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Tytuł:
Brachiopods from the Lower Red Formation (Lower Oligocene) of the Isfahan Province, Central Iran
Autorzy:
Bitner, Maria Aleksandra
Bahrami, Ali
Yazdi, Mehdi
Zágoršek, Kamil
Powiązania:
https://bibliotekanauki.pl/articles/27311288.pdf
Data publikacji:
2023
Wydawca:
Polskie Towarzystwo Geologiczne
Tematy:
Brachiopoda
new species
Early Oligocene
Rupelian
Lower Red Formation
Ramsheh section
Iran
Opis:
The study presents the first record of Early Oligocene brachiopods from the Lower Red Formation of the Isfahan Province, Central Iran. The assemblage comprises six brachiopod taxa, belonging to five genera, Novocrania Lee and Brunton, Thecidellina Thomson, Argyrotheca Dall, Joania Álvarez, Brunton and Long, and Platidia Costa. Two species are described as new, Thecidellina persica sp. nov. and Argyrotheca ramshehensis sp. nov. The discovery of Thecidellina in Iran is the first confirmed occurrence of this genus in Oligocene deposits, filling the gap between known Eocene and Miocene occurrences. At the species level, the brachiopods investigated here show no affinity to those from the Lower Miocene Qom Formation.
Źródło:
Annales Societatis Geologorum Poloniae; 2023, 93, 4; 411--422
0208-9068
Pojawia się w:
Annales Societatis Geologorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Facies Analysis and Depositional Environmental Interpretation of The Upper Oligocene, Block 09- 2/10, Cuu Long Basin
Autorzy:
Nguyen, Muoi Duy
Le, Anh Ngoc
Nguyen, Hoa Minh
Bui, Ngan Thi
Powiązania:
https://bibliotekanauki.pl/articles/27323232.pdf
Data publikacji:
2023
Wydawca:
Polskie Towarzystwo Przeróbki Kopalin
Tematy:
Cuu Long basin
upper oligocene
depositional environment
seismic facies
block 09-2/10
Oligocen
Wietnam
sejsmika
środowisko
Opis:
The article presents the facies and environment of the Upper Oligocene sediments in the area of block 09-2/10 based on the analysis of seismic facies and well data of the neighboring areas. The results of the interpretation of seismic data indicate that the upper Oligocene sediments are limited by the top C, top D seismic reflectors. The environment is formed from lagoons, lakes to deep lakes. Seismological facies analysis identified 03 facies including seismic facies with medium to poor reflection amplitude, medium continuous, low frequency reflecting the lacustrine sediments (80%) in most of the lake center. Strong reflective seismic facies, sigmoidal clinoforms reflect the lakeside sediments (15%) distributed in the lakeside shelf. The seismic facies with average and continuous amplitude poorly reflect alluvial sediments (5%) in the Northwest region. The direction of sediment transport is mainly from the Northwest and Southwest in the area. The sandstone sequences are distributed on the slopes of the lake and the lake bottom, which is potential reservoir.
Źródło:
Inżynieria Mineralna; 2023, 2; 155--162
1640-4920
Pojawia się w:
Inżynieria Mineralna
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Morphometric analysis of pebbles in verification of transport processes and interpretation of palaeoenvironment: A case study from the Ogwashi Formation (Oligocene), Niger Delta Basin, Nigeria
Autorzy:
Ogbe, Ovie B.
Osokpor, Jerry
Emelue, Chukwunomso V.
