bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reconstructing the erosion history of glaciated passive margins: applications of
in situ
produced cosmogenic nuclide techniques
Authors: Stroeven Arjen P. , Fabel Derek , Harbor Jon , Hättestrand Clas , Kleman Johan 
Published: April 2008

Abstract

Offshore sediment accumulations provide an intriguing record of the net sediment output resulting from geomorphological evolution of the circum-Atlantic continental margin since the commencement of Neogene glaciation. However, the onshore record of the timing, pattern and amount of bedrock erosion that produced these sediments is comparatively poorly constrained and understood, although there are good general models of glaciation history. The geomorphology of circum-Atlantic continental margin mountains, as assessed from remote sensing data and field observations, includes palimpsest landforms and landscapes that reflect a complex pattern of spatial and temporal variations in the impact of glacial, fluvial and periglacial processes. Perhaps most surprising is that, despite having been repeatedly overridden by large ice sheets, parts of the landscape appear to be relict, with nonglacial morphology. This has important implications both for glaciological conditions under ice sheets, and for sediment source areas and erosion rates. Conventional dating and analysis have provided an excellent way to begin unravelling the timing and pattern of erosion, landform development, and possible landform preservation under ice. However, testing hypotheses developed from current models, and addressing critical unresolved questions, requires additional approaches. The use of
in situ
cosmogenic nuclide production in bedrock is a new approach for investigating landscape evolution in mountainous areas. With careful interpretation of geomorphological settings, cosmogenic nuclides can be used to determine apparent surface exposure age and landscape preservation, and constrain erosion depths and duration of burial by ice. Here we provide a framework for the interpretation of cosmogenic nuclide concentrations in bedrock surfaces of landscapes affected by glacial, fluvial and periglacial processes, illustrated with examples from the northern Swedish mountains. This demonstrates potential uses of cosmogenic nuclide techniques, and provides a foundation for attempts to improve geomorphologically based reconstructions of relict landscapes, to reconstruct and analyse the dynamics of landscape change in glacial times, and to define the consequences of different process regimes in terms of erosion patterns, sediment transport, and the supply of sediments that are deposited offshore.
The thermotectonic development of southern Sweden during Mesozoic and Cenozoic time
Authors: Cederbom Charlotte 
Published: April 2008

Abstract
Late Carboniferous-Early Mesozoic exhumation of southern Sweden has previously been traced using apatite fission-track thermochronology. In addition, the morphotectonic development of the region has been studied using geomorphology. The aim of this study is to attain further knowledge of the Mesozoic and Cenozoic thermotectonic development of southern Sweden by integrating results from these methods.
Well-dated re-exposed palaeosurfaces and sedimentary records in the surrounding areas were used as constraints in the modelling of apatite fission-track data from the Precambrian basement. The obtained modelled thermal histories suggest that southern Sweden can be divided into three main tectonic areas associated with different cooling histories. In Triassic and Jurassic time, low to moderate exhumation in the central part was accompanied by more rapid exhumation in the SE and NW. Additionally, individual block movements may have occurred in the NW. It has also been possible to estimate the heating effect of renewed Cretaceous-Paleogene burial to 20–35°C on the west and SE coasts.
Final Cenozoic unroofing of the basement is indicated by the modelled thermal histories. Areas around the southern tip of Lake Vättern together with the SE coast experienced the most pronounced exhumation compared with the surrounding parts.
Cenozoic uplift and denudation of southern Norway: insights from the North Sea Basin
Authors: Huuse Mads 
Published: April 2008

