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H. Muhammad Ridha Adhari, S.T., M ... Klasifikasi Lipatan berdasarkan sudut antar sayap lipatan Adhari, M.R., Teknik Geologi Unsyiah Adhari, M.R., Teknik Geologi Unsyiah Adhari, M.R.,

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  • H. Muhammad Ridha Adhari, S.T., M.Sc

    Dept. of Mining Engineering

    Faculty of Engineering

    Syiah Kuala University

    Darussalam, Banda Aceh

    2017

  • Pengumuman Selasa depan (14-3-2017) direncanakan akan

    ada quiz Geologi Struktur.

    Materi dari Pertemuan pertama sampai terakhir

    hari ini.

  • Course Outline

    Secondary Structure

    Plastic Deformation

    Brittle Deformation

    Summary

  • What is Secondary Structures?

    Result from later deformation of the primary structures.

    The structures are most easily observed if the rocks have

    obvious primary structures, such as layering/bedding.

  • STENO’S PRINCIPLE

    THE PRINCIPLE OF SUPERPOSITION

    In a sequence of strata, any stratum is younger than the

    sequence of strata on which it rests, and is older than the

    strata that rest upon it.

    PRINCIPLE OF ORIGINAL HORIZONTALITY

    Strata are deposited horizontally and then deformed to

    various attitudes later.

    PRINCIPLE OF LATERAL CONTINUITY

    Strata can be assumed to have continued laterally far

    from where they presently end.

    Adhari, M.R., Teknik Geologi Unsyiah

  • Adhari, M.R., Teknik Geologi Unsyiah

  • Steno’s Principle Adhari, M.R., Teknik Geologi Unsyiah

  • Law of superposition

    Rock layers are deposited

    from the bottom up

    The deeper we dig, the

    farther back in time we see

    Adhari, M.R., Teknik Geologi Unsyiah

  •  Nicolas Steno laid down the basis of modern stratigraphy and

    palaeontology.

    Lateral Continuity Adhari, M.R., Teknik Geologi Unsyiah

  • What Happens to Steno’s Principle?

  • What Happens to Steno’s Principle?

  • What Happens to Steno’s Principle?

    Deformation  Caused by Differential Stress.

    Deformation : the changes in the shape or position

    of a rock body in response to differential stress.

    Adhari, M.R., Teknik Geologi Unsyiah

  • Forces that cause deformation of rocks Adhari, M.R., Teknik Geologi Unsyiah

  • Confining Pressure and Differential Stress

    Adhari, M.R., Teknik Geologi Unsyiah

  • Confining Pressure : Equal from all sides. Reduces

    volume without deformation.

    Differential Stress : Stress system where the

    forces acting on a unit cube are not the same in all

    directions.

    Type of Stress / Pressure

  • Adhari, M.R., Teknik Geologi Unsyiah

  • Adhari, M.R., Teknik Geologi Unsyiah

  • Adhari, M.R., Teknik Geologi Unsyiah

  • Primary depositional layering is always horizontal 

    Steno’s Principle.

    When layers are found that are not horizontal, the

    geologist assumes that some force has been exerted upon

    them that has destroyed their original horizontality.

    Adhari, M.R., Teknik Geologi Unsyiah

  • Secondary Structure:

     Plastic Deformation.

     Brittle Deformation.

    Adhari, M.R., Teknik Geologi Unsyiah

  • Behavior of rocks to stress & strain

    Adhari, M.R., Teknik Geologi Unsyiah

  • (c–f) Schematic cross sections showing the behavior of rock cylinders during the

    successive stages of a confined compression experiment and accompanying stress–

    strain plot, emphasizing the behavior of Griffith cracks (cracks shown are much larger

    than real dimensions). (c) Pre-deformation state, showing open Griffith cracks. (d)

    Compression begins and volume decreases due to crack closure. (e) Crack

    propagation and dilatancy (volume increase). (f) Merging of cracks along the future

    throughgoing shear fracture, followed by loss of cohesion of the sample (mesoscopic

    failure).

  • The atomic structure of materials. Solids are composed of

    atoms or ions that are connected to one another by chemical

    bonds that can be thought of as tiny springs.