Ocheli, Azuka
Powiązania:
https://bibliotekanauki.pl/articles/2204373.pdf
Data publikacji:
2023
Wydawca:
Uniwersytet im. Adama Mickiewicza w Poznaniu
Tematy:
grain morphometry
sandstone facies
bivariate plot
ternary diagram
mixed environments
Oligocene sediments
morfometria
frakcja
piaskowiec
osady
Oligocen
Opis:
The present paper discusses a palaeoenvironmental interpretation of the Oligocene Ogwashi Formation (Niger Delta Basin, Nigeria) through morphometric analysis of pebbles, a research method essentially depending on the quantitative evaluation of pebble size and shape which change during transport processes in a range of depositional environments. The relationship of bivariate and ternary-diagram plots of independent functions was determined from freshly exposed sandstone sections in quarries at Ibusa, near Asaba, Nigeria. The grain size of pebbles ranges from fine (11.00 mm) to very coarse (41.33 mm), with a mean size of 21.05 mm (coarse pebbles). A bivariate plot of the flatness index vs maximum projection sphericity index shows 37% of the pebbles to fall within a beach (marine) environment, and 33% within a fluvial environment; the remaining 30% are uncertain. The maximum projection sphericity index vs oblate-prolate index bivariate plot indicates that 47% of pebbles fall within a marine environment and 22% within a fluvial environment, while the remaining 31% are uncertain. The sphericity-form ternary diagram plot shows that the pebbles primarily comprise bladed, platy, very bladed and very platy of near-equal proportions with minor elongate and very elongate stones, which suggests that the pebbles are diverse in origin. The sphericity-form bivariate plot indicates that the pebbles are largely of disc and blade shapes with a minor number of spherical and rod shapes. The near-equal proportion of pebbles in different segments of the bivariate and ternary diagram plots, and the wide distribution of the pebble grain sizes and shapes suggest the Ogwashi Formation is composed of redeposited sediments that likely were transported and deposited in a mix of marine and fluvial settings with possible transitional environments. In other words, the pebbles can be interpreted as marine-influenced fluvial sediments in marginal-marine settings.
Źródło:
Geologos; 2023, 29, 1; 21--31
1426-8981
2080-6574
Pojawia się w:
Geologos
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Pseudo-shallow marine features in deep marine gravity-flow successions: lessons from the Menilite Beds at Skrzydlna (Oligocene; Western Outer Carpathians)
Autorzy:
Wendorff, Marek
Siemińska, Aneta
Powiązania:
https://bibliotekanauki.pl/articles/24202106.pdf
Data publikacji:
2023
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
Oligocene
Carpathians
Opis:
Quite common in publications devoted to the marine and lacustrine environments are differences of opinion on bathymetry of the basin receiving detrital sediment, especially when sedimentary structures are interpreted as indicators of specific depth-defined environments (following classic textbooks). However modern studies of deep-water environments, experimental work, modelling and numerous outcrop studies of ancient successions mitigate against such an approach. In this respect, the flysch succession of the Menilite Beds strata at Skrzydlna, which contains a variety of features that can confuse a cursory observer seems to serve as a universally applicable example. The succession at Skrzydlna records deposition in the western part of the synorogenic Dukla Basin during the Oligocene. The Menilite Beds are considered by most authors as deep marine deposits (the bathyal zone). The exposed section, almost 200-metre thick, is divided into three lithological intervals, each of which represents a radically different type of sedimentation. These are: i) a fine-grained association of terrigeonous and hemipelagic sediments; ii) infill of a canyon incised by about 40–50 m into the underlying strata, wider than outcrop and dominated by an olistostromal succession of debris flows with pebbles, boulders, slide and slump sheets; iii) succession of turbidites forming three fining-upwards sequences and ranging from thick, massive, amalgamated sandstones deposited by high-density flows in laterally migrating outcrop-scale channels, through ‘normal’ turbidites forming complete Bouma sequences (Ta-e), containing dunes and fining to Tce in the uppermost associations of thin-bedded sandstones and shales. These features suggest rapid uplift of the source area resulting in canyon incision and sudden onset of the olistostrome deposition that evolved upwards into proximal turbidite-fan sequence, which subsequently retrograded due to decreasing intensity of supply. The oldest interval (i) consists of predominantly finegrained facies, most characteristic of the Menilite Beds at their regional development. These are dark mudstones deposited in anoxic to dysoxic conditions and containing thin layers of fine-grained sandstones — turbidites with Bouma Tab; Tbc; Tabc; Tabe intervals, a 2–3 m thick intercalation of massive amalgamated sandstone, dark cherts, and locally silicified marls and limestones. The latter contain isolated lenses of medium-grained sandstone current ripple marks indicating three palaeocurrent directions. Two sets represent bipolar distribution of palaeocurrents, typical of shallow sea/ shelf sediments reworked by tidal currents. However, these are interpreted here as the products of tidal