Abstract
The Cenozoic evolution of the North Sea Basin is described, drawing on subsurface data and a series of palaeogeographical maps compiled from a variety of published studies, mainly emphasizing the development of the eastern part of the basin. A model that accounts for the sedimentation history of the North Sea Basin and the topography (including maximum and mean surface elevation) of southern Norway is proposed. The model involves regional plume-related uplift of an initial low-elevation peneplain in early Paleogene time followed by repeated episodes of climatic deterioration and eustatic fall, most notably at the Eocene-Oligocene transition, in late Mid-Miocene time, and eventually culminating with the development of full glacial conditions in southern Norway in Plio-Pleistocene time. These episodes correspond to periods of accelerated sediment supply from southern Norway that reflect increased rates of incision (dissection) of the source area. It is argued that the present-day elevation of > 2 km of mountain peaks in southern Norway adjacent to deep valleys and fjords could have been caused by isostatic uplift in response to dissection of a high-elevation peneplain. Hence it may not be necessary to invoke late Cenozoic tectonic uplift events to explain the present-day topography of southern Norway.
Tectonic impact on sedimentary processes during Cenozoic evolution of the northern North Sea and surrounding areas
Authors: Faleide Jan Inge , Kyrkjebø Rune , Kjennerud Tomas , Gabrielsen Roy H. , Jordt Henrik , Fanavoll Stein , Bjerke Morten D. 
Published: April 2008

Abstract
This paper focuses on the Cenozoic evolution of the northern North Sea and surrounding areas, with emphasis on sediment distribution, composition and provenance, as well as on timing, amplitude and wavelength of differential vertical movements. Quantitative information about palaeo-water depth and tectonic vertical movements has been integrated with a seismic stratigraphic framework to better constrain the Cenozoic evolution. The data and modelling results support a probable tectonic control on sediment supply and on the formation of regional unconformities. The sedimentary architecture and breaks are related to tectonic uplift of surrounding clastic source areas, thus the offshore sedimentary record provides the best age constraints on Cenozoic exhumation of the adjacent onshore areas. Tectonic subsidence accelerated in Paleocene time throughout the basin, with uplifted areas to the east and west sourcing prograding wedges, which resulted in large depocentres close to the basin margins. Subsidence rates outpaced sedimentation rates along the basin axis, and water depths in excess of 600 m are indicated. In Eocene times progradation from the East Shetland Platform was dominant and major depocentres were constructed in the Viking Graben area, with deep water along the basin axis. At the Eocene-Oligocene transition, southern Norway and the eastern basin flank became uplifted. The uplift, in combination with prograding units from both the east and west, gave rise to a shallow threshold in the northern North Sea, separating deeper waters to the south and north. The uplift and shallowing continued into Miocene time when a widespread hiatus formed in the northern North Sea, as indicated by biostratigraphic data. The Pliocene basin configuration was dominated by outbuilding of thick clastic wedges from the east and south. Considerable late Cenozoic uplift of the eastern basin flank is documented by the strong angular relationship and tilting of the complete Tertiary package below the Pleistocene unconformity. Cenozoic exhumation is documented on both sides of the North Sea, but the timing is not well constrained. Two major uplift phases in early Paleogene and late Neogene times are related to rifting, magmatism and break-up in the NE Atlantic and isostatic response to glacial erosion, respectively. Additional uplift events may be related to mantle processes and the episodic behaviour of the Iceland plume.
Sonic velocity analysis of the Tertiary denudation of the Irish Sea basin
Authors: Ware Philip D. , Turner Jonathan P. 
Published: April 2008

Abstract
Interaction between uplift related to the Cretaceous—Paleocene opening of the North Atlantic, Neogene shortening (basin inversion) and Pleistocene glacio-isostasy is illustrated by the complex denudation pattern of Britain; such denudation is greatest over the submergent East Irish Sea basin, some 500 km from the Atlantic margin. This paper reports on analysis of sedimentary porosities using sonic velocity logs from 42 wells in the East Irish Sea basin. We present a new map showing the variation in exhumation magnitude at the uppermost Mesozoic unconformity (i.e. thickness of denuded Mesozoic and Cenozoic sedimentary rocks), today buried beneath a thin veneer of Pleistocene sediment. It indicates that exhumation is mostly < 1500 m (632–2132 m; mean standard deviation 407 m), less than denudation results obtained from vitrinite reflectance and apatite fission-track data. The map also reveals substantial variation in exhumation over short distances, often between adjacent wells sited on opposing walls of individual faults. This is interpreted in terms of the influence of Neogene basin inversion on the exhumation of the EISB. The role of late Tertiary tectonics in western UK exhumation is therefore discussed.
Genesis and age of the Erlend Volcano, NE Atlantic Margin
Authors: Jolley David W. , Bell Brian R. 
Published: April 2008

