Stanislaw Mazur | Polish Academy of Sciences (original) (raw)

Uploads

Papers by Stanislaw Mazur

The Geology of Central Europe Volume 1: Precambrian and Palaeozoic

Geophysical and geological data from the eastern sector of the Central European Variscan belt are... more Geophysical and geological data from the eastern sector of the Central European Variscan belt are presented and reviewed in the regional tectonic context. Matched filtering of isostatic gravity, guided by results of spectral analysis, along with other derivatives of gravity and magnetic fields reveal a dominant WNW-ESE-trending pre-Permian structural grain in the external zones of the Variscan belt in Poland. This trend is confirmed by regional distribution of dips in Carboniferous and Devonian strata that were penetrated by boreholes beneath Permian-Mesozoic sediments. Based on these data, two alternative concepts explaining the connection of the Variscan belt and its NE foreland, those of strike-slip tectonics versus oroclinal bending, are discussed. The WNW-ESE structural trend in the Variscan foreland is parallel to a set of major strike-slip fault zones in the area, including those of Upper Elbe, Intra-Sudetic, Odra, Dolsk and Kraków-Lubliniec. These faults are considered to convey a significant dextral displacement between Laurussia and Gondwana. The revised position of the Variscan deformation front shows a similar, uninterrupted, generally WNW-ESE trend, up to the SE border of Poland, which indicates an initial continuation of the Variscan belt into the area of the present-day Western Carpathians. The geometry of the Variscan deformation front along with the pattern of the Variscan structural grain are inconsistent with the idea of an oroclinal loop affecting the external, non-metamorphic Variscan belt. However, the data presented do not entirely rule out an oroclinal loop within the Variscan internides. The still possible options are (1) a semi-oroclinal model postulating ~ 90° bending of the Variscan tectonostratigraphic zones into parallelism with the WNW-ESE strike-slip faults or (2) an orocline limited only to the belt linking the Wolsztyn High and Moravo-Silesian non-to weakly-metamorphic fold-and-thrust belt. Regardless of the kinematic model preferred, our data indicate that structural evolution of the Polish Variscides was concluded with the end-Carboniferous NNE-SSW shortening that resulted in the present-day extent of the Variscan deformation front.

Tectonics, 2015

The Laptev Shelf is the area where the Gakkel Ridge, an active oceanic spreading axis, approaches... more The Laptev Shelf is the area where the Gakkel Ridge, an active oceanic spreading axis, approaches a continental edge, causing a specific structural style dominated by extensive rift structures. From the latest Cretaceous to the Pliocene, extension exerted on the Laptev Shelf created there several deep subsided rifts and high-standing basement blocks. To understand syn-rift basin geometries and sediment supply relationships across the Laptev Shelf, accurate extension estimates are essential. Therefore, we used 2-D gravity modeling and 3-D gravity inversion to constrain the amount of crustal stretching across the North America-Eurasia plate boundary in the Laptev Shelf. The latest Cretaceous-Cenozoic extension in that area is partitioned among two rift zones, the Laptev Rift System and the New Siberian Rift. These rifts were both overprinted on the Eurasian margin that had been stretched by 190-250 km before the Late Cretaceous. While the Laptev Rift System, connected to the Gakkel Ridge, reveals increasing extension toward the shelf edge (190-380 km), the New Siberian Rift is characterized by approximately uniform stretching along strike (110-125 km). The architecture of the Laptev Rift System shows that the finite extension of about 500 km is sufficient to entirely eliminate crystalline continental crust. In the most stretched rift segment, continental mantle is exhumed at the base of the Late Mesozoic basement. The example of the Laptev Rift System shows that extension driven by divergent plate movement is a sufficient cause to produce almost complete continental breakup without an increased heat input from the asthenospheric mantle. 2. Geological Setting for Late Cretaceous-Recent Extension The east and west Siberian Shelf is underlain by Precambrian to Palaeozoic basement terranes of the North America and Eurasia Plates (Figure 2). The boundary between the two crosses the Laptev Shelf along the N-S oriented continental rifts that are overprinted on the Early Mesozoic Taimyr fold-and-thrust belt and MAZUR ET AL.

Two tectonic units of different metamorphic grade can be distinguished in the mica schists which ... more Two tectonic units of different metamorphic grade can be distinguished in the mica schists which crop out at the eastern margin of the Sudetic foreland near Kamieniec Ząbkowicki. The Kamieniec unit comprises mica schists containing garnet, staurolite and andalusite porphyroblasts, whereas the Byczeń unit is composed o f mica schists having porphyroblasts of albite. The Byczeń unit is situated to the west of the Kamieniec unit in the north of the study area. The reverse order of the two units apparent in the south of that area results from displacement of their tectonic contact along a shallow WSW-dipping normal-slip shear zone cross-cutting earlier steeply dipping structures. Both the Kamieniec and Byczeń tectonic units are exposed on the inverted limb of a large SE-vergent synform, F2, as indicated by NW asymmetry of mesofolds and by gently inclined cleavage S2 intersecting the steep foliation S i. The hinge zone of this fold is occupied by an orthogneiss body and the normal limb is represented by paragneiss of the Chałupki unit exposed further east. The mica schists in the vicinities of Kamieniec Ząbkowicki have recorded three deformation events, Di, D2 and D3. Deformation Di produced the main foliation Si, which, in the study area is now steeply NW-dipping. The locally preserved Li stretching lineation is trending, in general, E-W , although it is locally reoriented on the limbs of younger folds F2. The axes of the F2 folds are oriented NE-SW and the accompanying penetrative axial cleavage S2 show gentle dips to the W, SW or NW. The S2 foliation is represented either by crenulation cleavage or, more frequently, by transposition foliation that has completely replaced the older foliation Si. Intersecting S2 and Si surfaces define penetrative lineation L2, the most prominent linear structure in the area. Deformation D3 was confined to low-angle normal-slip shear zones dipping to the SW. The S3 foliation within the shear zones is parallel to S2, whereas the L3 stretching lineation parallels the intersection lineation L2. Kinematic indicators point to an E-directed overthrusting of the Byczeń unit by the Kamieniec unit during the Di event. The tectonic juxtaposition of both units resulted in metamorphic grade inversion. The subsequent deformation D2 involved an irrotational shortening in the NW-SE direction, which produced the large-scale NE-SW-trending synform F2. Its western, inverted limb was subjected to an intense subvertical shortening. The progressive shortening was followed by development o f normal-slip shallow-dipping shear zones D3 showing top-to-SW or to-WSW sense of shear. The normal-slip shearing was related to SW-directed extensional collapse D3 at the eastern margin of the Sudetic foreland.

