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Wyszukujesz frazę "Lower Oligocene" wg kryterium: Temat


Wyświetlanie 1-6 z 6
Tytuł:
Heavy minerals from Oligocene sandstones of the Menilite Formation of the Skole Nappe, SE Poland : a tool for provenance specification
Autorzy:
Salata, D.
Uchman, A.
Powiązania:
https://bibliotekanauki.pl/articles/2060508.pdf
Data publikacji:
2012
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
heavy minerals
provenance
Lower Oligocene
Menilite Formation
Skole Nappe
Opis:
Heavy minerals from sandstones belonging mostly to the Boryslav Sandstone and Kliva Sandstone members of the lower part of the Menilite Formation (Oligocene) in the northern part of the Skole Nappe, Polish Carpathians are characterized. In the study area, the sediments were deposited in the Rzeszów and Łańcut channel zones running from the northern margin of the basin. The most frequent heavy minerals in the sandstones examined include zircon, tourmaline, rutile, staurolite, kyanite and garnet. Single grains of andalusite, sillimanite, apatite, epidote, brookite and chrome spinel occur in some samples. The very small content of apatite is related to long, continental weathering in the source area, which is referred to the Paleozoic sedimentary cover of the Małopolska Block and the easternmost part of the Upper Silesian Block. Different preservation states, morphology, degree of roundness and colour varieties suggest that the heavy minerals studied derive from various petrographic types including metamorphic, igneous and sedimentary rocks. However, the Carboniferous and Permian conglomerates and sandstones seem to be the most probable source rocks.
Źródło:
Geological Quarterly; 2012, 56, 4; 803--820
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Radiometric dating of the Tertiary volcanics in Lower Silesia, Poland. VI. K-Ar palaeomagnetic data from basaltic rocks of the West Sudety Mountains and their northern foreland
Autorzy:
Birkenmajer, K.
Pécskay, Z.
Grabowski, J.
Lorenc, M. W.
Zagożdżon, P. P.
Powiązania:
https://bibliotekanauki.pl/articles/191464.pdf
Data publikacji:
2011
Wydawca:
Polskie Towarzystwo Geologiczne
Tematy:
K-Ar dating
Oligocene
Miocene
intraplate basaltic volcanics
Lower Silesia
Polska
Opis:
This article presents the sixth and final contribution in a series of papers focused mainly on the K-Ar dating of the Oligocene and Neogene (Miocene and Pliocene) intraplate basaltic volcanics of the Lower Silesia, SW Poland. The present paper includes 22 new K-Ar dates from the West Sudety Mountains and their northern foreland. The K-Ar dates range from 30.7 to 22.2 Ma. The data are supplied with geological description of the sampled outcrops, petrographic, geochemical and palaeomagnetic data of the analysed samples. Palaeomagnetic investigation confirmed the existence of two important volcanic episodes distinguished already in 1997: the reversed polarity Odra Event (mean age 28.2š1.2 Ma), and the normal polarity Gracze Event (mean age 26.28š1.8 Ma).
Źródło:
Annales Societatis Geologorum Poloniae; 2011, 81, No 2; 115-131
0208-9068
Pojawia się w:
Annales Societatis Geologorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
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:
Radiometric dating of the Tertiary volcanics in Lower Silesia, Poland
Autorzy:
Birkenmajer, K.
Pécskay, Z.
Grabowski, J.
Lorenc, M. W.
Zagożdżon, P. P.
Powiązania:
https://bibliotekanauki.pl/articles/191635.pdf
Data publikacji:
2004
Wydawca:
Polskie Towarzystwo Geologiczne
Tematy:
K-Ar dating
basaltic rocks
palaeomagnetism
Late Oligocene
Early Miocene
Lower Silesia
Polska
Opis:
The Tertiary volcanic rocks of the Fore-Sudetic Block (FSB), Lower Silesia (Poland), exposed between Strzelin in the east and Legnica in the west, typically represent within-plate basalts. Petrologically, they consist mainly of alkali basalts, basanites, tephrites and ankaratrites. 16 new K-Ar dates are recorded, spanning the Oligocene (31 Ma) through Early Miocene (Burdigalian c. 18 Ma) time. The majority of these K-Ar dates plot around two significantly different ages: 27š1.5 Ma, and 20š1.5 Ma. They indicate the presence in the FSB of two distinct separate phases of Tertiary vulcanicity: (i) the first phase, mainly Late Oligocene (Chattian), with a peak at c. 27; (ii) the second phase, Early Miocene (Aquitanian-Burdigalian), with a peak at about 20 Ma. These phases seem to be separated by a gap in vulcanicity about 3 Ma long at the Oligocene/Miocene boundary. Correlation of K-Ar-dated volcanic activity in the FSB with specific radiometrically-dated polarity intervals, poses some problems, and cannot be regarded definite at this stage of investigations. Considering the whole set of K-Ar and palaeomagnetic data from 40 sites, between the Opole area in the east and the Legnica area in the west, we suggest that volcanism of the first phase (Oligocene), although significantly spread out in time across multiple reversals, took place mostly during two well-defined, previously recognized events: (i) an older, reversed Odra event (within the C9r chron: 28.1š1.2 Ma); and (ii) a younger, normal Gracze event (within the C8n chron: 26.5š1.1 Ma). The second phase (Early Miocene) volcanism includes mainly a continuous set of reversely magnetized sites (mostly a single reversed C6r chron: 20.5š0.87 Ma).
