Preprints
Filtering by Subject: Geology
Audit of Petroleum Exploration Wells in the UK Rockall Basin: 1980-2006
Published: 2019-04-01
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics
The UK Rockall Basin is one of the most underexplored areas of the UK Continental Shelf (UKCS) with only 12 exploration wells drilled since 1980, in a basin area that is equal in size to the entire North Sea hydrocarbon province (NNS, CNS & SNS). With only one discovery, made in 2000 (Benbecula South 154/1-1 Gas discovery), the general view of the basin from an exploration viewpoint has not [...]
Comment on “Long-term strain oscillations related to the hydrogeological interaction between aquifers in intra-mountain basins: A case study from Apennines chain (Italy)” by Devoti, Riguzzi, Cinti and Ventura
Published: 2019-03-28
Subjects: Earth Sciences, Geology, Geomorphology, Physical Sciences and Mathematics, Tectonics and Structure
The paper by Devoti et al. (2018) analyses the GPS time series from seventeen stations located inside and in the neighboring of the L’Aquila intermountain basin. The authors suggest that the observed movements are due to regional hydrological processes likely associated with multi-annual climatic variations. The analysis performed by Devoti et al. (2018) contains an issue in the GPS-InSar [...]
3-D seismic images of an extensive igneous sill in the lower crust
Published: 2019-03-28
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics
When continents rift, magmatism can produce large volumes of melt that migrate upwards from deep below the Earth’s surface. To understand how magmatism impacts rifting, it is critical to understand how much melt is generated and how it transits the crust. Estimating melt volumes and pathways is difficult, however, particularly in the lower crust where the resolution of geophysical techniques is [...]
Direct observations of the coupling between quartz dissolution and Mg-silicate formation
Published: 2019-03-19
Subjects: Earth Sciences, Geochemistry, Geology, Physical Sciences and Mathematics
Although quartz is a stable mineral at Earth surface conditions, field samples have shown its rapid dissolution in combination with the precipitation of Mg-silicate phases. Atomic force microscopy (AFM) experiments were performed to investigate the dissolution of quartz and the precipitation of secondary phases in high-pH, Mg-rich solutions both in-situ and ex-situ. Experiments were conducted at [...]
Formation of magnesium silicate hydrate cement in nature
Published: 2019-03-19
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Sedimentology
Tillite lithified by magnesium silicate hydrate (M-S-H) cement has been formed at the surface of the Feragen Ultramafic Body in SE Norway. Serpentinization of olivine-rich rocks led to formation of brucite that dissolves during weathering to form a high pH (>9) Mg-rich fluid. This fluid dissolves quartz deposited by glaciers during the Weichselian glaciation. Subsequent evaporation leads to [...]
Obstructed Minibasins on a Salt-Detached Slope: An Example from above the Sigsbee Canopy, Northern Gulf of Mexico
Published: 2019-03-19
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics
Salt-detached gravity-gliding/spreading systems having a rugose base-of-salt display complex strain patterns. However, little was previously known about how welding of supra-salt minibasins to the sub-salt may influence both the downslope translation of minibasins on salt-detached slopes and the regional pattern of supra-salt strain. Using a regional 3D seismic reflection data set, we examine a [...]
Poroelastic effects destabilize mildly rate-strengthening friction to generate stable slow slip pulses
Published: 2019-03-18
Subjects: Applied Mechanics, Earth Sciences, Engineering, Geology, Geophysics and Seismology, Mechanical Engineering, Physical Sciences and Mathematics, Physics, Statistical, Nonlinear, and Soft Matter Physics, Tribology
Slow slip events on tectonic faults, sliding instabilities that never accelerate to inertially limited ruptures or earthquakes, are one of the most enigmatic phenomena in frictional sliding. While observations of slow slip events continue to mount, a plausible mechanism that permits instability while simultaneously limiting slip speed remains elusive. Rate-and-state friction has been successful [...]
