The multiple chronological techniques applied to the Lake Suigetsu SG06 sediment core,central Japan

The varved sediment of Lake Suigetsu (central Japan) provides a valuable opportunity to obtain high‐resolution, multi‐proxy palaeoenvironmental data across the last glacial/interglacial cycle. In order to maximize the potential of this archive, a well‐constrained chronology is required. This paper outlines the multiple geochronological techniques being applied – namely varve counting, radiocarbon dating, tephrochronology (including argon–argon dating) and optically stimulated luminescence (OSL) – and the approaches by which these techniques are being integrated to form a single, coherent, robust chronology. Importantly, we also describe here the linkage of the floating Lake Suigetsu (SG06) varve chronology and the absolute (IntCal09 tree‐ring) time scale, as derived using radiocarbon data from the uppermost (non‐varved) portion of the core. This tie‐point, defined as a distinct (flood) marker horizon in SG06 (event layer B‐07–08 at 1397.4 cm composite depth), is thus derived to be 11 255 to 11 222 IntCal09 cal. years BP (68.2% probability range).     

Correlation of the middle devonian formations of Australia

In the Precambrian rocks west and southwest of the Mount Isa Fault three significant fold generations are recognized. Within individual successions, units containing an early phase of deformation are juxtaposed by a late fault against a sequence that does not share these earlier events.

Many of the large‐scale structures in the Judenan Beds are first‐generation folds, whereas west of the Judenan Beds the area is dominated by second‐generation folds. These two sets of folds are tentatively correlated and are referred to as the Judenan Folds. An earlier set of pre‐Judenan folding is only found in the units west of the Judenan Beds. One phase of the Sybella Granite is also associated with the Judenan folding. Later small‐scale folds associated with a crenulation cleavage are, however, of little regional importance and are commonly found only in zones of highly deformed rocks.     

High-T, low-P metamorphism in the Palaeoproterozoic Halls Creek Orogen, northern Australia: the middle crustal response to a mantle-related transient thermal pulse

High‐T, low‐P metamorphic rocks of the Palaeoproterozoic central Halls Creek Orogen in northern Australia are characterised by low radiogenic heat production, high upper crustal thermal gradients (locally exceeding 40 °C km^?1) sustained for over 30 Myr, and a large number of layered mafic‐ultramafic intrusions with mantle‐related geochemical signatures. In order to account for this combination of geological and thermal characteristics, we model the middle crustal response to a transient mantle‐related heat pulse resulting from a temporary reduction in the thickness of the mantle lithosphere. This mechanism has the potential to raise mid‐crustal temperatures by 150–400 °C within 10–20 Myr following initiation of the mantle temperature anomaly, via conductive dissipation through the crust. The magnitude and timing of maximum temperatures attained depend strongly on the proximity, duration and lateral extent of the thermal anomaly in the mantle lithosphere, and decrease sharply in response to anomalies that are seated deeper than 50–60 km, maintained for <5 Myr in duration and/or have half‐widths <100 km. Maximum temperatures are also intimately linked to the thermal properties of the model crust, primarily due to their influence on the steady‐state (background) thermal gradient. The amplitudes of temperature increases in the crust are principally a function of depth, and are broadly independent of crustal thermal parameters. Mid‐crustal felsic and mafic plutonism is a predictable consequence of perturbed thermal regimes in the mantle and the lowermost crust, and the advection of voluminous magmas has the potential to raise temperatures in the middle crust very quickly. Although pluton‐related thermal signatures significantly dissipate within <10 Myr (even for very large, high‐temperature intrusive bodies), the interaction of pluton‐ and mantle‐related thermal effects has the potential to maintain host rock temperatures in excess of 400–450 °C for up to 30 Myr in some parts of the mid‐crust. The numerical models presented here support the notion that transient mantle‐related heat sources have the capacity to contribute significantly to the thermal budget of metamorphism in high‐T, low‐P metamorphic belts, especially in those characterised by low surface heat flow, very high peak metamorphic geothermal gradients and abundant mafic intrusions.     

