h. muhammad ridha adhari, s.t., m...klasifikasi lipatan berdasarkan sudut antar sayap lipatan...
TRANSCRIPT
H. Muhammad Ridha Adhari, S.T., M.Sc
Dept. of Mining Engineering
Faculty of Engineering
Syiah Kuala University
Darussalam, Banda Aceh
2017
PengumumanSelasa 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 PrincipleAdhari, 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 ContinuityAdhari, 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 rocksAdhari, 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
JointAdhari, M.R., Teknik Geologi Unsyiah
JointAdhari, M.R., Teknik Geologi Unsyiah
Gold Vein Adhari, M.R., Teknik Geologi Unsyiah
Gold VeinsAdhari, M.R., Teknik Geologi Unsyiah
VeinsAdhari, M.R., Teknik Geologi Unsyiah
VeinsAdhari, 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.