Kaledonidy i waryscydy Sudetów Zachodnich

Jerzy Don



In the Sudetes there are several geological units which, although adjacent to one another, do not display any spatial nor time correlation of processes of their development. For example, facies-structural development of the Kaczawa Mts is found to be markedly different from that of the adjacent Karkonosze-Izera Block (Pt3 -Cm2?; O-S, D1?; D3). The former region has been folded and epizonally metamorphosed in the Sudetic phase whereas in the latter sedimentation was temporarily interrupted by the Sardinian foldings (accompanied here by extensive intrusion of porphyraceous Izera-Rumburk granites) and major folding and eastwards increasing dynamomorphosis - between the Early and Late Devonian. Phenomena which would represent equivalents of emplacement of the granites or their subsequent intense dynamometamorphis are not known from the adjacent basin of the Kaczawa Mts. In turn, the Sudetic phase had no significant effect on metamorphic and tectonic history of the Karkonosze-Izera rock series in the Kaczawa Mts and it even did not result in interruption of Carboniferous sedimentation in the adjacent Intra-Sudetic Basin. Other examples include contrasts in development of the Intra-Sudetic Basin and the adjacent Świebodzice Depression, Sowie Mts and Bardo Mts in N and NE. The contrasts are also striking in the case of unmetamorphosed rock series (O-C1) of the Bardo Mts and the adjacent epizonal complex (O?-S-D1) of the Kłodzko region in SW, folded and metamorphosed before the Late Devonian.
The Kaczawa Mts are separated from the Karkonosze- Izera Block by the Main Intra-Sudetic (MIS) Fault, which has been the subject of some controversy in the last years. According to the present Author, this fault displays all the features of a deep, long-living NW - SE oriented fracture separating geological units differing in facies structural development. In NW it separates the Gorlitz Synclinorium and Lusatian Błock, and in SE - the lntra-Sudetic Basin and Kaczawa Mts, Świebodzice Depression and Sowie Mts - Block, and still further to SE - the Kłodzko Metamorphic Complex and Bardo Mts. It should be noted that geological units occurring south of the MIS Fault display effects of the Sardinian phase and Late Caledonian dynamometamorphosis but not those of the Sudetic phase. In turn, the latter phase is strongly marked north of the MIS Fault. It follows that the fault divides the western Sudetes into two clearly distinct segments: Caledonian Kłodzko-Izera- Lusatian and Early Hercynian Gorlitz (Zgorzelec)- Kaczawa- Bardo.
The geological units occurring south of the MIS Fault were previously assumed to be significantly affected by the Assyntian orogeny. However, recent paleontological studies have shown continuous sedimentation from the Eocambrian to Middle Cambrian in the Sudetes and Lusatia. Some break in sedimentation, associated with folding and acid intrusions, took place due to the Sardinian phase but the rock series were subjected differential to regional metamorphosis not before the Late Caledonian orogeny. This is evidenced by unmetamorphosed Upper Devonian conglomerates and limestones resting on the metamorphic complex of Kłodzko, and Lower Carboniferous molasse of the Intra-Sudetic Basin and Doberlug-Kirchhain Basin (Lusatia), markedly differing in facies-structural development from folded (Sudetic phase) Lower Carboniferous successions of the Gorlitz Synclinorium and Kaczawa Mts. Caledonian age of the folding is also indicated by style of deformation of pre-Sardinian supracrustal series and Sardinian intrusives, similar to that of the metamorphic series (O-S -D1) of the Kłodzko region and the southern Karkonosze. In the metamorphic complex of Śnieżnik and Bystrzyckie-Orlickie Mts, similarly as in the Karkonosze-Izera Block, it was the Sardinian folding that ceased sedimentation of the Stronie Series and caused emplacement of porphyraceous granites. In turn, the Caledonian orogeny was responsible for their subsequent dynamometamorphosis into augen gneisses of the Śnieżnik type and post-deformational development of migmatites of the Gierałtów type.
In the Caledonian segment of the western Sudetes the units are mainly W - E oriented. That is why its tectonics differ from that of the Early Hercynian segment, with generally NW - SE oriented units. After the Sudetic phase (after C2), further development of these two segments became similar.

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