Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 19

Liczba wyników na stronie
first rewind previous Strona / 1 next fast forward last
Wyniki wyszukiwania
Wyszukiwano:
w słowach kluczowych:  Cenozoic
help Sortuj według:

help Ogranicz wyniki do:
first rewind previous Strona / 1 next fast forward last
EN
Currently, three stratigraphically distinct lignite seams of Early to Middle Miocene age are exploited in Poland, namely the third Ścinawa lignite seam (ŚLS-3), the second Lusatian lignite seam (LLS-2) and the first Mid-Polish lignite seam (MPLS-1). All of these are composed of numerous macroscopically distinguishable layers defined as lignite lithotypes. In the present paper, the lithotypes of Polish lignites are grouped into seven major lithotype associations that originated in various types of mire. Therefore, an approximate reconstruction of mire type can be based on lignite lithotypes. Within the Polish lignite seams examined, the commonest in order of importance are: xylodetritic (XDL), detroxylitic (DXL), detritic (DL) and xylitic (XL) lithotype associations, mostly with a massive (m) or horizontal (h) structure. They are particularly dominant in lignite opencasts belonging to the Konin and Adamów mines. However, in the lowermost seams at the Turów and Bełchatów mines, a substantial part of the seams comprises the bitumen-rich (BL) lithotype association. These seams also lignite lithotypes that in large quantities have a gelified (g) and/or nodular (n) structure. In contrast, lignites from the Sieniawa mine are characterised by an admixture of the best-developed lithotype associations of both fusitic (FL) and weathered (WL) lignites. Moreover, the vast majority of these lignites have a folded (fo) and/or faulted (fa) structure, because they were completely deformed by glaciotectonics.
EN
The Pogórska Wola palaeovalley of combined tectonic and erosional origin dissects the Mesozoic floor of the Carpathian Foredeep Basin to a depth exceeding 1200 m. It formed during Paleogene times presumably due to fluvial and submarine erosion, concentrated along a local pre-Late Badenian graben system. All members of the foredeep’s Badenian-Sarmatian sedimentary fill attain distinctly greater values inside the palaeovalley than on top of elevated plateaux on palaeovalley shoulders. The fill comprises the Early to Late Badenian sub-evaporite Skawina Formation, the laterally equivalent Late Badenian evaporite Krzyżanowice and Wieliczka formations and the supra-evaporite Late Badenian to Early Sarmatian Machów Formation. Over the plateaux and in the highest palaeovalley segment, the evaporites are developed in the sulphate facies Krzyżanowice Formation, whereas in the lower palaeovalley segments chloride-sulphate facies evaporites of the Wieliczka Formation occur. The rock salt-bearing rocks are involved in thrusting and folding at the Carpathian orogenic front, which helps to assess the lateral extent of the Wieliczka Formation in seismic records. The deep palaeotopographic position of the evaporites inside the palaeovalley, combined with their lithological and sedimentary features, point to their formation via subaqueous gravity flow-driven redeposition of originally shallow-water evaporites, preferentially halite-bearing, presumably combined with precipitation from sulphate and chloride brines at the palaeovalley floor. Both the redeposited sediments and the brines must have come from the adjacent plateaux and from a thrust-sheet top basin, approaching from the south on top of the Cretaceous-Paleogene Carpathian flysch thrust wedge.
3
Content available Where was the Magura Ocean?
EN
In the Late Jurassic to Early Cretaceous palaeogeography of the Alpine Tethys the term Ocean is used for different parts of these sedimentary areas: eg. Ligurian – Piedmont and Penninic, Magura, Pieniny, Valais and Ceahlau-Severins oceans. The Magura Ocean occupied the more northern position in the Alpine-Carpathian arc. During the Late Cretaceous–Paleogene tectono-sedimentary evolution the Magura Ocean was transformed into several (Magura, Dukla, Silesian, sub-Silesian and Skole) basins and intrabasinal source area ridges now incorporated into the Outer Western Carpathians.
