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51.
Timothy Pietsch Justine Kemp Colin Pardoe Rainer Grün Jon Olley Rachel Wood 《第四纪科学杂志》2019,34(8):662-673
Kiacatoo Man, a large, rugged Aboriginal adult buried in the Lachlan riverine plains of southeastern Australia, was discovered in 2011. Laser‐ablation uranium series analysis on bone yielded a minimum age for the burial of 27.4 ± 0.4 ka (2σ). Single‐grain, optically stimulated luminescence ages on quartz sediment in which the grave had been dug gave a weighted mean age of 26.4 ± 1.5 ka (1σ). Luminescence samples from the grave infill and from sediment beneath the grave exhibit overdispersed dose distributions consistent with bioturbation or other disturbance, which has obscured the burial signal. The overlap between the minimum (U‐series) and maximum (luminescence) ages places the burial between 27.0 and 29.4 ka (2σ). Luminescence ages obtained from the channel belt of between 28 ± 2 and 25 ± 3 ka indicate that fluvial sedimentation was occurring before the Last Glacial Maximum, which is consistent with the broader geomorphic setting. Together, these results are internally and regionally consistent, and indicate that Kiacatoo Man was one of the more ancient individuals so far identified in Australia. His remains are important to our understanding of patterns of biological variation and other processes that have shaped people in the Murray‐Darling Basin through time. Copyright © 2019 John Wiley & Sons, Ltd. 相似文献
52.
Hamid El Maanaoui Fabian Wilangowski Aditya Maheshwari Hans-Dieter Wiemhöfer Rainer Abart Nicolaas A. Stolwijk 《Physics and Chemistry of Minerals》2016,43(5):327-340
We measured the ion conductivity of single-crystal alkali feldspar originating from two different locations in the Eifel/Germany, named Volkesfeld and Rockeskyller sanidine and having potassium site fractions \(C_\mathrm{K}\) of 0.83 and 0.71, respectively. The dc conductivities resulting from electrochemical impedance spectroscopy over the temperature range of 300–900 \(^{\circ }\hbox {C}\) show a weak composition dependence but pronounced differences between the b-direction [\(\perp (010)\)] and \(c^{*}\)-direction [\(\perp (001)\)] of the monoclinic feldspar structure. Conductivity activation energies obtained from the observed linear Arrhenius plots are close to 1.2 eV in all cases, which is closely similar to the activation energies of the \(^{22}\mathrm{Na}\) tracer diffusivity in the same crystals. Taking into account literature data on K tracer diffusion and diffusion correlation effects, the present results point to a predominance of the interstitialcy mechanism over the vacancy mechanism in mass and charge transport on the alkali sublattice in potassium-rich alkali feldspar. 相似文献
53.
54.
Gültekin?Topuz Rainer?AltherrEmail author Muharrem?Sat?r Winfried?H.?Schwarz 《International Journal of Earth Sciences》2004,93(1):72-91
In the Pulur complex (Sakarya Zone, Eastern Pontides, Turkey) a low-grade tectonometamorphic unit (Doankavak) is exposed in three tectonic windows beneath a complex medium-pressure high-temperature metamorphic unit of late Carboniferous age. The thrust plane between both units is transgressively covered by Liassic conglomerates. The Doankavak unit comprises a sequence of metabasites with MORB-type chemical compositions and phyllites, with subordinate calcareous phyllites, marbles, quarzofeldspathic schists and metacherts. This sequence is interpreted as a former accretionary complex related to the consumption of the Palaeotethys. Mineral parageneses in the metabasites allow for the distinction of two domains with slightly different peak metamorphic conditions, i.e. 375–425 °C/0.5–0.8 GPa (greenschist facies) and 400–470 °C/0.6–1.1 GPa (albite-epidote amphibolite facies). The age of metamorphism is constrained at ~ 260 Ma (early Late Permian) by two Rb-Sr mineral-whole rock ages (hornblende, phengite) and one 40Ar/39Ar single step total fusion age (phengite). In conjunction with previous data on other accretionary complexes in the Sakarya zone in Northern Turkey, the data presented in this study suggest a continuous subduction of the Palaeotethys at least from Early/Late Permian to Late Triassic and a discontinuous preservation of accretion complexes in both space and time. 相似文献
55.
