Brittle faulting in the southern contact zone of the Karkonosze granite near Karpacz Krzysztof Gaidzik, Jerzy Żaba Department of Fundamental Geology Faculty of Earth Sciences University of Silesia
Aim - Reconstruct paleostress tensor responsible for development definite brittle faults populations in the area of Karpacz Methodolody d Field -Collect fault-slip data; -Define direction and sense of movement along fault planes; -Find out relative relations between fault populations. Labo oratory -Angelier and Hoeppener diagrams; -Classify heterogenous fault-slip data into homogenous populations; -Apply methods: right dihedra method, inverse method; -Present results on diagrams and maps.
Geological sketch map of the Karkonosze granite and its metamorphic cover (after Aleksandrowski & Mazur, 2002). Study area - southern contact t zone of the Karkonosze granite in the area of Karpacz: Sowia Valley, Malina Valley, Łomniczka Valley, Księża Mt., Kozi Ridge.
The right dihedra (P/T quadrant) method - principles Fault plane + N plane perpendicular to the slip lineation on the fault T=Two compressional quadrants (σ 1 ) Two tensional quadrants (σ 3 )
Faults from the area of Karpacz Angelier diagram Hoeppener diagram Datasets: 50 Mostly: strike-slip faults (dextral), oblique faults with dominant strike-slip component Lower hemisphere
Fault planes: -dominant direction (strike) NE-SW; -mostly steep and very steep dip angle (strikeslip faults). Slip lineations: -dominant dip direction SW; -mostly low and very low dip angle (strike- slip faults).
Fault planes with slip lineation, steps - examples Karkonosze granite Kozi Ridge Metamorphic cover Sowia Valley
Metamorphic cover Sowia Valley Karkonosze granite Sowia Valley
Karkonosze granite Sowia Valley
Tectonic striae on mesofaults surfaces Tectonic st triae (Dip angle) 90 80 70 Sinistral Dextral 1 60 Normal-dextral Normal-sinistral 50 Reverse-dextral 40 Reverse-sinistral Reverse 30 Normal THorizontal 3 20 Unknown 10 0 4 0 10 20 30 40 50 60 70 80 90 Mesofaults (Dip angle) 2 5
First ( normal ) population Datasets: 7 Hoeppener diagram Angelier diagram
First ( normal ) population Planes: -dominant NNE-SSW, NE-SW; -steep (50-70º). Slip lineations: -dominant NW; -steep (50-70º).
First ( normal ) population Normal regime The Right Dihedra method σ1 77/68 σ 2 212/16 σ 3 307/15 The Inverse method
Predominant (second) population Datasets: 25 Hoeppener diagram Angelier diagram
Predominant (second) population Rose diagram Planes: -dominant NE-SW; -Steep and very steep (60-90º). Rose diagram Slip lineations: -dominant towards SW; -low and very low angles (0-20º).
Predominant (second) population Strike-slip regime Right Dihedra method σ 1 38/11 σ 2 256/76 σ 3 130/08 Inverse method
Third population Datasets: 5 Hoeppener diagram Angelier diagram
Third population Planes: -dominant NE-SW; -intermediate angles to steep. Slip lineations: -dominant towards SW; -intermediate angles (30-50º).
Third population Strike-slip regime Normal regime The Right Dihedra method σ1 192/34 σ 2 356/55 σ 3 97/08 The Inverse method
Fourth ( Reverse ) population Datasets: 2 Hoeppener diagram Angelier diagram
Fourth ( Reverse ) population Planes: -dominant W-E, NW- SE; -intermediate angles. Slip lineations: -dominant SW; -low angles (20-30º).
Fourth ( Reverse ) population Reverse regime σ 1 37/16 The Right Dihedra method σ 2 130/13 σ 3 259/69
Fifth ( strike-slip ) population Datasets: 5 Hoeppener diagram Angelier diagram
Fifth ( strike-slip ) population Planes: -dominant NW-SE; -very steep (80-90º). Slip lineations: -dominant SE; -low angles (10-20º).
Fifth ( strike-slip ) population Strike-slip regime The Right Dihedra method σ1 294/06 σ 2 69/82 σ 3 204/06 The Inverse method
Compressional (white) and tensional (black) sectors for every fault from the area of Karpacz on the basis of geological sketch of the studied area. Karkonosze granite Gneiss Mica schist Lower hemisphere
Conclusions - Strike-slip faults are predominant; - Fault planes strike NE-SW, steep and very steep; - Slip lineations mostly towards SW, low and very low angle; - 5 homogenous fault populations; - All possible regimes (strike-slip, slip, normal gravitational, ti reverse) were involved; - Normal population is older than predominant; - Predominant population was developed in strike-slip slip regime (σ 1 towards NE-SW SW, σ 3 towards NW-SE); - Except one example σ 1 more or less towards NE-SW; - Except one example σ 3 more or less towards NW-SE.
σ 1 red σ 2 black σ 3 blue