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

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.

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

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.

Hydrogeologic properties of a thrust fault within the Oregon Accretionary Prism

1995 ◽  
Vol 100 (B10) ◽  
pp. 20025-20035 ◽  
Author(s):  
Elizabeth J. Screaton ◽  
Bobb Carson ◽  
Gerard P. Lennon
Keyword(s):  
Accretionary Prism ◽  
Thrust Fault

Roles of Hydrothermal Circulations on Heat Flow in the Fore-arc, Northeast Japan Subduction Zone, A Numerical Modeling Study.

2021 ◽  
Author(s):  
Dongwoo Han ◽  
Changyeol Lee
Keyword(s):  
Heat Transfer ◽  
Heat Flow ◽  
Oceanic Crust ◽  
Numerical Models ◽  
Accretionary Prism ◽  
High Heat ◽  
Pacific Plate ◽  
Model Calculations ◽  
The Pacific ◽  
Japan Subduction Zone

<p>Heat flow in the fore-arc, Northeast Japan shows characteristic highs and lows in the seaward and landward regions of the trench axis, respectively, compared to 50 mW/m<sup>2</sup> that is constrained from the corresponding half-space cooling model (135 Ma). For example, the high average of 70 mW/m<sup>2</sup> at the 150-km seaward region from the trench was observed while the low average of 30 mW/m<sup>2</sup> at the 50-km landward region was. To explain the differences between the constraints and observations of the heat flow, previous studies suggested that the high heat flow in the seaward region results from the reactivated hydrothermal circulations in the oceanic crust of the Pacific plate along the developed fractures by the flexural bending prior to subduction. The low heat flow is thought to result from thermal blanket effect of the accretionary prism that overlies the cooled subducting slab by the hydrothermal circulations. To understand heat transfer in the landward region of the trench, a series of two-dimensional numerical models are constructed by considering hydrothermal circulations in the kinematically thickening accretionary prism that overlies the converging oceanic crust of the Pacific plate where hydrothermal circulations developed prior to subduction. The model calculations demonstrate no meaningful hydrothermal circulations when the reasonable bulk permeability of the accretionary prism(<10<sup>-14</sup>m<sup>2</sup>) is used; the thermal blanket effect significantly hinders the heat transfer, yielding only the heat flow of 10 mW/m<sup>2</sup> in the landward region, much lower than the average of 30 mW/m<sup>2</sup>. This indicates that other mechanisms such as the expelled pore fluid by compaction of the accretionary prism play important roles in the heat transfer across the accretionary prism.</p>

scholarly journals Seismic scatterers in the lower mantle near subduction zones

2019 ◽  
Vol 219 (Supplement_1) ◽  
pp. S2-S20 ◽  
Author(s):  
Satoshi Kaneshima
Keyword(s):  
Oceanic Crust ◽  
Lower Mantle ◽  
Subduction Zones ◽  
P Waves ◽  
Waveform Data ◽  
Basaltic Rocks ◽  
Short Period ◽  
Subducted Oceanic Crust ◽  
Conversion Depth ◽  
Seismic Networks

SUMMARY We investigate the global distribution of S-to-P scatterers in the shallow to mid-lower mantle beneath subduction zones, where deep seismicity extends down to the bottom of the upper mantle. By array processing broadband and short period waveform data obtained at seismic networks, we seek anomalous later phases in the P coda within about 15–150 s after direct P waves. The later phases usually arrive along off-great circle paths and significantly later than S-to-P conversion from the ‘660 km’ discontinuity, often show positive slowness anomalies relative to direct P, and do not show a conversion depth that is consistent among nearby events. They are thus adequately regarded as scattered waves, rather than conversion at a global horizontal discontinuity. The S-to-P scattered waves often show amplitudes comparable to ‘S660P’ waves, which indicates that a spatial change in elastic properties by several percent occurs at the scatterers as abruptly as the post-spinel transformation and should arise from compositional heterogeneity. We locate prominent S-to-P scatterers beneath Pacific subduction zones and beneath southern Spain. Nearly half of 137 S-to-P scatterers located in this study and previous studies by the authors are shallower than 1000 km, and the number of scatterers decreases with depth. Scatterers deeper than 1800 km are rare and mostly weak. We examine relations between the locations of the scatterers and recently subducted slabs inferred from seismic tomography. The scatterers of mid-mantle depths, deeper than about 1000 km, are located distant from tomographic slabs. On the other hand, the majority of shallower scatterers are located beneath the slabs rather than near their fastest portions, which would indicate that chemically heterogeneous materials are not extensively entrained within thickened and folded slabs when the slabs impinge on the lower mantle. We also find scatterers near the locations where basaltic rocks of recently subducted oceanic crust are expected to exist, which suggests that oceanic crust is not delaminating when slabs impinge on the lower mantle.