  • How can a strong layer of rock permanently bend into a

    fold/fault?

    Elastic deformation  recoverable (nonpermanent).

    Plastic deformation  Permanent  Fold.

    Brittle deformation  Permanent  Fault, Joint, Vein.

    Ductile/Plastic Deformation

    Adhari, M.R., Teknik Geologi Unsyiah

  • Fold. Plastic Deformation.

    Adhari, M.R., Teknik Geologi Unsyiah

  • Fold. Plastic Deformation. Adhari, M.R., Teknik Geologi Unsyiah

  • Types of Fold

    Anticlines.

    Synclines.

    Monoclines. Anticlines. Synclines.

    Monoclines. Adhari, M.R., Teknik Geologi Unsyiah

  • Adhari, M.R., Teknik Geologi Unsyiah

  • Monoclines.

    Adhari, M.R., Teknik Geologi Unsyiah

  • Klasifikasi Lipatan berdasarkan simetri dan orientasinya

    Adhari, M.R., Teknik Geologi Unsyiah

  • Klasifikasi Lipatan berdasarkan sudut antar sayap lipatan

    Adhari, M.R., Teknik Geologi Unsyiah

  • Adhari, M.R., Teknik Geologi Unsyiah

  • Adhari, M.R., Teknik Geologi Unsyiah

  • Ptygmatit Fold

    Parasitic Fold

  • Dua lapisan yang terlipat dengan ketebalan yang berbeda.

    Lipatan yang atas mempunyai wavelength yang lebih kecil daripada yang dibawah. Ketika lapisan yang tebal mengalami

    pelipatan, lipatan kecil pada lapisan

    batuan menjadi parasitic dan asimetri

    karena flexural flow.

    Adhari, M.R., Teknik Geologi Unsyiah

  • Brittle deformation : The permanent change that occurs

    in a solid material due to the growth of fractures and/ or

    due to sliding on fractures.

    Brittle deformation only occurs when stresses exceed a

    critical value, and thus only after a rock has already

    undergone some elastic and/or plastic behavior.

    Brittle Deformation :

    Fracture

    Joint (Tensile Facture)

    Fault (Shear Fracture)

    Vein

    Brittle Deformation

    Adhari, M.R., Teknik Geologi Unsyiah

  • Types of brittle deformation. (a) Orientation of the principal

    stress directions. (b) A tensile crack (c) A shear fracture.

    Adhari, M.R., Teknik Geologi Unsyiah

  • Normal Fault Adhari, M.R., Teknik Geologi Unsyiah

  • Dip-slip fault : slip parallel to dip (up or down plane).

     Normal Fault, Thrust (Reverse) Fault

    Strike-slip fault : slip parallel to strike (horizontal).

     Transform Fault

    Oblique-slip : have both strike-slip (horizontal) and

    dip-slip (vertical) motion.

    Type of Fault

    Adhari, M.R., Teknik Geologi Unsyiah

  • Dip-Slip Faults Adhari, M.R., Teknik Geologi Unsyiah

  • Strike-Slip Faults

    Adhari, M.R., Teknik Geologi Unsyiah

  • Oblique-Slip Faults

    Adhari, M.R., Teknik Geologi Unsyiah

  • Joint Adhari, M.R., Teknik Geologi Unsyiah

  • Joint Adhari, M.R., Teknik Geologi Unsyiah

  • Gold Vein Adhari, M.R., Teknik Geologi Unsyiah

  • Gold Veins Adhari, M.R., Teknik Geologi Unsyiah

  • Veins Adhari, M.R., Teknik Geologi Unsyiah

  • Veins Adhari, M.R., Teknik Geologi Unsyiah

  • Summary

    Elastic deformation  Recoverable (nonpermanent).

    Plastic deformation  Permanent  Fold.

    Brittle deformation  Permanent  Fault, Joint, Vein.

    Secondary Structure : Plastic deformation and Brittle

    deformation.

    Type of Fold : Anticlines, Synclines, Monoclines.

    Type of Fault : Dip-slip fault, Strike-slip fault, Oblique.