Depositional architecture and evolution of progradationally stacked lobe complexes in the Eocene Central Basin of Spitsbergen

The down‐dip portion of submarine fans comprises terminal lobes that consist of various gravity flow deposits, including turbidites and debrites. Within lobe complexes, lobe deposition commonly takes place in topographic lows created between previous lobes, resulting in an architecture characterized by compensational stacking. However, in some deep water turbidite systems, compensational stacking is less prominent and progradation dominates over aggradation and lateral stacking. Combined outcrop and subsurface data from the Eocene Central Basin of Spitsbergen provide a rare example of submarine fans that comprise progradationally stacked lobes and lobe complexes. Evidence for progradation includes basinward offset stacking of successive lobe complexes, a vertical change from distal to proximal lobe environments as recorded by an upward increase in bed amalgamation, and coarsening and thickening upward trends within the lobes. Slope clinoforms occur immediately above the lobe complexes, suggesting that a shelf‐slope system prograded across the basin in concert with deposition of the lobe complexes. Erosive channels are present in proximal axial lobe settings, whereas shallow channels, scours and terminal lobes dominate further basinward. Terminal lobes are classified as amalgamated, non‐amalgamated or thin‐bedded, consistent with turbidite deposition in lobe axis, off‐axis and fringe settings, respectively. Co‐genetic turbidite–debrite beds, interpreted as being deposited from hybrid sediment gravity flows which consisted of both turbulent and laminar flow phases, occur frequently in lobe off‐axis to fringe settings, and are rare and poorly developed in channels and axial lobe environments. This indicates bypass of the laminar flow phase in proximal settings, and deposition in relative distal unconfined settings. Palaeocurrent data indicate sediment dispersal mainly towards the east, and is consistent with slope and lobe complex progradation perpendicular to the NNW–SSE trending basin margin.     

Carbon,nitrogen and phosphorus dynamics in nine sub-systems of the Sylt-Rømø Bight ecosystem,German Wadden Sea

Flow networks of nine sub-systems consisting of 59 components each of the Sylt-Rømø Bight, German Wadden Sea, were constructed depicting the standing stocks and flows of material and energy within and between the sub-systems. Carbon, nitrogen and phosphorous were used as currencies for each sub-system, thus resulting in 27 network models, which were analyzed by ecological network analytical protocols. Results show substantial variability in the dynamics of these elements within and between the nine sub-systems, which differ in habitat structure, species diversity and in the standing stocks of their constituent living and non-living components. The relationship between the biodiversity and selected information indices and ratios, derived from ecological network analysis, of individual sub-systems is variable and differ substantially between them. Ecosystem properties such as the structure and magnitude of the recycling of these elements, number of cycles, and total sub-system activity were calculated and discussed, highlighting the differences between and complexity of the flow of C, N and P in a coastal marine ecosystem. The average number of cycles increase from 179 for C, to 16,923 and 20,580 for N and P respectively, while the average amount of recycled material, as measured by the Finn Cycling Index (FCI), increase from 17% for C, to 52% for P and to 61% for N. The number of cycles and the FCI vary considerably between the sub-systems for the different elements. The largest number of cycles of all three elements was observed in the muddy sand flat sub-system, but the highest FCIs were computed for both C (32%) and N (85%) in the Arenicola Flats, and in sparse Zostera noltii sea grass beds for P (67%). Indices reflecting on the growth, organization and resilience of the sub-systems also showed considerable variability between and within the inter-tidal ecosystems in the Bight. Indices such as, for example, the relative ascendency ratios increase on average from C to N to P, whereas others, such as the Average Mutual Information and Flow Diversity indices, were found to be higher in the N models than in the C or P ones.     

