Preprints
Filtering by Subject: Geology
Sedimentology and reservoir properties of tabular and erosive offshore transition deposits in wave-dominated, shallow-marine strata: Book Cliffs, USA
Published: 2017-11-28
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Sedimentology
Facies models for wave-dominated shorelines include an "offshore transition zone" between shelfal mudstones and nearshore shoreface sandstones. Offshore transition zone deposits are commonly tabular sandstone beds interbedded with continuous mudstone beds. However, observations from the Blackhawk Formation show that the offshore transition zone locally consists of erosive-based sandstone beds [...]
How, where and when do radial faults grow near salt diapirs?
Published: 2017-11-27
Subjects: Earth Sciences, Geology, Other Earth Sciences, Physical Sciences and Mathematics, Tectonics and Structure
We examine 3-D seismic reflection data from the Santos Basin, offshore Brazil to determine how, where and when do radial faults grow near a sub-circular salt diapir (stock). We show roof stretching alone cannot account for the large heights and lengths of the kilometre-scale radial faults, suggesting stock widening (‘stem push’), a mechanism implied in numerical models but not yet documented in [...]
The evolution of REE mineralisation within the Ditrău Alkaline Complex, Romania: interplay of magmatic and hydrothermal processes
Published: 2017-11-27
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics
The Ditrău Igneous Complex (NE Romania) is a tilted Mesozoic layered alkaline intrusion (~19 km diameter), with enrichments in rare earth elements (REE), niobium, tantalum and molybdenum. It has the potential to contribute to a secure and sustainable European REE mining industry, ensuring supply security for these critical metals. The complex comprises layered ultramafic rocks, alkali gabbros, [...]
The role of coseismic Coulomb stress changes in shaping the hard-link between normal fault segments
Published: 2017-11-27
Subjects: Earth Sciences, Geology, Geomorphology, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure
The mechanism and evolution of fault linkage is important in the growth and development of large faults. Here we investigate the role of coseismic stress changes in shaping the hard-links between parallel normal fault segments (or faults), by comparing numerical models of the Coulomb stress change from simulated earthquakes on two en echelon fault segments to natural observations of hard-linked [...]
Throw Rate Variability on Gravity-Driven Normal Faults; Constraints from the Gudrun Fault, South Viking Graben, Offshore Norway
Published: 2017-11-24
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Tectonics and Structure
The growth and throw rate variability on normal faults can reflect fault interaction, plate tectonic forces and, in gravity-driven systems, variations in sediment loading. Because earthquakes may occur as faults slip, it is important to understand what processes influence throw rate variability on normal faults to be able to predict seismic hazards in extensional terranes. Furthermore, the rate [...]
Temporal evolution of extensional fault-propagation folds
Published: 2017-11-23
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Stratigraphy, Tectonics and Structure
Integration of three-dimensional seismic and well data from the Upper Jurassic North Sea rift provides insights into the temporal evolution of fault-propagation folds in extensional settings. The hangingwall of the Oseberg fault zone is characterised by an asymmetric, fault-parallel syncline interpreted as the hangingwall portion of a breached monocline which formed in response to an [...]
High curvatures drive river meandering
Published: 2017-11-20
Subjects: Earth Sciences, Geology, Geomorphology, Physical Sciences and Mathematics
One of the long- and widely held ideas about the dynamics of meandering rivers is that migration slows down in bends with higher curvatures. Identifying the radius of curvature at which migration is fastest is standard practice in field studies of meandering rivers. High-resolution measurements of local migration rates in time-lapse Landsat images from two rapidly migrating rivers in the Amazon [...]
Scientific and risk-reduction benefits of involving citizens in monitoring volcanic activity
Published: 2017-11-20
Subjects: Earth Sciences, Environmental Monitoring, Environmental Sciences, Geology, Physical Sciences and Mathematics, Volcanology
Citizen science involves volunteers, regardless of scientific background, in conducting scientific investigations. Although the extent of citizen involvement varies, the reported benefits of such activities include: the generation of new knowledge; increased public understanding of and confidence in science, and ‘real-time’ insights into rapidly evolving events such as natural hazards. In [...]
Unravelling intrusion-induced forced fold kinematics and ground deformation using 3D seismic reflection data
Published: 2017-11-17
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics
Sills emplaced at shallow-levels are commonly accommodated by overburden uplift, producing forced folds. We examine ancient forced folds developed above saucer-shaped sills using 3D seismic reflection data from the Canterbury Basin, offshore SE New Zealand. Seismic-stratigraphic relationships indicate sill emplacement occurred incrementally over ~31 Myr between the Oligocene (~35–32 Ma) and Early [...]
Fault growth and interactions in a multiphase rift fault network: Horda Platform, Norwegian North Sea
Published: 2017-11-15
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Tectonics and Structure
Physical models predict that multiphase rifts that experience a change in extension direction between stretching phases will typically develop non-colinear normal fault sets. Furthermore, multiphase rifts will display a greater frequency and range of styles of fault interactions than single-phase rifts. Although these physical models have yielded useful information on the evolution of fault [...]
Distribution of discontinuous mudstone beds within wave-dominated shallow-marine deposits: Star Point Sandstone and Blackhawk Formation, Eastern Utah, USA
Published: 2017-11-08
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Sedimentology, Stratigraphy
Deposits of wave-dominated shorelines are typically considered to act as relatively simple hydrocarbon reservoirs and are commonly modeled as “tanks of sand”. However, important heterogeneities that can act as barriers to fluid flow occur at the parasequence, bedset and bed scales, especially in viscous oil or low permeability oil fields. Heterogeneities at the parasequence and bedset scale have [...]
Environmental signal propagation in sedimentary systems across timescales
Published: 2017-11-07
Subjects: Earth Sciences, Geology, Geomorphology, Physical Sciences and Mathematics, Sedimentology, Stratigraphy
Review of concepts of environmental signal (climate, tectonics, anthropogenic, etc.) propagation in sedimentary systems from source to sink.
Sequential growth of deformation bands in carbonate grainstones in the hangingwall of an active growth fault: Implications for deformation mechanisms in different tectonic regimes
Published: 2017-11-06
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Tectonics and Structure
Deformation bands in porous sandstones have been extensively studied for four decades, whereas comparatively less is known about deformation bands in porous carbonate rocks, particularly in extensional settings. Here, we investigate porous grainstones of the Globigerina Limestone Formation in Malta, which contain several types of deformation bands in the hangingwall of the Maghlaq Fault: (i) [...]
Pastoralism may have delayed the end of the green Sahara
Published: 2017-11-06
Subjects: Earth Sciences, Environmental Studies, Geology, Physical Sciences and Mathematics, Social and Behavioral Sciences
The benefits of pastoralism for marginal, arid environments are often not appreciated. One notable past example of the human response to encroaching desertification comes from the regional climate deterioration after the most recent African Humid Period, which ended around 5,500 years ago. Recent evidence points to a population expansion in northern Africa prior to this, associated with the [...]
Rifts and Rifted Margins: A Review of Geodynamic Processes and Natural Hazards
Published: 2017-11-06
Subjects: Earth Sciences, Geology, Other Earth Sciences, Physical Sciences and Mathematics, Tectonics and Structure
This review provides an introduction to the geodynamic processes that influence tectonic rift evolution and rifted margin architecture. With a strong focus on numerical modeling, I summarize classical and recent insights on rift evolution with differentiation between 2D and 3D concepts and models. One of the key processes during rift evolution is crust-mantle coupling, which controls not only the [...]