Preprints
Filtering by Subject: Geology
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: 2021-05-24
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 [...]
The influence of rock uplift rate on the formation and preservation of individual marine terraces during multiple sea level stands
Published: 2021-05-13
Subjects: Climate, Geology, Geomorphology
Marine terraces are a cornerstone for the study of paleo sea level and crustal deformation. Commonly, individual erosive marine terraces are attributed to unique sea level high-stands. This stems from early reasoning that erosive marine platforms could only be significantly widened at the beginning of an interglacial. However, this implies that wave erosion is insignificant during the vast [...]
The influence of crustal strength on rift geometry and development – Insights from 3D numerical modelling
Published: 2021-05-07
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Tectonics and Structure
The lateral distribution of strength within the crust is non-uniform, dictated by crustal lithology and the presence and distribution of heterogeneities within it. During continental extension, areas of crust with distinct lithological and rheological properties manifest strain differently, influencing the structural style, geometry and evolution of the developing rift system. Here, we use 3D [...]
Fracture distribution in a folded fluvial succession: the Puig-reig anticline (South-eastern Pyrenees)
Published: 2021-05-07
Subjects: Geology, Sedimentology, Stratigraphy, Tectonics and Structure
Sedimentary rocks of foreland fold-and-thrust belts typically undergo intensive fracturing as fold grows. The resulting fracture networks can present significant variations depending on the distribution of sedimentary facies and the complex structural characteristics of fold-and-thrust belts. The Puig-reig anticline, located in the south-eastern Pyrenees, mainly exposes proximal fluvial deposits [...]
Syn- to post-rift alluvial basin fill: seismic stratigraphic analysis of Permian-Triassic deposition in the Horda Platform, Norway
Published: 2021-05-02
Subjects: Geology, Geomorphology, Sedimentology, Stratigraphy, Tectonics and Structure
Discrepancies in models of continental rift-basin dynamics and stratigraphic response calls on further investigation on the subject. Geometric- and lithological trends between stages of faulting is studied in the Permian- Triassic continental rift succession in the Horda Platform. The Horda Platform occupies the northeastern margin of the North Sea aulacogen where Late Permian-Early Triassic [...]
Late Paleozoic–Early Mesozoic granitoids in the Khangay–Khentey basin, Central Mongolia: Implication for the tectonic evolution of the Mongol–Okhotsk Ocean margin
Published: 2021-04-26
Subjects: Geochemistry, Geology
The Mongol–Okhotsk Belt is the youngest segment of the Central Asian Orogenic Belt, which is the venue of the massive juvenile crust emplacement, and it is formation and evolutions are still pending problems. This paper presents the first up-to-date U-Pb zircon ages, Hf-in-zircon isotope, geochemical and whole-rock Nd isotope data from igneous rocks of the Khangay–Khentey basin, Central Mongolia. [...]
Bridging Spatiotemporal Scales of Normal Fault Growth During Continental Extension Using High-Resolution 3D Numerical Models
Published: 2021-04-22
Subjects: Earth Sciences, Geology, Geophysics and Seismology, Other Earth Sciences, Physical Sciences and Mathematics, Tectonics and Structure
Continental extension is accommodated by the development of kilometre-scale normal faults, which grow during metre-scale slip events that occur over millions of years. However, reconstructing the entire lifespan of a fault remains challenging due to a lack of observational data with spatiotemporal scales that span the early stage (<10^6 yrs) of fault growth. Using 3D numerical simulations of [...]