currents reworking bottom sediments of the bathyal zone, the case known from contemporary environments. In this context, the third direction, perpendicular to the bipolar flows does not represent reworking by littoral current on shelf but deep marine contour current. The main channel, or canyon (ii) incised into the slope sediments fed the depositional system with olistostrome deposits supplied from the rapidly uplifted source zone. Above there is a thinning upwards, turbidite sequence of four sub-complexes (A-D): A – conglomerate and sandstone fill three laterally migrating narrow, outcrop-scale erosional channels with a maximum depth of 15 m; B  – two shallow (up to 2 m deep) distributary channels filled with very thick, massive or normally graded sandstones; C  – turbidites Tb, Tc, Tbc with single occurrences of hummocky-like cross stratification and sandstone beds forming dunes at the mouth of distributary channels; D  – less ordered interval of thick-, medium- and thin-bedded sandstones interbedded with mudstones, forming various incomplete sequences of Bouma intervals. Interbeds of hummocky-like cross stratification, commonly found on the shelf, are interpreted in the deep-sea environment as the effect of Kelvin-Helmholtz instability or other complex flow processes, e.g. reflections of turbidity currents. A few occurrences of ripplemarks symmetrical in outer shape show unidirectional cross-lamination in cross section. These were modified by erosion that could have resulted from occasional extremely violent storms or flow reflections off channel margins. In spite of the external shape reminiscent of symmetrical ripplemarks these features do not possess the internal structure of composite cross laminae characteristic for oscillatory reworking of sand by prolonged, rhythmic action of waves. Solitary current ripplemarks showing flow directions opposite to the main transport direction are antidunes or deposits of currents reflected/deflected by channel sides. In summary, in spite of geometrical and structural similarity to the features traditionally considered as formed on shelf, the structures described here, assessed in association with facies and evidence referred to in the introductory paragraphs, fall into the category of deposits known also from below the ‘normal’ wave base and below the shelf edge, i.e. in the slope region. Hence from deep-sea environment for which the occurrence of bipolar currents, dunes, hummocky cross-stratification and symmetrical ripplemarks are neither typical nor diagnostic, but do exist.
Źródło:
Geotourism / Geoturystyka; 2023, 1-2 (72-73); 79--80
1731-0830
Pojawia się w:
Geotourism / Geoturystyka
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A new genus of chemosymbiotic vesicomyid bivalves from the Oligocene of western North America
Autorzy:
Hybertsen, F.
Goedert, J.L.
Kiel, S.
Powiązania:
https://bibliotekanauki.pl/articles/31341392.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
paleontology
new genus
bivalve
Bivalvia
Vesicomyidae
Oligocene
North America
cold-seep deposit
deep-water formation
Źródło:
Acta Palaeontologica Polonica; 2022, 67, 3; 703-709
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Causes of groundwater level and chemistry changes in an urban area; a case study of Warsaw, Poland
Autorzy:
Krogulec, Ewa
Gruszczyński, Tomasz
Kowalczyk, Sebastian
Małecki, Jerzy J.
Porowska, Dorota
Sawicka, Katarzyna
Trzeciak, Joanna
Wojdalska, Anna
Zabłocki, Sebastian
Zaszewski, Daniel
Powiązania:
https://bibliotekanauki.pl/articles/24024702.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
urban area
Quaternary aquifer
Oligocene aquifer
groundwater level changes
infiltration
groundwater chemistry
Warsaw
obszar miejski
czwartorzędowe piętro wodonośne
oligoceńskie piętro wodonośne
zmiany poziomu wód gruntowych
infiltracja
chemizm wód podziemnych
Warszawa
Opis:
The presented studies focus on changes in groundwater levels and chemistry, and the identification of important factors influencing these changes on short- and long-term scales in urban areas. The results may be useful for rational and sustainable groundwater planning and management in cities. The studies concerned three aquifers: (1) the shallow Quaternary aquifer, (2) the deep Quaternary aquifer, and (3) the Oligocene aquifer in the capital city of Warsaw (Poland). The spatial variability of groundwater recharge was determined and its changes in time were characterized. The characteristics of groundwater levels were based on long-term monitoring series. The results indicate that urban development has caused overall reduction in infiltration recharge (from 54 to 51 mm/year), which is particularly clear in the city suburbs and in its centre, where land development has significantly densified during the last 30 years. Studies of groundwater levels indicate variable long-term trends. However, for the shallowest aquifer, the trends indicate a gradual decrease of the groundwater levels. In the case of the much deeper Oligocene aquifer, groundwater table rise is observed since the 1970s (averagely c. 20 m), which is related with excessive pumping. Based on the studied results, the groundwater chemistry in the subsurface aquifer indicates strong anthropogenic influence, which is reflected in multi-ionic hydrogeochemical types and the occurrence of chemical tracers typical of human activity. The Oligocene aquifer is characterized by a chemical composition indicating the influence of geogenic factors.
