Wyniki wyszukiwania - BazTech

1

Zjawiska krasowe w skałach metamorficznych w Masywie Śnieżnika (Sudety Wschodnie ): aktualny stan badań oraz znaczenie dla poznania ewolucji Sudetów w późnym kenozoiku

Sobczyk A., Kasprzak M., Marciszak A., Stefaniak K.

Przegląd Geologiczny

|

2016

|

Vol. 64, nr 9

710--718

EN

The paper reviews the recent state ofstudies for karst phenomena on northern slopes of the Śnieżnik Massif, Krowiarki range and Zlote Mts in East Sudetes with particular reference to Biała Lądecka basin. Conflned spatial character of the d/ainagf basinand cave sites within allow a better understanding of landscape response to climate and tectonic proxies controlling landscape evolution at least since the end ofMiocene (Messinian). New karst passages discoveries from Niedźwiedzia Cave resulted in the recognition of several sites of allochthonous sediments deposited at different cave morphological levels up to 50 metres above Kleśnica river floor. Furthermore, a new model ofpolygenetic origin for some karst chambers in Niedźwiedzia Cave originating from karstification processes and mass-movements superimposed has been suggested. Presumably, it may be linked with neotectonic processes and/or climatic changes affecting East Sudetes during the Late Cenozoic.

2

Tectonic control of cave developmen t: a case study of the Bystra Valley in the Tatra Mts., Poland

Szczygieł J., Gaidzik K., Kicińska D.

Annales Societatis Geologorum Poloniae

|

2015

|

Vol. 85, No. 2

387--404

EN

Tectonic research and morphological observations were carried out in six caves (Kalacka, Goryczkowa, Kasprowa Niżna, Kasprowa Średnia, Kasprowa Wyżnia and Magurska) in the Bystra Valley, in the Tatra Mountains. There are three cave levels, with the youngest active and the other two inactive, reflecting development partly under epiphreatic and partly under phreatic conditions. These studies demonstrate strong control of the cave pattern by tectonic features, including faults and related fractures that originated or were rejuvenated during uplift, lasting from the Late Miocene. In a few local cases, the cave passages are guided by the combined influence of bedding, joints and fractures in the hinge zone of a chevron anticline. That these cave passages are guided by tectonic structures, irrespective of lithological differences, indicates that these proto-conduits were formed by “tectonic inception”. Differences in the cave pattern between the phreatic and epiphreatic zones at a given cave level may be a result of massif relaxation. Below the bottom of the valley, the effect of stress on the rock mass is related to the regional stress field and only individual faults extend below the bottom of the valley. Thus in the phreatic zone, the flow is focused and a single conduit becomes enlarged. The local extension is more intense in the epiphreatic zone above the valley floor and more fractures have been sufficiently extended to allow water to flow. The water migrates along a network of fissures and a maze could be forming. Neotectonic displacements (of up to 15 cm), which are more recent than the passages, were also identified in the caves. Neotectonic activity is no longer believed to have as great an impact on cave morphology as previously was thought. Those faults with displacements of several metres, described as younger than the cave by other authors, should be reclassified as older faults, the surfaces of which have been exposed by speleogenesis. The possible presence of neotectonic faults with greater displacements is not excluded, but they would have had a much greater morphological impact than the observed features suggest.

3

Artesian origin of a cave developed in an isolated horst: a case of Smocza Jama (Kraków Upland, Poland)

Gradziński M., Motyka J., Górny A.

