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SESAR MENDATAR
Arie Noor Rakhman, S.T., M.T
SESAR GESER MENDATAR
Nama lain: RIFTS STRIKE SLIP TRANCURRENT WRENCH TRANSFORM TEAR
Strike slip fault are generally vertical fault that accommodate horizontal shear within the crust.
Batasan: Sesar yang antar dindingnya telah saling bergeser relatif mendatar
Results in the formation of Oceanic Crust
Plate Tectonics
Divergent Boundary
Transform Boundary
Plate Tectonics
Shearing (coupling)
Lateral slip creates faults
Common at transform
Shearing Forces
SIFAT UMUM
Kemiringan bidang sesar tegak / curam mudah dikenal pada foto udara jejak sesar di peta lurus
Umumnya panjang dan lurus (arahnya) lebar jalur dapat mencapai ratusan meter ribuan meter
Reconstruction of a horizontal section (a) to the situation prior to dike intrusion (b). Arrows can be drawn between points that once were neighbors to find displacement vectors. For small strains these vectors approximate sH.
From Fossen (1998).
SIFAT UMUM
Produk sesarnya Gouge / milonit, gores garis, breksi sesar merupakan jalur peta erosi
Pergeseran besar
Semangko Fault 25 30 km
San Andreas Fault 500 km
Earthquake and Plate TectonicsTransform Boundary and Earthquakes
The western US
is somewhat
anomalous
Note: absence of
deep earthquakes
from: http://www.pmel.noaa.gov/vents/coax/coax.html
Earthquake and Plate TectonicsTransform Boundary and Earthquakes
SIFAT UMUM
Pembentukan depresi dan pembumbungan akibat penyimpangan arah sesar
Tatanan stratigrafi yang saling menindih dan tidak sama
Struktur penyerta:
Kekar
Sesar
Lipatan
MACAM SESAR MENDATAR
Berdasarkan terdapatnya di bumi:
Transform fault di Samodera (MOR)
Strike slip fault, Wrench fault (en enchelon fault) di benua (daratan)
Arah pergeseran:
Sesar mendatar mengkanan Right / Dextral Slip Fault
Sesar mendatar mengkiri Left / Sinistral Slip Fault
Strike-slip fault near Las Vegas, NV,
Source: M. Miller, U. of Oregon
Strike-Slip Fault (Sesar mendatar)
Strike-Slip Fault (left-lateral)
Sesar / Patahan (Faults)
Strike-slip fault displacement in orchard
Sesar / Patahan (Faults)
Wrench fault = en enchelon fault sering terdapat tegasan-tegasan setempat.
Wrench fault
Kelompok Struktur PenyertaSesar Mendatar
Lipatan merencong (En Enchelon Fold) lazimnya arah sumbunya SEJAJAR poros panjang strain -Ellipsoidnya
Sesar Sungkup (Thrust) / Geser Naik sejajar poros lipatan
Hinge
Oldest rocks
in middle
AnticlineParts of a fold: axial plane limbs hinge
Lipatan
Folds Classification
Lipatan
Kelompok Struktur PenyertaSesar Mendatar
Sesar Turun / Rekahan Tarik tegak lurus poros lipatan
Sepasang sesar mendatar Right/Dextral Slip Fault (Synthetic) dan Left/Sinistral Slip Fault (Anthitetic)
Secara teoritis kelompok struktur ini terbentuk pada saat yang bersamaan