Abstract

The Palaeogene Erlend Volcano subcrops in the Faroe-Shetland Basin on the NE Atlantic Margin and was first recognized on the basis of its pronounced positive gravity and magnetic anomalies. Three hydrocarbon exploration wells (209/3-1; 209/4-1A; 209/9-1) have penetrated thick sequences of subaerial facies basaltic lavas and subaqueous volcanic breccias (the ‘Basaltic Suite’), overlying Palaeogene (Thanetian) and Cretaceous (Maastrichtian and Campanian) sedimentary rocks interbedded with medium to fine-grained silicic igneous rocks (the ‘Acidic Suite’). Detailed palynological and petrological analysis indicates that the basaltic rocks were contemporaneous with the Faroes Lower Lava Formation at
c.
56.6-55 Ma, and were erupted into environments ranging between dry land and brackish to freshwater lagoons at the margin of a marine channel separating the Erlend Volcano from the Brendan’s Volcano to the north. The subjacent Acidic Suite is interpreted as a series of sills emplaced approximately contemporaneously with the volcanic rocks on the basis of their diachronous relationship with interbedded sedimentary rocks, together with high Thermal Alteration Index values of
in situ
fossils.
Rates of volcanic deposition, facies changes and movements in a dynamic basin: the Nuussuaq Basin, West Greenland, around the C27n-C26r transition
Authors: Pedersen Asger K. , Larsen Lotte M. , Riisager Peter , Dueholm Keld S. 
Published: April 2008

Abstract

The initial stages of Palaeogene volcanism in the Nuussuaq Basin in West Greenland were characterized by eruption of basaltic and picritic magmas through sediments of Cretaceous to early Paleocene age into a marine or lowlying coastal environment. Recent magnetostratigraphic work has recognized the C27n-C26r transition (estimated duration less than 10 ka and here assumed to be 5 ka) as a
c.
170 m thick zone within a succession of thin picritic lava flows. Multimodel photogrammetry combined with chemical and lithological analysis of the volcanic rocks has allowed detailed 3D analysis of the facies variation within this narrow time window. Subaerial lavas flowed eastwards over a more than 40 km wide front. On northern Disko they covered an existing lava plateau and buried a subaerial landscape of dipping Cretaceous sandstones, while on Nuussuaq they flowed into an up to 700 m deep marine embayment and formed prograding hyaloclastite fans passing into fine-clastic mass flows. With a progradation rate of 0.5–1 m a
−1
the palaeogeography of the basin changed considerably during the short time interval. In addition to substantial basin subsidence, the volcanic facies changes have also preserved a record of synvolcanic differential movement of extensional fault blocks. The following parameters are estimated for the volcanism within the Nuussuaq Basin during the C27n-C26r transition: Production rate
c.
0.042 km
3
a
−1
, productivity
c.
1.2 × 10
−3
km
3
a
−1
km
−1
(rift), volcanic aggradation
c.
33 m ka
−1
, subsidence
c.
25 m ka
−1
. If the volcanism evolved continuously at this high aggradation rate, all of the Vaigat Formation could have erupted in 70 ka. However, the complex geological record indicates a much longer total duration, and the volcanism must have had an intermittent character.
The properties, morphology and distribution of igneous sills: modelling, borehole data and 3D seismic from the Faroe-Shetland area
Authors: Smallwood John R. , Maresh Jenny 
Published: April 2008

