Filtering by Subject: Tectonics and Structure

A record of plume-induced plate rotation triggering seafloor spreading and subduction initiation

Douwe J.J. van Hinsbergen, Bernhard Steinberger, Carl Guilmette, Marco Maffione, Derya Gürer, Kalijn Peters, Alexis Plunder, Peter McPhee, Carmen Gaina, Eldert L. Advokaat, Reinoud L.M. Vissers, Wim Spakman

Published: 2021-02-23
Subjects: Earth Sciences, Geology, Tectonics and Structure

The formation of a global network of plate boundaries surrounding a mosaic of lithospheric fragments was a key step in the emergence of Earth’s plate tectonics. So far, propositions for plate boundary formation are regional in nature but how plate boundaries are being created over 1000s of km in short periods of geological time remains elusive. Here, we show from geological observations that a [...]

The surface deformation of the 2020 Doğanyol-Sivrice earthquake (Mw 6.8) and the earlier events suggest Mw˂7.0 earthquakes do not create significant surface slip along the East Anatolian Fault Zone

Kenan Akbayram, Kemal Kıranşan, Çağlar Özer, Sadık Varolgüneş

Published: 2021-02-18
Subjects: Geology, Geophysics and Seismology, Tectonics and Structure

The 2020 Mw 6.8 Doğanyol-Sivrice earthquake occurred on the Pütürge Segment of the left-lateral East Anatolian Fault Zone (EAFZ). Our field investigation within 6 weeks after the earthquake suggests the following results. (1) The 2020 earthquake created a ~54-km-long surface deformation zone along the Pütürge Segment. (2) No co-seismic surface slip has been formed after the earthquake. (3) The [...]

Structural and stratigraphic development of Offshore NW Sulawesi, Indonesia

Herwin Tiranda, Robert Hall

Published: 2021-02-14
Subjects: Earth Sciences, Geology, Geomorphology, Sedimentology, Stratigraphy, Tectonics and Structure

The area of the Offshore NW Sulawesi lies between eastern Sundaland (Borneo) and the North Arm of Sulawesi. Possible influences on the basins include Paleogene rifting in the Celebes Sea and Makassar Strait, Neogene subsidence and uplift in Borneo, late Neogene subduction at the present-day North Sulawesi Trench, and displacements related to the Palu-Koro Fault. This study presents the results of [...]

234U/230Th coral growth dating yields reliable ages in restricted basins despite anomalous δ234Ui values

Jenni Robertson, Diana Sahy, Gerald P Roberts, Marco Meschis

Published: 2021-02-10
Subjects: Geochemistry, Geology, Tectonics and Structure

Late Quaternary coral growth ages from uplifted coastal regions, such as marine terraces and associated palaeoshorelines, are an essential tool used to derive tectonic and fault controlled uplift and deformation rates, and thus contribute to seismic hazard analysis and constrain past global sea levels. Fossil coral growth ages are assessed for reliability based upon whether the δ234Ui (or [...]

Shear wave velocity structure beneath North-Western Himalaya and adjoining areas

Ramees R Mir, Imtiyaz A Parvez, Vinod K Gaur

Published: 2021-01-30
Subjects: Earth Sciences, Physical Sciences and Mathematics, Tectonics and Structure

Shear wave velocity structure, together with Moho depths have been estimated in northwestern Himalaya, Hindu Kush and the Pamirs at a potential resolution of 0.5×0.5 degrees and at 1×1 degrees in the surrounding area, by inverting fundamental mode Rayleigh wave group velocities calculated from regional earthquake (Δ ≤ 2500 km) data, and also from their joint inversions with teleseismic receiver [...]

Fault Throw and Regional Uplift Histories from Drainage Analysis: Evolution of Southern Italy

Jennifer Quye-Sawyer, Alexander C Whittaker, Gareth Roberts, Dylan H. Rood

Published: 2021-01-25
Subjects: Earth Sciences, Geology, Geomorphology, Tectonics and Structure

Landscapes can record elevation changes caused by multiple tectonic processes. Here we show how coeval histories of spatially coincident normal faulting and regional uplift can be deconvolved from river networks. We focus on Calabria, a tectonically active region incised by rivers containing knickpoints and knickzones. Marine fauna indicate that Calabria has been uplifted by >1 km since [...]

Observational estimates of dynamic topography through space and time

Mark Hoggard, Jacqueline Austermann, Cody Randel, Simon Stephenson

Published: 2021-01-24
Subjects: Biogeochemistry, Cosmochemistry, Earth Sciences, Geochemistry, Geology, Geomorphology, Geophysics and Seismology, Paleobiology, Physical Sciences and Mathematics, Sedimentology, Stratigraphy, Tectonics and Structure, Volcanology

Earth's mantle undergoes convection on million-year timescales as heat is transferred from depth to the surface. Whilst this flow has long been linked to the large-scale horizontal forces that drive plate tectonics and supercontinent cycles, geologists are increasingly recognising the signature of convection through transient vertical motions in the rock record, known as "dynamic topography". A [...]

The building blocks of igneous sheet intrusions: insights from 3D seismic reflection data

Jonas Köpping, Craig Magee, Alexander R. Cruden, Christopher A-L Jackson, James Norcliffe

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

Vincent Twomey, William McCarthy, Craig Magee

Published: 2021-01-06
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

Gavin Elliott, Christopher A-L Jackson, Robert Leslie Gawthorpe, Paul Wilson, Ian Roger Sharp, Lisa Michelsen

Published: 2020-12-22
Subjects: Geology, Other Earth Sciences, Sedimentology, Tectonics and Structure

In salt-influenced rift basins the presence of a pre-rift salt layer will control the tectono-stratigraphic evolution of the rift due to the decoupling of the sub- and suprasalt faults leading to temporal and spatial variations in structural style. Lateral variations in rift flank structure will control the dispersal and volumes of sediment deposited in rifts and along rifted margins, which in [...]

The 2020 Mw 6.5 Monte Cristo Range, Nevada earthquake: relocated seismicity shows rupture of a complete shear-crack system

Anthony Lomax

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

Leif Tokle, Greg Hirth

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

Alexander Robert Blanchette, Simon L Klemperer, Walter D Mooney, Hani M Zahran

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

Haibin Yang, Mark Quigley, Tamarah King

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

Alexander Robert Blanchette, Simon L Klemperer, Walter D Mooney, Hani M Zahran

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 [...]


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