Six C1 chondrite samples and a C2 xenolith from the Plainview H5 chondrite were analyzed by radiochemical neutron activation for the elements Ag, Au, Bi, Br, Cd, Ce, Cs, Eu, Ge, In, Ir, Lu, Nd, Ni, Os, Pd, Pt, Rb, Re, Sb, Se, Sn, Tb, Te, Tl, Yb, and Zn. The data were combined with 9 earlier analyses from this laboratory and examined for evidence of chemical fractionation in C1 chondrites.A number of elements (Br, Rb, Cs, Au, Re, Os, Ni, Pd, Sb, Bi, In, Te) show small but correlated variations. Those of the first 8 probably reflect hydrothermal alteration in the meteorite parent body, whereas those of Sb, Bi, In, and Te may at least in part involve nebular processes. Br and Au show systematic abundance differences from meteorite to meteorite, which suggests hydrothermal transport on a kilometer scale. The remaining elements vary from sample to sample, suggesting transport on a centimeter scale.There is no conclusive evidence for nebular fractionation affecting C1 's. Though C1 chondrites have lower and ratios than do other chondrite classes, these ratios vary in other classes, suggesting that those classes rather than C1's are fractionated. Three fractionation-prone REE—Ce, Eu, and Yb have essentially the same relative abundances in C1's and all other chondrite classes, and hence apparently are not fractionated in C1's. We did not confirm the large Tb and Yb variations in C1's reported by other workers.We present revised mean C1 abundances for 35 elements, based on the new data and a critical selection of literature data. Changes are generally less than 10%, except for Br, Rb, Ag, Sb, Te, Au, and the REE.The Plainview C2 xenolith has normal trace element abundances, except for 3 elements falling appreciably above the C2 range: Rb, Cs, and Bi. Hydrothermal alteration may be the reason for all 3, though nebular fractionation remains a possibility for Bi. 相似文献
56.
Floristic surveys, vegetation mapping, and detailed transect analyses rendered a macrophyte flora of 14 native and five alien taxa of flowering plants in the River Erft, a contributory of the River Rhine in Northrhine-Westphalia. Water temperatures of this river do not fall below 10 °C all the year round, for reasons of geothermically heated water discharged from nearby opencast mining areas. Macrophyte stand structures, composed of the neophytes Azolla filiculoides and Lemna minuta (floating) and Myriophyllum aquaticum, Egeria densa, and Vallisneria spiralis (rooted in the muddy or sandy ground of the river) are described and the ecological requirements of these taxa are characterized. The alien species can be seen as elements that increase the α-diversity of the aquatic vegetation of the River Erft. They do not replace any of the native species, even if shifts in the competition dynamics occur. The colonization by neophytes of the abnormally warmed River Erft can be appreciated as paradigmatic for trends in the macrophyte vegetation of medium-sized rivers in Central Europe when climate-related or discharge-based heating of the waterbody occurs and propagules of alien plants imported by waterfowl or – more important – plants from aquarium waste will find suitable places of existence and spread. 相似文献
57.