Abstract
An extensive suite of igneous sills, collectively known as the Faroe-Shetland Sill Complex, has been intruded into the Cretaceous and Tertiary sedimentary section of the Faroe-Shetland Channel area. These sills have been imaged offshore by three-dimensional (3D) reflection seismic surveys and penetrated by several exploration boreholes. Data from wireline log measurements in these boreholes allow us to characterize the physical properties of the sills and their thermal aureoles. The borehole data has been compiled to produce new empirical relationships between sonic velocity and density, and between compressional and shear sonic velocities within the sills. These relationships are used to assist in calculation of synthetic seismic traces for sills intruded into sedimentary section, in order to calibrate the seismic response of the sills as observed in field data. This paper describes how the seismic amplitude response of the sills can be used to predict sill thickness where there is some nearby well control, and use this technique to estimate the volume of one well-imaged sill penetrated by Well 205/10-2b. Since the sills have a high impedance contrast with their host rocks, they return strong seismic reflections. 3D seismic survey data allow mapping of the morphology of the sills with a high level of confidence, although in some instances disruption of the downgoing seismic wavefield causes the seismic imaging of deeper sills and other structures to be very poor. Examples of sub-circular and dish-shapes sills, and also semi-conical and sheet-like intrusions, which are highly discordant are shown. The introduction of intrusive rocks can play an important role in the subsequent development of the sedimentary system. An example is shown in which differential compaction or soft sediment deformation around and above the sills appears to have controlled deposition of a reservoir quality sand body. The positioning of the sills within sedimentary basins is discussed, by constructing a simple model in which pressure support of magma from a crustal magma chamber provides the hydrostatic head of magma required for intrusion at shallow levels. This model is made semi-quantitative using a simple equation relating rock densities to intrusion depth, calibrated to observations from the Faroe-Shetland area. The model predicts that sills can be intruded at shallower levels in the sedimentary section above basement highs, which agrees with observations detailed in this paper.
The monitoring and modelling of mine water recovery in UK coalfields
Authors: Whitworth Keith R. 
Published: April 2008

Abstract
This paper draws together the information that has been obtained on mine water recovery since the large-scale closure of coal mines in the 1980s and 1990s. The data show that, following cessation of pumping, mine water recovery follows an exponential curve similar to the recovery of an aquifer following a pumping test. Several previously unpublished examples of mine water recovery data from around the UK are included in the paper and there is a detailed assessment of mine water recovery in the East Fife Coalfield in Scotland. The reasons for this type of mine water recovery are discussed and examples are given of the use of the data for both the interpretation and modelling of mine water recovery. In coal mining areas where no water-level recovery data are available, methods for the prediction of mine water inflow and recovery modelling are proposed and the problems associated with mine water recovery modelling are discussed.
The paper concludes that modelling of mine water recovery, based on mine water inflow and estimated void space, can be used to give reasonably accurate predictions of recovery times and flows, but that water level monitoring is essential for precise predictions.
The control of mine water during the period when coal mining was a nationalized industry was generally based on a safety first principle. This meant that when doubt existed about underground connections between modern mines and old abandoned areas of workings, mine water pumping always continued in the old areas. The result of this policy was a general lack of experience of mine water recovery and continuing doubt about underground connections.
The large-scale closure of mines in the 1980s and 1990s mean that in many cases whole coalfields were abandoned and that the pumping of mine water either completely stopped or was greatly reduced. Estimations of mine water recovery made by British Coal at the time of these closures were generally based on a water inflow related to the volume of water pumped from a mine and a residual void-space calculation. The void-space was calculated using roadway dimensions for supported excavations and a figure of 10% of the original extractions thickness for unsupported (total extraction) workings (National Coal Board 1972). Using this principle it was assumed that mine water recovery would proceed as a series of steps, with very little recovery when water was ‘filling’ a large void, followed by a period of more brisk recovery until the next large void was reached.
The monitoring of mine water recovery by IMC Consulting Engineers on behalf of the Coal Authority (the government agency set up to look after the non-privatized areas of coal mining) has shown that, at least at large scales, mine water recovery follows precise exponential curves that appear to be independent of the distribution of mining voids. These curves are very similar to the recovery curves observed following an aquifer pumping test.
Effects of longwall mining in the Selby Coalfield on the piezometry and aquifer properties of the overlying Sherwood Sandstone
Authors: Dumpleton Stephen 
Published: April 2008

