Preprints
Filtering by Subject: Tectonics and Structure
A genetic model of the magnetite-apatite deposits on El Laco volcano by extrusion of iron-rich melt
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
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 [...]
Extensional Deformation of a Shale-dominated Delta: Tarakan Basin, Offshore Indonesia
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
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
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 local to sites or has 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 mechanical [...]
Slab to back-arc to arc: fluid and melt pathways through the mantle wedge beneath the Lesser Antilles
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
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.
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
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
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
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
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
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”
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 [...]
The signature of lithospheric anisotropy at post-subduction continental margins: new insight from XKS splitting analysis in northern Borneo
Published: 2022-05-02
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure
The relative paucity of recent post-subduction environments globally has meant that, so far, little is known about tectonic processes that occur during and after subduction termination, as previously convergent tectonic plates adjust to the new stress regime. The region of Southeast Asia that now encompasses northern Borneo has been host to two sequential episodes of subduction—both now [...]