EN
The paper presents results of valorization of geosites in the Łysogóry Region of the Holy Cross Mountains, which warrant creation of the Łysogóry Geopark. Numerous geosites of different Paleozoic rocks offer a great educational potential, combining many fields of knowledge, such as geology, geomorphology, paleontology, paleoecology, ancient metallurgy industry and historical monuments. Geodiveristy makes this area very attractive for geotourism.
EN
The Pelotas Basin, located on the SE Brazilian shelf, has evolved since the Aptian. Stratigraphical data from the basin can be used for delineation of the unconformity-bounded units (synthems) on the shelf, which is a first step towards a full understanding of its stratigraphic architecture, evolution, and hydrocarbon potential. Hiatuses in the Cenozoic succession of the Pelotas Basin are established with both biostratigraphic (planktonic foraminifers and calcareous nannofossils) and isotopic (87Sr/86Sr) data. The seven recognised hiatuses are dated respectively as (1) Palaeocene (Danian-Thanetian), (2) Palaeocene/Eocene boundary (Thanetian-Ypresian), (3) Eocene (Ypresian-Lutetian), (4) Eocene-Oligocene (Lutetian-Rupelian), (5) early-late Oligocene (Rupelian-Chattian), (6) early Miocene (Aquitanian-Burdigalian), and (7) middle-late Miocene (Serravallian-Tortonian). These intervals between the hiatuses are correlated with those of the Santos and Campos Basins north from the Pelotas Basin. The breaks in sedimentation that these basins have in common occurred (1) at the Palaeocene-Eocene and (2) Eocene-Oligocene transitions, (3) in the early Miocene, and (4) in the middle-late Miocene. These main unconformities outline five synthems on the SE Brazilian shelf, viz. the SEBS-1 (Palaeocene), SEBS-2 (Eocene), SEBS-3 (Oligocene), SEBS-4 (early-middle Miocene) and SEBS-5 (late Miocene-Holocene). The above unconformities are correlated with those established in the Cenozoic sedimentary successions of different regions such as Western Siberia, Arabia, NW and NE Africa, peninsular India, S Australia, the Gulf of Mexico, NW Europe, and South Africa. The only regional unconformity, near the Oligocene/Miocene boundary, coincides with the nearly-global sedimentation break. The latter was resulted from a climatic event, i.e., the ‘Mi-1 glaciation’. Thus, a eustatic origin is supposed for this regional unconformity. The other regional unconformities also correspond to global sea-level falls (probably with an exception for the Palaeocene/Eocene surface), which suggests that global eustatic movements controlled the development of the regional synthem architecture.
PL
Artykuł prezentuje trzy przykłady interpretacji zdarzeń geologicznych oraz warunków paleogeograficznych i paleośrodowiskowych dokonanych na podstawie badań form krasowych w skałach węglanowych dewonu Gór Świętokrzyskich. Pierwszy relacjonowany kierunek badań dotyczy kopalnych form krasowych w dwu stanowiskach Wietrznia oraz Jaworznia i dokumentuje późnopermską ewolucję rzeźby i jej tektoniczne odmłodzenie na początku triasu. Następne interpretacje dotyczą form krasu kenozoicznego. Analiza przestrzennego rozwoju podziemnych systemów krasowych umożliwiła określenie poziomów stabilizacji bazy erozyjnej w neogenie. Najwyższy poziom krasowy (Łagów) był zapewne związany z poziomem neogeńskiego zbiornika morskiego w zapadlisku przedkarpackim. Z kolei badania osadów piaszczystych w wypełnieniach form krasowych, w tym przede wszystkim analiza obtoczenia i kształtu ziarn pozwoliły na wyróżnienie pięciu typów ziarn piasków o różnym pochodzeniu, w tym pochodzących z lokalnych zwietrzelin różnych skał oraz ziarn pirogenicznych. Analiza ta stała się podstawą do określenia zasięgu pokrywy dolnotriasowej, oceny rozwoju krasu w czwartorzędzie, a także do sformułowania sugestii dotyczących paleośrodowiska neogenu.