Abstract
In the UK, the first longwall faces at Wistow Mine in the Selby Coalfield, with only 80 m depth of cover to the base of the Permian, experienced several inrushes of groundwater derived from the overlying Lower Magnesian Limestone, causing serious disruption to coal production. Subsequent decrease in panel width coupled with increased depth of cover to the Permian reduced the incidence of water problems. However, there has never been any quantitative investigation to determine the effects of mining on the hydraulic properties of the stratigraphically higher Permo-Triassic age Sherwood Sandstone, a major aquifer of regional importance.
This opportunistic study fills that gap. Precautionary observation boreholes had been drilled above and around the margins of two proposed longwall panels prior to working the 2.5-m thick Barnsley seam at a depth of 550–600 m. Data loggers permitted continuous monitoring of the Sherwood Sandstone and Drift piezometric levels over a 2-year period. Widespread drawdown and recovery effects due to intermittent groundwater abstraction from a nearby factory were observed. Standard aquifer pumping test analyses of the hydrographs allowed transmissivity and storativity to be determined before, during and after mining. The results showed apparently permanent post-mining transmissivity increases of up to 149% around the margins of the panels, and up to 234% directly over the first panel. Post-mining storativity remained mostly unchanged. However, the greatest effects were noted during the closest approach by the second longwall panel, which also caused some additional subsidence over the first panel, when peak transmissivity increases of 1979% and storativity increases of 625% occurred. Anomalous, intra-cycle, recovery-drawdown events were also observed during this phase and interpreted as indicating rapid mining-induced dilation and compression of fractures within the aquifer fabric.
The results are consistent with similar investigations carried out at relatively shallow depths (<220 m) in USA coalfields. However, the Selby study shows that mining at much greater depths still has a significant impact on shallow aquifers, with implications for enhanced aquifer recharge, abstraction well yield and possible increased contaminant transport rates.
Depressurization of the north wall at the Escondida Copper Mine, Chile
Authors: McKelvey Patrick , Beale Geoff , Taylor Adam , Mansell Simon , Mira Benjamin , Valdivia Cristian , Hitchcock Warren 
Published: April 2008

Abstract
Concurrent dewatering and slope depressurization operations have been underway at the Escondida open pit since 1996. A hydrogeological investigation has been undertaken as part of the depressurization operation on the north wall. It has shown that there are two distinct hydrogeological units in the slope, the altered and unaltered Escondida Porphyry. The hydrothermally altered Escondida Porphyry is clay rich and has relatively high matrix permeability. The underlying silicified, or unaltered porphyry, has very low matrix permeability and groundwater flow is in steeply dipping NW-trending fracture systems. Pore pressures in the silicified porphyry are higher than the altered material.
A system of horizontal drains and vertical wells has been in operation to reduce pore pressures in the altered porphyry. To investigate effective drainage measures for the silicified porphyry, a groundwater model of the slope was constructed. This analysis showed that a drainage tunnel with horizontal drains was the most effective method of draining significant areas of the slope to the required pore pressure targets.
Hydrogeological framework for assessing the possible environmental impacts of large-scale gold mines
Authors: Kuma J. S. , Younger P. L. , Bowell R. J. 
Published: April 2008

Abstract
Hydrogeological information is crucial to the development of a sound environmental impact assessment (EIA) for a proposed mine, as well as the management of potential environmental impacts during and after exploitation. However, the determination of hydrogeological parameters is not customarily included in mineral exploration surveys, with the result that many EIAs end up being rather light in hydrogeological content. Examples from the Tarkwa gold mining district of Ghana illustrate this point. Consequences of such an inadequate hydrogeological understanding are potentially serious, ranging from an inability to predict future problems in water quality after the cessation of mining, to a lack of understanding of hydrogeological controls on slope stability, which is arguably manifest in the catastrophic spill of cyanide-rich processing effluents from a breached tailings dam at Wassa West, near Tarkwa, on 16 October 2001. To redress this deficiency, we propose that a hydrogeological database be assembled during the mineral exploration phase, according to a specified protocol (‘check-list’). Using these data, a rational conceptual hydrogeological model for the mine site and its surrounding area can be developed, providing the basis for a thorough consideration of groundwater aspects within the statutory Environmental Impact Assessment, which is (as in most other countries) required by Ghanaian government statute before a mining lease is approved. The resources required to set-up such a database are small compared to the benefits.