Preprints
Filtering by Subject: Tectonics and Structure
The building blocks of igneous sheet intrusions: insights from 3D seismic reflection data
Published: 2021-01-19
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Tectonics and Structure, Volcanology
The propagating margins of igneous sills (and other sheet intrusions) may divide into laterally and/or vertically separated sections, which later inflate and coalesce. These components elongate parallel to and thus record the magma flow direction, and can form either due to fracture segmentation (i.e., ‘segments’) or brittle and/or non-brittle deformation of the host rock (i.e., ‘magma fingers’). [...]
Structural controls on the emplacement and evacuation of magma from a sub-volcanic laccolith; Reyðarártindur Laccolith, SE Iceland
Published: 2021-01-07
Subjects: Earth Sciences, Geology, Higher Education, Physical Sciences and Mathematics, Science and Mathematics Education, Tectonics and Structure, Volcanology
Tectono-stratigraphic development of a salt-influenced rift margin: Halten Terrace, offshore Mid-Norway
Published: 2020-12-22
Subjects: Geology, Other Earth Sciences, Sedimentology, Tectonics and Structure
Pre-rift salt controls structural style variability within rifts by decoupling sub- and supra-salt faults. However, the way in which this variability controls sediment erosion and dispersal, and facies distributions within the coeval syn-rift stratigraphic succession, remains poorly known. We here use 3D seismic reflection and borehole data to study the tectono-stratigraphic development of the [...]
The 2020 Mw 6.5 Monte Cristo Range, Nevada earthquake: relocated seismicity shows rupture of a complete shear-crack system
Published: 2020-12-18
Subjects: Earth Sciences, Geology, Geophysics and Seismology, Tectonics and Structure
The predominant model for earthquake faulting is a shear crack, including surrounding damage zones. Observation of this complete shear crack system at seismogenic depth, however, has been elusive. Shear cracks with damage zones are related to fault formation and growth, and earthquake rupture physics and size, but observational and analytical limitations impede use of the shear crack paradigm in [...]
Assessment of quartz grain growth and the application of the wattmeter to predict recrystallized grain sizes
Published: 2020-12-04
Subjects: Geology, Mineral Physics, Tectonics and Structure
We investigated relationships between the recrystallized grain size and stress in experimentally deformed water-added quartz aggregates. For stresses >100 MPa there is a variation in the measured recrystallized grain size for a given stress. We found this variation correlates with a change in the c-axis fabric in general shear experiments, where samples with larger recrystallized grain sizes for [...]
Mantle earthquakes in recently thinned Neoproterozoic lithosphere: Harrat Lunayyir, Saudi Arabia
Published: 2020-11-20
Subjects: Geophysics and Seismology, Tectonics and Structure
We use earthquake geothermometry, measured heat flow, and structural constraints from P-wave receiver functions to model the thermal evolution of the lithosphere beneath Harrat Lunayyir. We suggest that the lithosphere thinned to its present 60-km thickness in a second stage of lithospheric thinning at 15–12 Ma following initial Red Sea extension at ~27 Ma. Harrat Lunayyir is an active volcanic [...]
Surface slip distributions and geometric complexity of intraplate reverse-faulting earthquakes
Published: 2020-11-09
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure
Earthquake ground surface ruptures provide insights into faulting mechanics and inform seismic hazard analyses. Surface ruptures for eleven historical (1968 to 2018) moment magnitude (Mw) 4.7 to 6.6 reverse earthquakes in Australia are analyzed using statistical techniques and compared to magnetic, gravity, and stress trajectory datasets. Of the total combined (summative) length of all surface [...]
Thickness of the Saudi Arabian Crust
Published: 2020-11-05
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure
We analyzed P-wave receiver functions from seismic stations covering most of Saudi Arabia to map the thickness of the crust across the Arabian plate. We present an update of crustal-thickness estimates and fill in data gaps for the western shield and the rifted margin at the Red Sea, as well as the eastern Arabian platform. Our application of a conventional H-k stacking algorithm included [...]
Influence of ductile substrates and layer thickness on the spacing and topology of layer bound fault systems
Published: 2020-11-02
Subjects: Earth Sciences, Geology, Geophysics and Seismology, Sedimentology, Tectonics and Structure
Polygonal fault systems are extraordinary features of many fine grained sedimentary succession and have been described from a significant number of deepwater sedimentary basins over the last two decades. Their formation represents an important mechanism by which fine grained sediments compact often resulting in a variety of complex patterns for which several controlling factors have been [...]
Salt-magma interactions influence intrusion distribution and salt tectonics in the Santos Basin, offshore Brazil
Published: 2020-10-25
Subjects: Earth Sciences, Geology, Tectonics and Structure, Volcanology
Many sedimentary basins host thick evaporite (salt) deposits. Some of these basins also host extensive igneous intrusion networks. It thus seems inevitable that, in some locations, magma will interact with salt. Yet how interaction between these materials may influence salt tectonics or magma emplacement, particularly at the basin-scale, remains poorly understood. We use 3D seismic reflection [...]
Mapping and classifying large deformation from digital imagery: application to analogue models of lithosphere deformation
Published: 2020-10-25
Subjects: Geophysics and Seismology, Tectonics and Structure
Particle Image Velocimetry (PIV), an image cross-correlation technique, is widely used for obtaining velocity fields from series of images of deforming objects. Rather than instantaneous velocities, we are interested in reconstructing cumulative deformation, and use PIV-derived incremental displacements for this purpose. Our focus is on analogue models of tectonic processes, which can accumulate [...]
A single multi-scale and multi-sourced semi-automated lineament detection technique for detailed structural mapping with applications to geothermal energy exploration
Published: 2020-10-23
Subjects: Geology, Geomorphology, Tectonics and Structure
A multitude of semi-automated algorithms, many incorporating multi-sourced datasets into a single analysis, now exist. However, these operate at a fixed pixel resolution resulting in multi-sourced methods being limited by the largest input pixel size. Multi-scale lineament detection circumvents this issue and allows increased levels of detail to be captured. In this study we present a [...]
Multi-layered salt-prone stratigraphy and its influence on rift-basin development; The Slyne and Erris basins, offshore NW Ireland
Published: 2020-10-21
Subjects: Tectonics and Structure
While salt-influenced rift basins have been identified across the European Atlantic margin, the Irish Atlantic margin remains the exception despite salt being proven in several boreholes. Using an extensive seismic database coupled with data from exploration wells and shallow boreholes, this study maps the distribution and composition of salt layers and investigates their role in the structural [...]
Fernandes and Roberts (2020) - preprint
Published: 2020-08-17
Subjects: Earth Sciences, Environmental Sciences, Geology, Geomorphology, Paleobiology, Physical Sciences and Mathematics, Planetary Sciences, Tectonics and Structure
There are many geoscience problems for which constraining histories of uplift or subsidence of Earth’s surface is of direct or indirect importance, for example reconstructing tectonics, mantle convection, geomorphology, sedimentary and chemical flux, biodiversity, glacio-eustasy and climate change. The least equivocal constraints on timing and amplitude of vertical motions on geological [...]
Taking the pulse of salt-detached gravity gliding in the eastern Mediterranean
Published: 2020-08-06
Subjects: Earth Sciences, Physical Sciences and Mathematics, Tectonics and Structure
We investigate early-stage salt-detached gliding using a 3D seismic dataset from the Levant Margin in the Eastern Mediterranean, where gravitational instability due to margin uplift has caused north-westward translation of the Messinian salt sheet and its Plio-Pleistocene clastic overburden. Large, NE-trending, base-salt anticlines have allowed the basinward translation to be recorded by the [...]