Climatology of Ozone, PAN, CO, and NMHC in the Free Troposphere Over the Southern North Atlantic 总被引:1,自引:0,他引:1
Free tropospheric measurements of ozone, peroxyacetylnitrate andprecursors (CO, NMHC) that were made within the framework of the EUROTRACsub-project TOR (Tropospheric Ozone Research) between 1990 and 1995 at theGAW station Izana, Tenerife (28°18N, 16°30W) arediscussed. The average annual cycles reveal the importance of transport fromnorthern mid-latitudes and the role of photo-chemistry. According toair-mass trajectories, which were supplied to us from AEROCE(Atmosphere/Ocean Chemistry Experiment), transport from northernmid-latitudes is associated with high precursor concentrations in winter,whereas ozone concentrations in winter are not much influenced by transportpatterns, suggesting a rather uniform distribution over the northern part ofthe Northern Hemisphere around mean value of 43 ± 5 ppb. In summer,high ozone concentrations of up to 90 ppb are often encountered duringtransport from north, while the levels of precursors are much lower than inwinter, because of photochemical destruction. Trajectories from southerlylatitudes and the Sahara usually have the lowest ozone concentrationsassociated with them. 相似文献
58.
Providing Geographical Information Systems with mechanisms for processing geo‐data based on their semantics may help to solve problems like heterogeneity. This is because GIS could process geo‐data focusing on their meaning and not on their syntax and/or structure. An important aspect for achieving these objectives is the establishment of an automatic means of correspondence between geo‐data and their conceptualization in Higher Levels Ontologies (HLO). In this article, a new type of Ontology is proposed (Data‐Representation Ontology (DRO)). This Ontology describes the semantic embedded in geo‐data, which cannot be represented in current types of Ontologies. Across this Ontology, heterogeneous geographical data can be integrated in the semantic space contributing positively to the development of solutions for the problems of interoperability between heterogeneous systems. Likewise, we propose a new method for the automatic generation of the DRO and its interrelationships with HLO, based on pattern classification techniques. The experiments show that once the DRO is generated, the classifier can classify all data correctly. Thus, these data are semantically enriched. Moreover, this article shows how the topological relationships can enrich the semantics in the generated Ontology and increase the effectiveness of spatial analysis. 相似文献
59.
Gültekin Topuz Aral I. Okay Rainer Altherr Winfried H. Schwarz Gürsel Sunal Lütfi Altınkaynak 《Island Arc》2014,23(3):181-205
Within the Tethyan realm, data for the subduction history of the Permo–Triassic Tethys in the form of accretionary complexes are scarce, coming mainly from northwest Turkey and Tibet. Herein we present field geological, petrological and geochronological data on a Triassic accretionary complex, the A?vanis metamorphic rocks, from northeast Turkey. The A?vanis metamorphic rocks form a SSE–NNW trending lozenge‐shaped horst, ~20 km long and ~6 km across, bounded by the strands of the active North Anatolian Fault close to the collision zone between the Eastern Pontides and the Menderes–Taurus Block. The rocks consist mainly of greenschist‐ to epidote‐amphibolite‐facies metabasite, phyllite, marble and minor metachert and serpentinite, interpreted as a metamorphic accretionary complex based on the oceanic rock types and ocean island basaltic, mid‐ocean ridge basaltic and island‐arc tholeiitic affinities of the metabasites. This rock assemblage was intruded by stocks and dikes of Early Eocene quartz diorite, leucogranodiorite and dacite porphyry. Metamorphic conditions are estimated to be 470–540°C and ~0.60–0.90 GPa. Stepwise 40Ar/39Ar dating of phengite–muscovite separates sampled outside the contact metamorphic aureoles yielded steadily increasing age spectra with the highest incremental stage corresponding to age values ranging from ~180 to 209 Ma, suggesting that the metamorphism occurred at ≥ 209 Ma. Thus, the A?vanis metamorphic rocks represent the vestiges of the Late Triassic or slightly older subduction in northeast Turkey. Estimated P–T conditions indicate higher temperatures than those predicted by steady state thermal models for average subduction zones, and can best be accounted for by a hot subduction zone, similar to the present‐day Cascadia. Contact metamorphic mineral assemblages around an Early Eocene quartz diorite stock, on the other hand, suggest that the present‐day erosion level was at depths of ~14 km during the Early Eocene, indicative of reburial of the metamorphic rocks. Partial disturbance of white‐mica Ar–Ar age spectra was probably caused by the reburial coupled with heat input by igneous activity, which is probably related to thrusting due to the continental collision between Eastern Pontides and the Menderes–Taurus Block. 相似文献
60.