Stratigraphy in an accretionary prism: the Ordovician rocks in North Down, Ireland

1984 ◽  
Vol 74 (4) ◽  
pp. 183-191 ◽  
Author(s):  
Lorraine E. Craig
Keyword(s):  
Oceanic Crust ◽  
Accretionary Prism ◽  
Black Shales ◽  
Ocean Floor ◽  
Middle Ordovician ◽  
Iapetus Ocean ◽  
Lower Palaeozoic

ABSTRACTSediments, mainly sandstones, conglomerates and shales, accumulated in small turbidite fans along the northern arc–trench margin of the Iapetus Ocean from middle Ordovician to Silurian time. These fans, together with the underlying pelagic facies and part of the oceanic crust, were sliced and accreted northward resulting in the Lower Palaeozoic accretionary prism which forms the Scottish Southern Uplands and the Longford-Down inlier in Ireland. North Down is the continuation of the Northern belt of the Southern Uplands of Scotland into Ireland, bounded to the S by the Orlock Bridge fault. Lithological and petrographical comparison with the rest of the Northern belt indicates closer affinities with the Southern Uplands of Scotland than with the western end of the Longford-Down inlier. Major ENE—WSW-trending Caledonian strike faults define five blocks, in which new formations of Caradoc and ? Ashgill age are defined. Pillowed spilitic rock, interpreted as a fragment of the ocean-floor, is only recognised in the Ballygrot block. Pelagic and hemipelagic black shales and cherts are overlain by arenaceous sediments in all blocks.

scholarly journals Discrete Element Modelling of Sedimentation and Tectonics: Implications for the Growth of Thrust Faults and Thrust Wedges in Space and Time, and the Interpretation of Syn-Tectonic (Growth) Strata

2021 ◽  
Vol 9 ◽  
Author(s):  
Stuart Hardy ◽  
Nestor Cardozo
Keyword(s):  
Numerical Models ◽  
Element Model ◽  
Discrete Element ◽  
Thrust Fault ◽  
Discrete Element Modelling ◽  
Thrust Faults ◽  
Growth Strata ◽  
Modelling Studies ◽  
Mountain Belts ◽  
Insight Into

Thrust faults, and thrust wedges, are an important part of the surface morphology and structure of many contractional mountain belts. Analogue models of thrust wedges typically provide a map- and/or side-view of their evolution but give limited insight into their dynamic development. Numerical modelling studies, both kinematic and mechanical, have produced much insight into the various controls on thrust wedge development and fault propagation. However, in many studies, syn-tectonic sediments or “growth strata” have been modelled solely as passive markers and thus have no effect on, or do not feedback into, the evolving system. To address these issues, we present a high-resolution, 2D, discrete element model of thrust fault and wedge formation and the influence that coeval sedimentation may have on their evolution. We use frictional-cohesive assemblies, with flexural-slip between pre-defined layers, to represent probable cover rheologies. The syn-tectonic strata added during contraction are frictional-cohesive and we can think of them as “mechanical growth strata” as they interact with, and influence, the growing thrust wedge. In experiments of thrust wedge development without syn-tectonic sedimentation, a forward-breaking sequence is seen: producing a typical thrust-wedge geometry, consistent with analogue and numerical models. In general, the inclusion of syn-tectonic sedimentation produces thrust wedges composed of fewer major forward-vergent thrusts and with only minor thrust activity in the foreland. In most of these models the sequence of thrust activity is complex and not simply forward-breaking. With increasing sedimentation, the frontal thrust has much greater displacement and overrides a much thicker package of earlier syn-tectonic sediments. Very high syn-tectonic sedimentation results in the formation of a single basin-bounding thrust fault and no thrust-wedge per se. At the local (outcrop) scale of individual fault-related folds, high syn-tectonic sedimentation alters fault-fold evolution by producing steeper ramps, whereas low syn-tectonic sedimentation allows shallower ramps that may flatten and propagate into the syn-tectonic strata. Implications of these results for the interpretation of thrust faults and wedges and their interaction with associated growth strata are discussed.

Evidence for seamount accretion to a peri-Laurentian arc during closure of Iapetus 1This article is one of a series of papers published in CJES Special Issue: In honour of Ward Neale on the theme of Appalachian and Grenvillian geology.2 Geological Survey of Canada Contribution 20100465.

