Topography of the Magura floor thrust and morphotectonics of the Outer West Carpathians in Poland

Neotectonic (Pliocene-Quaternary) elevations and depressions detected on maps of subenvelope surfaces of the topography of the Outer West Carpathians of Poland are, to a certain extent, portrayed on the map showing topography of the Magura floor thrust, particularly in the western segment of the study area. The floor thrust of the Magura Nappe is highly uneven, its position changing from 725 m a.s.l. to more than 7,000 m b.s.l. The most prominent depression is located in the medial (S of Dunajec and Poprad confluence) segment of the Polish Outer Carpathians (2-7 km b.s.l.), and its axis trends NW-SE from the eastern margin of the Mszana Dolna tectonic window to the Poprad River valley. Another, much more shallower, Jordanów depression (2 km b.s.l.) is to be found NW of the Mszana Dolna tectonic window, shortly north of the Skawa River valley. Elevated structures, in turn, include the Mszana Dolna tectonic window, Sól-Skomielna (on the west), and Limanowa (on the east) elevations of subparallel orientation. Still farther to the east, a longitudinal elevation extending between the Klęczany-Pisarzowa and Świątkowa tectonic windows is to be seen some 10-15 km south of the Magura frontal thrust. South of this area, the Magura floor thrust slopes steeply down to more than 4 km b.s.l. A comparison between the pattern of elevated and subsided structures of the Magura floor thrust and subenvelope surfaces of different orders shows that in the western part of the Polish Outer Carpathians the highest-elevated neotectonic structures (in the southern portion of that area) coincide with depressions of the Magura thrust, whereas farther north a reverse pattern becomes dominant: neotectonic elevations coincide either with the Magura frontal thrust or with elevations of its surface. This is particularly true for an area comprised between 20° and 20°30’E meridians. The origin of such relationships is difficult to explain. We infer that one of possible factors could be Pliocene-Quaternary reactivation of faults cutting the Magura floor thrust, and particularly that one, which appears to separate the western-medial segment of the Outer Carpathians from their more eastern portion

Jointing in the Dukla Nappe (Outer Carpathians, Poland) : an attempt at palaeostress reconstruction

The joint network in the portion of the Dukla Nappe studied originated in two stages showing different orientations of the stress field axes. The older, compressive stage I was characterized by a N45^{\circ}E-orientated (at present coordinates) horizontal s1 and formation of the diagonal, shear (SL and SR) joint system. The younger, extensional stage II was characterized by vertical s1 and horizontal, N35^{\circ}E-orientated (also at present coordinates) s3 suitable for formation of the fold-parallel joints. At the turn of the first stage, under diminishing horizontal compression (s1 trending N35^{\circ}E), the cross-fold T joints developed. The orientation of the maximum compression axis changed between stages I and II. The first stage probably commenced while strata which were not fully lithified underwent shortening, and lasted until the termination of nappe emplacement. The second stage, in turn, is associated with pat-orogenic collapse of the Carpathians, whose onset in the study region began at least in Late Miocene times

Młode uskoki w północnym Wietnamie : przykład ze strefy uskoku Rzeki Czerwonej

Strefa uskoku Rzeki Czerwonej wyznacza granicę pomiędzy blokami Chin południowych i Indochinami. Była ona ukształtowana w dwóch fazach: podczas lewoskrętnego ścinania w warunkach podatnych, w okresie 27-16 Ma z późniejszym wypiętrzeniem i ekshumacją z głębokości 20-25 km, a następnie w warunkach kruchego ścinania prawoskrętnego w plio-czwartorzędzie. Wielkość post-mioceńskiego przemieszczenia prawoskrętnego była rekonstruowana na 20 do 57 km, podczas gdy rozmiar przemieszczenia czwartorzędowych dolin był szacowany na 9 m do blisko 2 km. Dlatego ruch ten odpowiada tempu 1 do 9 mm/rok lub 1 do 4 mm/rok. Strefa uskokowa spełnia więc warunki umożliwiające w przyszłości generowanie silnych trzęsień ziemi.The Red River Fault Zone marks the boundary between the South China and Indochina blocks. It was shaped in two phases: during sinistral, ductile shear active 27-16 Ma, followed by exhumation and uplift from depths of 20-25 km, and then as dextral, predominantly brittle shear active in Plio-Quaternary times. The amount of post-Miocene dextral offset has been variously reconstructed as 20 to 57 km, whereas the size of individual offset of Quaternary valleys has been calculated as 9 m to nearly 2 km. Therefore, the corresponding rates of Quaternary dextral slip range between 1 and 9 mm/yr or 1 and 4 mm/yr. The fault zone is capable of generating relatively strong earthquakes in the future

Cainozoic evolution of Lower Silesia, SW Poland : a new interpretation in the light of sub-Cainozoic and sub-Quaternary topography

An analysis of the youngest tectonic movements by the use of either morphometric or instrumental techniques should take into account both exposed and buried fault zones. The sub-Cainozoic and sub-Quaternary surface maps presented in this study display buried palaeotopography whose interpretation proves helpful in identification of tectonic dislocations. Such a kind of analysis has been conducted for the area of Lower Silesia, including the Sudetes, Fore-Sudetic Block, and Fore-Sudetic Monocline. The maps have been constructed on the basis of well-bore data, vertical geoelectrical soundings, and detailed mapping of exposures of pre-Quaternary rocks. Well-bore data have been reinterpreted with a view to reconstruct the original depth to the top of the crystalline basement. Many archival borehole descriptions place the boundary between Tertiary strata and the Proterozoic-Palaeozoic substratum at the top of poorly weathered rocks, including regoliths of the crystalline substratum into the Tertiary cover. The presented maps portray for the first time the actual morphology of the sub-Cainozoic surface. A comparison between the sub-Cainozoic and sub-Quaternary surface maps enables us to document changes in tectonic mobility throughout Cainozoic times. An additional source of information is provided by the attached thickness maps of individual time-slices of the Cainozoic

A new find of mammoth tusk in loess-like sediments of the Zakliczyn Basin (Outer Western Carpathians, Poland)

In June 2007, in a valley side of a small stream close to Janowice in the Western Outer Carpathians of Poland, a 1.8 m long mammoth tusk was found within loamy-debris solifluction sediments, ca. 1 m thick. These discordantly overlie a 4-m-high strath built up of steeply dipping sandstones of the Krosno beds of the Skole Nappe, being in turn covered by 7.5-m-hick loessial silts and loess-like slopewash sediments. The latter are overlain at the top by another solifluction cover, ca. 1.5 m thick. The mammoth tusk belonged to an adult animal, probably 30-60 years old. The succession of malacofaunistic assemblages within loess-like sediments indicates a cold, polar climate, and an environment resembling tundra developed upon moderately moist substratum during the last glacial stage. The lower part of malacological sequence enriched in mesophile species probably refers to the Vistulian (Weichselian) interpleniglacial period. The middle part, indicative of more dry habitats, can be associated with the younger Pleniglacial, whereas the top part should represent the terminal phase of the latter. Sediments bearing the mammoth tusk were probably deposited at the turn of the Vistulian older Pleniglacial and Interpleniglacial time