EN
The paper presents three examples of interpretations of geological events and paleogeographic and paleoenvironmental conditions made on the basis of studies of karst forms in Devonian carbonate rocks of the Świętokrzyskie (Holy Cross) Mountains, central Poland. The first study concerns paleokarst forms in two sites: Wietrznia and Jaworznia which record the Late Permian relief evolution and its tectonic rejuvenation at the beginning of the Triassic period. The next two interpretations concern the Cenozoic karst forms. Analysis of spatial development of subsurface karst systems made possible to determine of erosional base stabilization levels during the Neogene. The highest karst horizon (Łagów) was most probably related to the level of one of the transgressions in the Fore-Carpathian marine basin. In turn, the study of sand sediments filling karst forms, particularly analysis of roundness and shape of sand grains enables to distinguish five types of sand grains of different genesis, among which are grains originated from various local weathered rocks as well as pyrogenic particles. On the basis of this analysis the extent of Lower Triassic cover was determined and karst development during the Quaternary period was assessed, as well as some suggestions on the Neogene paleoenvironment were formulated.
PL
Fragmenty kopalnego drewna wśród osadów drobnoziarnistych są spotykane w wielkopolskich odkrywkach węgla brunatnego. Obecność ksylitów w osadach neogeńskich udokumentowano w odkrywkach Kazimierz N i Drzewce (KWB Konin S.A.), a pochodziły prawdopodobnie ze stropowych części niżej zalegających torfów i/lub z roślinności porastającej brzegi basenu sedymentacyjnego.
EN
Fragments of fossil wood among fine-grained deposits are found in Wielkopolska lignite opencasts. The presence of xylites in Neogene sediments have been documented in the opencasts Kazimierz N and Drzewce (Konin Lignite Mine), and Paleogene sediments in the opencast Koźmin N (Adamów Lignite Mine). Fragments of wood, which later became xylites, probably came from the upper part of the lower lying peat and/or from the vegetation growing in the areas surrounding the sedimentary basin.
EN
The paper deals with the origin of caves in Sokola Hill (Polish Jura). The caves abound in solution cavities in the walls and ceilings, many of them arranged hierarchically, some others arranged in rising sets. Blind chimneys and ceiling half-tubes are also present. These features collectively indicate that the caves originated under Phreatic conditions by an ascending flow of water, probably of elevated temperature. Phreatic calcite spar, crystallized from water of elevated temperature, lines the cave walls. During the formation of the caves the Jurassic limestone aquifer was confined by impermeable cover. Three possible scenariosfor the origin of the caves are suggested. The firstscenario pointsto formation of the caves during the Palaeogene prior to the removal of the confining Cretaceous marls. The second connectsthe origin of the caves with regional palaeoflow driven by tectonic loading by Carpathian nappes to the south, while the third refers to local topographically driven palaeoflow. Both the second and third scenarios assume that the Polish Jura had a cover of Miocene impermeable clastics. All the scenarios account for the origin of the caves in Sokola Hill and explain the common occurrence of ascending caves throughout the Polish Jura. In the subsequentstages of evolution the caves were partly filled with various deposits. Conglomerates composed of Jurassic limestone clasts, quartz sands and sandstones are preserved as erosional remnants, locally covered by or interfingered with calcite flowstones. The clastic deposits were laid down by surface streams that invaded the caves earlier than 1.2 Ma. The caves were not invaded by water from Pleistocene glaciers, which is proved by the assemblage of heavy minerals in the cave clastics.
10
Content available Overview of magmatism in Northwestern Vietnam
EN
Amalgamation of tectonic plates of Southeast Asia occurred in northwestern Vietnam. Six groups of magmatic rocks are related to the tectonic events. The first group corresponds to the major episodes of crustal formation in the South China block, or is linked with the formation of Gondwana. The second group includes granitoids in connection with the collision and formation of the Caledonian-Hercynian folding event. The third group contains Upper Permian ophiolites, as well as the Permian extrusives, formed in intraplate setting, related to back-arcs spreading. The fourth group is related to Triassic Indosinian orogeny, the fifth group comprises Jurassic-Cretaceous intraplate granitoids. Finally, during Cenozoic times, magmatic rocks were represented by alkaline granitoids - the effect of strike-slip faulting related to the collision of India and Eurasia plates.
