Latest Quaternary papers

Thursday, 17 July 2014
Earth and Planetary Science News

o o Inner structure of anchor ice and ice dams in steep channels

Mathieu Dubé, Benoit Turcotte, Brian Morse

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Thursday, 17 July 2014
Earth and Planetary Science News

o Dolní Věstonice IIa: Gravettian microstratigraphy, environment, and the origin of baked clay production in Moravia

Jiří Svoboda, Šárka Hladilová, Ivan Horáček, Jozef Kaiser, Miroslav Králík, Jan Novák, Martin Novák, Petr Pokorný, Sandra Sázelová, Libuše Smolíková, Tomáš Zikmund

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Thursday, 17 July 2014
Earth and Planetary Science News

o Numerical modeling of slope flows entraining bottom material

o M.E. Eglit, A.E. Yakubenko

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Thursday, 17 July 2014
Earth and Planetary Science News

o Palaeoecological record of natural changes and human impact in a small river valley in Central Poland

o Dominik Pawłowski, Krystyna Milecka, Piotr Kittel, Michał Woszczyk, Waldemar Spychalski

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Thursday, 17 July 2014
Earth and Planetary Science News

o Rare earth elements in cold seep carbonates from the southwestern Dongsha area, northern South China Sea

o Shuhong Wang, Wen Yan, Zhong Chen, Nan Zhang, Han Chen

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Thursday, 17 July 2014
Earth and Planetary Science News

o Relative sea-level changes in the Basque coast (northern Spain, Bay of Biscay) during the Holocene and Anthropocene: The Urdaibai estuary case

o Ane García-Artola, Alejandro Cearreta, Eduardo Leorri

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Thursday, 17 July 2014
Earth and Planetary Science News

o The Davie Fracture Zone and adjacent basins in the offshore Mozambique Margin – A new insights for the hydrocarbon potential

o E.S. Mahanjane

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Thursday, 17 July 2014
Earth and Planetary Science News

o Variation in short-term ice-induced load amplitudes on a ship’s hull and related probability distributions

Mikko Suominen , Pentti Kujala

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Wednesday, 16 July 2014
Boreas

Stable isotopes reveal ecological differences amongst now-extinct proboscideans from the Cincinnati region, USA

The mobility and dietary preferences of now-extinct proboscideans have not been comprehensively examined in the central USA. We used stable carbon (δ13C), oxygen (δ18O) and strontium (87Sr/86Sr) isotopic signatures in molar enamel to investigate the foraging ecology of four mastodons (Mammut americanum) and eight mammoths (Mammuthus spp.) from southwestern Ohio and northwestern Kentucky. We tested two hypotheses: (i) these individuals were nomadic migrants that were passing through the region when they died; and (ii) mammoths and mastodons foraged in different environments. Unexpectedly, our results suggest that 11 of the 12 sampled individuals were regional residents. With the exception of one mastodon, 87Sr/86Sr ratios for proboscideans and regional water samples were statistically indistinguishable; slightly lower ratios for waters suggest glacial loess has an impact on modern samples. Amongst the individuals identified as residents, 87Sr/86Sr ratios indicate that mammoths and mastodons foraged in discrete geographical areas, and δ13C values imply dietary differences between the genera, which is consistent with our expectations. Oxygen isotope values may be able to distinguish animals that lived during the Last Glacial Maximum (LGM) from those that lived more recently. Three mammoths and one mastodon yielded δ18O values that are similar to modern regional precipitation and surface water, but too high for estimated drinking water during the LGM. We propose that these individuals lived during a relatively warm period following the LGM. Compellingly, the mammoth with the highest δ18O value also has the lowest δ13C value, suggesting that this individual was alive after regional vegetation shifted from open parkland to deciduous forest dominated by C3 species. Our results demonstrate that a wealth of information can be gleaned from fossil museum specimens and lay a foundation for future work on the foraging ecology of proboscideans and other extinct megafauna from the Midwest USA.

