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

New age and petrological constraints on Lower Silesian basaltoids, SW Poland

Fifteen samples of basaltoid rocks were analysed from Lower Silesia, SW Poland, all of them situated close to the Sudetic Marginal Fault. K-Ar datings were 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 gave dates ranging between 21-38 Ma, whereas that derived from a borehole in the Mokrzeszów graben was dated to 44 Ma. Another borehole sample (Jeżów Sudecki B-5) is of 59 Ma age. On the other hand, the supposedly “Quaternary” basalts from the Dębowiec area fall into the interval of 29-30 Ma.The southeasternmost occurrences of the Lower Silesian basalts 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. Most of the samples studied show properties typical of the two phases of volcanic activity, hitherto recorded in the Opole area by other authors

Post-alpine tectonics of the Upper Nysa Kłodzka Graben : a reply

The paper aims to answer the critical remarks presented by Don and Wojewoda (in this issue) related to our papers published in Acta Montana (Badura et al., 2002, Badura et al., 2003). Answering those we have noticed that the terms brachysyncline and brachyanticline are improper with regard to the young Alpine rebuilding of the Upper Nysa Kłodzka Graben. In this paper we present the basic reasons for our hypothesis of young tectonic movements in the studied area more widely. Our morphotectonic analyses are based on the digital elevation models (DEM) and the electroresistance survey of the researched area located near Kamienna and north of Długopole Zdrój. The results of our research show that despite of the long history of the geological studies - longer than 100 years, the region is still a very challenging research area. In this paper we point out that application of the DEM and electroresistivity methods gives the new important results. Those should definitely be taken into consideration together with palaeontological research and geological mapping. We really wonder that the authors of the critical paper unequivocally negate the results of our studies and suggest that the continuation of such research and geodetic survey in the area is aimless

New data on age and petrological properties of Lower Silesian Cenozoic basaltoids, SW Poland

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