Preprints
Filtering by Subject: Earth Sciences
The hazards of unconfined pyroclastic density currents: a new synthesis and classification according to their deposits, dynamics, and thermal and impact characteristics
Published: 2021-06-08
Subjects: Earth Sciences, Physical Sciences and Mathematics, Volcanology
Pyroclastic density currents (PDCs) that escape their confining channels are among the most dangerous of volcanic hazards. These unconfined PDCs are capable of inundating inhabited areas that may be unprepared for these hazards, resulting in significant loss of life and damage to infrastructure. Despite their ability to cause serious impacts, unconfined PDCs have previously only been described [...]
Spatial and morphometric relationships of submarine landslides offshore west and southwest Iberia
Published: 2021-06-08
Subjects: Earth Sciences, Geology, Geomorphology, Sedimentology, Stratigraphy
Submarine landslides are ubiquitous geohazards in marine environments occurring at multiple scales. Increasing efforts have been made to catalogue and categorise submarine landslides in comprehensive databases, aiming to better understand their preconditioning and trigger factors. Using the recently compiled, open-access MAGICLAND dataset, we investigate the distribution and morphometric trends [...]
The effect of temperature-dependent material properties on simple thermal models of subduction zones
Published: 2021-06-03
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
To a large extent, the thermal structure of a subduction zone determines where seismicity occurs through the transition from brittle to ductile deformation and the depth of dehydration reactions. Thermal models of subduction zones can help understand this seismicity by accurate modelling of the thermal structure of the subduction zone. Here, we assess a common simplification in thermal models of [...]
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 [...]
Novel sensor array helps to understand submarine cable faults off West Africa
Published: 2021-05-28
Subjects: Earth Sciences, Environmental Sciences, Physical Sciences and Mathematics
Seabed telecommunication cables can be damaged or broken by powerful seafloor flows of sediment (called turbidity currents), which may runout for hundreds of kilometres into the deep ocean. These flows have the potential to affect multiple cables near-simultaneously over very large areas, so it is more challenging to reroute traffic or repair the cables. However, cable-breaking turbidity currents [...]
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 [...]
Quantifying the influence of conduit inclination on Taylor Bubble behaviour in basaltic magmas.
Published: 2021-05-27
Subjects: Earth Sciences, Physical Sciences and Mathematics, Volcanology
The ascent of single Taylor bubbles suspended in a range of Newtonian liquids, scaled to mimic basaltic magmas, within vertical and inclined tubes has been studied experimentally over the range 0° to 70° (where 0° is vertical and 90° is horizontal). Using measurements of Taylor bubble parameters (ascent velocity and film thickness) and morphology, alongside dimensionless numbers, we show that [...]
Quantifying the impact of lagged hydrological responses on the effectiveness of groundwater conservation
Published: 2021-05-27
Subjects: Earth Sciences, Hydrology, Physical Sciences and Mathematics
Many irrigated agricultural areas seek to prolong the lifetime of their groundwater resources by reducing pumping. However, it is unclear how lagged responses, such as reduced groundwater recharge caused by more efficient irrigation, may impact the long-term effectiveness of conservation initiatives. Here, we use a variably saturated, simplified surrogate groundwater model to: 1) analyze aquifer [...]
High-resolution petrographic evidence confirming detrital and biogenic magnetites as remanence carriers for Zongpu carbonates in the Gamba area, South Tibet
Published: 2021-05-26
Subjects: Earth Sciences
Paleocene carbonates from the Gamba area of South Tibet provide the largest paleomagnetic dataset for constraining the paleogeography of the India-Asia collision in the early stage. The characteristic remanences (ChRMs) obtained from this unit were, however, argued for a chemical remagnetization via orogenic fluids. This study carries out a high-resolution petrographic study on the Paleocene [...]
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 [...]
A Short Note on the Age of the Marwar Supergroup, NW India
Published: 2021-05-23
Subjects: Earth Sciences
We report a summary of geochronological data derived from detrital zircons in the Marwar Supergroup, Rajasthan, India. Although the age of deposition for the Marwar sequence was inferred to be post-Cryogenian, there is a lack of any direct age data. Two recent papers reached different conclusions based on geochronological data. A Rb-Sr age on a felsic flow within the Sonia sandstone yielded [...]
Tectonostratigraphy of the northern Okavango Delta and Rift Zone, Botswana
Published: 2021-05-21
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure
The Okavango Rift Zone (ORZ) and Okavango Delta in Northwest Botswana are Earth’s youngest continental rift system and largest inland delta. The delta and its underlying sediments record the effects of incipient rifting on the geomorphology and stratigraphy within the (incipient) southwestern arm of the East African Rift System in Botswana. Three open questions that we use river-borne [...]
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 [...]
Chromium evidence for protracted oxygenation during the Paleoproterozoic
Published: 2021-05-18
Subjects: Earth Sciences, Geochemistry, Paleobiology
It has commonly been proposed that the development of complex life—e.g., aerobic eukaryotes—coincided with atmospheric oxygenation. To test this hypothesis, we measured chromium-based oxygen proxies in a >2400-m core from the Onega Basin (NW-Russia), deposited ~2.1–2.0 billion years ago—closely preceding the first eukaryote fossils. Fractionated chromium isotopes are documented throughout the [...]