Źródło:
Acta Geologica Polonica; 2022, 72, 4; 495--517
0001-5709
Pojawia się w:
Acta Geologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Early Oligocene brachiopods from the rocky-shore deposits at Mammendorf, central Germany
Autorzy:
Bitner, Maria Aleksandra
Müller, Arnold
Powiązania:
https://bibliotekanauki.pl/articles/2133937.pdf
Data publikacji:
2022
Wydawca:
Polskie Towarzystwo Geologiczne
Tematy:
Brachiopoda
Early Oligocene
Rupelian
predation
North Sea Basin
Opis:
Thirteen species, belonging to eleven genera, i.e., Discinisca Dall, Novocrania Lee and Brunton, Lacazella Munier-Chalmas, Pliothyrina van Roy, Terebratulina d’Orbigny, Megathiris d’Orbigny, Argyrotheca Dall, Bronnothyris Popiel-Barczyk and Smirnova, Joania Álvarez, Brunton and Long, Platidia Costa and Megerlia King, have been identified in the lower Oligocene rocky-shore deposits at Mammendorf, central Germany. The occurrence of the species Discinisca fallens (Wood), Argyrotheca bitnerae Dulai and Megerlia truncata (Linnaeus) extends their stratigraphic range back to the early Oligocene. The affinity to the early Oligocene brachiopod fauna of the Mainz Basin is noted.
Źródło:
Annales Societatis Geologorum Poloniae; 2022, 92, 1; 87--107
0208-9068
Pojawia się w:
Annales Societatis Geologorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Geological and palaeogeographical peculiarities of the Adamów Graben area, central Poland
Autorzy:
Widera, Marek
Dzieduszyńska, Danuta
Petera-Zganiacz, Joanna
Powiązania:
https://bibliotekanauki.pl/articles/2204352.pdf
Data publikacji:
2022
Wydawca:
Uniwersytet im. Adama Mickiewicza w Poznaniu
Tematy:
marine rocks
Oligocene clays
Oligocene pebbles
Miocene sandstone
glacial lake
periglacial involutions
fossil forest
skała morska
iły oligoceńskie
piaskowiec mioceński
jezioro polodowcowe
inwolucje peryglacjalne
Opis:
From a geological and palaeogeographical point of view, the area of the Adamów Graben in the vicinity of Turek ranks amongst the best known in central Poland, with several opencast mines located here where lignite was exploited for 57 years. These large-surface exposures provide a good opportunity for detailed geological studies of strata of Late Cretaceous to Holocene age. However, the present research focuses mainly on those deposits, forms and structures that have been most thoroughly examined and are best exposed. These are Cretaceous marls and gaizes, Paleogene ‘blue clays’ and the ‘Koźmin Gravels’, Neogene sandstones, as well as the Quaternary glacial ‘Lake Koźmin’, involutions and ‘Koźmin Las’. Some of these, e.g., the ‘Koźmin Gravels’ and ‘Koźmin Las’, are not known from other Polish territories. Furthermore, results obtained by the authors over a period of nearly 30 years also include data on palaeogeographical changes across some Cenozoic intervals, especially during the early Oligocene and late Weichselian.
Źródło:
Geologos; 2022, 28, 1; 1--17
1426-8981
2080-6574
Pojawia się w:
Geologos
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
New craniodental material of the typotherian notoungulates from the upper Oligocene of Mendoza, central-western Argentina and their taxonomical importance
Autorzy:
Hernandez Del Pino, S.
Seoane, F.D.
Cerdeno, E.
