Preprints

Filtering by Subject: Tectonics and Structure

Rapid fault healing after seismic slip

John Bedford, Takehiro Hirose, Yohei Hamada

Published: 2022-09-01
Subjects: Earth Sciences, Geology, Geophysics and Seismology, Tectonics and Structure

Fault strength recovery (healing) following an earthquake is a key process in controlling the recurrence of future events; however, the rates and mechanisms of fault healing are poorly constrained. Here, by performing high-velocity friction experiments, we show that granite and gabbro fault gouges recover their strength rapidly after experiencing dynamic weakening during seismic slip. The healing [...]

A genetic model of the magnetite-apatite deposits on El Laco volcano by extrusion of iron-rich melt

Tobias Keller, Fernando Tornos, John M. Hanchar, et al.

Published: 2022-08-25
Subjects: Dynamical Systems, Earth Sciences, Fluid Dynamics, Geochemistry, Geology, Numerical Analysis and Scientific Computing, Physical Sciences and Mathematics, Tectonics and Structure, Volcanology

Magnetite-apatite deposits are important sources of iron and other metals. A prominent exam- ple are the magnetite lavas at the El Laco volcano, Northern Chile. Their formation processes remain debated. Here, we test the genetic hypothesis that an Fe-rich melt separated from silicate magma and ascended along collapse-related fractures. We complement recent analy- ses with thermodynamic modelling [...]

Drift velocity partitioning indicates anomalous high westward drift component for the Indian plate during ~65 ± 2 Ma

Amarjeet Ramesh Bhagat, S J Sangode, Ashish Dongre

Published: 2022-08-17
Subjects: Earth Sciences, Geology, Tectonics and Structure

Rapid northward drift of the Indian plate after 130 Ma has also recorded significant plate rotations due to the torques resulting from multiple vector force components. Seismic tomography of the Indian Ocean and palaeomagnetic database of the Deccan Traps are used here to constrain drift velocities at different temporal snapshots, resulting into estimates of 263.2 to 255.7 mmyr-1 latitudinal [...]

DEFORMATION OF A SHALE-DOMINATED DELTA: TARAKAN BASIN, OFFSHORE INDONESIA

Aurio Erdi, Christopher Aiden-Lee Jackson, Juan I. Soto

Published: 2022-08-04
Subjects: Geology, Sedimentology, Tectonics and Structure

Deformation on shale-rich continental margins is commonly associated with thin-skinned extension above mobile shales. Normal faulting and shale mobilization are widespread on such margins, being associated with and controlled by progradation and gravitational failure of deltaic sedimentary wedges. However, due to limitations in our ability to seismically imaging these mobile shales, our [...]

Time-variable Strain and Stress Rates Induced by Holocene Glacial Isostatic Adjustment in Continental Interiors

Timothy J Craig, Eric Calais, Luce Fleitout, et al.

Published: 2022-08-04
Subjects: Tectonics and Structure

In continental interiors, tectonically-driven deformation rates are low, often to the point where they are undetectable with modern geodesy. However, a range of non-tectonic surface processes, particularly relating to hydrological, cryospheric, and sedimentological mass changes, can produce strain-rates which on geologically-short timescales are substantially greater than those produced by [...]

Mechanical Analysis of Fault Slip Rate Sites within the San Gorgonio Pass Region, Southern California USA

Jennifer L. Hatch, Michele Lynn Cooke, Hanna Marie Elston

Published: 2022-07-16
Subjects: Earth Sciences, Tectonics and Structure

Crustal deformation models show incompatibility between inferred fault geometry and geologic slip rates where model and geologic slip rates disagree. We do not know if the impact of these incompatibilities is limited to near sites or have wider effect on the fault system deformation. Here, we investigate the roles of structural position of sites and uncertainty of slip rates using one suite of [...]

Slab to back-arc to arc: fluid and melt pathways through the mantle wedge beneath the Lesser Antilles

Stephen Paul Hicks, Lidong Bie, Catherine Rychert, et al.

Published: 2022-07-14
Subjects: Earth Sciences, Geochemistry, Geophysics and Seismology, Tectonics and Structure, Volcanology

Volatiles expelled from subducted plates melt the overlying warm mantle, feeding arc volcanism. However, debates continue over the factors controlling melt generation and transport and how these determine the placement of volcanoes. To broaden our synoptic view of these fundamental mantle wedge processes, we image seismic attenuation beneath the Lesser Antilles arc, an end-member system that [...]

Understanding Sampling Bias in the Global Heat Flow Compilation

Tobias Stål, Anya M. Reading, Sven Fuchs, et al.

Published: 2022-06-17
Subjects: Databases and Information Systems, Earth Sciences, Geology, Tectonics and Structure

Geothermal heat flow is commonly inferred from the gradient of temperature values in boreholes. Such measurements are expensive and logistically challenging in remote locations and, therefore, often targeted to regions of economic interest. As a result, measurements are not distributed evenly. Some tectonic, geologic and even topographic settings are overrepresented in global heat flow [...]

