Preprints
Filtering by Subject: Earth Sciences
Using bar preservation to constrain reworking in channel-dominated fluvial stratigraphy
Published: 2018-08-16
Subjects: Earth Sciences, Physical Sciences and Mathematics, Sedimentology, Stratigraphy
Fluvial deposits comprising more than 80% channel facies are often thought to have accumulated during intervals of relatively slow subsidence in sedimentary basins. This interpretation stems from the conceptual model that migrating and avulsing rivers rework their own deposits during times of limited accommodation creation, preferentially removing and bypassing fine floodplain deposits. [...]
Zealandia 2008
Published: 2018-08-16
Subjects: Earth Sciences, Physical Sciences and Mathematics, Tectonics and Structure
Zealandia is a submerged continent in the southwest Pacific Ocean that can be regarded as a rifted part of eastern Australia and West Antarctica. Described simply, the pre-Gondwana-breakup Zealandia geological record is one of a Cambrian to Early Cretaceous Gondwana convergent margin, followed by Late Cretaceous continental rifting. Arizona Geological Society Digest 22, 227-233.
Landers 1992 "reloaded": Integrative dynamic earthquake rupture modeling
Published: 2018-08-15
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
The 1992 $M_w$ 7.3 Landers earthquake is perhaps one of the best studied seismic events. However, many aspects of the dynamics of the rupture process are still puzzling, e.g. the rupture transfer between fault segments. We present 3D spontaneous dynamic rupture simulations, incorporating the interplay of fault geometry, topography, 3D rheology, off- fault plasticity and viscoelastic attenuation. [...]
Dalangtan Saline Playa in a Hyperarid Region of Tibet Plateua-III: Correlated Multiscale Surface Mineralogy and Geochemistry Survey
Published: 2018-08-15
Subjects: Earth Sciences, Geochemistry, Geology, Physical Sciences and Mathematics
We report the first multiscale, systematic field-based testing of correlations between orbital scale advanced spaceborne thermal emission and reflection radiometer visible near-infrared (VNIR)/shortwave infrared (SWIR) reflectance and thermal infrared relative emissivity and outcrop scale Raman spectroscopy, VNIR reflectance, X-ray diffraction (XRD), and laser-induced breakdown spectroscopy [...]
Weak and slow, strong and fast: How shear zones evolve in a dry continental crust (Musgrave Ranges, Central Australia)
Published: 2018-08-15
Subjects: Earth Sciences, Physical Sciences and Mathematics, Tectonics and Structure
The strike-slip Davenport Shear Zone in Central Australia developed during the Petermann Orogeny (~ 550 Ma) in an intracontinental lower crustal setting under dry sub-eclogite facies conditions (~ 650 °C, 1.2 GPa). This ca. 5 km wide mylonite zone encloses several large low-strain domains, allowing a detailed study of the initiation of shear zones and their progressive development. [...]
Intraplate seismic events off Sumatra: 3-D source evolution
Published: 2018-08-15
Subjects: Earth Sciences, Physical Sciences and Mathematics
Four large, dominantly strike-slip, earthquakes have occurred in recent years in the Wharton Basin off the coast of Sumatra. The southernmost was the Mw 7.9 event on 2000 June 18, followed by the largest known intraplate earthquake – the Mw 8.6 event on 2012 April 11, with an Mw 8.2 ‘aftershock’ within a few hours. The most recent Mw 7.8 event on 2016 March 2 happened in an area with no [...]
The different character of the recent eruptions of Galápagos shield volcanoes (Ecuador): La Cumbre vs. Sierra Negra
Published: 2018-08-14
Subjects: Earth Sciences, Physical Sciences and Mathematics, Volcanology
In the last year, two Galápagos volcanoes had shown eruptive activity. The three observed eruptions produced multiple lava flows along eruptive fissures and vents covering several square kilometers. After eight years of quiescence, La Cumbre volcano, Fernandina Island experienced two short-lived eruptions, on 4 September 2017 and 16 June 2018. The eruptions were characterized by very short [...]