Powiązania:
https://bibliotekanauki.pl/articles/31341361.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
paleontology
new material
craniodental material
typotherian notoungulate
notoungulate
Notoungulata
fossil mammal
Mammalia
Archaeohyracidae
Hegetotheriidae
Interatheriidae
Agua de la Piedra Formation
Deseadan
Mendoza province
Oligocene
Upper Oligocene
Mendoza
Argentina
taxonomy
Źródło:
Acta Palaeontologica Polonica; 2022, 67, 4; 983-997
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An Oligocene olistostrome with exotic clasts in the Silesian Nappe (Outer Ukrainian Carpathians, Uzh River Basin)
Autorzy:
Hnylko, Oleh
Hnylko, Svitlana
Heneralova, Larysa
Tsar, Maria
Powiązania:
https://bibliotekanauki.pl/articles/2058691.pdf
Data publikacji:
2021
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Ukrainian Carpathians
Silesian Nappe
Oligocene
olistostrome
foraminifers
biostratigraphy
palaeogeography
Opis:
In the Ukrainian part of the Silesian Nappe (Outer Carpathians, Uzh River Basin) the exotic clast-bearing Uzhok Olistostrome (up to 60 m thick) occurs within the Oligocene Krosno Formation and underlies the Pikui Sandstone (Otryt Sandstone in Poland). The Uzhok Olistostrome consists of debris/grain/mud flow deposits with clasts of schist and bioclastic limestone. These deposits contain redeposited pelagic sediments with planktonic foraminifers including Parogloborotalia pseudocontinuosa (Jenkins), Ciperoella ciperoensis (Bolli), Globoturborotalita woodi (Jenkins), Chiloguembelina adriatica Premec Fucek, Hernitz Kucenjak and Huber. The age of the Uzhok Olistostrome based on planktonic foraminifers correlates with the middle Oligocene within the middle O2–O5 zones. The source area for the Uzhok Olistostrome and Pikui Sandstone was a mid-Oligocene intrabasinal palaeouplift (the Pikui Ridge) interpreted as the fore-bulge located in the Silesian Sub-basin ahead the emerging Outer Carpathian accretionary prism (including the Dukla Nappe and other West Carpathian inner flysch nappes).
Źródło:
Geological Quarterly; 2021, 65, 4; 3--20
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Multispecies leatherback turtle assemblage from the Oligocene Chandler Bridge and Ashley formations of South Carolina, USA
Autorzy:
Fallon, B.R.
Boessenecker, R.W.
Powiązania:
https://bibliotekanauki.pl/articles/2082243.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Chelonioidea
Natemys
Egyptemys
Psephophorus
Paleogene
Oligocene
North America
Opis:
Paleogene dermochelyid species richness far exceeded that of today. Leatherback sea turtles were most species rich in the Paleogene, but their richness declined sharply during the Neogene with only one species existing today, Dermochelys coriacea. We describe the fossil remains of three leatherback genera (Natemys, Psephophorus, and Egyptemys) from the upper Oligocene Chandler Bridge Formation and two (Natemys and Psephophorus) from the lower Oligocene Ashley Formation of South Carolina, USA. The fossils consist of isolated and some associated carapacial ossicles. Several ossicles are referred to Natemys sp. because their scalloped edges are indicative of the carapacial sunflower pattern specific to this genus. Additionally, two Natemys morphotypes (Natemys sp. 1 and 2) are distinguished based on differences in ossicle thickness and internal structure. We refer two ossicles to cf. Psephophorus sp. because of their internal diploic structure and because one has a dorsal radial pattern while the other has a prominent ridge that exhibits strong visceral concavity. Finally, we refer one ossicle to cf. Egyptemys sp. because it has a shallow keel that shows little expression on the visceral surface, although we also acknowledge the ossicle’s similarity to some ridged ossicles of the genus Psephophorus. These ossicles represent the first multispecies assemblage of leatherback fossils reported worldwide. Furthermore, the specimens fill both temporal and geographic gaps for extinct leatherback genera and represent the first formally described dermochelyids from South Carolina and the Oligocene of the Atlantic Coastal Plain.
Źródło:
Acta Palaeontologica Polonica; 2020, 65, 4; 763-776
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dinoflagellate cyst stratigraphy of the Popiele Member and Menilite Formation in the Boryslav-Pokuttya Nappe (Aksmanice, SE Poland)
Autorzy:
Suchocka, Arleta
Barski, Marcin
Bieńkowska-Wasiluk, Małgorzata
Powiązania:
https://bibliotekanauki.pl/articles/2058577.pdf
Data publikacji:
2019
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
dinoflagellate cysts
biostratigraphy
Oligocene
Menilite Formation
Outer Carpathians
flysch
Opis:
In the Paratethys Sea, isolation, the development of anoxia and stratification of the water column resulted in deposition of organic-rich sediments. In the Western Carpathians (Central Paratethys) these sediments now lie within the Menilite Formation. Whereas the Eocene-Oligocene transition has been studied in the Western Carpathians and is documented by dinoflagellate cyst assemblages, the dinoflagellate cyst stratigraphy of the Menilite Formation members has been uncertain. The Popiele Member and the Menilite Formation exposed at Aksmanice (Boryslav-Pokuttya Nappe, Western Outer Carpathians) reflect palaeogeographic changes at the beginning of the Oligocene. These previously studied deposits have been assigned to lithostratigraphic units, though without biostratigraphic documentation. The age of the Menilite Fm. in the Carpathian sedimentary succession is particularly interesting due to the diachronous character of the facies development. In this study we provide biostratigraphic data based on well-preserved organic-walled dinoflagellate cyst assemblages. The marker taxa recovered indicate a Rupelian age (Early Oligocene) for the Menilite Fm. A different assemblage occurs in the Popiele Member underlying the Menilite Fm. Here, the dinoflagellate cysts are more diverse and abundant, and represented by typical Eocene taxa attributed to Areosphaeridium spp. and Charlesdowniea spp. The Popiele Member may be assigned to the Priabonian (Late Eocene).
