Preprints
Filtering by Subject: Tectonics and Structure
The Leaning Puy de Dôme
Published: 2019-07-09
Subjects: Earth Sciences, Geomorphology, Physical Sciences and Mathematics, Tectonics and Structure, Volcanology
Acidic lava domes are a special monogenetic volcano type with explosive eruption hazards. Such domes raise questions about the nature of monogenetic volcanism. We study the iconic Puy de Dôme (Chaîne des Puys, Auvergne) that gave its name to dome landforms. It is asymmetric with one side more rugged and steeper than the other. Using mapping and paleomagnetism we find that it was tilted by ~20° [...]
Tectonic stress controls saucer-shaped sill geometry
Published: 2019-07-05
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Tectonics and Structure, Volcanology
Saucer-shaped sills are common in sedimentary basins worldwide. The saucer shape relates to asymmetric stress distributions at the sill-tip during intrusion caused by bending of the overburden. Most saucer-shaped sill models are conducted without tectonic stress. Model results are poorly correlated with natural sills in that: (1) modelled saucers are much steeper than natural sills; and (2) [...]
Finite element simulations of sill intrusion during tectonic loading
Published: 2019-07-05
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Tectonics and Structure, Volcanology
Igneous sills are common features in tectonically active regions, acting as nascent magma storage systems, or feeding eruptions at large lateral distances from the magma source. Sills reaching a critical radius, rc, relative to their initial depth, H, interact with Earth’s surface, leading to mild discordant growth at angle [theta] typically <10[deg] forming saucer-shaped sills; commonly [...]
Tectonic controls on the Maastrichtian-Danian transgression in the Magallanes-Austral foreland basin (Chile): Implications for the growth of the Southern Patagonian Andes
Published: 2019-07-05
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Sedimentology, Stratigraphy, Tectonics and Structure
The Maastrichtian-Danian transgression was one of the most extensive Atlantic-derived marine incursions in Patagonia. This study examines its stratigraphic record and origin in the Magallanes-Austral Basin, revealing an interplay of sedimentation, tectonism, and base-level changes, which contribute to our understanding of foreland basin dynamics. We present a multidisciplinary approach from a [...]
Segmentation of the Main Himalayan Thrust inferred from geodetic observations of interseismic coupling
Published: 2019-07-04
Subjects: Computer Sciences, Earth Sciences, Environmental Sciences, Geology, Geomorphology, Geophysics and Seismology, Physical Sciences and Mathematics, Probability, Statistics and Probability, Tectonics and Structure
Mapping the distribution of locked segments along subduction megathrusts is essential for improving quantitative assessments of seismic hazard. Previous geodetic studies suggest the Main Himalayan Thrust (MHT) is homogeneously locked (or coupled) along its complete length over a down-dip extent of ~100 km. However, an increasing number of seismological and geophysical observations suggests the [...]
From prodigious volcanic degassing to caldera subsidence and quiescence at Ambrym (Vanuatu): the influence of regional tectonics
Published: 2019-06-29
Subjects: Earth Sciences, Physical Sciences and Mathematics, Tectonics and Structure, Volcanology
Eruptive activity shapes volcanic edifices. The formation of broad caldera depressions is often associated with major collapse events, emplacing conspicuous pyroclastic deposits. However, caldera subsidence may also proceed silently by magma withdrawal at depth, more difficult to detect. Ambrym, a basaltic volcanic island, hosts a 12-km wide caldera and several intensely-degassing lava lakes [...]
Multiple episodes of sand injection leading to accumulation and leakage of hydrocarbons along the San Andreas/San Gregorio fault system, California.
Published: 2019-06-22
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Sedimentology, Tectonics and Structure
The presence of sand injections has proven to enhance the likelihood of hydrocarbon traps within siliciclastic successions. Through the development of large interconnected networks of sills and dykes, sand injection complexes provide a volume of porous and permeable rocks within the low permeability host units. Overall, the formation of sand injection complexes requires extensive fracturing and [...]
Are magnetic stripes on the Cuvier Abyssal Plain (offshore NW Australia) diagnostic of oceanic crust?
