Preprints
Filtering by Subject: Geology
Spatial characteristics and kinematics of floodplain aggradation cycles in the lower Eocene Willwood Formation of the Bighorn Basin, Wyoming, USA
Published: 2021-06-07
Subjects: Geology, Sedimentology, Stratigraphy
Interaction of allogenic and autogenic forcing in building alluvial stratigraphy remains a complex subject that is critical for paleoenvironmental and paleoclimate reconstruction and subsurface rock property prediction. Autogenic processes may act at similar vertical and lateral scales at which astronomical climate forcing drives alluvial stratigraphic deposition, making it difficult to [...]
Interphase misorientation as a tool to study metamorphic reactions and crystallization in geological materials
Published: 2021-06-07
Subjects: Geology, Mineral Physics, Other Earth Sciences
Interphase boundaries are planar defects that separate two different minerals, which in general have different compositions and/or crystalline structures and may play an important role as a pathway for fluids in rocks and affect their physical properties. For the proper characterization of interphase boundaries, one needs to define the misorientation between adjacent grains and the orientation of [...]
Syn-Depositional Halokinesis in the Zechstein Supergroup (Lopingian) Controls Triassic Minibasin Genesis and Location
Published: 2021-06-03
Subjects: Geology, Sedimentology, Tectonics and Structure
Salt tectonics is typically caused by the flow of mobile evaporites in response to post-depositional gravity gliding and/or differential loading by overburden sediments. This situation is considerably more complex near the margins of salt basins, where carbonate and clastic rocks may be deposited at the same time and interbedded with more mobile evaporitic strata. In these cases, syn-depositional [...]
Ductile deformation during carbonation of serpentinized peridotite
Published: 2021-06-01
Subjects: Geology
Carbonated serpentinites (listvenites) in the Oman Ophiolite record mineralization of several GT of CO2, but the mechanisms providing permeability for continued reactive fluid flow are unclear. Samples of the Oman Drilling Project show that listvenites with a penetrative foliation have abundant microstructures related to crystal growth and indicate that the carbonation reaction occurred during [...]
Tectonic Studies Group Equality Diversity and Inclusion report 2021
Published: 2021-05-28
Subjects: Earth Sciences, Geology, Tectonics and Structure
In 2021, the TSG Annual Meeting was held online due to the coronavirus pandemic. To build on our 2019 gender diversity report, we wanted to begin gathering diversity data proactively and anonymously. This will enable us to be more inclusive of marginalised genders, avoid mis-gendering participants and to collect a wider range of diversity data. We ran a survey of the presenters and session chairs [...]
Deep-water syn-rift stratigraphy as archives of Early-Mid Pleistocene palaeoenvironmental signals and controls on sediment delivery
Published: 2021-05-27
Subjects: Earth Sciences, Geology, Geomorphology, Sedimentology, Stratigraphy
The timing and character of coarse siliciclastic sediment delivered to deep-water environments in active rift basins is governed by the complicated interactions of tectonics, climate, eustasy, hinterland geology, and shelf process regime. The stratigraphic archives of deep-water syn-rift basin-fills provide records of palaeoenvironmental changes (e.g. climate and vegetation) in onshore [...]
Meteorites that produce K-feldspar-rich ejecta blankets correspond to mass extinctions.
Published: 2021-05-24
Subjects: Applied Statistics, Atmospheric Sciences, Earth Sciences, Geology, Other Planetary Sciences, Paleontology, Physical Sciences and Mathematics
Meteorite impacts load the atmosphere with dust and cover the Earth‘s surface with debris. They have long been debated as a trigger of mass extinctions through Earth‘s history. Impact winters generally last <100 years, whereas ejecta blankets persist for 10^3-10^5 years. Here we show that only meteorite impacts that emplaced ejecta blankets rich in K-feldspar (Kfs) correlate to Earth system [...]
What sets aeolian dune height?
