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PETER FRENZEL DIETMAR KEYSER FINN ANDREAS VIEHBERG 《Boreas: An International Journal of Quaternary Research》2010,39(3):567-575
Frenzel, P., Keyser, D. & Viehberg, F.A. 2010: An illustrated key and (pala6e6o)ecological primer for Postglacial to Recent Ostracoda (Crustacea) of the Baltic Sea. Boreas, Vol. 39, pp. 567–575. 10.1111/j.1502‐3885.2009.00135.x. ISSN 0300‐9483 This synopsis of Baltic Sea brackish water Ostracoda gives an overview of all known Recent species for the first time. It also includes Holocene taxa now extinct in the area. There are 131 species, two of which are recorded only from Yoldia stage (Preboreal) sediments. The illustrated key is based exclusively on valve morphology, providing a taxonomical base for geoscience and biological studies using ostracods from the Baltic Sea area. A list of ecological tolerances and preferences as well as the latitudinal distribution of all species is intended as a reference for palaeoenvironmental analyses. Salinity, temperature and oxygen tolerance values as well as preferences for latitudinal distribution, water depth and energy, habitat and substrate are given. The data are based on quantitative sampling in the southern, central and western Baltic Sea and on information gained from literature. 相似文献
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JAN‐PIETER BUYLAERT SÉBASTIEN HUOT ANDREW S. MURRAY PETER VAN DEN HAUTE 《Boreas: An International Journal of Quaternary Research》2011,40(1):46-56
Buylaert, J.‐P., Huot, S., Murray, A.S. & Van den haute, P.: Infrared stimulated luminescence dating of an Eemian (MIS 5e) site in Denmark using K‐feldspar. Boreas, 10.1111/j.1502‐3885.2010.00156.x. ISSN 0300‐9483. Infrared stimulated luminescence (IRSL) dating of K‐feldspars may be an alternative to quartz optically stimulated luminescence (OSL) dating when the quartz OSL signal is too close to saturation or when the quartz luminescence characteristics are unsuitable. In this paper, Eemian (MIS 5e) coastal marine sands exposed in a cliff section on the coast of southern Jutland (Denmark) are used to test the accuracy and precision of IRSL dating using K‐feldspars. This material has been used previously to test quartz OSL dating ( Murray & Funder 2003 ): a small systematic underestimation of <10% compared to the expected age of ~130 ka was reported. In our study, a single‐aliquot regenerative‐dose (SAR) IRSL protocol is used to determine values of equivalent dose (De) and the corresponding fading rates (g values). A significant age underestimation (of up to ~35%) is observed; this is attributed to anomalous fading. Using a single site‐average fading rate of 3.66 ± 0.09%/decade to correct the IRSL ages for all samples provides good agreement between the average fading‐corrected K‐feldspar age (119 ± 6 ka) and the independent age control (132–125 ka). This is despite the reservations of Huntley & Lamothe (2001) that their fading correction method is not expected to work on samples older than ~20–50 ka. This fading‐corrected feldspar result is not significantly different from the overall revised quartz age (114 ± 7 ka) also presented here. We conclude that fading‐corrected IRSL ages measured using K‐feldspar may be both precise and accurate over a greater age range than might be otherwise expected. 相似文献
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DARREL A. SWIFT DAVID C. W. SANDERSON PETER W. NIENOW ROBERT G. BINGHAM IAN C. COCHRANE 《Boreas: An International Journal of Quaternary Research》2011,40(3):446-458
Swift, D. A., Sanderson, D. C. W., Nienow, P. W., Bingham, R. G. & Cochrane, I. C. 2010: Anomalous luminescence of subglacial sediment at Haut Glacier d'Arolla, Switzerland – a consequence of resetting at the glacier bed? Boreas, Vol. 40, pp. 446–458. 10.1111/j.1502‐3885.2010.00196.x. ISSN 0300‐9483. Luminescence has the potential to elucidate glacial geomorphic processes because primary glacial sediment sources and transport pathways are associated with contrasting degrees of exposure to light. Most notably, sediment entrained from extraglacial sources should be at least partially reset, whereas sediment produced by glacial erosion of subglacial bedrock should retain substantial luminescence commensurate with a geological irradiation history. We set out to test the validity of this assumption at Haut Glacier d'Arolla, Switzerland using sediment sampled extraglacially and from the glacier bed. Contrary to our expectations, the subglacial samples exhibited natural signals that were substantially lower than those of other sample groups, and further (albeit limited) analyses have indicated no obvious differences in sample‐group luminescence characteristics or behaviour that could account for this observation. For glaciological reasons, we can eliminate the possibilities that the subglacial sediment has been extraglacially reset or exposed in situ to heat or light. We therefore advocate investigation of possible resetting processes related to subglacial crushing and grinding, and speculate that such processes, if more generally present, may enable the dating of subglacially deposited tills using luminescence‐based techniques. 相似文献
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PETER WRIGHT 《Sedimentology》1976,23(5):705-712
Previous attempts to quantify beach processes with techniques involving direct measurement have met with varying degrees of success. Problems encountered can be attributed to three main areas of difficulty: (1) the rapidity of change in both process operation and the subsequent production and development of bed forms; (2) the inclement nature of the weather conditions during which the most rapid beach changes take place; (3) interference with the flows being measured, by the equipment. A photographic method is described here, which to a great extent overcomes these problems, and can be operated cheaply by a solitary field investigator. 相似文献
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PETER NEUMANN-MAHLKAU 《Sedimentology》1976,23(3):421-425
Sand volcanoes are small volcano-like features. They range in diameter from a few centimetres to several metres. Five volcanoes with a maximum diameter of 2 m were observed during the construction of a dike on the coast of Northwestern Germany. The cones reached heights of about 15 cm with craters in the middle. The rise of the volcanoes is explained by de-watering of sediment. 相似文献
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Phase relationships on the vapor-saturated liquidus surfacein the system CaO-MgO-CO2-H2O have been deduced from data inthe systems CaO CO2-H2O, CaO-MgO-CO2, and MgO-CO2-H2O, and frompreliminary experiments in the quaternary system. These areillustrated in composition tetrahedra, and in isobaric sectionsthrough the petrogenetic model. The univariant PT curve forthe beginning of melting lies between 625? C and 600? C in thepressure range 10 bars to 4 kilobars, in the presence of a vaporphase rich in H2O. The curve is divided into three sectionsby two invariant points, each section having a different primarymagnesian phase involved in the melting reaction. Periclaseoccurs on the low-pressure section (less than about 1 kilobar),and with increasing pressure first brucite and then dolomitebecome stable on the liquidus. The pressure of the second invariantpoint, above which dolomite is stable on the liquidus, is notknown. The effect of FeO as an additional component is considered.Processes of crystallization resulting from changes in temperature,in pressure, and in the composition of the vapor phase are discussed.These processes are applied to the crystallization and differentiationof carbonatite magmas, and the reverse processes involving fusionare applied to the metamorphism of dolomites. Crystallizationdifferentiation of a carbonatite magma could produce the sequenceof intrusion observed at some carbonatite complexes: calcitics?vite, followed by ankeritic s?vite, and finally sideriticcarbonatite. Partial melting may occur during the thermal metamorphismof dolomites, but melting is unlikely during regional metamorphism. 相似文献
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