Late Weichselian glaciation history of the northern North Sea

Based on new data from the Fladen, Sleipner and Troll areas, combined with earlier published results, a glaciation curve for the Late Weichselian in the northern North Sea is constructed. The youngest date on marine sedimentation prior to the late Weichselian maximum ice extent is 29.4 ka BP. At this time the North Sea and probably large parts of southern Norway were deglaciated (corresponding to the Alesund interstadial in western Norway). In a period between 29.4 and c. 22 ka BP, the northern North Sea experienced its maximum Weichselian glaciation with a coalescing British and Scandinavian ice sheet. The first recorded marine inundation is found in the Fladen area where marine sedimentation started close to 22 ka BP. After this the ice fronts receded both to the east and west. The North Sea Plateau, and possibly parts of the Norwegian Trench, were ice-free close to 19.0 ka, and after this a short readvance occurred in this area. This event is correlated with the advance recorded at Dimlington, Yorkshire, and the corresponding climatostratigraphic unit is denoted the Dimlington Stadial (18.5 ka to 15.1 ka). The Norwegian Trench was deglaciated at 15.1 ka in the Troll area. The data from the North Sea, together with the results from Andwa, northern Norway (Vorren et al . 1988; Møller et al . 1992), suggest that the maximum extent of the last glaciation along the NW-European seaboard from the British Isles to northern Norway was prior to c . 22 ka BP.     

A summary of sulfur dioxide emission rate measuremnts from Guatemalan volcanoes

Measurements of the sulfur dioxide (SO₂) emission rate from three Guatemalan volcanoes provide data which are consistent with theoretical and laboratory studies of eruptive and shallow magma chamber processes. In particular, unerupted magma makes a major contribution to the measured SO₂ emission rates at Santiaguito, a continuously erupting dacitic volcanic dome. Varying shallow magma convection rates can explain the variations in SO₂ emission rates at Santiaguito. At Fuego, a basaltic volcano currently in repose, SO₂ emission rate measurements are consistent with a high level magma body that is crystallizing and releasing volatiles. At Pacaya, a continuously erupting basaltic volcano, recent SO₂ emission rate measurements support laboratory simulation studies of strombolian eruptions; these studies indicate that the majority of gas escapes during eruptions and little gas escapes between eruptions.Average SO₂ emission rates over the last 20 years for Santiaguito, Fuego and Pacaya are 80, 160 and 260 Mg/d, respectively. On a global scale, these three volcanoes account for 1% of the annual global volcanic output of SO₂. Santiaguito and Pacaya, together, emit 6% of the total annual SO₂ emitted by continuously erupting volcanoes.Even though SO₂ measurements at these volcanoes have been made infrequently and by different investigators, the collective data help to establish a useful baseline by which to judge future changes. A more complete record of SO₂ emission rates from these volcanoes could lead to a better understanding of their eruption mechanisms and reduce the impact of their future eruptions on Guatemalan society.     

An evaluation of hemolymph cholinesterase activities in the tropical scallop,Euvola (Pecten) ziczac,for the rapid assessment of pesticide exposure

The use of sequential measurements of hemolymph cholinesterase activities as a non-invasive biomarker of seasonal organophosphate/carbamate exposure was investigated for the tropical scallop, Euvola (Pecten) ziczac. Overall activities of both acetylcholinesterase and butyrylcholinesterase were relatively high compared to studies with bivalve tissues. Acute in vivo experiments showed inhibition of hemolymph acetylcholinesterase activity at concentrations of the organophosphate insecticide chlorpyrifos of 0.1, 1 and 10 ng l(-1). Monthly sampling of hemolymph from scallops at two sites in Bermuda over a 15 month period showed seasonal acetylcholinesterase and butyrylcholinesterase inhibition. Direct and indirect evidence suggests that this inhibition did not relate to biochemical or physiological changes associated with gonad maturation and spawning, but rather reflected diffuse contamination of the marine environment by cholinesterase inhibitors or increased bioavailability of such inhibitors at these times. Repetitive sampling of scallop hemolymph for cholinesterase activities represents a rapid, sensitive and non-invasive method for assessing seasonal, sublethal pesticide exposure in these commercially important bivalves and suggests a wider use in marine pollution monitoring.     

