Download Canggaan (Deformation) - Universiti Sains Malaysia

Canggaan, Sesar dan Lipatan
(Deformation, Faults and
Folds)
KEKAR
CANGGAAN
SESAR
PENGARUH
TEGASAN &
TERIKAN
LIPATAN
JENIS2
JENIS2
PROSES GEOLOGI
KAJIAN TAPAK
PETA
GEOLOGI
objektif
Memberi takrifan jenis2 tegasan yang boleh
dialami batuan
Memberi takrifan ragam (behaviour) batuan bila
dikenakan tegasan
Membandingkan pelbagai jenis lipatan (folds)
seperti sinklin, antiklin, monoklin, dom (dome) dan
empangan (basin)
Membandingkan pelbagai jenis sesar (normal,
songsang, thrust, gelincir jurus) dan tegasan yang
menghasilkan sesar
Memahami penggunaan jurus dan sudut miring
(dip and strike) atau sudut miring dan arah sudut
miring (dip/dip direction)
Melihat kejadian kekar dan pengaruhnya terhadap
pembinaan struktur
Deformation refers to the changes in
volume or shape of a body of rock
(canggaan merujuk kepada perubahan
isipadu atau bentuk sesuatu jasad batuan)
Bumi kita adalah dinamik => senantiasa
berubah, dan berubah dalam bentuk yg
tertib dan mengikut hukum tertentu
Bumi dikelilingi dengan daya; ada yang
dapat dirasa dan dilihat, dan sebaliknya.
Contoh: daya magnet, daya tektonik
Kita lebih berminat dgn apa yang boleh kita
kawal walaupun kadangkalanya tak dapat
kita fahami, terutama di permukaan bumi
Kadang2 kita berminat benda yg di luar
kawalan kita….
INTERAKSI PELBAGAI FAKTOR =>
MENGHASILKAN PELBAGAI PRODUK
mineral
batuan
tekanan
tanah
Tegasan-Terikan
(Stress-Strain)
Cause-and-effect
Stress is the FORCE acting on a body of
rock. Stress = Force / area = daya/luas
Strain is the response of a rock to stress.
It generally involves a change in shape or
volume of the rock
 Strain = change in shape
Strain
= change in length
= volume change
==> result in being shortened/elongated
STRAIN => DAPAT KITA LIHAT
STRESS => TAK DAPAT KITA LIHAT TETAPI
LEBIH PADA APA MINDA KITA DAPAT RASA
DAN BAYANGKAN (mental learning?)
Types of stress
1. Compressional
2. Tensional
3. Shear
Hubungan tegasan-terikan
deformation
deformation
Types of strain
Elastic deformation (Canggaan kenyal) - changes in
shape of rock are reversible. Deform it, remove the
stress, and it returns to its original shape (like a rubber
band or a piece of elastic)
Plastic deformation (Canggaan plastik) - changes in
shape of rock are permanent and not reversible (like
folding).
Rock Behavior (Ragam batuan)
– Brittle - the rock breaks
– Ductile - the rock flows or bends (folds are produced)
Once the elastic limit is surpassed, rocks will deform
plastically if the rock is ductile (mulur) or they will fracture
(rupture) if the rock is brittle (rapuh).
San Andreas Fault
SESAR/FAULTS
TERHASIL DRPD CANGGAAN KENYAL
(ELASTIC DEFORMATION) BAHAN YG
RAPUH (BRITTLE)
Jenis2 sesar
fault
Retak pd batuan yg ada pergerakan yg jelas
Dinding kaki & dinding gantung
(Hanging & footwall)
Normal & reverse fault
Oblique slip
Strike slip
graben
Normal faults
Thrust fault
fault
fault
fault
Cara memperihalkan orientasi sesar dan lipatan
Describing the orientation of layers of rock
When we describe the orientation of
sedimentary rock units, we must keep in mind
that these rocks were originally deposited as
sediment in horizontal (flat) layers (Remember
from geologic time: Law of original horizontality)
Tectonic forces cause the rock layers to be
folded and uplifted, and sedimentary rocks can
be in any orientation, including vertical.
Law of horizontality
Jurus dan sudut miring
(Strike and dip)
If we examine a small area of a layer of rock, we
can describe its orientation in space using two
directional components:
The angle at which the rock "dips" (with respect to
the horizontal) - called dip (sudut miring)
The compass direction along which the bed of rock
trends (with respect to north) - called strike
(Jurus)
Strike dip
Rocks dipping to the right 45o
Ahli geologi gemar menggunakan jurus
(strike) dan sudut miring (dip) sementara
Jurutera lebih suka menggunakan sudut
miring (dip) dan arah sudut miring (dip
direction)
Rocks dip to the right 45 degrees
45o
Strike and dip & soil failure as creep
LIPATAN/FOLD
TERHASIL DRPD CANGGAAN PLASTIK
BAHAN MULUR (DUCTILE)
Types of folds (formed as a
result of plastic deformation)
During mountain building or compressional
stress, rocks may deform plastically to
produce folds.
The up-folds and the down-folds are
adjacent to one another, and grade into
one another. In geology each is given a
separate descriptive name.
Basic types of folds
anticlines - upfolds
synclines - downfolds
Types of folds
fold
fold
fold
fold
fold
lineation
Vertical fold –
after weathering
and erosion
original fold
cannot be seen
anymore. This
is based on field
observation
Plunging fold
Mountains and the Continents
Stress and tectonic setting
Building continents: Orogenic belts vs.
cratons
Fault block ranges
Fold and thrust ranges
Volcanic ranges
Akan dibincang sekali lagi bersama
dgn topik Tektonik Keping
Syncline Late Paleozoic strata,
Maryland
Folds
Chilhowee Group Quartzite
Mountain City Window
Chevron folds in shale
North Carolina or Tennessee
Wills Creek Formation (Silurian)
North of Hancock, Maryland,
Syncline
Eastern
Tennessee
Parts of a fold:
fold axis
axial plane
limb
Axial plane
Fold shapes
symmetrical
asymmetrical
overturned - tipped in one direction so that
one of the limbs is overturned
recumbent - lying on its side
dome
basin
Fold shapes
Orientation of the axis of the fold:
plunging - the axis of the fold dips
non-plunging - the axis of the fold is
horizontal
Joints-Changkat Jering, K Kangsar
Joints- Pos Slim, Simpang Pulai
Kekar di Changkat Jering, K
Kangsar
fracture
Lineation: bukti yg terdapat pd batuan
metamorfik menandakan tegasan yg dialami
amat hebat sekali (UCS berapa?)
foliation
Apa itu foliasi?
Apa kepentingannya?
Di mana berlaku?
Next lecture
Hidrologi dan air tanah