Published: 2019-06-22
Subjects: Earth Sciences, Geology, Geophysics and Seismology, Other Earth Sciences, Physical Sciences and Mathematics, Tectonics and Structure
Magnetic stripes have long been used to define the presence and age of oceanic crust. However, continental crust heavily intruded by magma can record magnetic reversals akin to those observed in oceanic crust. We re-evaluate the nature of the Cuvier Abyssal Plain (CAP), offshore NW Australia, which hosts magnetic stripes and has previously been defined as oceanic crust. We use magnetic, 2D [...]
Active fault scarps in southern Malawi and their implications for the distribution of strain in incipient continental rifts
Published: 2019-06-19
Subjects: Earth Sciences, Geomorphology, Physical Sciences and Mathematics, Tectonics and Structure
The distribution of deformation during the early stages of continental rifting is an important constraint on our understanding of continental breakup. Incipient rifting in East Africa has been considered to be dominated by slip along rift border faults, with a subsequent transition to focussed extension on axial segments in thinned crust and/or with active magmatism. Here, we study [...]
Evaluating the relationship between the area and latitude of large igneous provinces and Earth’s long-term climate state
Published: 2019-06-12
Subjects: Earth Sciences, Geochemistry, Geology, Physical Sciences and Mathematics, Tectonics and Structure
One of the hypothesized effects of large igneous provinces (LIPs) is planetary cooling on million-year timescales associated with enhanced silicate weathering of the freshly-emplaced basalt. This study combines reconstructions of the original surface extent and emplacement ages of LIPs, a paleogeographic model, and a parameterization of LIP erosion to estimate LIP area in all latitudinal bands [...]
Lower crustal earthquakes in the East African Rift System: Insights from frictional properties of rock samples from the Malawi rift
Published: 2019-06-06
Subjects: Earth Sciences, Physical Sciences and Mathematics, Tectonics and Structure
Earthquakes in the southern part of the East African Rift System (EARS) occur at depths up to 45 km in the lower crust, unusually deep for an extensional regime. Typically, earthquakes in continental crust nucleate at temperatures less than 350°C, the temperature at which crystal plastic creep in quartz becomes efficient, corresponding to a depth of ~15 km with an average continental geothermal [...]
Creep on seismogenic faults: Insights from analogue earthquake experiments
Published: 2019-05-30
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure
Tectonic faults display a range of slip behaviors including continuous and episodic slip covering rates of more than 10 orders of magnitude (m/s). The physical control of such kinematic observations remains ambiguous. To gain insight into the slip behavior of brittle faults we performed laboratory stick-slip experiments using a rock analogue, granular material. We realized conditions under which [...]
Slab Rollback Orogeny model for the evolution of the Central Alps: Seismo-Thermo-Mechanical test
Published: 2019-05-30
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Tectonics and Structure
Forces associated with subduction of cold and dense oceanic plates control the motions and deformations of convergent margins. However, how these forces sustain mountain building processes — especially after slab breakoff — is still poorly known. Here we investigate this conundrum by performing 2-D, visco-elasto-plastic, seismo-thermo-mechanical numerical modeling, which simulates both tectonic [...]
Gondwana accretion tectonics and implications for the geodynamic evolution of eastern Arabia: first structural evidence of the existence of the Cadomian Orogen in Oman (Jabal Akhdar Dome, Central Oman Mountains)
Published: 2019-05-30
Subjects: Earth Sciences, Physical Sciences and Mathematics, Tectonics and Structure
The present work describes two early Cambrian folding events within Cryogenian to earliest Cambrian rocks of the western Jabal Akhdar Dome (Central Oman Mountains). This sequence is truncated at an angular unconformity and topped by Permo-Mesozoic sedimentary shelf strata. The Permo-Mesozoic is brittlely deformed and largely unfolded. This differs in style and intensity of deformation with the [...]
Shallow slow slip events along the Nankai Trough detected by the GNSS-A
Published: 2019-05-17
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure
Various slow earthquakes (SEQs), including tremors, very-low-frequency events, and slow slip events (SSEs), occur along megathrust zones. In a shallow plate boundary region, although many SEQs have been observed along pan-Pacific subduction zones, SSEs with a duration on the order of a year or with a large slip have not yet been detected due to difficulty in offshore observation. We try to [...]