Annales Societatis Geologorum Poloniae

|

2009

|

Vol. 79, No 2

159-168

EN

The cave of Smocza Jama located in the centre of Kraków is developed in the Wawel Horst built of Upper Jurassic limestone and surrounded by grabens with Miocene clays. The cave is composed of two series: the old one has been known for ages and the new one was discovered when an artificial shaft was mined in 1974. The new series comprises small chambers separated by intervening thin walls while the old series consists of three connected together spatial chambers. The cave abounds in extensively developed solution cavities – cupolas and ceiling pockets. The internal fine-grained deposits, predominantly representing clay fraction are built of illite, mixed layer illite-smectite, kaolinite and iron oxides. They are probably the residuum after dissolution of Jurassic limestone. The cave originated in phreatic condition due to water input from below. The new series represents juvenile stage of cave evolution. The water rose through fissure-rifts located in chamber bottoms, circulated convectionally within particular chambers, finally led to bleaching of intervening walls, and hence to connection of the neighbouring chambers. The evolution of the old series is far more advanced. The rounded solution cavities imply that the cave was formed by water of elevated temperature. The lack of coarse-grained fluvial deposits, Pleistocene mammal remains and Palaeolithic artefacts prove that the cave was isolated since its inception till Holocene time. The cave originated due to artesian circulation, when the Wawel Horst was covered by imper- meable Miocene clays. A foreland basin with carbonate basement, filled with fine-grained molasse-type deposits seems to be particularly favourable for the development of artesian caves.

4

Karst processes and time

Bosak Pavel

Geologos

|

2008

|

Vol. 14, No. 1

19--36

EN

Karst evolution depends particularly on the time available for process evolution and on the geographical and geological conditions of the exposure of the rock. The longer the time, the higher the hydraulic gradient and the larger the amount of solvent water entering the karst system, the more evolved is the karst. In general, stratigraphic discontinuities directly influence the intensity and extent of karstification. Unconformities influence the stratigraphy of the karst through the time-span that is available for subaerial processes. The end of karstification can also be viewed from various perspectives. The definite end occurs at the moment when the host rock, together with its karst phenomena, has completely been eroded/denuded. Karst forms of individual evolution stages (cycles) can also be destroyed by erosion, denudation and abrasion without the necessity of the destruction of the whole succession of karst rocks. Temporary and/or final interruption of the karstification process can be caused by the “fossilisation” of the existing karst phenomena due to loss of hydrological activity. The shorter the time available for karstification, the greater is the likelihood that karst phenomena are pre-served in the stratigraphic record. While products of short-lived karstification on shallow carbonate platforms can be preserved by deposition during a immediately succeeding sea-level rise, products of more pronounced karstification can be destroyed by various geomorphological processes. The longer the duration of subaerial exposure, the more complex these geomorphological agents are.

PL

Rozwój procesów krasowych jest funkcją czasu oraz geograficznych i geologicznych warunków odsłonięcia skał. Im dłuższy czas ekspozycji skał na czynniki meteorologiczne, większy gradient hydrauliczny, większa ilość wody w układzie krasowym, tym bardziej zaawansowana jest ewolucja krasu. Intensywność i zasięg krasowienia zależą też od niezgodności stratygraficznych, czyli przerw w sedymentacji. Zakończenie rozwoju procesów krasowych rozpatrywać można w różnych kategoriach. Za definitywny koniec należy uznać czas, gdy skały podlegające krasowieniu ulegną całkowitej denudacji/erozji. O wiele częściej bywa, że zniszczeniu ulegają tylko formy krasowe, natomiast niżej położone skały systemu krasowego pozostają zachowane. Okresowe lub całkowite przerwanie procesów krasowych może być spowodowane przez fosylizację systemu krasowego, która zachodzi w efekcie zaniku aktywności hydrologicznej. Taka fosylizacja może być spowodowana przez metamorfizm, transgresję morską, pogrzebanie osadami kontynentalnymi lub skałami wulkanicznymi, w wyniku np. ruchów tektonicznych, zmiany klimatu, itp. Im krótszy jest czas krasowienia, tym większe jest prawdopodobieństwo zachowania śladów procesów krasowych. I tak, produkty krótkookresowej karstyfikacji na płytkich, okresowo wynurzanych platformach węglanowych mogą ulegać łatwemu zachowaniu poprzez pogrzebanie osadami deponowanymi podczas podniesienia poziomu morza. Natomiast efekty długotrwałego krasowienia bywają często niszczone przez późniejsze degradacyjne procesy geomorfologiczne. Charakter tych ostatnich jest tym bardziej skomplikowany, im dłużej trwa subaeralna ekspozycja skrasowiałych skał.