Clearance rates of ephyrae and small medusae of the common jellyfish Aurelia aurita offered different types of prey

Prey selection and knowledge of the amounts of water processed by the early stages of the common jellyfish Aurelia aurita may at certain times of the year be crucial for understanding the plankton dynamics in marine ecosystems with mass occurrences of this jellyfish. In the present study we used two different methods (“clearance method” and “ingestion-rate method”) to estimate the amount of water cleared per unit of time of different types and sizes of prey organisms offered to A. aurita ephyrae and small medusae. The mean clearance rates of medusae, estimated with Artemia sp. nauplii as prey by both methods, agreed well, namely 3.8 ± 1.4 l h^? 1 by the clearance method and 3.2 ± 1.1 l h^? 1 by the ingestion-rate method. Both methods showed that copepods (nauplii and adults) and mussel veligers are captured with considerably lower efficiency, 22 to 37% and 14 to 30%, respectively, than Artemia salina nauplii. By contrast, the water processing rates of ephyrae measured by the clearance method with A. salina nauplii as prey were 3 to 5 times lower than those measured by the ingestion-rate method. This indicates that the prerequisite of full mixing for using the clearance method may not have been fulfilled in the ephyrae experiments. The study demonstrates that the predation impact of the young stages of A. aurita is strongly dependent on its developmental stage (ephyra versus medusa), and the types and sizes of prey organisms. The estimated prey-digestion time of 1.3 h in a steady-state feeding experiment with constant prey concentration supports the reliability of the ingestion-rate method, which eliminates the negative “container effects” of the clearance method, and it seems to be useful in future jellyfish studies, especially on small species/younger stages in which both type and number of prey can be easily and precisely assessed.     

A late Holocene record of land-use history,soil erosion,lake trophy and lake-level fluctuations at Bjäresjösjön (south Sweden)

Land-use history, soil erosion, lake trophy and lake-level fluctuations during the last 3000 years were reconstructed through a multidisciplinary palaeolimnological study (pollen, plant macrofossils, diatoms, physical and chemical analysis, magnetic measurements and radiometric methods) of a small eutrophic lake in southern Sweden (Bjäresjösjön, Scania). There are striking responses in diatom, chemical, sediment yield and magnetic records to land-use changes documented by pollen analysis or historical sources, and to lake-level changes identified from sedimentary changes. Our multidisciplinary approach assists interpretation of the processes controlling long-term changes and separation of the effects of different factors (land-use changes, lake-level fluctuations) on individual biostratigraphical records. Climate has controlled processes in the lake indirectly, through lake-level fluctuations, from the Late Bronze Age to the Viking Age (700 BC-AD 800). Since the Viking Age, land-use controlled most of the changes observed in the lake's development and soil erosion processes. Major changes in lake development occurred during the last 200 years, due to a drastic increase in soil erosion and water eutrophication during a period of agricultural modernization.     

Petrology of the Strathgordon area,Western Tasmania: Si4+‐content of phengite mica as monitor of metamorphic grade

Important mineral assemblages of metapelite and quartzite of the Strathgordon area are phengite + chlorite + tourmaline + quartz and phengite + garnet + chlorite + tourmaline + quartz. Over a limited area the Si⁴⁺‐content of phengite does not vary significantly and is considered to depend only on the PT regime. The Si⁴⁺‐content of phengite coexisting with almandine‐grossular‐spessartine garnet and tourmaline indicate that the maximum metamorphism of the area occurred at 400 ± 50°C and 3 ± 1 kb.     

Mobility in marginalized spaces: Manoeuvring for survival among the Veddas in Sri Lanka

In Sri Lanka the indigenous population, the Veddas, are rapidly losing their traditional habitats due to cash cropping and infrastructure development, and they are being forced to find new means of living. The purpose of the article is to show how mobility is an inherent characteristic of the new economy in the country and that mobility is gendered. The author documents how one group of Veddas has become immobilized (Dambane study village, which has turned into a tourist site) while another group has been forced to be more mobile (Henanigale study village, where emigration is increasingly practised) due to the same development policies. The study reveals that the market-led economy has caused spatial fixations that limit people more than they liberate them. These fixations take place in the domestic sphere as well as in the villages and they change gender relations, showing that mobility is intertwined with social processes that change local structures and relationships. In the case of the Veddas, living in marginalized places conditions their motility. Mobility is therefore a selective process and as much about the fact of moving as it is entangled with meaning and the power to produce (im)mobility at different scales.     