Źródło:
Annales Societatis Geologorum Poloniae; 2004, 74, No 1; 1-19
0208-9068
Pojawia się w:
Annales Societatis Geologorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Radiometric dating of the Tertiary volcanics in Lower Silesia, Poland. V. K-Ar and palaeomagnetic data from Late Oligocene to Early Miocene basaltic volcanics of the North-Sudetic Depression
Datowanie radiometryczne trzeciorzędowych wulkanitów Dolnego Śląska. V. daty K-AR i wyniki badań paleomagnetycznych póznooligoceńskich i wczesnomioceńskich skał bazaltowych niecki północnosudeckie
Autorzy:
Birkenmajer, K.
Pécskay, Z.
Grabowski, J.
Lorenc, M. W.
Zagożdżon, P. P.
Powiązania:
https://bibliotekanauki.pl/articles/191682.pdf
Data publikacji:
2007
Wydawca:
Polskie Towarzystwo Geologiczne
Tematy:
K-Ar dating
basaltoid volcanics
palaeomagnetism
Late Oligocene
Early Miocene
Lower Silesia
Polska
Opis:
This is the fifth contribution to geochronological, petrologic-geochemical and palaeomagnetic studies of the Tertiary basaltoids of Lower Silesia, Poland. It covers the area of the North-Sudetic Depression close to its contact with the Fore-Sudetic Block (6 new sites). The oldest K-Ar date was obtained from basanite plug at Sichów (BP-34: 27.80ą1.27 Ma) located exactly on the Sudetic Marginal Fault. It determines the age of the fault as Late Oligocene. Five other sites (BP-35-39) yielded radiometric ages between 20.07ą0.90 Ma and 18.72ą0.81 Ma (Early Miocene). The volcanics investigated are typical within-plate basaltoids represented by ankaratrite and basanite. The Late Oligocene Sichów intrusion (BP-34) is normally magnetized, the Early Miocene basaltic rocks (ankaratrite BP-39 and basanites: BP-35-38) reveal reversed magnetization.
Piąta część datowań K-Ar i badań paleomagnetycznych trzeciorzędowych wulkanitów Dolnego Śląska obejmuje odsłonięcia tych skał w obszarze niecki północnosudeckiej, w sąsiedztwie sudeckiego uskoku brzeżnego. Otrzymano sześć dat w granicach 27,80š1,27 Ma (późny oligocen: Sichów, BP-34) – 18,72š0,81 Ma (niższy miocen = burdygał: Wilków, BP-37). Późnooligoceńska data dla ankaratrytowego czopu Sichowa (BP-34), który znajduje się na sudeckim uskoku brzeżnym, określa taki wiek tego uskoku. Zbadane skały bazaltowe – bazanity i ankaratryty (melabazanity) są typowymi przedstawicielami wulkanizmu sródpłytowego. Skład chemiczny ogniska magmowego podlegał ewolucji, co przejawiło się w badanych skałach wzrostem zawartości potasu i kobaltu w okresie czasu między wyższym oligocenem a niższym miocenem. Czopy ankaratrytu i bazanitu zostały zbadane pod względem paleomagnetycznym: najstarszy z nich, 27,80 Ma (BP-34: ankaratryt) wykazuje namagnesowanie normalne, pozostałe pięć, 20,07–18,72 Ma (BP-39: ankaratryt; BP-35–38 – bazanity) wykazuje namagnesowanie odwrócone.
Źródło:
Annales Societatis Geologorum Poloniae; 2007, 77, No 1; 1-16
0208-9068
Pojawia się w:
Annales Societatis Geologorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Reassessment of the generic attribution of Numidotherium savagei and the homologies of lower incisors in proboscideans
Autorzy:
Delmer, C.
Powiązania:
https://bibliotekanauki.pl/articles/21470.pdf
Data publikacji:
2009
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
generic attribute
Numidotherium savagei
lower incisor
proboscidean
Proboscidea
Barytherium
Elephantiformes
phylogenesis
Paleogene
Libya
Eocene
Oligocene
Opis:
Near the end of the twentieth century, a medium−sized early proboscidean found in Dor El Talha (late Eocene to early Oligocene), Libya, originally identified as a small species of Barytherium, was described as a new species of Numidotherium and designated Numidotherium savagei. Poorly known, this taxon has been excluded from most of the recent debate about the origin and diversification of the order Proboscidea. New specimens described herein show strong structural similarities of the upper teeth with those of bunolophodont early proboscideans (e.g., Moeritherium and Phiomia) and document the shared presence of derived traits in the postcranial skeleton. The newly referred material also demonstrates some unique characteristics of this taxon, notably in its mandibular morphology and the microstructure of its dental enamel. Included for the first time in a cladistic analysis (207 anatomical characters applied to all early tethytheres), N. savagei is distinct from both Numidotherium and Barytherium, and lies in an “intermediate” position between the strictly lophodont Eocene proboscideans and the bunolophodont moeritheres and elephantiforms. Accordingly, the species is herein referred to a new genus, Arcanotherium. New data on its mandibular symphysis and, especially, on its lower incisors loci and morphology, bring new support to a hypothesis of homology between the lower incisors of early proboscideans and the ever−growing lower tusks of the elephantiforms, which are identified here as di1 and i1.
Źródło:
Acta Palaeontologica Polonica; 2009, 54, 4
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-6 z 6

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