Preprints
Filtering by Subject: Geology
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: 2019-03-14
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: 2019-02-28
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 [...]
Structural and geodynamic modelling of the influence of granite bodies during lithospheric extension: application to the Carboniferous basins of northern England
Published: 2019-02-22
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Tectonics and Structure
Intra-basinal highs within classic ‘block and basin’ style tectonic frameworks, in areas such as northern England, are underpinned by large granite bodies. This is widely believed to relate to the relative ‘rigidity’ and ‘buoyancy’ of granite in relation to accommodating basement. It has been suggested that during periods of tectonic extension, normal faulting around the peripheral regions of [...]
Lithological, petrophysical and seal properties of mass-transport complexes (MTCs), northern Gulf of Mexico
Published: 2019-02-22
Subjects: Earth Sciences, Engineering, Engineering Science and Materials, Geology, Physical Sciences and Mathematics, Sedimentology
Mass transport complexes (MTCs) are one of the most sedimentologically and seismically distinctive depositional elements in deep-water depositional systems. Seismic reflection data provide spectacular images of their structure, size, and distribution, although a lack of borehole data means there is limited direct calibration between MTC lithology and petrophysical expression, or knowledge of how [...]
The influence of base-salt relief, rift topography and regional events on salt tectonics offshore Morocco
Published: 2019-02-20
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Tectonics and Structure
This study integrates borehole-calibrated 2D and 3D seismic interpretation with numerical models to provide a regional analysis of the complex salt tectonics offshore central Morocco. We investigate the mechanisms controlling along-margin structural variations, the effects of thick-skinned shortening and the sequential evolution of allochthonous sheets. Additionally, we analyse how base-salt [...]
Minibasin depocentre migration during diachronous salt welding, offshore Angola
Published: 2019-02-17
Subjects: Earth Sciences, Geology, Other Earth Sciences, Physical Sciences and Mathematics, Tectonics and Structure
Salt tectonics is an important part of the geological evolution of many continental margins, yet the four-dimensional evolution of the minibasins, the fundamental building block of these and many other salt basins, remains poorly understood. Using high-quality 3D seismic data from the Lower Congo Basin, offshore Angola we document the long-term (>70 Myr) dynamics of minibasin subsidence. We [...]
McHargue et al Architectural Diversity of Submarine Lobes
Published: 2019-02-15
Subjects: Earth Sciences, Geology, Geomorphology, Physical Sciences and Mathematics, Sedimentology, Stratigraphy
The most popular model for submarine unconfined lobate deposits has the following attributes: (1) a single feeder channel that delivers sediment, (2) a set of distributary channels present only in the proximal part of the lobate body, and (3) unchannelized tabular deposits present in the middle and distal part of the lobate deposit. This model has become a standard to guide interpretation of [...]
The Stratigraphic Record of Minibasin Subsidence, Precaspian Basin, Kazakhstan
Published: 2019-02-14
Subjects: Earth Sciences, Geology, Other Earth Sciences, Physical Sciences and Mathematics, Stratigraphy, Tectonics and Structure
Minibasins are fundamental components of many salt-bearing sedimentary basins, where they may host large volumes of hydrocarbons. Although we understand the basic mechanics governing their subsidence, we know surprisingly little of how minibasins subside in three-dimensions over geological timescales, or what controls such variability. Such knowledge would improve our ability to constrain initial [...]
Current Problems of Water Supply and Usage in Central Asia, Tian Shan Basin
Published: 2019-02-14
Subjects: Earth Sciences, Ecology and Evolutionary Biology, Environmental Studies, Geography, Geology, Geomorphology, Glaciology, Hydrology, Life Sciences, Other Geography, Physical and Environmental Geography, Physical Sciences and Mathematics, Social and Behavioral Sciences, Spatial Science
The paper focuses on analysis of Central Asian hydro-energetic system and water usage in Tian Shan region. Tian Shan system is an important water resource in Central Asia: river waters are intensely taken for hydropower energy, urban systems, irrigation. But geopolitics in Tian Shan is difficult: it crosses five densely populated countries. The problem consists in water delivery between countries [...]