scholarly journals High-Resolution 3D Seismic Imaging of Fault Interaction and Deformation Offshore San Onofre, California

2021 ◽  
Vol 9 ◽  
Author(s):  
James J. Holmes ◽  
Neal W. Driscoll ◽  
Graham M. Kent
Keyword(s):  
High Resolution ◽  
Strike Slip ◽  
Fault System ◽  
3D Seismic ◽  
Fault Interaction ◽  
Slip Rates ◽  
Slip Step ◽  
Well Data ◽  
Splay Faults ◽  
Step Over

The Inner California Borderland (ICB) records a middle Oligocene transition from subduction to microplate capture along the southern California and Baja coast. The closest nearshore fault system, the Newport-Inglewood/Rose Canyon (NIRC) fault complex is a dextral strike-slip system that extends primarily offshore approximately 120 km from San Diego to Newport Beach, California. Holocene slip rates along the NIRC are 1.5–2.0 mm/year in the south and 0.5 mm/year along its northern extent based on trenching and well data. High-resolution 3D seismic surveys of the NIRC fault system offshore of San Onofre were acquired to define fault interaction across a prominent strike-slip step-over. The step-over deformation results in transpression that structurally controls the width of the continental shelf in this region. Shallow coring on the shelf yields a range of sedimentation rates from 0.27–0.28 mm/year. Additionally, a series of smaller anticlines and synclines record subtle changes in fault trends along with small step-overs and secondary splay faults. Finally, sedimentary units onlapping and dammed by the anticline, place constraints on the onset of deformation of this section of the NIRC fault system. Thickness estimates and radiocarbon dating yield ages of 560,000 to 575,000 years before present for the onset of deformation.

scholarly journals Geometric and Dynamic Patterns of the Golmud Segment in the Southern Marginal Fault of the Qaidam Basin

2021 ◽  
Vol 9 ◽  
Author(s):  
Hao Luo ◽  
Ji Wang ◽  
Yasen Gou ◽  
Hongmei Yu ◽  
Peng Shu ◽  
...  
Keyword(s):  
High Resolution ◽  
Late Quaternary ◽  
Qaidam Basin ◽  
Structural Evolution ◽  
Strike Slip ◽  
Fault System ◽  
Tibet Plateau ◽  
Deformation Pattern ◽  
Slip Rates ◽  
Lateral Extrusion

The southern marginal fault of the Qaidam Basin (SMQBF) is a block-bounding border fault that has played a key role in the structural evolution of the Kunlun Fault. However, its geometric and dynamic deformation patterns since the Late Pleistocene have not been clearly observed. Field investigations, combined with high-resolution imagery and shallow seismic profiles, show that the SMQBF is a thrust fault with a sinistral strike-slip component composed of several secondary faults. Its Late Quaternary deformation pattern is characterized by piggyback thrust propagation, and the frontal fault may not be exposed to the surface. Due to the flexural slip of the hanging strata of the secondary fault, sub-parallel faults with widths of thousands of meters have formed on high terraces; these are important when assessing the seismic hazard of this area. Based on high-resolution topographic data obtained using an unmanned erial vehicle and optically stimulated luminescence chronology, the slip rates of several secondary faults were obtained. The vertical and strike-slip rates of the SMQBF were determined to be 0.96 ± 0.33 mm/a and 2.66 ± 0.50 mm/a, respectively, which may be the minimum rates for the fault. Considering that the SMQBF is composed of several secondary faults, these rates possibly correspond to minimum deformation only. The evident sinistral strike-slip of the SMQBF indicates that although the sinistral slip of the Kunlun Fault system is concentrated in main fault of this system, the branch faults have a significant influence on the lateral extrusion of the Qinghai-Tibet Plateau.

Fragmentation of the Sinai Plate indicated by spatial variation in present-day slip rate along the Dead Sea Fault System

2020 ◽  
Vol 221 (3) ◽  
pp. 1913-1940
Author(s):  
Francisco Gomez ◽  
William J Cochran ◽  
Rayan Yassminh ◽  
Rani Jaafar ◽  
Robert Reilinger ◽  
...  
Keyword(s):  
Continental Margin ◽  
Plate Boundary ◽  
Slip Rate ◽  
Dead Sea ◽  
Fault System ◽  
Slip Rates ◽  
Dead Sea Fault System ◽  
The Dead ◽  
Gps Velocities ◽  
Splay Faults

SUMMARY A comprehensive GPS velocity field along the Dead Sea Fault System (DSFS) provides new constraints on along-strike variations of near-transform crustal deformation along this plate boundary, and internal deformation of the Sinai and Arabian plates. In general, geodetically derived slip rates decrease northwards along the transform (5.0 ± 0.2 to 2.2 ± 0.5 mm yr−1) and are consistent with geological slip rates averaged over longer time periods. Localized reductions in slip rate occur where the Sinai Plate is in ∼N–S extension. Extension is confined to the Sinai side of the fault and is associated with prominent changes in transform geometry, and with NW–SE striking, left-lateral splay faults, including the Carmel Fault in Israel and the Roum Fault in Lebanon. The asymmetry of the extensional velocity gradients about the transform reflects active fragmentation of the Sinai Plate along the continental margin. Additionally, elastic block modelling of GPS velocities requires an additional structure off-shore the northern DSF segment, which may correspond with a fault located along the continental margin, suggested by prior geophysical studies.

