Brittle Deformation. FAULT is a structural plane along which considerable amount of movement is visible. Prof.Dr.Kadir Dirik Lecture Notes

Transcription

1 Brittle Deformation FAULT is a structural plane along which considerable amount of movement is visible. 1

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6 Fault Fault zone Shear zone 6

7 Three basic criteria: Criteria for the Recognition of Faults 1. Fault rocks 2. Effects on geological and stratigraphical units 3. Effects on topography (physiographic elements) 1. Fault rocks Cataclastic Rocks, Fault Breccia, Mylonite Non-cohesive cataclasites Cataclastic fault rocks Cohesive cataclasites Mylonitic fault rocks 7

8 Cataclastic rocks: (A) Megabreccia; (B) cataclasite 8

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10 Cataclasite Mylonite 10

11 Structures on the fault plane 11

12 oluklar sırtlar groove ridges Striations/fault lines çizikler 12

13 Fault steps Grooves and fault steps Prof.Dr.Kadir Dirik Ders Notları 13

14 Chatter marks Ridel fractures 14

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18 2- The effects on geological and stratigraphical units A Juxtaposition (Yanyana Gelme ) 18

19 B Ommision and Repetition of Strata (Eksik/Kayıp ve Bindirme/ Tekrarlanma Alanları) Kuyu karot Normal istif Tavan blok Kuyu karot Normal istif Tavan blok Kısalma miktarı Tekrarlayan birim Uzama miktarı Kaybolan / Eksik birim Ters Fay Normal Fay 19 19

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23 C Drag Folds (Sürüklenme /Sürüme Kıvrımları) D Rollover Anticlinal (Ters Sürüme Kıvrımı) 23

24 3- Effects on topography (physiographic elements) A Fault Scarp 24

25 B Fault Line Scarp Fay çizgisi Sarplığı Dayanımlı katman 25

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28 C Triangular facets and alluvial fans (Fay zonunda görülen üçgen yüzeyler ve sıralı birikinti konileri) () 28

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33 CLASSIFICATION OF FAULTS Basically two criteria are used for the classification of faults: (1) Position of the fault plane; (2) Slip direction. (1) Classification Based on Position of the fault plane; Inclined Faults Vertical Faults 33

34 (2) Classification based on Slip direction. 34

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36 ANDERSON classification Based on the principal stress directions Normal Faults Reverse/thrust faults Strike-slip faults 36

37 Faults and Principal Stress Directions 37

38 AA- anticlinal axis MF- master fault NF- normal fault OF- extensional joint P- splay fault PDZ- main displacement zone R- sintetic Ridel fracture R - antitetic Ridel fracture RF- reverse fault SA- synclinal axis TF- thrust fault 38

39 Normal Fault Dip amount of fault plane: > 45 o, <90 o in general: 60 o 39

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42 Reverse Fault Dip amount of fault plane: > 45 o, Low angle reverse fault: ~30 o named as Thrust fault 42

43 Thrust Fault Nappe 43

44 Strike-slip fault Movement vector is paralel to the strike of fault and perpendicular to the dip of fault plane. 44

45 Prof.Dr.Kadir Dirik Ders Notları 45

46 Prof.Dr.Kadir Dirik Ders Notları 46

47 Oblique-slip fault Movement vector is oblique to the strike of fault. 47

48 Rotational (Pivotal/Burulma) Faults 48

49 JOINT is a fracture/structural plane along which no considerable amount of movement is visible. Types of Joint 1- Tectonic joints 2- Non-tectonic joints 1- Tectonic Joints (a) Extensional joints; (b) Shear joints; (c) Tension gashes 49

50 (a) Extensional joints 50

51 (a) Extensional joints Orthogonal joints 51

52 If the space of extensional joints are filled by calcite, quartz or some other minerals, they are named as vein. 52

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55 (b) Shear joints 55

56 (c) Tension gashes Tension gashes are a special type of vein that can form rather spectacular patterns 56

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59 2- Non-tectonic joints (a) Mudcracks 59

60 (b) Cooling joints (columnar joints) 60

61 (b) Sheet joints Formed by pressure release 61

62 UNCONFORMITIES Representing times of nondeposition, erosion or both Paraconformity Disconformity Angular unconformity Nonconformity 62

63 DISCONFORMITY Uplift Deposition Disconcormity Uplift and erosion (Monroe&Wicander, 2005) Deposition 63

64 ANGULAR UNCONFORMITY Uplift Deposition Angular unconformity (Monroe&Wicander, 2005) Erosion Uplift and tilting Deposition 64

65 NONCONFORMITY Uplift Deposition Nonconformity Uplift and erosion of overlying sediments (Monroe&Wicander, 2005) Intrusion of magna 65

66 Prof.Dr.Kadir Dirik Ders Notları 66