Revisiting the Borrobol Tephra

The Borrobol Tephra has been identified as one of the key tephra horizons for the Lateglacial time period but it also exemplifies many of the promises and problems of tephrochronology. Additional horizons with similar major element composition and approximately the same age have been identified around the North Atlantic region. Here, we revisit the Borrobol Tephra identified at two Swedish sites, Hässeldala port and Skallahult, and also the Borrobol type‐site in Scotland. We present the first set of minor element data (trace and rare earth analyses) along with new analyses of major elements from these three sites. The analysed minor and the trace elements have a similar signature; however, the glass from the Scottish type‐site seems to imply two populations. To answer if this truly represents two populations, or if it reflects magmatic differentiation additional and larger data sets of minor elements are needed. The new major elements are compared to other Borrobol‐type tephras identified in the North Atlantic region. Our results are in line with earlier investigations, which showed no differences in major elements. Further, comparison of minor elements from glass analyses from our sites with those for eruptions associated with Icelandic central volcanoes implies an Icelandic origin for the Borrobol‐type tephras.     

Validating a Swedish varve chronology using radiocarbon,palaeomagnetic secular variation,lead pollution history and statistical correlation

We use statistical correlation of palaeomagnetic secular variation (PSV) curves from a varved Holocene lake sediment sequence in west central Sweden (Lake Kälksjön) against those of a Fennoscandian master stack (FENNOSTACK) to correct for an apparent error in the varve chronology. Additional correlation between a lead pollution-derived chronology for the last 2000 years corroborates the PSV results. Use of the FENNOSTACK palaeomagnetic master curve reveals no significant difference in duration between large-scale features from ～2500 to ～8000 cal. yrs BP. Statistical correlation, however, implies that 270 years are missing from the younger part (<1000 cal. yrs BP) of the varve chronology, and that there is an overestimation by approximately 230 years in the number of varves counted in the early Holocene (>8000 cal. yrs BP). A similar comparison between the PSV-determined ages and calibrated bulk radiocarbon ages suggests that the sediments of mid-Holocene age contain substantial amounts of old carbon, probably of soil origin, which causes bulk sediment-calibrated mean ¹⁴C ages to be up to 850 years older than the corrected varve chronology, which extends to 9193 ± 186 cal. yrs BP. This study highlights both the use of statistical correlation as a technique for detecting errors between chronologies, and the importance of validating incremental chronologies with more than one independent method.     

Torneträsk tree-ring width and density ad 500–2004: a test of climatic sensitivity and a new 1500-year reconstruction of north Fennoscandian summers

This paper presents updated tree-ring width (TRW) and maximum density (MXD) from Torneträsk in northern Sweden, now covering the period ad 500–2004. By including data from relatively young trees for the most recent period, a previously noted decline in recent MXD is eliminated. Non-climatological growth trends in the data are removed using Regional Curve Standardization (RCS), thus producing TRW and MXD chronologies with preserved low-frequency variability. The chronologies are calibrated using local and regional instrumental climate records. A bootstrapped response function analysis using regional climate data shows that tree growth is forced by April–August temperatures and that the regression weights for MXD are much stronger than for TRW. The robustness of the reconstruction equation is verified by independent temperature data and shows that 63–64% of the instrumental inter-annual variation is captured by the tree-ring data. This is a significant improvement compared to previously published reconstructions based on tree-ring data from Torneträsk. A divergence phenomenon around ad 1800, expressed as an increase in TRW that is not paralleled by temperature and MXD, is most likely an effect of major changes in the density of the pine population at this northern tree-line site. The bias introduced by this TRW phenomenon is assessed by producing a summer temperature reconstruction based on MXD exclusively. The new data show generally higher temperature estimates than previous reconstructions based on Torneträsk tree-ring data. The late-twentieth century, however, is not exceptionally warm in the new record: On decadal-to-centennial timescales, periods around ad 750, 1000, 1400, and 1750 were equally warm, or warmer. The 200-year long warm period centered on ad 1000 was significantly warmer than the late-twentieth century (p < 0.05) and is supported by other local and regional paleoclimate data. The new tree-ring evidence from Torneträsk suggests that this “Medieval Warm Period” in northern Fennoscandia was much warmer than previously recognized.