11
Content available remote Kenozoik na pograniczu Ziemii Lubuskiej, Pomorza i Wielkopolski
PL
Zróżnicowany miąższościowo, od kilku do 200 m, kompleks kenozoiczny pokrywa w obrębie bloku Gorzowa utwory górnokredowe. Obejmuje morskie skały oligoceńskie (formacja mosińska dolna i górna, formacja rupelska) oraz osady z pogranicza lądu i morza (formacja czempińska). Z niewielką przerwą na utworach oligoceńskich leżą lądowe osady mioceńskie (formacja gorzowska, krajeńska, adamowska i poznańska). Czwartorzęd reprezentuje sześć poziomów litostratygraficznych glin lodowcowych i towarzyszących im piasków i żwirów wodnolodowcowych oraz piasków i mułków zastoiskowych. Z okresu interglacjału ferdynandowskiego, wielkiego, zlodowaceń północnopolskich, holocenu i prawdopodobnie interglacjału lubelskiego i eemskiego notowane są osady rzeczne, a z interglacjałów wielkiego i eemskiego znane są osady jeziorne. Obszar przecinają wielkie, wydłużone, wycięte w podłożu czwartorzędu glacidepresje. Pospolite są też formy mniejsze, zamknięte, o średnicy kilku kilometrów i głębokości 100 m. Tworzą struktury glacitektoniczne I i II rzędu. Struktury te wypełnione są osadami glacjalnymi zlodowacenia nidy. Nidziańskie osady glacjalne oraz skały ich podłoża zorganizowane są w struktury fałdowo-łuskowe, o amplitudach od kilku- do kilkudziesięciu metrów i promieniach od kilkudziesięciu do 200 m, tworzące struktury glacitektoniczne III rzędu. Łącznie nadają one obszarowi charakterystyczny styl budowy geologicznej cechujący się zaburzonym pograniczem skał czwartorzędowych i ich podłoża, obecnością głębokich depresji glacitektonicznych i ich fałdowo-łuskowych wypełnień oraz towarzyszących depresjom mniej wyrazistych glacielewacji. Za proces deformacji i wypełniania odpowiada przede wszystkim najstarszy na analizowanym obszarze, nidziański lądolód. Utworzone przezeń struktury zostały później zmodyfikowane przez młodsze lądolody. Zaburzone osady paleogeńskie, neogeńskie i czwartorzędowe budują glacitektoniczne plejstoceńskie piętro strukturalne. Podścielają je horyzontalnie zalegające utwory paleogeńsko-neogeńskiego piętra strukturalnego, a nadbudowują lokalnie zaburzone w morenach spiętrzonych osady czwartorzędowe plejstoceńsko-holoceńskiego piętra strukturalnego. Łącznie piętra te tworzą kenozoiczny kompleks strukturalny.
EN
The Upper Cretaceous deposits in the area of Gorzów Block underlie the Cenozoic Sequence with highly diversified thickness varying from a few to 200 m. The complex is composed of marine Oligocene sediments (Lower and Upper Mosina formation, Rupel formation) and brackish facies (Czempiń formation). The Oligocene deposits are overlain with a small gap by the continental Miocene sequence (Gorzów, Krajenka, Adamów and Poznań formations). The Quaternary is represented by six lithostratigraphic glacial tills accompanied by glaciofluvial sand and gravel as well as by glaciolacustrine sand and silt. The oldest alluvial deposits date back to the Ferdynandów Interglacial, whereas the first lacustrine ones are ascribed to the Great Interglacial. The area is cut by immense elongated negative landforms (several tens of km long, up to 20 km wide and 100 m deep). Smaller, closed forms of a few kilometres in diameter and 100 m in depth are commonly observed. Altogether, they form the glaciotectonic structures of type I and II. They are filled with glacial sediments of the Nidanian Glaciation. The Nidanian glacial sediments and the deposits underlying the structures of type I and II are organized in a fold-slice form with the amplitudes varying from a few to several tens of metres and the radii from several tens to 200 m. These are the glaciotectonic structures of type III. In total, they contribute to a specific geological composition of the area, which is characterized by deep glaciotectonic depressions and their fold-slice fills as well as by deformed contacts between the Quaternary rocks and their basement. The processes of filling and deformation were due to the activity of the Nidanian ice sheet, the oldest one in the study area. The disturbed Paleogene, Neogene and Quaternary deposits form the Pleistocene glaciotectonic structural level. It is underlain by horizontal deposits of the Paleogene-Miocene structural level and overlain by Quaternary deposits of the Pleistocene-Holocene structural level composed of horizontal sediments locally deformed to form push-moraines. Together, they form the Cenozoic structural sequence.
