Preprints
Filtering by Subject: Earth Sciences
Chevrons: origin and relevance for the reconstruction of past wind regimes
Published: 2020-12-15
Subjects: Climate, Earth Sciences, Geology, Geomorphology, Meteorology, Other Life Sciences, Sedimentology, Stratigraphy
Since its first use in the late 80’s, the term chevron has been employed in numerous studies to describe large U- and V-shaped ridges found in or near shorelines worldwide. Most studies have so far focused on Bahamian chevrons that are exclusively of Late Pleistocene age, and on the supposed Holocene chevrons found in S-Madagascar and Australia. In the Bahamas, these deposits have been [...]
Anatomy of Strike Slip Fault Tsunami-genesis
Published: 2020-12-13
Subjects: Earth Sciences, Engineering, Fluid Dynamics, Geophysics and Seismology, Physical Sciences and Mathematics, Physics
Tsunami generation from earthquake induced seafloor deformations has long been recognized as a major hazard to coastal areas. Strike-slip faulting has generally been believed as insufficient for triggering large tsunamis, except through the generation of submarine landslides. Herein, we demonstrate that ground motions due to strike-slip earthquakes can contribute to the emergence of large [...]
Inference of thermodynamic state in the asthenosphere from anelastic properties, with applications to North American upper mantle
Published: 2020-12-13
Subjects: Earth Sciences, Physical Sciences and Mathematics
Inference of thermodynamic state and full-spectrum mechanical behavior of the lithosphere and asthenosphere is a central problem in geophysics, implicating our understanding of the convection patterns, transient responses and chemical composition of the planet. Anelasticity is responsible for significant relaxation of stress associated with seismic wave propagation in the asthenosphere, while [...]
Atmospheric CO2 estimates for the last 17 million years based on foraminiferal δ11B at Ocean Drilling Program Sites 806 and 807 in the Western Equatorial Pacific
Published: 2020-12-13
Subjects: Earth Sciences, Environmental Sciences, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
Constraints on the evolution of atmospheric CO2 levels throughout Earth’s history are foundational to our understanding of past variations in climate. Despite considerable effort, estimates of past CO2 levels do not always converge. Here we reconstruct atmospheric CO2 values across major climate transitions over the past 17 million years using the boron isotopic composition (δ11B) of planktic [...]
Mixed carbonate-siliciclastic tidal sedimentation in the Miocene to Pliocene Bouse Formation, palaeo-Gulf of California
Published: 2020-12-09
Subjects: Earth Sciences
Mixed carbonate-siliciclastic deposits provide unique insights into hydrodynamic processes that control sedimentation in tidal systems. This study presents sedimentologic an¬¬d ichnologic data from the upper Miocene¬ to lower Pliocene Bouse Formation, which accumulated during regional transgression at the margin of a tidal strait near the north end of the ancestral Gulf of California. The basal [...]
The precession constant and its long-term variation
Published: 2020-12-08
Subjects: Astrophysics and Astronomy, Earth Sciences, Physical Sciences and Mathematics, Planetary Sciences
The dynamical flattening of the Earth, H, related to the precession constant, is a fundamental astro-geodetic parameter that appears in studies of the Earth's rotation and orbital evolution. We present numerical predictions and observations of the variation in H over time scales ranging from tens of millions of years to decades. The geophysical processes controlling this variation include [...]
VESIcal Part I: An open-source thermodynamic model engine for mixed volatile (H2O-CO2) solubility in silicate melts
Published: 2020-12-08
Subjects: Earth Sciences, Geochemistry, Geology, Physical Sciences and Mathematics, Planetary Geochemistry, Planetary Geology, Planetary Sciences, Volcanology
Thermodynamics has been fundamental to the interpretation of geologic data and modeling of geologic systems for decades. However, more recent advancements in computational capabilities and a marked increase in researchers’ accessibility to computing tools has outpaced the functionality and extensibility of currently available modeling tools. Here we present VESIcal (Volatile Equilibria and [...]