Summary The geographical distribution of organic matter and particles <20 m in North Sea sediments as well as the correlation between organic content, <20 m fraction and PCB (as the sum of content of 24 individual components), p, p-DDE, HCB, -HCH and Lindane (-HCH) is reported. High amounts of organic matter and fine particles have been found in Fladen Ground, Kattegat/Skagerrak/Norwegian Channel, and the inner German Bight. Organic matter settling in the Kattegat/Skagerrak/Norwegian Channel is probably degraded by benthic organisms, including mineralization by bacteria. The smelter in south Norway and the rivers Ems and Elbe are point sources for HCB, the mud-area south-east of Helgoland is a point source for HCB and PCBs. No point source, however, was found for p,p-DDE. Sediment content of PCB, p,p-DDE and HCB show a good correlation to the amount of organic matter and to the <20 m fraction. -HCH and Lindane are only poorly adsorbed onto sediments.
Zyklische organische Chlorverbindungen in Nordseesedimenten: Verteilung von organischer Substanz und feinpartikulärem Material
Zusammenfassung Es wird über die Verteilung von organischer Substanz und feinpartikulärem Material <20 m in Nordseesedimenten sowie über die Korrelation der Sedimentparameter mit den Konzentrationen von polychlorierten Biphenylen (24 Einzelisomere), p,p-DDE, HCB, -HCH und Lindan (-HCH) berichtet. Hohe Gehalte an organischer Substanz und der <20 m Fraktion wurden im Fladengrund, Kattegat/ Skagerrak/Norwegische Rinne sowie in der inneren Deutschen Bucht gefunden. Die Ergebnisse legen den Schluß nahe, daß ein Großteil des sedimentierten organischen Materials vor der norwegischen Küste von Benthosorganismen und Bakterien verstoffwechselt wird. Durch die mit Søderbergelektroden arbeitenden Metallschmelzen Südnorwegens sowie durch die Flüsse Elbe und Ems werden die Sedimente punktuell mit HCB belastet. Das Schlammgebiet südöstlich von Helgoland tritt als Emittent für PCBs in Erscheinung. Für p,p-DDE konnte keine Punktquelle nachgewiesen werden. Im Gegensatz zu -HCH und Lindan korrelieren die Sedimentkonzentrationen an PCBs, HCB und p,p-DDE gut mit den Gehalten an organischer Substanz bzw. feinpartikulärem Material.
Les Organochlorines cycliques dans les Sédiments de la Mer du Nord, relation avec la taille et les matières organiques
Résumé La distribution géographique de matière organique et des particules de taille inférieure à 20 m dans les sédiments de la Mer du Nord ainsi que la corrélation entre le contenu organique, (la fraction <20 m) et PCB (somme des contenus de 24 composants individuels), p, p-DDE, HCB, -HCH et Lindane (-HCH) est décrite. D'importantes quantités de matières organiques et de particules fines ont été trouvées à Fladen Ground, Kattegat/Skagerrak/Norwegian Channel et dans le baie intérieur allemende. Les composants organiques qui se trouvent dans le Kattegat/ Skagerrak/Norwegian Channel sont probablement soumis à la dégradation par des organismes (benthic), et aussi à une minéralisation par bactéries. Les usines de métallurgie du Sud de la Norvège et la rivière l'Ems et l'Elbe sont des points sources pour HCB, les zones de boue au Sud Est de Helgoland sont des points sources pour HCB et PCB. Aucun point source ne fût trouvé cependant pour p, p-DDE. Le contenu en sédiment de PCB, p, p-DDE et HCB montre une bonne corrélation avec la quantité de matière organique et la fraction <20 m. -HCH et Lindane ne sont que peu absorbés dans les sédiments.相似文献