Źródło:
Geological Quarterly; 2019, 63, 3; 539--557
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Identification of the Oligocene-Miocene boundary in the Central Iran Basin (Qom Formation) : Calcareous nannofossil evidences
Autorzy:
Parandavar, Mohammad
Hadavi, Fatemeh
Powiązania:
https://bibliotekanauki.pl/articles/2058670.pdf
Data publikacji:
2019
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Oligocene-Miocene boundary
calcareous nannofossils
biohorizons
Central Iran Basin
Qom Formation
“c1” Sub-member
Opis:
A diverse Late Oligocene to Early Miocene calcareous nannofossil assemblage was examined from the Qom Formation in the Central Iran Basin, and the Oligocene-Miocene boundary was identified based on the quantitative analysis of the assemblages in 303 smear slides. Eleven well-established calcareous nannofossil bio-events are delineated in the Upper Oligocene through Lower Miocene. The results clearly show that the Highest Occurrence (HO) of Sphenolithus delphix is the closest bio-event to the boundary as traditionally delineated on the lithostratigraphic criteria, and provides a distinct biohorizon below it. The Lowest Occurrence (LO) of the species Discoaster druggii is the oldest Miocene bio-event that is observed shortly after the HO of S. delphix, showing that calcareous nannofossils are well suited for approximating the Oligocene-Miocene boundary in the Qom Formation. The Oligocene-Miocene boundary is placed in the upper part of Sub-member “c1” in all three sections studied here and it is traceable throughout the Central Iran Basin, which makes a potentially reliable marker horizon for sequence stratigraphic and hydrocarbon studies in the area.
Źródło:
Geological Quarterly; 2019, 63, 2; 215--229
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Occurrence of clastic injectites in the Oligocene strata of the Carpathians and their significance in unravelling the Paleogene and Neogene evolution of the Carpathian orogeny (Poland, Ukraine and Romania)
Autorzy:
Jankowski, Leszek
Wysocka, Anna
Powiązania:
https://bibliotekanauki.pl/articles/2058618.pdf
Data publikacji:
2019
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
injectites
dykes
Carpathians
Oligocene
Polska
Ukraine
Romania
Opis:
The irregular distribution of sand injections, traditionally termed “dykes” in the Polish geological literature, within individual Carpathian units and within individual lithofacies were observed during long-lasting field works. Injectites have been observed in the Magura Beds and in the Inoceramian Beds of the Polish and Romanian Carpathians, and in the Central Carpathian Paleogene deposits. However, they are most common in the Oligocene-Miocene Menilite Beds, where they are typical and abundant, particularly in the Skole Unit. Two clastic injectite types were distinguished: sedimentary (S-type) and tectonized (T-type). Based on the occurrence and interpretation of these injectites a new two-stage conceptual model is proposed for the Polish segment of the progressive Oligocene-Miocene Carpathian orogenic belt evolution. Type S clastic injectites are interpreted as having formed in the compressional stage, during foredeep basin migration while depositional slope changes were taking place in the Late Oligocene to Early Miocene. Type T injectites are interpreted as having formed by reactivation of S-type injectites in the last, mainly strike-slip, phases of Carpathian orogenic belt formation.
