Preprints
Filtering by Subject: Geology
Continental scale hydrostratigraphy: comparing geologically informed data products to analytical solutions
Published: 2023-09-12
Subjects: Civil and Environmental Engineering, Geology, Hydrology
This study synthesizes two different methods for estimating hydraulic conductivity (K) at large scales. We derive analytical approaches that estimate K and apply them to the contiguous US. We then compare these analytical approaches to three-dimensional, national gridded K data products and three transmissivity (T) data products developed from publicly available sources. We evaluate these data [...]
The Role of Normal Fault Growth History in Influencing Fault Seal Potential, Samson Dome, Offshore Norway
Published: 2023-09-02
Subjects: Geology
The growth of normal faults can influence subsurface fluid flow and entrapment within rift basins. However, fault seal studies typically view faults as static structures, with their growth and the potential related temporal changes in hydraulic properties being ignored. In this study, we use borehole data and a high-quality 3D full-stack depth migrated seismic reflection volume to analyse the [...]
Full-waveform inversion as a tool to predict fault zone properties
Published: 2023-09-02
Subjects: Geology
Understanding the physical properties of fault zones is essential for various subsurface applications, including carbon capture and geologic storage, geothermal energy, and seismic hazard assessment. Despite improvements in fault imaging and visualisation, predicting the physical properties of faults and fault zones in the subsurface remains challenging, even with high-quality seismic reflection [...]
Generation of LOMU type alkali basalts in East Asia by melting and melt metasomatism of the asthenospheric mantle by a Paleoproterozoic subducted slab component
Published: 2023-08-30
Subjects: Geochemistry, Geology, Volcanology
The origin of alkali basalts with distinctive time-integrated low U/Pb (low µ, LOMU) from East Asia is controversial due to the complex geochemical and tectonic signatures reported from this region. We report new data on the petrology and geochemistry of the Higashi-Matsuura and Kita-Matsuura alkali basalts from southwest Japan, which confirm the presence of a LOMU-type mantle component below the [...]
Garnet zoning patterns record multiple processes of chemical transfer during subduction
Published: 2023-08-24
Subjects: Geology, Other Earth Sciences
Subduction facilitates the transfer of volatiles from the Earth’s surface to its interior. However, the rock-scale processes that govern the efficiency of deep volatile transfer are not fully understood. Garnets from subduction zone rocks commonly have fine-scale, oscillatory elemental zoning that is typically considered to record external fluid ingress/transfer. Elemental and oxygen-isotope [...]
Spontaneous Unsteadiness and Sorting in Pyroclastic Density Currents and their Deposits
Published: 2023-08-22
Subjects: Geology, Sedimentology, Stratigraphy, Volcanology
Pyroclastic density currents (PDCs) pose substantial risk to populations living on and around active volcanoes, but their structure and internal dynamics are poorly understood. Much of this understanding is derived from interpretation of their widespread deposits. Scaled experiments are able to probe different conditions, to explore how changing flow dynamics relate to the wide variety of [...]
Generation of evolving plate boundaries and toroidal flow from visco-plastic damage-rheology mantle convection and continents
Published: 2023-08-17
Subjects: Geology, Geophysics and Seismology, Tectonics and Structure
Earth's style of planetary heat transport is characterized by plate tectonics which requires rock strength to be reduced plastically in order to break an otherwise stagnant lithospheric lid, and for rocks to have a memory of past deformation to account for strain localization and the hysteresis implied by geological sutures. Here, we explore $\sim$10$^7$ Rayleigh number, visco-plastic, [...]
Eocene (50-55 Ma) greenhouse climate recorded in nonmarine rocks of San Diego, CA, USA
Published: 2023-08-08
Subjects: Chemistry, Climate, Earth Sciences, Geochemistry, Geology, Physical Sciences and Mathematics, Soil Science, Stratigraphy
Nonmarine rocks in sea cliffs of southern California store a detailed record of weathering under tropical conditions millions of years ago, where today the climate is much drier and cooler. This work examines early Eocene (~50-55 million-year-old) deeply weathered paleosols (ancient, buried soils) exposed in marine terraces of northern San Diego County, California, and uses their geochemistry and [...]
