class5- khe nut.pdf
TRANSCRIPT
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Class 05.
PH HY V KHE NT
TS. Ng Xun ThnhKhoaa cht
Trng H M - a cht
Ph hy v khe nt
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Ph hy: L thut ngm tmt vt cht bmt tnhlin tc do bph hy.
Ko cng: Hai cnh ca ph hy btch ri nhau ra tonn khe nt. Xit p (Shear): Hai cnh dch trt ln nhau dc theomt ph hy -> t gy
Ph hy ko cng (hay tch gin)
thng c smrng mt ph
hy v khng c sdch chuyn
dc hai bn cnh.
Cc khe nt c hng khc nhau
to nn hthng khe nt.
Khe nt
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H thng khe nt
Gc ca h thng khe nt
Khe nt kin to trn vTrit
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Khe nt kin to
Thng k hthng khe nt
Theo cc khe nt tch Thng cc hthng c lpy bi cc khong vt thnhto sau
ai mch
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Nhng du hiu nhn bit khe nt c stch gin hay khng
Xem hai bn cnh
Cu to dngrng lc
Mch ca cccu trc bdchchuyn.
ai mch mrng to ccmch c thnhphn a hakhc bit.
Cc mch hnhthnh c slintc trong chaibn cnh.
Mt thnh to
trc khng bdchchuyn(offset)
Cchhnh thnh ph hy
1. Ph hy cng gin
Ko cng
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Cc ph hy ko cng to
cu trc ph hy trong ,
dc i khe nt khong c
dch chuyn.
2. Ph hy do bp nn(compression) vdo b ko cng(extension)
Cchhnh thnh ph hy
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3. Ph hy do thotlc
Cchhnh thnh ph hy
Cchhnh thnh ph hy
Cc hthng phhy
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4. Cp khe nt xitp
Cchhnh thnh ph hy
1. Khe nt lng v: Nhn bit hng xit p
t gy nghch hay chm t gy thun
Cp khe nt xit p
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3. Cp khe nt cng sinh & xit p kiu R
Cp khe nt xit p
Khe nt lng v
Plumose Structure
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Qu trnh hnh thnh
Do skhng ng nht ca
Ph hy theo cchngoi sinh
Basalt dng ct
Xy ra trong phun tro basalt
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Tectonic Origin
Residual Stress
Khe nt do xut l
Khe nt dng mi
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Sheeting Joints/Exfoliation
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Phn loi theo hnh thi cc khe nt
A. Theo cu trc mt lp(1) Khe nt theo hng dc: Joint strike parallel
to dip of beds(2) Strike joints: Joint strike parallel to strike of
beds(3) Oblique joints: Joint strike oblique to strike
of beds
Dip joints
Strike joints
Oblique joints
Geometrical classification of joints
B. Beds folded(1) Longitudinal joints (ab
joints): Release joints.(2) Transverse or cross-
joints (ac joints): Extensionjoints.
(3) Diagonal joints- Intersect parallel to b-
direction (shear joint that form
during compression)
- Intersect parallel to a-
direction (Release shear
joints after folding)
(4) Radial joints: Tensionfractures in outer arc of the
buckling type fold
Longitudinal
joints
Transverse or
cross-joints
Diagonal joints
Radial joints
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Why arent joint surface smooth??
Plumose Structure
Plumose structure
Joint origin: The point on the joint at which the fracture began to propagate
Mirror region: A portion of a joint surface where the surface is very smooth
Mist region: A portion of a joint surface where the fracture surface begins to roughen
Hackle zone: The main part of a plumose structure, where the surface is relatively rough
Twist hackle: One of a set of small en echelon joints formed along the edge of a larger
joints.
Arrest line: An arcuate ridge on a joint surface, where the joint front stopped during
propagation of the joint
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Why plumose structure form??
Rocks are not homogeneous and Isotropic
Crack Tip Propagation speed
Twist Hackle
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Straight Plumose
Curvy Plumose
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Columnar Jointing
Jointing that break rock into hexagonal columns; they form
during cooling and contraction in hypabyssal intrusions of lava
flows
Tectonic Origin
Residual Stress
Sheeting Joints/Exfoliation
Jointing parallel to the exposure surface (like layers of an onion)
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Sheeting Joints/Exfoliation
Sheeting Joints/Exfoliation