12
Content available remote Cenozoic dynamic evolution of the Polish Platform
EN
The Cenozoic tectonic evolution of the Polish Platform reflects repeated changes in loading conditions at the Alpine–Carpathian and Arctic–North Atlantic margins of the European continent. After the Late Creta ceous–Paleocene main phase of the Mid-Polish Basinin - version, a second phase of limited uplift of the Mid-Polish Swell occurred during the Middle–Late Eocene. End Eocene and Early Oligocene subsidence of narrow grabens on the Fore-Sudetic Monocline was coeval with normal faulting in the East Alpine foredeep basin and the development of the Central European rift system. At the same time the Outer Carpathian flysch basins were rearranged, presumably in response to the build-up of compressional stresses at crustal levels, whilst subsidence and erosion patterns changed in the Carpathian Foreland from being dominated by the NW–SE trending Mid-Polish Swell to being controlled by the development of the W–E trending Meta-Carpathian Swell. At the end of the Oligocene the Fore-Sudetic graben system propagated into the area of the Trans-European Suture Zone and the Sudetes and remained active during the Early and Middle Miocene. This was paralleled by intensified subduction activity and thrusting of the Carpathians and the development of their flexural foredeep basin. A short early Sarmatian episode of basement in volving transpression along the SW margin of the Mid-Polish Swell correlates with the termination of north-directed nappe transport in the Outer Carpathians. This was followed by eastward migration of the subsidence centre of the Carpathian Foredeep Basin and the gradual termination of tectonic activity in the grabens of the Polish Lowlands. After a period of post-orogenic relaxation the present-day compressional stress regime built up during the Pliocene and Quaternary. Intensified ridge push forces exerted on the Arctic–North Atlantic passive margins contribute to this compressional stress field that is dominated by collision-related stresses reflecting continued indentation of the Adriatic Block. This sequence of events is interpreted in terms of changing tectonic loads in the Carpathians, Alps and at the NW passive margin of Europe. The complex and diachronous interaction of mechanically coupled and uncoupled plates along collision zones probably underlies the temporally varying response of the Carpathian Foreland that in addition was complicated by the heterogeneous structure of its lithosphere. Progressively increasing ridge push on the passive margin played a secondary role in the stress differentiation of the study area.
13
Content available Tectonics and magmatism in Northwest Vietnam
PL
Na tle tektoniki płyt Azji południowo-wschodniej przedstawiono położenie północno-wschodniego Wietnamu i pięć grup skał magmowych genetycznie związanych z tą tektoniką. Najstarsza związana jest z powstawaniem Gondwany, druga obejmuje granitoidy związane z kolizjami i powstawaniem struktur kaledońsko-hercyńskich, trzecia zawiera ofiolity Paleotetydy, czwarta to anorogeniczne, jurajsko-kredowe granitoidy wewnątrzpłytowe, piąta, kenozoiczna, reprezentowana jest przez granitoidy - efekt uskoków po kolizji Indii z Azją.
EN
The northern part of theWestern Carpathians suffered polyphase deformation at the boundary between their Central and Outer parts. Palaeostress analysis in the Orava region revealed the existence of five different stress fields in the period from the Late Eocene to the Quaternary. The evolution of the stress fields was determined by detailed structural analysis of the fault slip and fold orientation data. The orientation of the stress fields shows an apparent clockwise rotation from the Late Eocene to the Quaternary. During the Late Eocene to Oligocene, E-W compression and perpendicular tension affected this area. This was the time when the Central Carpathian Palaeogene Basin formed. After this compression, the palaeostress field rotated approximatly 40-50[degrees], and NW-SE compression and NE-SW tension took place in the Early Miocene. The Middle Miocene to Pliocene was characterised by progressive rotation of the palaeostress field from NW-SE to the NE-SW direction of the maximum principal compressional stress axis ([sigma][1]). This clockwise rotation of the Oligocene to Quaternary palaeostress fields here is explained by the effect of the counterclockwise rotation of the ALCAPA microplate, and by the regional stress field changes in this region. The Quaternary stress field was reconstructed on the basis of structural measurements in the Pliocene sedimentary formations of the Orava-Nowy Targ Basin. The results of the palaeostress analysis show that the Quaternary stress field is characterised by E-W-oriented S[h] (minimum horizontal compression) and N-S-oriented S[H] (maximum horizontal compression).