How to drain a megalake: Comments on a study by Palcu et al. (2021) Scientific Reports 11, Art. Nr.: 11471.

Michal Šujan, Natália Hudáčková, Imre Magyar

Published: 2022-05-27
Subjects: Earth Sciences, Geology, Oceanography, Paleobiology, Paleontology, Sedimentology, Stratigraphy, Tectonics and Structure

In a recent paper by Palcu et al. (2021: Scientific Reports 11, Art. Nr.: 11471), the Cape Panagia section on the Taman peninsula (Russian Black Sea) was dated using magnetostratigraphy, in order to calibrate the timing of previously published regressions of the Paratethys megalake. The authors of the paper claim that this “largest megalake in the geological record” experienced four major [...]

Salt-detached strike-slip faulting, Outer Kwanza Basin, Offshore Angola

Aurio Erdi, Christopher Aiden-Lee Jackson

Published: 2022-05-25
Subjects: Geology, Geophysics and Seismology, Stratigraphy, Tectonics and Structure

We here use a 3D seismic reflection dataset from Outer Kwanza Basin, offshore Angola to examine the structure and growth of salt-detached strike-slip faults. The faults occur in four, up to 13.8 km-long, NE-trending arrays that are physically linked by restraining bend and releasing stepovers, and which presently overlie Aptian salt and base-salt relief related to pre-salt faulting. We suggest [...]

Geometry and growth of syn-tectonic plutons emplaced in thrust shear zones: Insights from Abu Ziran Pluton, Egypt

Abdullah T. Mohammad, Yahia El Kazzaz

Published: 2022-05-20
Subjects: Earth Sciences, Physical Sciences and Mathematics, Tectonics and Structure

Coupling of deformation and magmatism has been reported in several old orogenic belts, particularly along thrust faults and shear zones. The syn-kinematic plutons in exhumed shear zones offer the best opportunity to understand the complex relationship between magmatism and regional deformation. The present paper investigates the geometry and internal structure of granite plutons emplaced in [...]

Time-Dependent Decrease in Fault Strength in the 2011--2016 Ibaraki-Fukushima Earthquake Sequence

Sam Wimpenny, Natalie Forrest, Alex Copley

Published: 2022-05-19
Subjects: Earth Sciences, Tectonics and Structure

Two near-identical Mw 5.8 earthquakes in 2011 and 2016 ruptured the Mochiyama Fault in the Ibaraki-Fukushima region of Japan. The unusually short repeat time between the two earthquakes provides a rare opportunity to estimate the evolution of stress on a fault through an earthquake cycle, as the stress drop in the first earthquake provides a reference value from which we can infer variations [...]

A very unconventional hydrocarbon play: the Mesoproterozoic Velkerri Formation of Northern Australia

Grant Cox, Alan S. Collins, Amber J.M. Jarrett, et al.

Published: 2022-05-16
Subjects: Geochemistry, Geology, Sedimentology, Stratigraphy, Tectonics and Structure

The ca. 1.5–1.3 Ga Roper Group of the greater McArthur Basin is a component of one of the most extensive Precambrian hydrocarbon-bearing basins preserved in the geological record, recently assessed as containing 429 million barrels of oil and eight trillion cubic feet of gas (in place). It was deposited in an intra-cratonic sea, referred to here as the McArthur-Yanliao Gulf. The Velkerri [...]

Complex fault system revealed from 3-D seismic reflection data with deep learning and fault network analysis

Thilo Wrona, Indranil Pan, Rebecca E. Bell, et al.

Published: 2022-05-13
Subjects: Artificial Intelligence and Robotics, Geology, Geophysics and Seismology, Tectonics and Structure

Understanding where normal faults are is critical to an accurate assessment of seismic hazard, the successful exploration for and production of natural (including low-carbon) resources, and for the safe subsurface storage of CO2. Our current knowledge of normal fault systems is largely derived from seismic reflection data imaging intra-continental rifts and continental margins. However, [...]

The CREp 36Cl exposure age calculator: development version “dev”

Irene Schimmelpfennig, Pierre-Henri BLARD, Jim Tesson, et al.

Published: 2022-05-04
Subjects: Geochemistry, Geology, Geomorphology, Glaciology, Sedimentology, Tectonics and Structure, Volcanology

Chlorine-36 (36Cl) is currently the only in situ cosmogenic nuclide applicable in carbonates, Ca- and K-rich feldspars and aphyric silicate rocks. Because the production reactions of 36Cl are more numerous and complex than those of other cosmogenic nuclides (e.g. 10Be, 3He), comprehensive and user-friendly calculators are essential for routine application of 36Cl to Earth surface research [...]

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