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Tuesday, 15 July 2014
Journal of Quaternary Science

Evidence for ca. 7-ka maximum Holocene transgression on the Peninsular Malaysia east coast

In situ fossil coral and shelly marine deposits occur up to 50 cm above mean sea level in north-east Peninsular Malaysia. The fossil reef comprises over 15 coral species and associated molluscs. Radiocarbon ages of corals range from 7238 to 6909 cal a BP. The reef occurs adjacent to bedrock hills that formed a mainland peninsula when the coral was living. Abundant well-preserved fossil molluscs with bivalves commonly articulated occur in ditch tailings from coastal plains flanking these hills. Landward, a sand ridge represents part of the maximum transgression shoreline. When alive, the fossil coral reef required clear water and full marine conditions seaward of the peninsula. The maximum transgression here occurred ca. 7 ka with stable environmental conditions persisting long enough for diverse coral reef development. Assuming a similar tidal range to today, relative sea level ca. 7 ka would have been between 1.4 and 3 m above present. Between then and ca. 6 ka, abundant sediment supply resulted in barrier-beach construction seaward of the coral reef, converting the area to a lagoonal environment unsuitable for coral and burial by muddy deposits. Assuming that regional relative sea-level data indicate maximum Holocene highstand up to +5 m between 6 and 4 ka are correct, then the maximum transgression preceded maximum sea level by at least 1000 years.

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Tuesday, 15 July 2014
Journal of Quaternary Science

Testate amoebae as a proxy for reconstructing Holocene water table dynamics in southern Patagonian peat bogs

Testate amoebae are abundant and diverse in Sphagnum peat bogs and have been used extensively as indicators of past water table depths. Although these unicellular protists are widely dispersed with globally similar hydrological preferences, regional variations in communities demand region-specific transfer functions. Here we present the first transfer function for southern Patagonian bogs, based on 154 surface samples obtained from transects in five bogs sampled in 2012 and 2013. Significant variance was explained by pH, electrical conductivity and, in particular, water table depth. Transfer functions for water table were constructed using weighted averaging and evaluated by cross-validation and independent test sets. The optimal transfer function has predictive ability, but relatively high prediction errors given the wide range in sampled water tables. The use of independent test sets, as well as cross-validation, allows a more rigorous assessment of model performance than most previous studies. For a subset of locations we compare surface and subsurface samples to demonstrate significant differences in community composition, possibly due to vertical zonation. Our results provide the first quantification of hydrological optima and tolerances for several rare species, which may include Southern Hemisphere endemics and pave the way for palaeohydrological reconstructions in southern Patagonian bogs.

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Tuesday, 15 July 2014
Journal of Quaternary Science

West Greenland and global in situ 14C production-rate calibrations

The in situ cosmogenic nuclide 14C is unique compared with other nuclides because of its short half-life, and when combined with longer-lived isotopes (e.g. 10Be), in situ 14C can be a powerful tool for deciphering recent and complex surface exposure histories. Like all in situ cosmogenic nuclides, quantifying earth surface processes with in situ 14C requires a well-constrained in situ 14C production rate. We present a production-rate calibration from an independently dated moraine in West Greenland, previously used as an in situ 10Be production-rate calibration site. The local in situ 14C production rate is 22.8 ± 1.4 atoms g−1 a−1 (69.28°N, 50.76°W; 350 m asl) and when scaled to sea level/high latitude using time-dependent Lal/Stone scaling (Lm), we calculate a spallation-only in situ 14C production rate of 12.0 ± 0.9 atoms g−1 a−1 and a 14C/10Be production rate ratio of 3.1 ± 0.2. The West Greenland in situ 14C production rate is indistinguishable from the New Zealand, Promontory Point and Scottish Highlands in situ 14C production rates. When combined, we calculate a global production rate of 12.1 ± 0.5 atoms g−1 a−1 (Lm).

