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Wyszukujesz frazę "late Miocene" wg kryterium: Temat


Wyświetlanie 1-5 z 5
Tytuł:
Extensional tectonics during Maghrebides Chain building since late Miocene: examples from Northern Sicily
Autorzy:
Giunta, G.
Nigro, F.
Renda, P.
Powiązania:
https://bibliotekanauki.pl/articles/191268.pdf
Data publikacji:
2000
Wydawca:
Polskie Towarzystwo Geologiczne
Tematy:
extensional tectonics
Late Miocene
Opis:
The Northern Sicilian-Maghrebian Chain courses W-E from the Trapani Mts to the Peloritani Mts and is composed by a set of tectonic units deriving from the Miocene-Pleistocene deformation of the Northern African Continental Margin. Inside it three main geotectonic elements ("external", Sicilide and "Austroalpine") are present and outcrop juxtaposed with a W-E trend. The external element composes the more western Trapani, Palermo and Western Madonie Mts, the Sicilide composes the Eastern Madonie and Nebrodi Mts, while the "Austroalpine" composes the more eastern Peloritani Mts. The orogen shows a culmination in the Trapani Mts and a depression in the Peloritani Mts. The main plicative stages are relatable to late Oligocene-early Miocene from the more internal sectors, while the deformation of the more external sectors starts from early-middle Miocene. The Sicilian chain body is re-involved in tectonism since late Tortonian, which persists until the recent time. During this interval, the deformation of the Sicilian Chain continued by activation of fault systems with different displacements. In the present paper, an important extensional tectonic stage is recognised, starting from the Tortonian; it is supported by structural data and shows through several geological sections across the northern sectors of the Sicilian orogen. This deformation is of exceeded wedge critical taper values, controls the early stages of the Tyrrhenian Basin opening, and is represented by low-angle fault system, producing tectonic omissions in the stratigraphic sequence. The detachment fault system is subsequently displaced by a complicated grid of Plio-Pleistocene net- and strike-slip fault system that controls the genesis of tectonic depressions in the northern off-shore areas of the Sicilian Chain. This neotectonic system may be reconnect to a W-E trending simple shear system, which controls the more recent Tyrrhenian Basin development.
Źródło:
Annales Societatis Geologorum Poloniae; 2000, 70, 1; 81-98
0208-9068
Pojawia się w:
Annales Societatis Geologorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Neogene karst sinkhole and its deposits from Górażdże Quarry, Upper Silesia : archive for palaeoenvironmental reconstructions
Autorzy:
Szulc, J.
Worobiec, E.
Powiązania:
https://bibliotekanauki.pl/articles/191351.pdf
Data publikacji:
2012
Wydawca:
Polskie Towarzystwo Geologiczne
Tematy:
palaeokarst
sinkhole deposits
palynology
Late Miocene
Upper Silesia
Opis:
A sinkhole, developed in Middle Triassic limestones and filled with clastic and organic deposits, including lignite, was studied, in terms of its origin and age. The sinkhole represents a solution sinkhole, which originated through the subsidence of surficial deposits into an underlying cave system. The study permitted the recognition of three main stages of sinkhole evolution. During the initial stage, subterranean and surface karstification proceeded concurrently. As a result, a terra rossa cover developed at the surface and a cavern system was formed in the underlying bedrocks. During the second phase, both systems became connected and the soil cover subsided. This, in turn, involved the formation of a depression at the land surface and ponding of the drainage water. The pond was filled with plant debris, later giving rise to lignite formation. During the third and final stage, the sinkhole was filled with quartz sands with kaolinite, derived from eroded, Upper Cretaceous sandstones and marls. Results of pollen analysis from the sinkhole indicate the presence of mesophytic forests and show a significant role of riparian forests and herbaceous vegetation. The occurrence of abundant, freshwater algae and the pollen of aquatic plants evidences sedimentation of the infill in a water body (pond). The apparent dominance of arctotertiary and cosmopolitan, palaeofloristical elements, as well as the occurrence of only sparse, palaeotropical elements (mainly subtropical), indicate a warm-temperate climate (cooler than during the Early and Middle Miocene period). A comparison of the sporomorph association from the sinkhole with those from other Neogene sites provides evidence of its Late Miocene age (Late Pannonian–Early Pontian).
Źródło:
Annales Societatis Geologorum Poloniae; 2012, 82, 4; 371--385
0208-9068
Pojawia się w:
Annales Societatis Geologorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stratigraphy and geological structure of the Magura Nappe in the south-western part of the Gorce Mountains, Outer Carpathians, Poland
Autorzy:
Szczęch, Mateusz
Waśkowska, Anna
Powiązania:
https://bibliotekanauki.pl/articles/24201044.pdf
Data publikacji:
2023
Wydawca:
Polskie Towarzystwo Geologiczne
Tematy:
Late Cretaceous–Early Miocene
stratigraphy
foraminiferal assemblages
tectonics
highresolution DEM
Opis:
The south-western part of the Gorce Mts (Outer Carpathians) is composed of flysch deposits of the Krynica and Bystrica subunits of the Magura Nappe. The Krynica Subunit includes the Late Cretaceous–Paleocene Ropianka Fm, the Early Eocene Beloveža Fm, the Early Eocene–Oligocene Magura Fm and the Oligocene–Early Miocene Malcov Fm, while the Bystrica Subunit includes the Middle Eocene–?Oligocene Magura Fm, represented mainly by the thick-bedded Magura Sandstone. Thin- and medium-bedded sandstone-shale turbidites predominate in the other formations. The lithostratigraphic units are dated on the basis of foraminifers. The studied deposits accumulated in the southern part of the Magura Basin. Their detrital material was derived from a ridge, bounding the basin in the south. In the study area, the Krynica Subunit overthrusts the Bystrica Subunit. The studied deposits are folded, thrust and cut by numerous faults. The Turbacz Thrust Sheet and the newly identified Kudłoń Thrust Sheet were distinguished in the Krynica Subunit. Faults of different lengths and throws are transverse or oblique. Some of them form complex dislocation zones with lengths of up to several km. In general, the high-resolution digital elevation model DEM contributed significantly to progress in the geological and geomorphological research.
Źródło:
Annales Societatis Geologorum Poloniae; 2023, 93, 2; 103--136
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
    Wyświetlanie 1-5 z 5

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