Źródło:
Geological Quarterly; 2019, 63, 1; 106--125
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Using digital photographs and orthophotomaps of a quarry to assess the geometry and density of discontinuities in a sandstone deposit
Wykorzystanie cyfrowych fotografii i ortofotomapy kamieniołomu do oceny geometrii i intensywności spękań w złożu piaskowców
Autorzy:
Figarska-Warchoł, Beata
Stańczak, Grażyna
Powiązania:
https://bibliotekanauki.pl/articles/219796.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
oligocen
warstwy krośnieńskie
Karpaty zewnętrzne
system spękań
wskaźnik bloczności
skały bloczne
dimension stones
Outer Carpathians
oligocene
Krosno Beds
joint system
quantity of blocks
Opis:
A lithological profile and measurements of the orientation and spacings of natural discontinuity planes were carried out in the Górka-Mucharz sandstone excavation (Krosno Beds, Outer Carpathians, Poland). In addition, the density of the discontinuities was assessed by measuring their spacings using oriented digital photographs of the quarry walls. An orthophotomap was also used in assessing the orientation and density of fractures with the tools available in QGIS. It was shown that digital image analysis can be used as an alternative to direct field measurements, especially in situations where access to an outcrop is difficult. The distributions of spacings larger than 40 cm, obtained by direct measurements and based on digital images of the quarry, were comparable. As a consequence, both measurement techniques yielded similar values of the quantity of blocks (QB), which differed by less than 2% for the minimum block volume in the range 0.4-1.0 m3 and by 6-7% for larger blocks. On the other hand, measurements of discontinuity spacings that were taken on the basis of an orthophotomap can only serve to estimate the approximate maximum value of this parameter. However, the use of orthophotomaps gives a more explicit spatial pattern of the main vertical joint sets than direct measurements in the quarry.The analysis results also showed the following: (i) the presence of tectonic disturbances visible at the highest level of the deposit; (ii) higher density of set A fractures with planes deepening in the NE direc-tion and a considerable reduction of the QB parameter, particularly in the peripheral NE and SW parts of the deposit; (iii) differences in the orientation of the discontinuity system between particular beds. The variable density of the discontinuities in the excavation is related to the presence of the faults that limit the Górka-Mucharz deposit.
Przedstawiono profil litologiczny oraz wyniki pomiarów orientacji i odległości naturalnych płaszczyzn podzielności w wyrobisku złoża piaskowców krośnieńskich Górka-Mucharz (Karpaty Zewnętrzne, Polska). Ponadto, intensywność występowania spękań oceniono pomiarami ich rozstępów z wykorzystaniem cyfrowych fotografii zorientowanych ścian kamieniołomu. W ocenie orientacji i intensywności spękań wykorzystano też ortofotomapę wykorzystując do analizy narzędzia GIS. Wykazano, że analiza zdjęć cyfrowych może być wykorzystana jako alternatywa bezpośrednich pomiarów terenowych, szczególnie w sytuacji utrudnionego dostępu do odsłonięć. Uzyskane metodą bezpośrednich pomiarów i na podstawie cyfrowych zdjęć kamieniołomu rozkłady rozstępów były zbliżone dla wartości tego parametru powyżej 40 cm. W konsekwencji obie techniki pomiarów dały podobne wartości wskaźnika bloczności (QB), różniące się o niespełna 2% dla objętości bloku minimalnego w zakresie 0,4-1,0 m3 i 6-7% dla bloków większych. Natomiast pomiar rozstępów płaszczyzn podzielności wykonany na podstawie ortofotomapy może służyć jedynie do oceny przybliżonych maksymalnych wartości tego parametru. Jednak, wykorzystanie ortofotomapy daje bardziej jednoznaczny obraz przestrzennej orientacji głównych zespołów pionowych spękań niż pomiary bezpośrednie w kamieniołomie.W wyniku analizy stwierdzono również: (i) obecność zaburzeń tektonicznych widocznych w najwyższym poziomie złoża; (ii) wyższą intensywność spękań zespołu A o płaszczyznach zapadających w kie-runku NE i znaczne zmniejszenie bloczności (QB), szczególnie w peryferyjnych NE i SW fragmentach złoża; (iii) różnice w orientacji systemu nieciągłości odnotowane pomiędzy poszczególnymi warstwami. Ponadto, wykazano, że obecność uskoków ograniczających złoże Górka-Mucharz może wiązać się ze zmienną intensywnością płaszczyzn nieciągłości w wyrobisku.
Źródło:
Archives of Mining Sciences; 2019, 64, 3; 509-532
0860-7001
Pojawia się w:
Archives of Mining Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 76

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