Regional Tectonics & Structural Framework of Offshore Aceh's Andaman Sub-Basin, Northern Sumatra, Indonesia

2021 ◽  
Author(s):  
S. Clark
Keyword(s):  
High Resolution ◽  
Late Eocene ◽  
Strike Slip ◽  
Hydrocarbon Exploration ◽  
Fault System ◽  
Earth Model ◽  
The West ◽  
Structural Framework ◽  
Geochemical Models ◽  
Regional Tectonics

The three-way collision of the Indo-Australian, Eurasian and Pacific plates have resulted in Southeast Asia being the most tectonically complex region on Earth. This is particularly true for Offshore Aceh’s Andaman Sub-Basin, which has undergone complex late Eocene-Recent evolution. Despite a long history of hydrocarbon exploration and production, data scarcity in the offshore means that the Sub-Basin’s regional tectonics and structural framework have been poorly understood. Pre-1996 2D seismic data were low-fold and low-offset, however the 2019 PGS (NSMC3D) regional 3D survey imaged the entire Cenozoic sequence, enabling the delineation of a high-resolution tectonic framework for the first time. Integration of interpretations drawn from geophysical datasets with a 2019 biostratigraphy study has refined the ages of critical sequence boundaries and advanced the understanding of major structural elements. GEM™, the Geognostics Earth Model, has been used to place these interpretations in a regional tectonic and kinematic context using a series of high resolution plate animations. Andaman Sub-Basin formation initiated in response to the northward motion of India and collision with Eurasia, suturing the West Burma and Sibumasu Terranes through the middle-late Eocene. Continued northward motion of the Indo-Australian Plate resulted in further subduction along the Sunda Trench with associated oblique back-arc extension in present-day onshore and offshore Java and Sumatra. Concurrent rotation of Sundaland, with sinistral strike-slip motion along the Ranong and Khlong Mauri fault zones, resulted in the two rifting phases within the late Eocene (~40Ma) to early Oligocene in the Andaman Sub-Basin. Significant inversion events at 30Ma and 23Ma formed in response to dextral transpression associated with rotational extrusion of Indochina and Sundaland. Rapid subsidence followed the 30Ma inversion, resulting in a switch to post-rift sag and bathyal conditions during which turbidites infilled seabed topography. The onset of dextral strike slip between the West Burma Terrane along the Saigang fault system occurred at ~26Ma, causing transtension in the Andaman Sub-basin that terminated at 23Ma. At approximately 5Ma inversion and toe thrusts developed along the Sub-Basin’s southern margin due to uplift within the Barisan mountains. Refinement of the tectonic model, integrated with updated biostratigraphic and geochemical models, resulted in a revised tectono-stratigraphy for the Andaman Sub-Basin, which provides a predictive depositional model in which paleogeography and structural reactivation can be understood in a regional context.

scholarly journals Active fault segments along the North Anatolian Fault system in the Sea of Marmara: implication for seismic hazard

2021 ◽  
Author(s):  
Luca Gasperini ◽  
Massimiliano Stucchi ◽  
Vincenzo Cedro ◽  
Mustapha Meghraoui ◽  
Gulsen Ucarkus ◽  
...  
Keyword(s):  
High Resolution ◽  
Seismic Hazard ◽  
Seismic Reflection ◽  
Strike Slip ◽  
North Anatolian Fault ◽  
Sediment Supply ◽  
Fault System ◽  
Sea Of Marmara ◽  
Seismic Reflection Data ◽  
The North

AbstractA new analysis of high-resolution multibeam and seismic reflection data, collected during several oceanographic expeditions starting from 1999, allowed us to compile an updated morphotectonic map of the North Anatolian Fault below the Sea of Marmara. We reconstructed kinematics and geometries of individual fault segments, active at the time scale of 10 ka, an interval which includes several earthquake cycles, taking as stratigraphic marker the base of the latest marine transgression. Given the high deformation rates relative to sediment supply, most active tectonic structures have a morphological expression at the seafloor, even in presence of composite fault geometries and/or overprinting due to mass-wasting or turbidite deposits. In the frame of the right-lateral strike-slip domain characterizing the North Anatolian fault system, three types of deformation are observed: almost pure strike-slip faults, oriented mainly E–W; NE/SW-aligned axes of transpressive structures; NW/SE-oriented trans-tensional depressions. Fault segmentation occurs at different scales, but main segments develop along three major right-lateral oversteps, which delimit main fault branches, from east to west: (i) the transtensive Cinarcik segment; (ii) the Central (East and West) segments; and (iii) the westernmost Tekirdag segment. A quantitative morphometric analysis of the shallow deformation patterns observed by seafloor morphology maps and high-resolution seismic reflection profiles along the entire basin allowed to determine nature and cumulative lengths of individual fault segments. These data were used as inputs for empirical relationships, to estimate maximum expected Moment Magnitudes, obtaining values in the range of 6.8–7.4 for the Central, and 6.9–7.1 for the Cinarcik and Tekirdag segments, respectively. We discuss these findings considering analyses of historical catalogues and available paleoseismological studies for the Sea of Marmara region to formulate reliable seismic hazard scenarios.

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