Hydrogeologic properties of a thrust fault within the Oregon Accretionary Prism

Elizabeth J. Screaton; Bobb Carson; Gerard P. Lennon

doi:10.1029/95jb02152

PEMBENTUKAN PRISMA AKRESI DI TELUK CILETUH KAITANNYA DENGAN SESAR CIMANDIRI, JAWA BARAT

JURNAL GEOLOGI KELAUTAN ◽

10.32693/jgk.13.3.2015.272 ◽

2016 ◽

Vol 13 (3) ◽

pp. 173

Author(s):

Lili Sarmili ◽

Deny Setiady

Keyword(s):

Oceanic Crust ◽

Accretionary Prism ◽

Thrust Fault ◽

Seismic Reflection Profile ◽

Thrust Faults ◽

Basalt Lava ◽

Basaltic Rocks ◽

Collision Zone ◽

Accretionary Prisms ◽

Basic Rocks

Kumpulan sesar naik yang ditafsirkan dari penampang seismic refleksi di teluk Ciletuh mengindikasikan adanya prisma akresi di daerah penelitian. Prisma akresi di daerah penelitian terletak di perairan teluk Ciletuh yang ditandai olef kumpulan sesar naik akibat adanya zona tumbukan antara kerak benua dan kerak samudera. Kerak samudera yang terangkat dan tersingkap di daratan teluk Ciletuh berupa batuan basalt (lava bantal), batuan ultra basa dan batuan bancuh. Prima akresi ini diduga berumur lebih tua dari prisma akresi yang masih terjadi saat ini, diperkirakan umurnya Tersier. Posisi prisma akresi di daerah penelitian ini berada di utara zona subduksi yang masih aktif di selatan di pulau Jawa. Beberapa struktur sesar naik juga terdapat di utara teluk Pelabuhan Ratu. Kumpulan sesar naik di sekitar teluk Pelabuhan Ratu dapat dianggap sebagai prisma akresi tua, dan mempunyai kaitan dengan kumpulan sesar naik di teluk Ciletuh. Posisi sesar-sesar naik yang terpisah antara sesar naik di lokasi teluk Pelabuhan Ratu dan di teluk Ciletuh diperkirakan terpisah oleh suatu sesar. Sesar yang memisahkan kedua kumpulan sesar naik ini diduga adalah sesar Cimandiri dengan jenis sesar mendatar menganan Kata kunci prisma akresi, teluk Ciletuh, batuan ultra basa, sesar sisnistral Cimandiri. A series of thrust faults which is interpreted from seismic reflection profile at Ciletuh bay indicate the occurrence of accretionary prism in the study area. The accretionary Prism in the study area indicated by series of thrust faults as a product of the collision zone between continental crust and oceanic crust. Uplifted oceanic crust was exposed on Ciletuh mainland such as basaltic rocks, pillow lavas, ultra basic rocks and melange. The accretionary prism is thought to be older than the accretionary prism that is still occurs on south Java island, and it was estimated Tertiary in age. The position of accretionary prisms in this study area is in the northern active subduction zone in the south of Java island. Some thrust faults are also found in the northern of Pelabuhan Ratu Gulf. A series of these faults can be regarded as an old accretionary prism, and have a relationship with a series of thrust fault at Ciletuh bay. The position of these thrust faults separate between the thrust of Pelabuhan Ratu bay and the thrust of Ciletuh bay and estimated have been disturbed by a fault. Fault which separates these two sets thrust fault is interpreted due to Cimandiri dextral fault. Keywords: the accretionary prism, Ciletuh bay, ultra basic rocks, Cimandiri sinistral fault.