15
Content available remote Tectonic evolution of the late Cretaceous Nysa Kłodzka Graben, Sudetes, SW Poland
EN
The Nysa Kłodzka Graben, located in the Sudetes of SW Poland, developed as a result of Coniacian (middle Upper Cretaceous) N-trending faulting of the Variscan crystalline basement rocks that comprise the crest of the Orlica-Śnieżnik Dome. The graben was transgressed by a late Cretaceous sea that encroached during the Cenomanian from the northwest. Up to 700 m of Coniacian shales, sandstones and conglomerates were deposited in the graben, with shales (the ~500 m thick Idzików 'clays') dominating the graben's central section. On the western side of the graben, shales grade upwards to greywackes in a style that resembles a turbidite sequence; on the eastern side, shales are overlain by sandstones and conglomerates (the Idzików conglomerates) that represent extensive late Cretaceous fan deltas. These within-graben fan deltas date the onset of fault-block movements that uplifted the Sudetes region during the late Cretaceous-Cenozoic. By the end of the Cretaceous, both the sedimentary infill and the underlying Cenomanian and Turonian strata were steepened at the graben margins and were gently folded, the fold axes paralleling the graben's marginal faults. Subsequent Cretaceous-Paleocene ('Laramian') deformations resulted in NW-trending reverse faulting, which restructured the earlier N-S template of the graben, and in transcurrent faults, which cut the N-trending folds, modified the north and south ends of the graben and strongly affected the graben's western walls. The total thickness of the Upper Cretaceous strata of the Nysa Kłodzka Graben is 3 times that of the Intra-Sudetic Synclinorium, implying that the two units developed independently.
EN
The Poznań-Oleśnica Fault Zone (P-OFZ) of central-west Poland is an over 150 km long, up to 10 km wide, and up to 200 m deep graben that developed during Early Oligocene to Pliocene times on the flank of the NE-dipping Fore-Sudetic Homocline. Fault systems of this extensional structure appear to reach pre-Zechstein basement in the area ofthe Fore-Sudetic Homocline that forms an integral part of the Bohemian Massif. The P-OFZ was affected by several stages of subsidence, separated by periods of inversion and/or tectonic quiescence between the Triassic and Cenozoic. Structurally, this dislocation zone can be linked with the Variscan faults, reactivated at that time. During the second half of the last century, the northern parts of the P-OFZ graben were intensively explored by cored boreholes because of their lignite content. Conventional back-stripping methods could not be applied to the tectonic analysis of the POFZ due to the limited thickness of the graben fill, its poor dating and the presence of relatively thick lignite seams. Therefore, phases of accelerated subsidence were determined by comparing the thickness of individual lithostratigraphic units within the graben and on its flanks. The total subsidence of the different graben segments was quantified by determining the aggradation coefficient (AC) and by taking the consolidation coefficient (CC) of lignite seams into consideration. Subsidence analyses indicate that the initial Early Oligocene extensional phase of the P-OFZ was followed by an Early.Middle Miocene extensional subsidence phase and a probably latest Miocene.Pliocene final extensional phase.
