenetic permeability modification.</p> <p>Overall, our models robustly demonstrate that high-temperature fault-controlled dolomite bodies can form from mixed convection and act as a sink for Mg in the circulating seawaters. In addition, comparison of our 3D simulations with simplifications to 2D indicate that 2D models misrepresent critical aspects of the system. This has important implications for modelling of systems ranging from geothermal resources and mineralisation to carbonate diagenesis, including hydrothermal karstification and ore genesis as well as dolomitisation.</p>

SEBASTIANO BARCA, MYRIAM DEL RIO , PAOLA PITTAU DEMELIA

The subject of this paper is new geological and stratigraphical data regarding the Paleozoic in the Sarrabus area (Southeastern Sardinia). More particularly Tremadocian (Lower Ordovician) acritarchs have been found in samples taken for microfossils research from the weakly metamorphosed terrigenous sediments of the San Vito Sandstone. Until recently only acritarchs from the Middle and Upper Cambrian has been found in the San Vito Sandstone. This new finding provides a more precise dating of the San Vito Sandstone, a more exact correlation between this Sarrabus formation and analogous formations with acritarchs in Central- Eastern Sardinia and also further confirmation of the Intraordovician age of the Sarrabese Phase and of the corresponding Sardic Phase of Iglesiente-Sulcis area (Southwestern Sardinia).

Kai Shao, Longyi Shao, Dongmin Ma et al.

Abstract The Early Cretaceous is an important coal accumulation period in China. Abundant coal resources were formed in the southeastern margin of Songliao Basin. Sequence stratigraphy and coal accumulation of the Early Cretaceous in the southeastern margin of Songliao Basin have been studied on the basis of extensive outcrop and borehole data. Based on regional unconformity, basal erosional surfaces of incised valley fills, and abrupt depositional facies-reversal surface, six sequence boundaries have been identified, which subdivide the Early Cretaceous coal-bearing series into 5 third-order sequences. Sequence I corresponds to Huoshiling Formation, sequences II and III correspond to member I and member II of Shahezi Formation. Sequences IV and V correspond to member I and member II of Yingcheng Formation. Sequence I developed at the initial subsiding stage, sequence II and III developed during the stable subsiding stage, while sequence IV and V developed during the basin shrinkage stage. The major coal seams were developed in the sequence II and III, which ensured the relative balance between the increase rate of the accommodation space and the rate of peat accumulation for a longer period, thus forming a thick coal seam.