Equifinality and preservation potential of complex eskers
Published: 2019-03-15
Subjects: Earth Sciences, Geology, Geomorphology, Glaciology, Hydrology, Physical Sciences and Mathematics
Eskers are useful for reconstructing meltwater drainage systems of glaciers and ice sheets. However, our process understanding of eskers suffers from a disconnect between sporadic detailed morpho-sedimentary investigations of abundant large-scale ancient esker systems, and a small number of modern analogues where esker formation has been observed. This paper presents the results of detailed field [...]
Early exhumation of the Frontal Cordillera (Southern Central Andes) and implications for Andean mountain-building at ~33.5°S
Published: 2019-03-13
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Tectonics and Structure
The Andes are the modern active example of a Cordilleran-type orogen, with mountain-building and crustal thickening within the upper plate of a subduction zone. Despite numerous studies of this emblematic mountain range, several primary traits of this orogeny remain unresolved or poorly documented. The onset of uplift and deformation of the Frontal Cordillera basement culmination of the Southern [...]
Zealandia’s Early Paleozoic sandstones: detrital mineralogy of the Greenland and Reefton Groups
Published: 2019-03-01
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics
New point counts of 13 Buller Terrane sandstones have been made. The results suggest a less quartzose and more lithic rich content of detrital sand grains in the Ordovician Greenland Group than indicated by an earlier published study (average Q:F:L = 58:16:26 and 23% matrix rather than 81:8:11 and 37% matrix). A low grade sedimentary-metasedimentary provenance is indicated. Detrital K-feldspar, [...]
Determining sources of placer minerals using U-Pb ages of detrital zircons: example of auriferous quartz pebble conglomerates in Otago and Southland, New Zealand
Published: 2019-03-01
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics
We have dated populations of detrital zircons in two Miocene gold-bearing quartz pebble conglomerates, one at St Bathans in Central Otago and one near Gore in Northern Southland. Both samples contain large numbers of Triassic-Permian zircon grains that indicate a source area dominated by Eastern Province Torlesse Composite Terrane protoliths. On the basis that the detrital quartz, zircon and gold [...]
Revised three-dimensional geometry of the platiniferous Hekeia Gabbro, Longwood Range, Southland
Published: 2019-03-01
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics
The Hekeia Gabbro in the Longwood Range of Southland is prospective for platinum group element mineralisation. Recently acquired geological and isotopic data, combined with reinterpreted aeromagnetic data, provide new constraints on the three dimensional extent and internal structure of the gabbro. Direct observations of in situ subvertical igneous layering give confidence that most curvilinear [...]
Cretaceous tectonics and gold mineralisation in the Otago Schist, New Zealand
Published: 2019-03-01
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics
This paper provides a regional-scale background for understanding gold-mineralising processes in the Otago Schist during the Cretaceous. At this time the schist belt was in the latter stages of formation as an accretionary complex with 2000 km strike length on the Pacific margin of Gondwana. The Otago Schist is interpreted as an exhumed accretionary wedge of structurally stacked clastic [...]
Regional geological framework of New Zealands mineral deposits
Published: 2019-03-01
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics
New Zealand is the emergent part of a 4.9 Mkm2, mainly submerged continent in the SW Pacific Ocean that was formerly part of the Gondwana supercontinent. The geology can be described in terms of two main Cambrian-Early Cretaceous basement units (Western and Eastern provinces) and a Late Cretaceous-Holocene sedimentary and volcanic cover (Zealandia Megasequence and Rūaumoko Volcanics). New Zealand [...]
New insights on lake sediment DNA from the catchment: importance of taphonomic and analytical issues on the record quality
Published: 2019-02-27
Subjects: Earth Sciences, Ecology and Evolutionary Biology, Geochemistry, Geology, Life Sciences, Physical Sciences and Mathematics, Sedimentology, Soil Science, Terrestrial and Aquatic Ecology
Over the last decade, an increasing number of studies have used lake sediment DNA to trace past landscape changes, agricultural activities or human presence. However, the processes responsible for lake sediment formation might affect DNA archiving via taphonomic and analytical processes. It is crucial to understand these processes to ensure reliable interpretations for “palaeo” studies. Here, we [...]