Geochemical correlations between effusive and explosive silicic volcanics in the Saraykent region (Yozgat), central Anatolia,Turkey

Two main volcanic events are distinguished between Saraykent and Akçakışla in the Yozgat province of central Anatolia: (1) early Late Cretaceous–Palaeocene effusive activity, that produced a sequence of intermediate to felsic ‘basal lavas’; and (2) marginally later Palaeocene explosive activity that formed a series of covering ignimbrite flows. Due to their close temporal and spatial relation, geochemical comparisons were made between the silicic members of the lavas and ignimbrites, to identify chemical groups and their relative petrogenesis. The basal lavas range from calc‐alkaline basaltic andesites to dominant rhyolites. Based on trace element correlations three main geochemical groups were identified: the Akçakışla rhyolites (present as domes); Akçakışla rhyodacites‐dacites (lava flows); and Ozan‐Saraykent rhyolites (lava flows). Large‐ion lithophile elements have been mobile in all the groups, but mainly in the Akçakışla rhyolites. Rare earth element (REE) patterns show marked similarity between the Ozan and Saraykent basal lavas. The Akçakışla dome rhyolites are more fractionated with lower La_N/Yb_N ratios (c.10), whereas the Akçakışla basal lavas have much higher La_N/Yb_N ratios (c.30). The chemical coherence and petrographic similarities between the Saraykent and Ozan lavas suggest a single suite related via fractionation. Three geochemical groups were also established for the ignimbrites: Saraykent ignimbrite; Bağlıca ignimbrite‐Toklu‐Kızıldağ crystal tuffs; and Keklikpınar ignimbrite. The ignimbrites, like the basal lavas, display a pronounced depletion in Ba on ORG‐normalized plots. Relative to the basal lavas, chondrite‐normalized patterns for the ignimbrites are different in displaying negative Eu anomalies that indicate feldspar fractionation. The lack of geochemical overlap or coherence between any of the lava and ignimbrite groups suggests that they represent distinct eruptive events and are not related in any simple volcanic development and cogenetic sense. Two geochemical features are common to all the volcanic rock groups: (1) the presence of a Nb‐Ta anomaly, which is generally accepted as a crustal signature; and (2) the relatively low Y abundances which appear characteristic for the region as a whole. These fundamental features of the local silicic volcanism largely reflect source composition and effects. Copyright © 2002 John Wiley & Sons, Ltd.     

Multi‐proxy study of Holocene environmental change and human activity in the Central Apennine Mountains,Italy

This paper describes a multi‐proxy palaeoecological investigation undertaken in conjunction with an archaeological survey of the Upper Sangro Valley in the Abruzzo National Park, Central Italy. Despite being a biodiversity hotspot and regarded as a near‐pristine area, the pollen, spore and diatom data all show major changes in the vegetation extending to over 2000 m a.s.l. during the mid to late Holocene. Although there are changes in ecological composition earlier in the Holocene they are different in type and magnitude from the changes which began about 800 cal a BC. The pollen and diatom evidence do not correlate well with regional palaeoclimate data, or on‐site isotopic evidence, but do appear to be related to Samnite (later Iron Age) clearance and upland grazing associated with transhumance and later annexation (and centuriation) of the lower slopes by Roman surveyors. The greatest change in vegetation was during the period c. AD 500–600 and corresponds with the Byzantine–Gothic Wars, and Lombard–Carolingian settlement reorganization into nucleated hilltop settlements which managed upland grazing. This pattern of intensive land use at all altitudes persisted until the early 20th century and only changed following rural depopulation after World War II. These data illustrate how cultural factors had a profound effect on this mountainous region which, in this case, far outweighed the effects of climatic fluctuations which are known to have occurred from both this study area and the region. Copyright © 2012 John Wiley & Sons, Ltd.     

Characterisation of Two New Reference Materials: STL-1, the Stewart Lepidolite and ZA-1, the Zapot Amazonite

The analysis of granitic pegmatites still remains a challenge because suitable natural reference materials are scarce or not available. Two new reference materials were prepared at the Smithsonian Institution, to provide an avenue to pursue the geochemical analysis of micas and feldspars in granitic pegmatites: STL-1, the Stewart lepidolite (NMNH 174041) and ZA-1, the Zapot amazonite (NMNH 174042). STL-1 was prepared from lepidolite collected from the lithium-rich Stewart pegmatite, San Diego County, California (33°22'52'N, 117°03'41'W). ZA-1 was prepared from an amazonite from the topaz-bearing Zapot pegmatite, Mineral County, Nevada, (38° 41'N, 118 °33'W). The results of this study indicated that STL-1 and ZA-1 are homogeneous and could be used as reference materials that would allow the expansion of calibration curves in XRF analysis up to 16000 μg g⁻¹ for Rb, 2000 μg g⁻¹ for Cs and 100 μg g⁻¹ for Tl. STL-1 and ZA-1 also contain unusually high concentrations of Ga and Tl, and STL-1 of Nb.     