Javad Rabbani, Majid Mirzaie Ataabadi, Elham Shahsavari

Abstract In order to reconstruct the sedimentary environment of marly strata related to the upper parts of Qom Formation, one stratigraphic outcrop have been studied. Studied section is located in the Zarrin-Abad area (South of Zanjan) and is composed of 135 meters of marls and argillaceous limestones. Theses strata are limited by thick bedded limestone (related to the F Member of the Qom Formation) at the base. There is a thick bed of evaporate layer at the top of these strata with sharp boundary that can be stratigraphically related to the Upper Red Formation. Based on petrographic and texture studies, eight microfacies have been identified. These microfacies are related to the distal parts of inner shelf, patch reef, slope, toe of slop and deep shelf sub environments. Based on microfacies analysis we can propose an open shelf as sedimentary environment for these strata. Relative abundance of allochems show one cycle (rise and fall) in relative sea level along the stratigraphic column that can be correlated with eustasy curve.  Keywords: Microfacies, Sedimentary model, Qom Formation, Zarrin-Abad, Zanjan.   Introduction The Qom Formation (Oligocene–Miocene) in central Iran is composed of carbonate and silisiclastic strata that is related to the lagoon, reef and basin sedimentary environments (Reuter et al. 2009). Due to the hydrocarbon potential, this formation has been considered by many geologists. Different sedimentary environment (ramp and/orshelf) have been proposed for this formation. Thus, this study try to reconstruct the sedimentary environment for these strata in the south of Zanjan to complete the comprehensive plan for the sedimentary environment of the Qom Formation. This formation in the studied section (Zarrin-Abad) is unconformably underlain by silisiclastic strata of the Lower Red Formation (Aalipour et al. 2017) and overlain (covered boundary) by the evaporitic package of Upper Red Formation. This study focused on upper parts of Qom Formation (marls and argillaceous limestones) in order to reconstruct sedimentary environment.   Material & Method One stratigraphic section has been sampled in the South of Zanjan (Sothwest of Zarrin-Abad). Forty two samples from 135 meters of marls and argillaceous limestones (Upper parts of Qom Formation) have been collected and thin sections were prepared. Sampling intervals were about three meters in average and included hard and semi-hard sediments. The microfacies analysis using polarized microscope have allowed the reconstruction on carbonate environment of upper parts of the Qom Formation in this section. Carbonate rock classification, facies study and environmental interpretation on thin sections was based on Dunham (1962) and Flugel (2010). All thin sections have been housed in Paleontological Laboratory, Department of Geology, University of Zanjan.   Discussion of Results & Conclusions Biostratigraphic studies confirm a Burdigalian age for these strata based on two index fossils (Borelis meo curdica, Meandropsina Iranica). One biozone has been identified based on first occurrence of Borelis melo curdica in the base of section (S1) and last occurrence of ­Meandropsina Iranica in the top of section (S39). This biozone can be correlated with (Adams and Bourgeois 1967) and (Daneshian and Ramezani Dana 2019) zonations. Microfacies analysis lead to identification of eight microfacies (1- Bioclast benthic foraminifera algal grainstone, 2- Coral boundstone, 3- Bioclast wackestone, 4- Sandy bioclast grainstone, 5- Sandy bioclast packstone, 6- Bioclast mudstone, 7- Pelagic mudstone/wackestone and 8- Pelagic packstone) related to the middle to outer carbonate shelf environment. Coral reef facies in lower parts of studied section can approve a carbonate shelf as sedimentary environment. Moreover, bioclast particles that consist of corals, benthic foraminifera, algae and some other fossils beside coral boundstone facies show fore reef facies in front of the platform margin. Based on presence of clastic particles in pelagic facies, we can conclude that there were some channels in coral reef areas that connect back reef environments to the open marine areas. Based on field observation and microfacies analysis, we proposed non-rimmed carbonate shelf as sedimentary environment for the studied strata. Based on quantitative analysis on environmental data, most of samples (strata) are related to the deep shelf environment. Quantitative analysis diagrams (allochems percentage) shows in each samples that there were rising trend in relative sea level from the base of section to the middle part. Following this trend the falling trend towards the end of the section have been recorded. This trends can be correlated with the global sea level changes during this time (Burdigalian). Thus it can be concluded that the Burdigalian basin in this area had been connected to the open oceans.

ANDREA TINTORI

The Norian beds of the Southern Calcareous Alps have yielded at least four species belonging to Saurichthys. Their vertebral column has large praezygapophyses, which, in each of these nominai species, at­tain a different relative length. The latter is inversely proportional to age: in fact, the youngest two, coeval spe­cies have the longest praezygapophyses, at least six times as long as a vertebral segment. Such a conspicuous change in an otherwise conservative genus, is here relateci to a major ichthyofaunal break that saw the florish­ing of the Pholidophoridae. The relative length of the praezygapophyses can be a very useful stratigraphical means, at least in the Norian (Upper Triassic).