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Tuesday, 15 July 2014
Journal of Quaternary Science

An 18 000-year pollen and sedimentary record from the cedar forests of the Middle Atlas, Morocco

A new record from the heart of the Moroccan Middle Atlas cedar forests spans the last 18 000 years and provides valuable insight into our understanding of the natural vegetation and environmental changes. The approach is based on the study of pollen content, geochemical elements and grain size analysis. The pollen data indicate that the vegetation was dominated by herbaceous plants until 9000 BP. Such open landscape allowed greater soil erosion and an input of chemical elements from the watershed. After 9000 BP, tree cover, mainly oak, increased slightly and was accompanied by a higher taxonomic diversity. However, several steppe elements remain well represented in the area until 5000 BP, which suggests that the climate was rather dry during the first part of the Holocene. After 6000 BP, the climate became more favourable to expansion of the forest ecosystems, including Cedrus atlantica, thereby reducing erosion. A strong reduction of the tree pollen percentages is recorded after 2000 BP, which may be related to increasing human activities during the Roman period. These forest changes are concomitant with an increase of lead and copper concentrations in the record, probably related to Roman metalworking activities.

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Tuesday, 15 July 2014
Journal of Quaternary Science

IntCal13 calibrated ages of the Vedde and Saksunarvatn ashes and the Younger Dryas boundaries from Kråkenes, western Norway

From Kråkenes Lake in western Norway there exist 118 accelerator mass spectrometry 14C dates for the time interval 12 000–8000 14C a BP that we earlier calibrated using the IntCal09 data set. These yielded the most accurate and precise ages available for the Younger Dryas boundaries and the Vedde and Saksunarvatn ashes. Here we present a new calibration using the recently published IntCal13 data set. All differences between the two sets of calibrated ages are within the ± 1σ error of the original IntCal09 results. The most significant differences are that the error for the Allerød/Younger Dryas boundary decreased, that this boundary became slightly older and that the length of the Younger Dryas increased slightly.

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Tuesday, 15 July 2014
Journal of Quaternary Science

36Cl production rate from K-spallation in the European Alps (Chironico landslide, Switzerland)

The abundant production of in situ cosmogenic 36Cl from potassium renders 36Cl measurements in K-rich rocks or minerals, such as K-feldspars, potentially useful for precisely dating rock surfaces, either in single-nuclide or in multi-nuclide studies, for example combined with 10Be measurements in quartz. However, significant discrepancies in experimentally calibrated 36Cl production rates from spallation of potassium (36PK-sp), referenced to sea-level/high-latitude (SLHL), limit the accuracy of 36Cl dating from K-rich lithologies. We present a new 36Cl calibration using K-feldspars, in which K-spallation is the most dominant 36Cl production pathway (>92% of total 36Cl), thus minimizing uncertainties from the complex multi-pathway 36Cl production systematics. The samples are derived from boulders of an ∼13.4 ka-old landslide in the Swiss Alps (∼820 m, 46.43°N, 8.85°E). We obtain a local 36PK-sp of 306 ± 16 atoms 36Cl (g K)−1 a−1 and an SLHL 36PK-sp of 145.5 ± 7.7 atoms 36Cl (g K)−1 a−1, when scaled with a standard scaling protocol (‘Lm’). Applying this SLHL 36PK-sp to determine 36Cl exposure ages of K-feldspars from 10Be-dated moraine boulders yields excellent agreement, confirming the validity of the new SLHL 36PK-sp for surface exposure studies, involving 36Cl in K-feldspars, in the Alps.

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Tuesday, 15 July 2014
Journal of Quaternary Science

Last glacial hydrological variations at the southern margin of sub-tropical North America and a regional comparison

Geochemical and magnetic characteristics of sediments from paleolake La Salada provide information about the last glacial hydrological conditions at the southern margin of sub-tropical North America. Proxy records of runoff, lake water salinity, brine composition and provenance of organic matter are based on multi-element concentration, magnetic susceptibility, mineralogy, carbonate content and C/N relation. Runoff was higher than average during ca. 43–36k cal a BP and at ca. 33k cal a BP. A shift in mineralogical assemblage from calcite > protodolomite–halite to protodolomite–gaylussite suggests that the brine composition changed from Ca–(Mg–Na)–HCO3–(Cl) to Mg–Na–Ca–HCO3 because of more runoff after the desiccation event at ca. 28k cal a BP. In general, organic matter deposited during the intervals of more runoff and deeper lake conditions were sourced from lacustrine phytoplankton. The contribution of terrestrial vegetation dominates during the intervals of reduced runoff. Comparison with other records provides a regional perspective of moisture variability. Humid conditions at ca. 33k cal a BP could be due to more summer precipitation in northern Mexico as well as increased winter rainfall in the south-western USA.