Little Ice Age advance and retreat sediment budgets for an outlet glacier in western Norway

Burki, V., Hansen, L., Fredin, O., Andersen, T. A., Beylich, A. A., Jaboyedoff, M., Larsen, E. & Tønnesen, J.‐ F. 2009: Little Ice Age advance and retreat sediment budgets for an outlet glacier in western Norway. Boreas, Vol. 39, pp. 551–566. 10.1111/j.1502‐3885.2009.00133.x. ISSN 0300‐9483 Bødalsbreen is an outlet glacier of the Jostedalsbreen Ice Field in western Norway. Nine moraine ridges formed during and after the maximum extent of the Little Ice Age (LIA). The stratigraphy of proglacial sediments in the Bødalen basin inside the LIA moraines is examined, and corresponding sediment volumes are calculated based on georadar surveys and seismic profiling. The total erosion rates (e_tot) by the glacier are determined for the periods AD 1650–1930 and AD 1930–2005 as 0.8 ± 0.4 mm/yr and 0.7 ± 0.3 mm/yr, respectively. These rates are based on the total amount of sediment delivered to the glacier margin. The values are almost one order of magnitude higher than total erosion rates previously calculated for Norwegian glaciers. This is explained by the large amount of pre‐existing sediment that was recycled by Bødalsbreen. Thus, the total erosion rate must be considered as a composite of eroded bedrock and of removed pre‐existing sediments. The total erosion rate is likely to vary with time owing to a decreasing volume of easily erodible, unconsolidated sediment and till under the glacier. A slight increase in the subglacial bedrock erosion is expected owing to the gradually increasing bedrock surface area exposed to subglacial erosion.     

A study of late Pleistocene loess deposits,South Canterbury,New Zealand: Part I. Forms and amounts of phosphorus compared with other techniques for identifying paleosols

Four paleosols, and soil horizons within paleosols, were clearly identified in the thick calcium carbonate-free loess sections at Timaru, South Island, New Zealand, by changes in the distribution of total phosphorus and calcium phosphate in the upper 2 m to each paleosol. Extractable manganese was also sensitive in identifying paleosols, particularly the upper horizons. The distribution of bulk density values was useful in identifying paleosols; however, the maximum bulk density (>1.7 g/cc) occurred in horizons identified as B2 rather than fragipan horizons in three of four cases. The distribution of clay particles was useful in understanding the genesis of the modern soil and paleosols, but not in identifying paleosols.     

The inhibition of microorganisms by heavy metals

This paper examines the effects of heavy metals on microorganisms in the aqueous environment; the mechanisms by which metals may exert toxic effects on microbes and the factors affecting microbial response to metals; the ways in which microbial activity may alter the metal balance of an environment and the modifications produced in microbes by heavy metal ions; the effects of the toxic copper ion on the growth, respiration, magnesium content, cytochrome synthesis and osmotic sensitivity of some organisms studied in the laboratory; and the feasibility of the participation of microbes in geochemical processes considering the demonstrable resistance to toxic metals by some bacteria and the fact that natural environments may contain high levels of metals rendered less toxic by binding to natural chelating compounds.

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Zusammenfassung In dieser Arbeit werden verschiedene Wirkungen von Schwermetallen auf Mikroorganismen in wäßrigem Milieu untersucht. Es wird gezeigt, daß Schwermetalle toxische Wirkungen auf Mikroorganismen ausüben können und welche Faktoren die Reaktionen von Mikroben gegenüber Metallen bestimmen. Weiter wird beschrieben, wie die Mikrobenaktivität das Metallgleichgewicht in einem gegebenen Milieu verändern und beeinflussen kann und wie andererseits Änderungen in den Mikroben selbst durch Schwermetall-Ionen hervorgerufen werden. Dabei wird besonders die Wirkung des toxischen Kupfer-Ions auf das Wachstum, die Atmung, den Magnesiumgehalt, die Cytochromsynthese und die osmotische Empfindlichkeit einiger Mikroorganismen dargestellt. Die Anwesenheit von Mikroben bei geochemischen Prozessen wird unter Berücksichtigung der Resistenz einiger Bakterien gegenüber toxischen Metall-Ionen diskutiert. Dabei spielt die Tatsache eine große Rolle, daß durch Chelatbildung die Schwermetall-Ionen in der natürlichen Umwelt der Mikroorganismen ihre toxische Wirkung verlieren.

     

Is the Kolmogoroff model applicable to large-scale turbulence?

We discuss the difficulties encountered when the Heisenberg-Kolmogoroff model for turbulence is applied to the large-scale turbulence in: (A) molecular clouds (specifically the velocity vs size relationship) and (B) stars (specifically, the estimate of convective fluxes).A new model for large-scale turbulence is, therefore, needed.