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Canggaan, Sesar dan Lipatan (Deformation, Faults and Folds). KEKAR. CANGGAAN. SESAR. JENIS2. PENGARUH TEGASAN & TERIKAN. JENIS2. LIPATAN. PROSES GEOLOGI. PETA GEOLOGI. KAJIAN TAPAK. objektif. Memberi takrifan jenis2 tegasan yang boleh dialami batuan
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KEKAR CANGGAAN SESAR JENIS2 PENGARUH TEGASAN & TERIKAN JENIS2 LIPATAN PROSES GEOLOGI PETA GEOLOGI KAJIAN TAPAK
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 suhu air 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 • Compressional • Tensional • Shear
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).
SESAR/FAULTS • TERHASIL DRPD CANGGAAN KENYAL (ELASTIC DEFORMATION) BAHAN YG RAPUH (BRITTLE) • Jenis2 sesar
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.
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)
Ahli geologi gemar menggunakan jurus (strike) dan sudut miring (dip) sementara • Jurutera lebih suka menggunakan sudut miring (dip) dan arah sudut miring (dip direction)
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