Published: 2021-05-23
Subjects: Climate, Earth Sciences, Geology, Geomorphology, Physical Sciences and Mathematics, Sedimentology, Stratigraphy
Earth's major sand seas are often populated with giant dunes, up to hundreds of meters in height and kilometers in wavelength. These massive sediment piles, visible from space on our planet and across the Solar System, indicate that conditions for sand transport have persisted for millenia. Unraveling how giant dunes form therefore has implications for understanding atmospheric flows and climatic [...]
Inferring rheology and geometry of subsurface structures by adjoint-based inversion of principal stress directions
Published: 2021-05-21
Subjects: Geology, Geophysics and Seismology, Tectonics and Structure
Imaging subsurface structures, such as salt domes, magma reservoirs, or subducting plates, is a major challenge in geophysics. Seismic imaging methods are, so far, the most precise methods to open a window into the Earth. However, the methods may not yield the exact depth or size of the imaged feature and may become distorted by phenomena such as seismic anisotropy, fluid flow, or compositional [...]
Exhuming the Canadian Shield: preliminary interpretations from low-temperature thermochronology and significance for the sedimentary succession of the Hudson Bay Basin
Published: 2021-05-20
Subjects: Earth Sciences, Geochemistry, Geology, Physical Sciences and Mathematics, Stratigraphy, Tectonics and Structure
The geological history of the Canadian Shield is difficult to constrain because the sedimentary record is missing in those areas where Precambrian basement is exposed at the surface. This study presents preliminary results and interpretations of new apatite fission-track (AFT) analyses to elucidate the low-temperature (< 120 °C) history across Canada. The AFT modelling of samples from Southampton [...]
Nature and timing of anatectic event of the Hida Belt (Japan): Constraints from titanite geochemistry and U-Pb age of clinopyroxene-bearing leucogranite
Published: 2021-05-17
Subjects: Geochemistry, Geology
The Hida Belt, central Japan, is a continental fragment, which was once a part of the crustal basement of the East Asian continental margin. It consists mainly of Permo-Triassic granite-gneiss complexes with both syn-to-late-metamorphic migmatite or granite bodies. Clinopyroxene-bearing leucogranite, locally called as 'Inishi'-type migmatite, occurs characteristically in the migmatite zone [...]
AMS and rock magnetism in the Caviahue-Copahue Volcanic Complex (Southern Andes): emission center, flow dynamics, and implications to the emplacement of non-welded PDCs
Published: 2021-05-14
Subjects: Earth Sciences, Geology, Geophysics and Seismology, Physical Sciences and Mathematics, Volcanology
Pyroclastic deposits can cover significant areas and register major geological events. Despite their importance, understanding depositional dynamics of pyroclastic density currents (PDCs) and linking explosive deposits to their emission centers is still a challenge, especially in the case of non-welded, massive ignimbrites. Located in the Southern Andes, the Caviahue Copahue Volcanic Complex [...]
A damage model for the frictional shear failure of brittle materials in compression
Published: 2021-05-13
Subjects: Applied Mathematics, Computational Engineering, Earth Sciences, Engineering, Geology, Materials Science and Engineering, Physical Sciences and Mathematics
Damage models have been successfully employed for many decades in the modelling of tensile failure, where the crack surfaces separate as a crack grows. The advantage of this approach is that crack trajectories can be computed simply and efficiently on a fixed finite element mesh without explicit tracking. The development of damage models for shear failure in compression, where the crack faces [...]
Geochemical signatures of rare earth elements and yttrium in the vicinity of an ion-adsorption type deposit: roles of source sediment control
Published: 2021-05-13
Subjects: Biogeochemistry, Geochemistry, Geology, Hydrology
The elevated concentrations of rare earth elements (REE) and yttrium (REE+Y) in acid mine drainage (AMD) constitute an opportunity for REE+Y recovery. However, the source and control of REE+Y signatures in AMD remains uncertain. Water, rock, sediment and sludge samples were collected from an ion-adsorption rare earth mining area to investigate REE+Y concentration and fractionation patterns in [...]
Influence of variable decoupling between vertically separated fault populations on structural inheritance – The Laminaria High, NW Shelf of Australia
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 [...]