2012 ◽  
Vol 49 (1) ◽  
pp. 147-165 ◽  
Author(s):  
A. Zagorevski ◽  
V. McNicoll
Keyword(s):  
Accretionary Prism ◽  
Special Issue ◽  
Volcanic Arc ◽  
Bay Area ◽  
Mylonite Zone ◽  
Iapetus Ocean ◽  
Subduction Erosion ◽  
Area Preserve ◽  
Laurentian Margin ◽  
Accretionary Prisms

The Red Indian Line is the fundamental Iapetus suture zone in the Newfoundland Appalchians along which the main tract of the Iapetus Ocean was consumed. Despite being the site of the closure of a wide ocean, few vestiges of the Iapetus plate have been accreted along Red Indian Line. Ordovician rocks in the Notre Dame Bay area preserve the only evidence for accretion of a seamount in Newfoundland. The seamount is characterized by alkali basalt and hypabyssal rocks that are juxtaposed with Darriwilian peri-Laurentian volcanic arc rocks (466 ± 4 and 467 ± 4 Ma) along a major mylonite zone. The mylonite zone lacks sedimentary rocks suggesting that the seamount was accreted to the arc along a sediment-starved interface and that significant subduction erosion took place along the Laurentian margin. Identification of subduction erosion indicates that an accretionary prism did not exist outboard of Laurentia in Newfoundland, in contrast to the well developed accretionary prisms of the Caledonides.

Fully oxidized chromite in the Serra Alta (South Portugal) quartzites: chemical and structural characterization and geological implications

1997 ◽  
Vol 61 (408) ◽  
pp. 627-638 ◽  
Author(s):  
Jorge Figueiras ◽  
Joāo C. Waerenborgh
Keyword(s):  
Oceanic Crust ◽  
Structure Refinement ◽  
Chemical Characterization ◽  
Thrust Fault ◽  
Heavy Minerals ◽  
X Ray Diffraction ◽  
Mineral Contents ◽  
Chemical Character ◽  
South Portugal ◽  
Unique Chemical

AbstractSeveral quartzite bodies outcrop along the Ferreira-Ficalho Thrust Fault (South Portugal), a major accident of the Iberian Variscan Orogen. The sediment is a very pure quartz sandstone, with trace amounts of ultra-resistant heavy minerals and chromite. Chemical characterization (microprobe analyses and Mössbauer spectroscopy) showed the chromite to be unique: besides being Zn-rich, complexly zoned and a cation deficient spinel, all the iron was found to be fully oxidized to Fe3+. Structure refinement of single-crystal X-ray diffraction intensities unambiguously identifies the mineral as a chromite and the Mössbauer data are consistent with tetrahedrally coordinated Fe3+ in the spinel structure. Current geodynamical models see the Ferreira-Ficalho Thrust Fault as a first-order suture resulting from a complex collision of two distinct continental blocks with partial obduction of the intervening oceanic crust. The chromite grains could be envisaged as remnants of an early erosion of this obducted oceanic crust, but its unique chemical character does not allow any definite conclusion. Yet, the complete quartzite heavy mineral contents and its petrographic features are not consistent with their deposition within a continental collision situation.

scholarly journals The influence of detachment strength on the evolving deformational energy budget of physical accretionary prisms

Solid Earth ◽  
2018 ◽  
Vol 9 (6) ◽  
pp. 1421-1436 ◽  
Author(s):  
Jessica McBeck ◽  
Michele Cooke ◽  
Pauline Souloumiac ◽  
Bertrand Maillot ◽  
Baptiste Mary
Keyword(s):  
Energy Budget ◽  
Basal Layer ◽  
Thrust Fault ◽  
Acoustic Energy ◽  
External Work ◽  
Internal Work ◽  
Driving Mechanisms ◽  
Deformational Energy ◽  
Accretionary Prisms ◽  
The Impact

Abstract. Tracking the evolution of the deformational energy budget within accretionary systems provides insight into the driving mechanisms that control fault development. To quantify the impact of these mechanisms on overall system efficiency, we estimate energy budget components as the first thrust fault pair develops in dry-sand accretion experiments. We track energy budget components in experiments that include and exclude a basal layer of glass beads in order to investigate the influence of detachment strength on work partitioning. We use the measurements of normal force exerted on the backwall to estimate external work, and measurements of strain observed on the sides of the sand packs to estimate the internal work, frictional work and work against gravity done within increments of each experiment. Thrust fault development reduces the incremental external work and incremental internal work, and increases the incremental frictional work and incremental gravitational work. The faults that develop within higher-friction detachment experiments produce greater frictional work than the faults in experiments with glass bead detachments because the slip distribution along the detachments remains the same, while the effective friction coefficient of the detachment differs between the experiments. The imbalance of the cumulative work budget suggests that additional deformational processes that are not fully captured in our measurements of the energy budget, such as acoustic energy, consume work within the deforming wedge.

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