oerodkowosudeckiego, Starého Mìsta i morawsko-oel¹skiego (Mazur i in., 2010a). Dlaczego nie napis... more oerodkowosudeckiego, Starého Mìsta i morawsko-oel¹skiego (Mazur i in., 2010a). Dlaczego nie napisano nic ani o rozwoju tych basenów, ani o dowodach na ich istnienie? Dlaczego nie wspomniano w tekoecie o przeskoku strefy subdukcji z pó³nocnych brzegów terranu k³odzko-sowiogórskiego na jego po³udniowy sk³on w oerodkowym dewonie, co sugeruje rycina 1 (op.cit.)? Jakie s¹ dowody, ¿e terran oenie¿nicki zalega na ofiolicie oerodkowosudeckim, a ten ostatni nasuniêty jest na masyw Gór Sowich (ryc. 1, op.cit.)? W tekoecie podkreoelano, ¿e ofiolit oerodkowosudecki ma byae p³aszczowin¹ nadoecielaj¹c¹ masyw sowigórski (s. 141, op.cit.), a na przekroju C-D serpentynity kompleksu ofiolitowego podoecielaj¹ ten masyw (ryc. 4, op.cit.). Z czego wynikaj¹ te ró¿nice interpretacyjne? Dodatkowo, analizowany przekrój C-D przez masyw sowiogórski nie jest zgodny z przekrojami dla tego masywu z innej publikacji (¯elaŸniewicz & Aleksandrowski, 2008), ale tego samego wspó³autora. Na tych ostatnich ofiolit oerodkowosudecki na bloku przedsudeckim podoeciela prawie ca³¹ przedsu-deck¹ czêoeae masywu sowiogórskiego (op.cit.). Dlaczego przekrój geologiczny C-D zakoñczono na masywie Wzgórz Lipowych (ryc. 4, Mazur i in., 2010a)? Widnieje on tylko na tym przekroju i brak o nim jakiejkolwiek wzmianki w tekoecie; nie zaznaczono go na innych rycinach analizowanego artyku³u. Dlaczego przekroju C-1001

Proc. Indon Petrol. Assoc., 33rd Ann. Conv.

Geological Magazine, 2010

Seven granitoid gneisses from the contact zone between the eastern margin of the Variscan belt an... more Seven granitoid gneisses from the contact zone between the eastern margin of the Variscan belt and the Brunian microcontinent in SW Poland have been dated by ion-microprobe and 207Pb/206Pb single zircon evaporation methods. The zircons define two age groups for the gneiss protoliths: (1) late Neoproterozoic c. 576–560 Ma and (2) early Palaeozoic c. 488–503 Ma granites. The granitoid gneisses belonging to the basement of the Brunian microcontinent contain abundant Mesoproterozoic to latest Palaeoproterozoic inherited material in the range of 1200–1750 Ma. The gneisses of the Variscan crustal domain lack Mesoproterozoic inherited zircon cores. Trace element geochemistry of Proterozoic gneisses reveals features resembling either volcanic arc or post-collisional granites. The studied rocks are geochemically similar to other Proterozoic orthogneisses derived from the basement of the Brunian microcontinent. Gneisses with early Palaeozoic protolith ages are geochemically comparable to gran...

$Research paper thumbnail of Seismic refraction evidence for crustal structure in the central part of the Trans-European Suture Zone in Poland$

Geological Survey of Denmark and Greenland Bulletin, 2004

This paper presents implications of detailed map analysis, a semi-quantitative forward model and ... more This paper presents implications of detailed map analysis, a semi-quantitative forward model and two balanced cross-sections for the origin of the lens-shaped slivers of Permian (Zechstein) amid Triassic units, appearing along the main boundary fault of the Sontra Graben in central Germany at the southern margin of the Central European Basin System (CEBS). The paper shows how partial reactivation of the Sontra

The morphological features and typological distributions of zircon in the mylonites of the Niemcz... more The morphological features and typological distributions of zircon in the mylonites of the Niemcza Shear Zone (NZ) and in the gneisses and migmatites of the Gory Sowie Block (GSB), in the NE part of the Bohemian Massif, SW Poland, provide important petrogenetic indicators in the strongly deformed metamorphic rocks. The observed similarities be- tween the zircon populations (combined with other field and petrographic evidence) strongly suggest that at least a part of the mylonites developed at the expense of rocks similar to the GSB gneisses and migmatites. The protoliths of the gneisses and migmatites (both in the GSB and within the NZ) were predominantly of sedimentary character, but the zir- cons suggest that crustal-type granites (in the case of the NZ gneiss and mylonite protoliths) and hybrid mantle/crustal- type granites (in the case of the GSB migmatite protoliths) could have been important sources for the original, mostly de- trital (?) material. The large proportion of zirc...