Preprints
Filtering by Subject: Geology
Geometry and Kinematics of Salt-detached Ramp Syncline Basins
Published: 2017-12-23
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Stratigraphy, Tectonics and Structure
Ramp-syncline basins (RSBs) are characterized by asymmetric depocentres that form by translation above flat-ramp extensional faults or salt detachments having basal steps. Both types of RSBs are composed by landward-dipping and expanding strata defined by basinward-dipping axial traces. 3D seismic data from the São Paulo Plateau, Santos Basin, Brazil, image a series of RSBs formed above thick [...]
Slope-fan depositional architecture from high-resolution forward stratigraphic models
Published: 2017-12-18
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Sedimentology, Stratigraphy
Submarine fans in tectonically active continental-slope basins are targets of petroleum exploration and production. These slope fans commonly comprise compensationally stacked sandy and muddy architectural elements, including mass-transport deposits, weakly confined to distributary channel-and-lobe deposits, and leveed-channel deposits. The lateral continuity and vertical connectivity of these [...]
Stratigraphic modeling of the Western Taiwan foreland basin: sediment flux from a growing mountain range and tectonic implications
Published: 2017-12-11
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Sedimentology, Stratigraphy
Sediment flux signals in foreland basins preserve a record of tectonics, sea level and climate through erosion and sedimentation. However, longitudinal sediment transport often occurs in foreland basin, thus removing part of the orogenic material flux from foreland basins. Here we use mass balance calculation and stratigraphic simulations of sediment fluxes for the Taiwan orogen to provide a [...]
Structural signatures of igneous sheet intrusion propagation
Published: 2017-12-08
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Tectonics and Structure, Volcanology
The geometry and distribution of planar igneous bodies (i.e. sheet intrusions), such as dykes, sills, and inclined sheets, has long been used to determine emplacement mechanics, define melt source locations, and reconstruct palaeostress conditions to shed light on various tectonic and magmatic processes. Since the 1970’s we have recognised that sheet intrusions do not necessarily display a [...]
Subsurface expression of a tertiary salt weld, Gulf of Mexico
Published: 2017-12-06
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Tectonics and Structure
Salt welds form due to salt expulsion and thinning by mechanical (e.g. salt flow) and/or chemical (e.g. salt dissolution) processes. Despite being ubiquitous in salt-bearing sedimentary basins, where they may trap large volumes of hydrocarbons, little is published on weld thickness and composition. We here use 3D seismic reflection, borehole, and biostratigraphic data from the Atwater Valley [...]
Kinematics of Polygonal Fault Systems: Observations from the Northern North Sea
Published: 2017-12-05
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics
Layer-bound, low-displacement normal faults, arranged into a broadly polygonal pattern, are common in many sedimentary basins. Despite having constrained their gross geometry, we have a relatively poor understanding of the processes controlling the nucleation and growth (i.e., the kinematics) of polygonal fault systems. In this study we use high-resolution 3-D seismic reflection and borehole data [...]
Lithospheric flexure and rheology determined by climate cycle markers in the Corinth Rift
Published: 2017-11-28
Subjects: Earth Sciences, Geology, Geomorphology, Physical Sciences and Mathematics, Tectonics and Structure
Geomorphic strain markers accumulating the effects of many earthquake cycles help to constrain the mechanical behaviour of continental rift systems as well as the related seismic hazards. In the Corinth Rift (Greece), the unique record of onshore and offshore markers of Pleistocene ~100-ka climate cycles provides an outstanding possibility to constrain rift mechanics over a range of timescales. [...]
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 [...]