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The relationship between evolution of Frontal Ridge growth and sediment-routing system in the developing marine accretionary prism in offshore Southwest Taiwan

10.5194/egusphere-egu2020-13201 ◽

2020 ◽

Author(s):

Ting-Yi Liu ◽

Kenn-Ming Yang ◽

Liang-Fu Lin ◽

Char-Shine Liu

Keyword(s):

Accretionary Prism ◽

Thrust Fault ◽

The Other ◽

Seismic Section ◽

Submarine Channels ◽

Narrow Channels ◽

Growth Strata ◽

Sediment Routing ◽

Frontal Part ◽

Other Hand

Sediment-routing system in a developing marine accretionary prism is highly related to the thrusting and the accompanied fold structures. The main purpose of this study is to investigate how the thrust fault growth had spatially and temporally affected sediment transport paths in the frontal part of the developing accretionary prism in offshore Southwest Taiwan. This study attempts to reveal the lateral change in dipping angle of and displacement along thrust fault and the accompanied variation in trend of the submarine channels by interpreting a grid of seismic section.&#160;The Frontal Ridge is the outmost topographic high in the frontal part of the accretionary prism in offshore Southwest Taiwan and has been regarded as the resultant anticlinal fold caused by westward thrusting. The major structural trend of the ridge is NW-SE and the fold tightness with the displacement along the fold-forming thrust decreases southeastward. Beneath the backlimb of the fold, basal boundary of the growth strata can be defined by a major unconformity and the overlying strata wedging westward to the ridge. The backlimb dipping angle is smaller than that of the thrust ramp. While narrow channels appear in the growth strata and parallel to the strike of fault, a wide submarine fan can be observed in the pre-growth strata. In the lower part of the growth strata, upstream of the channels is characterized by several narrow, concentrated and deep-cutting channels younging toward the east. On the other hand, downstream of the narrow channels appears as the distributed channels, which are overlain by the younger narrow and concentrated channels that are running along a synclinal axis in the upper part of the growth strata.&#160;We propose that the Frontal Ridge is a manifestation of a shear fault-bend fold in the subsurface and the ridge uplifted first from its northwestern end and propagated toward the southeast. The southeastward propagating fold had strongly affected sediment-routing path and deposition. At each stage, the active thrusting and accompanied piggy-back structure offered the loci for narrow and deep-cutting channels in the upstream areas. On the other hand, in the downstream areas, the channels ran far from pre-existing thrust front and spread out into distributed channels. When the frontal thrust continued to propagate to the southeastern end, the younger channels developed and migrated gradually to be restricted in the synclinal axial area. Meantime, the distributed channels in the original downstream areas would become a part of the folded pre-growth strata underneath the ridge.&#160;Key words: Sediment-routing system, accretionary prism, syn-tectonic deposition, Southwest Taiwan

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Seismic expression of shallow structures in active tectonic settings in New Zealand

Exploration Geophysics ◽

10.1071/eg989287 ◽

1989 ◽

Vol 20 (2) ◽

pp. 287

Author(s):

C.D. Cape ◽

R.M. O'Connor ◽

J.M. Ravens ◽

D.J. Woodward

Keyword(s):

New Zealand ◽

Plate Boundary ◽

Accretionary Prism ◽

Seismic Profile ◽

Thrust Fault ◽

Strike Slip ◽

Normal Faults ◽

Thrust Faults ◽

Seismic Reflection Data ◽

Reflection Data

Late Cenozoic deformation along the Australian/Pacific plate boundary is seen in onshore New Zealand as zones characterised by extension- or transcurrent- or contraction-related structures. High-resolution multichannel seismic reflection data were acquired in several of these tectonic zones and successfully reveal the shallow structures within them. Thirty kilometres of dynamite reflection data in the Rangitaiki Plains, eastern Bay of Plenty, define a series of NE-trending normal faults within this extensional back-arc volcanic region. The data cross surface ruptures activated during the 1987 Edgecumbe earthquake. In the southern North Island, a 20 km Mini-Sosie? seismic profile details the Quaternary sedimentation history and reveals the structure of the active strike-slip and thrust fault systems that form the western and eastern edges of the Wairarapa basin, respectively. This basin is considered to sit astride the boundary between a zone of distributed strike-slip faults and an active accretionary prism. In the Nelson area, northwestern South Island, previously unrecognised low-angle thrust faults of Neogene or Quaternary age are seen from Mini-Sosie data to occur at very shallow depths. Crustal shortening here was previously thought to arise from movement on high-angle reverse faults, and the identification of these low-angle faults has prompted a reassessment of that model. A grid of 18 km of Mini-Sosie seismic data from the central eastern South Island delineates Neogene or Quaternary thrust faults in Cenozoic sediments. The thrusts are interpreted as reactivated Early Eocene normal faults, and the thrust fault geometry is dominated by these older structures.

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