O.B. Gintov

Survey data of geodynamic studies, completed during the latest 20 years in Ukraine for most of its regions, have been generalized in order to summarize the results of regional studies into geo-historical line from Eoarchean to Anthropogen. For this purpose the data of stratigraphy and isotopic geochronology obtained by Ukrainian and foreign scientists within the studied territory have been used in the work. It has been shown that the basic role in contemporary concepts on the character of geodynamic processes within the territory of Ukraine is played by the results of thorough studies of deep structure of the crust and mantle, fulfilled by the Institute of Geophysics NAS of Ukraine at the high methodic level with participation of many international organizations. Methods of seismometry and seismotomography, gravimetry and magnitometry, geothermic and deep electrometry as well as paleomagnetic and tectonophysical data were actively used. The data obtained show that geodynamic processes based on plate tectonics mechanisms arc clearly manifested in the studied territory since Neoarchean. For Eoarchcan and Mesoarchean plum-tectonic mechanisms are more probably specific. Present-day structure of the shield was definitely formed between 1,8 and 1,7 Ga isochronously with formation of the micro- continent Sarmatia, its affiliation with Fennoscandia and Volgo-Uralia into the continent Baltics on the background of the supercontinent Pangea-1. Geodynamic processes in Meso-Proterozoic and Early Paleozoic are examined in discussion form and it has been shown that up to Middle Devonian they were mainly concentrated in the western part of Ukraine in the territory of the present-day Carpathians and Volyn-Podolian plate. These processes were manifested as formation of Volyn-Polessian flexure (Middle Riphean), Galitsian-Belostok basin (Late Riphean), which joined the oceans Proto-Tethys and Proto-Yapetus westward of Baltic, formation in its place of orogen of Pre-Carpathians (Vendian), formation of the Dnister pericraton and (Upper Vendian) which finishes in the southwest by Pre-Galitsian foothills, TESZ zone and the Thornquist sea. Independent study of Vendian deposits of Ukraine by paleomagnetic and tectonophysical methods has shown that at this period virtual rotation axis of the Earth was sub-parallel to present-day latitudes. Activation of geodynamic processes in the remaining territory of Ukraine began in the Devonian after formation of supcrcontinent Euro-America: formation of the Donbass branch of the ocean Paleotethys and the Prypiat-Dnieper-Donets riftogen with possible sub- oceanic crust (Upper Devonian); separation of Misian, Scythian and Turanian microplates from East-European platform and their transformation into terrains of Paleotethys; affiliation of Gondvana with Lavrasia and formation of the supercontinent Pangaea (the Permian-Triassic). Paleomagnetic studies of the Permian and Triassic dyke complexes of the western part of the Ukrainian Shield allowed to make a choice between two models of Pangaea (A and B) and to prefer the model A (vengerovskaya). In Mesozoic-Cenozoic active geodynamic processes were concentrated in the Alpine margin of the East-European platform; formation of the Mesotethys ocean and its western part Alpine Tethys (Middle Triassic); opening of the Taurean basin (Middle Triassic—Early Jurassic), its closure and formation of folding of Taurean series of rocks in North Dobrogea and West Crimea (Middle Jurassic); the opening of the West Black Sea (Upper Cretaceous) and East Black Sea (Eocene) basins; closure of the oceans of the Alpine Tethys, westward movement of micro-plates Alcapa and Tissia-Dakia and formation of the arc of the Carpathian orogen (Upper Cretaceous-Neogene); collision process in the Crimean—Black Sea region in the variant of two-layered plate tectonics and the uplift of the Mountain Crimea (Pliocene—present-day). The data resulted show that the mechanisms of paleo- and present-day geodynamics — plate tectonics and plum-tectonics explain appropriately enough all geological and geophysical phenomena observed in nature, especially those ones which were revealed during the second part of the 20th — and 21st centuries.

Jo De Waele

Orosejski zaliv je eno najpomembnejših obalnokraških območij v Italiji. Številne nove meritve jam so omogočile boljše razumevanje speleogeneze na območju zaliva. Razvoj krasa na tem območju smo raziskovali z različnimi geomorfološkimi raziskavami na površju in pod morjem, ter spelološkimi raziskavami v jamah. Glavni faktorji morfoloških procesov so litologija, tektonika, paleoklima in nihanja morske gladine. Študija nekaterih pomembnih jamskih sistemov je pokazala kompleksen geološki razvoj, kjer so kraški procesi igrali pomembno vlogo od zgodnjega terciarja in dosegli višek v pliokvartarju. In the past ten years cave surveying has allowed better understanding of speleogenesis in the Orosei Gulf (Central-East Sardinia, Italy), one of the most important coastal karst areas of Italy. Surface geomorphologic research has been accompanied by subterranean and submarine landform analysis in order to try and understand the evolution of this coastal karst since its emersion in Upper Eocene. The main factors influencing the geomorphic processes are lithology, tectonics, palaeo-climate and sea level changes. The study of several important cave systems demonstrates a complex geological history with karst processes that started in Early Tertiary and accelerated during Plio-Quaternary.