International disparities in open access practices in the Earth Sciences
Published: 2020-12-08
Subjects: Earth Sciences, Physical Sciences and Mathematics
Background. Open Access (OA) describes the free, unrestricted access to and re-use of research articles. Recently, a new wave of interest, debate, and practice surrounding OA publishing has emerged. Objectives. The paper presented here focuses on international disparities in OA publication practices of the Earth Science community. We aim to provide an overview of actual publication practices and [...]
Reconstructing Magma Storage Depths for the 2018 Kīlauean Eruption from Melt inclusion CO2 Contents: The Importance of Vapor Bubbles
Published: 2020-12-05
Subjects: Earth Sciences
The 2018 lower East Rift Zone (LERZ) eruption and the accompanying collapse of the summit caldera marked the most destructive episode of activity at Kīlauea Volcano in the last 200 years. The eruption was extremely well-monitored, with extensive real-time lava sampling as well as continuous geodetic data capturing the caldera collapse. This multi-parameter dataset provides an exceptional [...]
Stalagmite carbon isotopes suggest deglacial increase in soil respiration in Western Europe driven by temperature change
Published: 2020-12-03
Subjects: Biogeochemistry, Climate, Earth Sciences, Geochemistry, Physical Sciences and Mathematics, Speleology
The temperate region of Western Europe underwent dramatic climatic and environmental change during the last deglaciation. Much of what is known about the terrestrial ecosystem response to deglacial warming stems from pollen preserved in sediment sequences, providing information on vegetation composition. Other ecosystem processes, such as soil respiration, remain poorly constrained over past [...]
Cascadia megathrust earthquake rupture model constrained by geodetic fault locking
Published: 2020-11-30
Subjects: Earth Sciences
Paleo-earthquakes along the Cascadia subduction zone inferred from offshore sediments and Japan coastal tsunami deposits approximated to M9+ and ruptured the entire margin. However, due to the lack of modern megathrust earthquake records and generally quiescence of subduction fault seismicity, the potential megathrust rupture scenario and influence of downdip limit of the seismogenic zone are [...]
Chemistry speedup in reactive transport simulations: purely data-driven and physics-based surrogates
Published: 2020-11-30
Subjects: Earth Sciences, Geochemistry
The computational costs associated with coupled reactive transport simulations are mostly due to the chemical subsystem: replacing it with a pre-trained statistical surrogate is a promising strategy to achieve decisive speedups at price of small accuracy losses and thus to extend the scale of problems which can be handled. We introduce a hierarchical coupling scheme in which ``full [...]
The shape of volcanic conduits inferred from bubble size distributions
Published: 2020-11-29
Subjects: Earth Sciences, Volcanology
The most intense known explosive volcanic eruptions on Earth are Plinian eruptions of silicic magma. Geospeedometers indicate that Plinian magma erupts from high pressure within the magma chamber at average speeds of 0.001-1 MPa/s. Concurrently dissolved magmatic volatiles, predominantly water, nucleate about one quadrillion bubbles per cubic meter of melt, preserved as vesicles within tephra. [...]
Carbonate clumped isotope analysis (Δ47) of 21 carbonate standards determined via gas source isotope ratio mass spectrometry on four instrumental configurations using carbonate-based standardization and multi-year datasets
Published: 2020-11-29
Subjects: Chemistry, Earth Sciences, Physical Sciences and Mathematics
Rationale: Clumped isotope geochemistry examines the pairing or clumping of rare, heavy isotopes in molecules and provides information about the thermodynamic and kinetic controls on their formation. Since clumped isotope measurements of carbonate minerals were first published 15 years ago, interlaboratory offsets in calibrations have been observed, and laboratory and community practices for [...]
Reconstructing the morphologies and hydrodynamics of ancient rivers from source to sink: Cretaceous Western Interior Basin, Utah, USA
Published: 2020-11-25
Subjects: Earth Sciences, Geology, Geomorphology, Hydrology, Sedimentology, Stratigraphy
Quantitative reconstruction of palaeohydrology from fluvial stratigraphy provides sophisticated insights into the response, and relative impact, of tectonic and climatic drivers on ancient fluvial landscapes. Here, field measurements and a suite of quantitative approaches are used to develop a four-dimensional (space and time) reconstruction of palaeohydrology in Late Cretaceous palaeorivers of [...]