Quaternary geology and deglaciation of the continental shelf off Troms, north Norway

The study is based mainly on 4700 km shallow seismic profiling, soil mechanical, and micropaleontological analyses from forty localities, and seven radiocarbon datings. Six foraminiferal assemblages are recognized. The thickness of Quaternary deposits ranges from sparse to more than 200 m. They consist of top sand, soft sensitive clay, and glacial drift divided into four seismic stratigraphic units. The oldest unit, which is the thickest and most extensive, is built up of various sediments and is partly eroded, especially in the southern part. The remaining units occur as three complex linear belts running broadly parallel to the present coast and were deposited during deglaciation. Dating of the outer unit, the Nordvestsnaget Drift, suggests a maximum age of 13,300 years B.P., and datings from the top of the middle unit, the Mulegga Drift, have given a minimum age of about 12,200 years B.P. Seismic stratigraphy shows that the inner unit, the Havbrobakken Drift, is younger than the Mulegga Drift, but no datings have been obtained so far.     

Value of Information Introduced by a Resource Model Updating Framework

A primary concern of the mining industry is to meet production targets, which are required and defined by customers. Deviations from these targets, in terms of quality and quantity, highly affect the economical aspect. Recently, an efficient resource model updating framework concept has been proposed aiming for the improvement of raw material quality control and process efficiency in any type of mining operation. The concept integrates online sensor measurements, obtained during production, into the resource model. In this way, due to the spatial variability, quality attributes of the blocks that will be produced in the next days or weeks are being updated based on real-time measurements. The concept has been applied in a lignite field with the aim of identifying local impurities in a lignite seam and to improve the prediction of coal quality attributes in neighbouring blocks. This paper investigates the added value of using the resource model updating framework by using the value of information analysis. The expected benefit of additional information (integration of the online sensor measurements into the resource model) is compared to a case where there is no additional information integrated into the process. These benefits are evaluated based on the economic impact determined by applying the resource model updating framework in mine planning.

     

Ore–Waste Discrimination in Epithermal Deposits Using Near-Infrared to Short-Wavelength Infrared (NIR-SWIR) Hyperspectral Imagery

Near-infrared (NIR) and short-wavelength infrared (SWIR) hyperspectral imagery can be used to detect certain alteration minerals. At epithermal deposits, the formation of alteration minerals is, in theory, related to the mineralisation of gold and silver. In order to provide foundations for developing sensor-based sorting applications at a mine that exploits such a deposit, it was investigated if NIR-SWIR hyperspectral imagery can be used to distinguish between ore and waste particles by characterising the alteration mineralogy. Maps were produced from the NIR-SWIR hyperspectral images of 827 drill core samples that show mineral occurrences, mineral absorption feature intensities and characteristics of the iron oxide mineralogy. Partial least squares discriminant analysis (PLS-DA) was applied to the information contained in these maps to investigate if this information can be used to discriminate between ore and waste. The results showed that NIR-SWIR hyperspectral imagery could be used to segment a population of waste samples by detecting occurrences of pyrophyllite, dickite and/or illite. This result can be explained by the fact that these minerals are commonly deposited further away from the ore-bearing epithermal veins, while the absence of SWIR-active minerals or detected occurrences of alunite are more closely associated with these structures. The ability to identify waste with NIR-SWIR spectral sensors means there is potential that sensor-based sorting can be used to remove this waste from mineral processing operations. Additional research is still required to assess the economic feasibility of such a sensor-based sorting application.

     

Australia’s no-take marine protected areas: Appropriate conservation or inappropriate management of fishing?

The absence of properly identified mechanisms to adequately protect the marine environment remains a major shortcoming in Australia’s commitment to biodiversity conservation. The current commitment to a National Representative System of Marine Protected Areas (NRSMPA) falls far short of providing adequate protection against the suite of existing and potential threats even though areas are designated as being ‘protected’. In this paper it is argued that the actions taken under the NRSMPA are disproportionately concentrated on regulating fishing, including the closing of areas in so-called sanctuary zones to all types of fishing. In the absence of clearly identified threats from most forms of fishing and without assessment of how best to manage those few fishing threats that have been identified, such actions are inefficient and mostly inappropriate. Moreover, they do not provide adequate protection against the full suite of threats to marine environments. Adequate measures for the proper conservation of these areas and/or the protection of marine biodiversity more generally are not being provided and in most cases threats are not even adequately described and evaluated.