LI Chunxiang, MIAO Xinyuan, LU Shugang et al.

Four <i>Dryopteris</i> Adanson species,<i>D.hondoensis</i> Koidz.,<i>D. simasakii</i> (H.Ito) Kurata, <i>D. lepidorachis</i> C.Christensen and <i>D.paraerythrosora</i> Ching et C.F.Zhang are newly recorded from Shanghai,and should be added to the most recent checklist of Shanghai vascular plants.The morphological differences between the newly recorded species and their close allies are discussed,their pictures of living plants and additional notes are provided.

Karem Azmy, Gabriella Bagnoli, Svend Stouge et al.

Aswan Aswan, S Rijani, Y. Riza

<p>DOI: <span><a href="http://dx.doi.org/10.17014/ijog.v8i1.151" target="_blank">10.17014/ijog.v8i1.151</a></span></p><p>Kaliwangu Formation cropping out around Sumedang area contains mollusk fossils dominated by gastropods and bivalves. In terms of sequence stratigraphy, each sedimentary cycle generally consists of four shell bed types: Early Transgressive Systems Tract (Early TST) deposited above an erosional surface or sequence boundary, that is characterized by shell disarticulation, trace fossils, gravelly content, no fossil orientation direction, and concretion at the bottom; Late Transgressive Systems Tract (Late TST) identified by articulated (conjoined) specimen in its life position, that shows a low level abration and fragmentation, adult specimen with complete shells, and variation of taxa; Early Highstand Systems Tract (Early HST) characterized by adult taxa that was found locally in their life position with individual articulation, juvenile specimens frequently occured; Late Highstand Systems Tract (Late HST) determined as multiple-event concentrations, disarticulated shell domination, and some carbon or amber intercalation indicating terrestrial influence. Shell bed identification done on this rock unit identified nineteen sedimentary cycles.<br /><br /></p>

Sandrine Prat, Stéphane C Péan, Laurent Crépin et al.

BACKGROUND: Anatomically Modern Humans (AMHs) are known to have spread across Europe during the period coinciding with the Middle to Upper Paleolithic transition. Whereas their dispersal into Western Europe is relatively well established, evidence of an early settlement of Eastern Europe by modern humans are comparatively scarce. METHODOLOGY/PRINCIPAL FINDING: Based on a multidisciplinary approach for the study of human and faunal remains, we describe here the oldest AMH remains from the extreme southeast Europe, in conjunction with their associated cultural and paleoecological background. We applied taxonomy, paleoecology, and taphonomy combined with geomorphology, stratigraphy, archeology and radiocarbon dating. More than 160 human bone remains have been discovered. They originate from a well documented Upper Paleolithic archeological layer (Gravettian cultural tradition) from the site of Buran-Kaya III located in Crimea (Ukraine). The combination of non-metric dental traits and the morphology of the occipital bones allow us to attribute the human remains to Anatomically Modern Humans. A set of human and faunal remains from this layer has been radiocarbon dated by Accelerator Mass Spectrometry. The direct-dating results of human bone establish a secure presence of AMHs at 31,900+240/-220 BP in this region. They are the oldest direct evidence of the presence of AMHs in a well documented archeological context. Based on taphonomical observations (cut marks and distribution of skeletal elements), they represent the oldest Upper Paleolithic modern humans from Eastern Europe, showing post-mortem treatment of the dead as well. CONCLUSION/SIGNIFICANCE: These findings are essential for the debate on the spread of modern humans in Europe during the Upper Paleolithic, as well as their cultural behaviors.

Ivan Iskra, Norbert Kávási, Janja Vaupotič

At the lowest point in the Postojnska Jama (jama = cave), concentration and size distribution of non-radioactive aerosols in the size range of 10–1,000 nm were measured and their concentrations are compared with those of radioactive aerosols carrying radon short-lived decay products (218Po, 214Pb and 214Bi) obtained previously. Concentration of non-radioactive aerosols during morning hours was in the range 600–2,750 cm–3, with about 90% of particles smaller than 50 nm. On the other hand, concentration of radioactive aerosols smaller than 50 nm was several radionuclide atoms per 1 cm3 and the bigger ones, less than 1 atom per 1 cm3.