Filtering by Subject: Tectonics and Structure
Published: 2021-05-13
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Tectonics and Structure
When extension events are greatly separated in time, older faults may be buried and stratigraphically separated from newly developing faults at shallower depths. During rifting, the buried structures may reactivate and propagate upwards to be expressed within the shallow system. The degree of linkage between structural levels determines the influence that the deeper structures can exert over the [...]
Published: 2021-05-13
Subjects: Earth Sciences, Physical Sciences and Mathematics, Tectonics and Structure
Little is known about rift kinematics and strain distribution during the earliest phase of extension due to the deep burial of the pre-rift and earliest rift structures beneath younger, rift-related deposits. Yet, this exact phase of basin development ultimately sets the stage for the location of continental plate divergence and breakup. Here, we investigate the structure and strain distribution [...]
Published: 2021-05-07
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Tectonics and Structure
The lateral distribution of strength within the crust is highly variable. When subject to extension, lithologically and rheologically distinct areas of crust manifest strain differently, influencing the structural style, geometry and evolution of the associated rift system. Here, we use 3D thermo-mechanical models of continental extension to explore how pre-rift upper crustal strength variations [...]
Published: 2021-05-07
Subjects: Geology, Sedimentology, Stratigraphy, Tectonics and Structure
Sedimentary rocks of foreland fold-and-thrust belts typically undergo intensive fracturing as fold grows. The resulting fracture networks can present significant variations depending on the distribution of sedimentary facies and the complex structural characteristics of fold-and-thrust belts. The Puig-reig anticline, located in the south-eastern Pyrenees, mainly exposes proximal fluvial deposits [...]
Published: 2021-05-02
Subjects: Geology, Geomorphology, Sedimentology, Stratigraphy, Tectonics and Structure
Discrepancies in models of continental rift-basin dynamics and stratigraphic response calls on further investigation on the subject. Geometric- and lithological trends between stages of faulting is studied in the Permian- Triassic continental rift succession in the Horda Platform. The Horda Platform occupies the northeastern margin of the North Sea aulacogen where Late Permian-Early Triassic [...]
Published: 2021-04-21
Subjects: Earth Sciences, Geology, Geophysics and Seismology, Other Earth Sciences, Physical Sciences and Mathematics, Tectonics and Structure
Continental extension is accommodated by the development of kilometre-scale normal faults, which grow by accumulating metre-scale earthquake slip over millions of years. Reconstructing the entire lifespan of a fault remains challenging due to a lack of observational data of appropriate scale, particularly over intermediate timescales (10^4-10^6 yrs). Using 3D numerical simulations of continental [...]
Published: 2021-04-20
Subjects: Tectonics and Structure
Recently, the influence of lithospheric extension on later orogeny has gained increasing interest. We make use of own geological mapping, interpretations of seismic reflection profiles and deep geophysical data to build an area-balanced cross-section across a key area of the Western Southern Alps and to model a series of structural restorations from the end of Mesozoic rifting to present-day. The [...]
Published: 2021-04-20
Subjects: Geophysics and Seismology, Tectonics and Structure
The 2019-2020 Indios, Puerto Rico earthquake sequence ruptured on multiple faults with several moderate magnitude earthquakes. Here we investigate the seismotectonics of this fault system using high precision hypocenter relocation and inversion of the near-field strong motions of five largest events in the sequence (5.6≤Mw≤6.4) for kinematic rupture models. The Mw6.4 mainshock occurred on an NE [...]
Published: 2021-04-20
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure
Stable cratons with a thick (> 200 km) and cold lithosphere form rheologically strong plates that move atop a ductile asthenospheric mantle. Various types of seismic observations show the presence of a potentially rheologically weak zone at depths of ca. 80 – 150 km termed the Mid-Lithosphere Discontinuity (MLD). While various mechanisms may explain the MLD, the dynamic processes leading to the [...]
Published: 2021-04-15
Subjects: Geology, Planetary Geology, Planetary Geophysics and Seismology, Tectonics and Structure
Shock metamorphism is the process by which rocks, and the minerals within them, transform during the passage of a shock wave. Shock effects, such as shatter cones, are critical for the identification of impact structures and have commonly been used to infer mechanical and structural information on the cratering process. To make these inferences, the mechanics of shock wave behavior must be [...]
Published: 2021-04-14
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure
The Pamir orogen protrudes $\sim$300-km between the Tajik and Tarim lithosphere of central Asia. It is debated, whether its salient location and shape is controlled by indentation of a promontory of Indian mantle lithosphere or by rollback of thinned Tarim--Tajik-basin lithosphere. We present a new local-seismicity and focal-mechanism catalog and a P-wave velocity model [...]
Published: 2021-04-09
Subjects: Geomorphology, Tectonics and Structure
Published: 2021-04-06
Subjects: Environmental Monitoring, Geophysics and Seismology, Tectonics and Structure
A number of recent modeling studies of induced seismicity have used the rate-and-state friction model of Dieterich (1994) to account for the fact that earthquake nucleation is not instantaneous. Notably, the model assumes a population of seismic sources accelerating towards instability with a distribution of intial slip speeds such that they would produce earthquakes steadily in absence of any [...]
Published: 2021-04-06
Subjects: Applied Mathematics, Geophysics and Seismology, Tectonics and Structure
Faults in the crust at seismogenic depths are embedded in a fluid-saturated, elastic, porous material. Slip on such faults may induce transient pore pressure changes through dilatancy or compaction of the gouge or host rock. However, the poroelastic nature of the crust and the full coupling of inelastic gouge processes and the host rock have been largely neglected in previous analyses. Here, we [...]
Published: 2021-03-25
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure
Between 2014 and 2017, almost 200 new seismic stations were installed in Alaska and northwestern Canada as part of the EarthScope USArray Transportable Array. These stations currently provide an unprecedented capability for the detection and location of seismic events in regions with otherwise relatively sparse station coverage. Two interesting earthquake sequences in 2018 and 2019 in the [...]