Quantification of the Bed-scale Architecture of Submarine Depositional Environments and Application to Lobe Deposits of the Point Loma Formation, California
Published: 2018-08-12
Subjects: Earth Sciences, Geology, Geomorphology, Physical Sciences and Mathematics, Sedimentology, Stratigraphy
As of August 2018, this work is in review in "The Depositional Record", a journal from the IAS (International Association of Sedimentologists) Submarine-fan deposits form the largest sediment accumulations on Earth and host significant reservoirs for hydrocarbons. While many studies of ancient fan deposits qualitatively [...]
Characterisation of submarine depression trails driven by upslope migrating cyclic steps: Insights from the Ceará Basin (Brazil)
Published: 2018-08-08
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Sedimentology
Circular to elliptical topographic depressions, isolated or organized in trails, have been observed on the modern seabed in different contexts and water depths. Such features have been alternatively interpreted as pockmarks generated by fluid flow, as sediment waves generated by turbidity currents, or as a combination of both processes. In the latter case, the dip of the slope has been [...]
Ocean Drilling Perspectives on Meteorite Impacts
Published: 2018-08-08
Subjects: Earth Sciences, Geophysics and Seismology, Oceanography and Atmospheric Sciences and Meteorology, Paleobiology, Paleontology, Physical Sciences and Mathematics, Planetary Geomorphology, Planetary Geophysics and Seismology, Planetary Sciences, Stratigraphy
Extraterrestrial impacts are a ubiquitous process in the solar system, reshaping the surface of rocky bodies of all sizes. On early Earth, impact structures may have been a nursery for the evolution of life. More recently, a large meteorite impact caused the end-Cretaceous mass extinction, causing the extinction of 75% of species known from the fossil, including non-avian dinosaurs, and clearing [...]
New evidence for a major late Quaternary submarine landslide on the external western levee of Laurentian Fan
Published: 2018-08-07
Subjects: Earth Sciences, Geology, Geomorphology, Physical Sciences and Mathematics, Sedimentology, Stratigraphy
The Laurentian Fan is one of the largest submarine fans on the western margin of the North Atlantic. Recently acquired high-resolution multibeam bathymetric data (60 m horizontal resolution) reveal a major mass transport deposit (MTD) on the Western Levee of Western Valley (WLWV), covering >14 000 km2 in water depths from 3900 m to >5000 m. Typical submarine landslide features are observed [...]
Shark-fins: overturned patterns linked to shear instabilities at the flow-bed boundary. Examples from the deposits of the 2006 pyroclastic currents at Tungurahua volcano (Ecuador)
Published: 2018-08-06
Subjects: Earth Sciences, Geology, Geomorphology, Physical Sciences and Mathematics, Sedimentology, Volcanology
Enigmatic structures grouped under the term "shark-fins" are documented in laminated deposits of pyroclastic currents. They consist of an overturning of a few laminae on a decimeter scale, forming overbent "flames" or convolute laminae, which occur in successive, periodic patterns. More than 200 shark-fins were investigated and measured in cross-laminated deposits from the 2006 pyroclastic [...]
Pyroclastic dune bedforms: macroscale structures and lateral variations. Examples from the 2006 pyroclastic currents at Tungurahua (Ecuador)
Published: 2018-08-06
Subjects: Earth Sciences, Geology, Geomorphology, Physical Sciences and Mathematics, Sedimentology, Volcanology
Pyroclastic currents are catastrophic flows of gas and particles triggered by explosive volcanic eruptions. For much of their dynamics, they behave as particulate density currents and share similarities with turbidity currents. Pyroclastic currents occasionally deposit dune bedforms with peculiar lamination patterns, from what is thought to represent the dilute low concentration and [...]
Backprojection to image slip
Published: 2018-08-01
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Waveform backprojection is a key technique of earthquake-source imaging, which has been widely used for extracting information of earthquake source evolution that cannot be obtained by kinematic source inversion. The technique enjoys considerable popularity, owing to the simplicity of its implementation and the robustness of its processing, but the physical meaning of backprojection images has [...]
Dynamic viability of the 2016 Mw 7.8 Kaikōura earthquake cascade on weak crustal faults
Published: 2018-07-26
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
We present a dynamic rupture model of the 2016 Mw 7.8 Kaikōura earthquake to unravel the event’s riddles in a physics-based manner and provide insight on the mechanical viability of competing hypotheses proposed to explain them. Our model reproduces key characteristics of the event and constraints puzzling features inferred from high-quality observations including a large gap separating surface [...]