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Tuesday, 15 July 2014
Journal of Quaternary Science

Erratum

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Tuesday, 15 July 2014
Journal of Quaternary Science

Climate over mainland Southeast Asia 10.5–5 ka

We assembled and evaluated Holocene palaeo-vegetation records regarding semi-quantitative precipitation and temperature for mainland Southeast Asia and compared these with precipitation reconstructions for the Indian Ocean (IOM) and East Asian (EAM) monsoon sub-systems. Our results indicate that temperatures and precipitation in mainland Southeast Asia generally exceeded 18 °C and 1100 mm a−1 during the Holocene. Mainland Southeast Asia experienced cool/wet climatic conditions between 10.5 and 10 ka BP, a warmer/drier climate between 10 and 9 ka BP, cooler/wetter conditions between 9 and 7 ka BP, and moderately warmer/drier conditions since 7 ka BP. The reconstructed summer monsoon intensity compares well with the reconstructed hydroclimate for the EAM region, but diverges from that of the IOM region between 10.5 and 9 ka BP and 7–6.5 ka BP. This discrepancy is explained by differences in land–sea configuration, and regional sea-level history. A strengthening/weakening of the Asian summer monsoon between 9 and 7 ka BP and after 6.5 ka BP, respectively, is observed across the whole Asian monsoon region. Our new data sets support an asynchronous onset of the Asian summer monsoon optimum.

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Tuesday, 15 July 2014
Journal of Quaternary Science

Online oxygen isotope analysis of sub-milligram quantities of biogenic opal using the inductive high-temperature carbon reduction method coupled with continuous-flow isotope ratio mass spectrometry

We present a method for determining sub-milligram quantities of biogenic opal. The method employs the inductive high-temperature carbon reduction method for dehydration of opal and reduction of silica, and a continuous-flow isotope ratio mass spectrometry system for direct analysis of the oxygen isotope ratio in the evolved carbon monoxide. The accuracy and precision of the online analytical system were evaluated by isotopic analysis of various quantities of standard SiO2 in the range 40–538 µg. The time required to analyse a single sample was relatively short (50 min); hence, our method is suitable for routine analysis for paleoenvironmental studies that require large amounts of time-series data. The method was validated for samples in the sub-milligram range and can be applied to oxygen isotope analysis of various types of biogenic opal that have not been analysed because of their small amounts in natural samples. We successfully applied our method to (i) the first oxygen isotope analysis of monospecific radiolarian skeletons and (ii) high-resolution oxygen isotope analysis of Holocene diatom frustules from the Southern Ocean.

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Tuesday, 15 July 2014
Journal of Quaternary Science

Processes of flood-triggered detrital layer deposition in the varved Lake Mondsee sediment record revealed by a dual calibration approach

A succession of 23 sub-millimetre to maximum 12-mm-thick, mostly flood-triggered detrital layers, deposited between 1976 and 2005, was analysed in 12 varved surface sediment cores from meso-scale peri-alpine Lake Mondsee applying microfacies and high-resolution micro X-ray fluorescence analyses. Detailed intrabasin comparison of these layers enabled identification of (i) different source areas of detrital sediments, (ii) flood-triggered sediment flux and local erosion events, and (iii) seasonal differences of suspended flood sediment distribution within the lake basin. Additional calibration of the detrital layer record with river discharge and precipitation data reveals different empirical thresholds for flood layer deposition for different parts of the basin. At proximal locations detrital layer deposition requires floods exceeding a daily discharge of 40 m3 s−1, whereas at a location 2 km more distal an hourly discharge of 80 m3 s−1 and at least 2 days of discharge above 40 m3 s−1 are necessary. Furthermore, we observe a better correlation between layer thickness and flood amplitude in the depocentre than in distal and proximal areas of the basin. Although our results are partly site-specific, the applied dual calibration approach is suitable to precisely decipher flood layer formation processes and, thereby, improve the interpretation of long flood time series from lake sediments.

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