17
Content available remote Nowe dane o wieku i petrologii kenozoicznych bazaltoidów dolnośląskich
EN
Fifteen samples of basaltoid rocks have been analysed from the Lower Silesia, SW Poland, some of them from localities close to the Sudetic Marginal Fault. K-Ar datings have been made on whole rock samples, using the methodology applied by the Institute of Nuclear Research, Hungarian Academy of Sciences, Debrecen, Hungary. Most of the samples give ages ranging between 21- 38 Ma, whereas that derived from a borehole in the Mokrzeszów Graben has been dated to 44 Ma. Another borehole sample (Jeżów Sudecki B-5), close to the Intrasudetic Fault, is of 59 Ma age. On the other hand, the supposedly "Quaternary" basaltoids from Dębowiec area fall into the interval of 29–30 Ma. The southeasternmost occurrences of the Lower Silesian basaltoids at Nowa Cerekiew display two generations of effusive activity: the older lava flows (26 Ma) are cut by plugs dated to 22 Ma. The Oligocene–Lower Miocene (26-33 Ma, 20'24 Ma) rocks represent alkali basalts and basanites. The alkali basalts consist of phenocrysts of olivine (chrysolite), altered to a different degree, and clinopyroxene (salite). In the matrix, clinopyroxene (Ti-salite), olivine (hyalosiderite), plagioclases (labradorite–andesine), and opaque minerals (titanomagnetite, ilmenite) occur. The basanites contain phenocrysts of altered olivine (chrysolite) and clinopyroxene (salite). Their matrix consists of clinopyroxene (Ti-salites), olivine (hyalosiderite), nepheline, plagioclases (bytownite–andesine), and opaque minerals. On the TAS diagram, samples of the studied basaltoids plot mainly in the fields of basalts and basanites/tephrites. The bimodality of some samples falling into two fields of basalts and basanites/nephelinites on the TiO2/Zr-Nb/y diagram results from their distinct geochemical signature.
EN
The basaltic rocks of Sośnica Hill near Targowica (Fore-Sudetic Block) belong to the Cenozoic Central European Volcanic Province. The volcanic succession at Sośnica is over 40 m thick and comprises pyroclastic fall deposits (mainly tuff breccias), subvolcanic intrusions (plug, dykes and other intrusive sheets) and aa-type lavas. Field relationships and structural data enable a detailed reconstruction of the vent location, morphology and eruptive history of the original volcano. Initial Hawaiian to Strombolian-type explosive eruptions produced a pyroclastic cone. Subsequently subvolcanic intrusions and lavas were emplaced. The lavas were fed from the central vent of the volcano, breached the cone and flowed southwards. Later eruptions resumed at a new vent on the western slopes of themain cone. The final volcanic edifice-a breached Strombolian scoria cone with a lava flow and a parasitic cone-was 500-1000 m in diameter at the base and 90-180mhigh. The preserved SWsector of this volcano, where the pyroclastic deposits were protected from erosion by the surrounding plugs and lavas, corresponds to ca. 1/2 of the height and 1/8 of the volume of the original volcano. Compared with many other remnants of Cenozoic volcanic centres in Lower Silesia, this volcano is exceptionally well preserved and exposed.
EN
Four major fault-boundedc tectonic blocks are recognized in the Gerlache Strait area, West Antarctica: (A) the Danco Coast Block; (B) the Brabant Island Block; (C) the Neumayer Channel Block; and (D) the Anvers-Melchior Islands Block. The blocks differ from each other in the succession and age of rocks: (A) metasediments of the Trinity Penisula Group (TPZG:? Upper Permian-Triassic). Uncorfarmably covered by a thich basaltic-andesitic effusive complex (Antarctid Penisula Volamic Group, APVG: Lower Cretaceous), intruded by granitic trough gabbroic plutons (Andean Intrusive Suite, AIS-I: Berriasian-Cenomanian) and by hypabyssal dykes and sillsof several generations (AIS-2: ?Upper Creataceous and /or Tertiary);(B) basaltic-andesitic effusive complex (APVG: ?Lower Cretaceous), intruded by a granodiorite aill (AIS-1) and by hypabyssal dykes of several generations (AIS-2), unconformably covered by /Late Tertiary volcanics; (C) Early Tertiary granite-granodiorite pluton, intruded by hypabyssal dykes of several generations, eroded and weathered, covered by strainform ? Late Tertiary volcanics; (D) effusive complex (?APVG), followed by granitoid and hybrid intrusions apparently representing there successive phases, of Late Paleocene, Eocene/Oligocene boundary, and Early Miocenes ages, intruded by several systems of hypabyssal dykes.
first rewind previous Strona / 1 next fast forward last
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.