Tephra dispersal and composition reveal the explosive onset of a large basaltic fissure eruption: Timanfaya, Lanzarote, 1730–1736 CE
Published: 2023-08-03
Subjects: Earth Sciences, Geochemistry, Geology, Physical Sciences and Mathematics, Stratigraphy, Volcanology
Basaltic fissure eruptions are chiefly characterized by sizable emissions of lava flows and volcanic gases, posing significant hazards. However, such eruptions may be punctuated by explosive episodes, which are comparatively poorly understood but may have important volcanic hazard and environmental implications. The 1730–1736 CE Timanfaya eruption on Lanzarote, Canary Islands, is a large basaltic [...]
Soil geochemistry of hydrogen and other gases along the San Andreas Fault
Published: 2023-07-23
Subjects: Environmental Chemistry, Geochemistry, Geology, Multivariate Analysis, Oil, Gas, and Energy, Soil Science
Natural hydrogen has generated great interest as a potential clean and renewable energy source. To understand the occurrence of natural hydrogen, 103 1-m deep soil gas samples were acquired near the San Andreas Fault at Jasper Ridge and Portola Valley, California, USA. The gas samples were analyzed for hydrogen, helium, carbon dioxide, light hydrocarbons, and fixed gas concentrations. Statistical [...]
Physically based Probabilistic Rainfall Intensity-Duration (ID) Thresholds for Runoff-Generated Debris Flows
Published: 2023-07-21
Subjects: Earth Sciences, Geology, Geomorphology, Hydrology
Runoff-generated debris flows are common hazards in mountainous regions, causing millions of dollars lost and hundreds of casualties yearly. Early warning systems based on rainfall thresholds have been implemented to reduce the impact of these hazards. These thresholds tend to be based on short monitoring periods, which cannot fully capture the varying responses of catchments to rainfall. As a [...]
Discovery of a new 12-km impact crater candidate at As Sail Al Kabeer, Saudi Arabia
Published: 2023-07-11
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Planetary Geology, Planetary Sciences
The Arabian shield of Saudi Arabia likely has many impact craters due to the old age of its rocks, however many of them have not yet been discovered due to their resemblance to plutons. Using satellite imagery, a 12-km wide circular structure with a central peak was identified at As Sail Al Kabeer, 40 kilometers north of the city of Taif in western Saudi Arabia. Fieldwork has shown that this [...]
Sedimentology and sequence stratigraphy of shallow-marine, coarse-grained siliciclastic deposits in the southern Utsira High: the Late Jurassic intra-Draupne Formation sandstones in the Johan Sverdrup Field (Norwegian North Sea).
Published: 2023-06-30
Subjects: Earth Sciences, Geology, Sedimentology, Stratigraphy, Tectonics and Structure
Thin, condensed coarse-grained shallow-marine successions can be difficult to describe and interpret, especially in the subsurface because they commonly lack finer grained intervals which are typically associated with sequence stratigraphic surfaces. This lack of mudstones and siltstones means that they also typically make excellent reservoir intervals. The Oxfordian to Volgian intra-Draupne [...]
Mind the uncertainty: Global plate model choice impacts deep-time palaeobiological studies
Published: 2023-06-23
Subjects: Biodiversity, Climate, Earth Sciences, Ecology and Evolutionary Biology, Geology, Life Sciences, Paleobiology, Paleontology, Physical Sciences and Mathematics, Tectonics and Structure
1. Global plate models (GPMs) aim to reconstruct the tectonic evolution of the Earth by modelling the motion of the plates and continents through time. These models enable palaeobiologists to study the past distribution of extinct organisms. However, different GPMs exist that vary in their partitioning of the Earth's surface and the modelling of continental motions. Consequently, the preferred [...]
Innovating and networking global geochemical data resources through OneGeochemistry
Published: 2023-06-14
Subjects: Biogeochemistry, Cosmochemistry, Databases and Information Systems, Geochemistry, Geology, Planetary Biogeochemistry, Planetary Geochemistry, Planetary Geology, Volcanology
A vision of the not-to-distant future: Imagine yourself as a researcher who is making plans for fieldwork in the Andes Mountains. You are behind your computer and load a three-dimensional visualisation of the Earth and its geology to investigate the research already done in the southern Patagonian regions. You zoom in to the mountain range of interest and select various data layers to show [...]