Deep reflection seismic imaging of iron-oxide deposits in the Ludvika mining area of central Sweden

Reflection seismic data were acquired within two field campaigns in the Blötberget, Ludvika mining area of central Sweden, for deep imaging of iron-oxide mineralization that were known to extend down to 800–850 m depth. The two surveys conducted in years 2015 and 2016, one employing a seismic landstreamer and geophones connected to wireless recorders, and another one using cabled geophones and wireless recorders, aimed to delineate the geometry and depth extent of the iron-oxide mineralization for when mining commences in the area. Even with minimal and conventional processing approaches, the merged datasets provide encouraging information about the depth continuation of the mineralized horizons and the geological setting of the study area. Multiple sets of strong reflections represent a possible continuation of the known deposits that extend approximately 300 m further down-dip than the known 850 m depth obtained from historical drilling. They show excellent correlation in shape and strength with those of the Blötberget deposits. Furthermore, several reflections in the footwall of the known mineralization can potentially be additional resources underlying the known ones. The results from these seismic surveys are encouraging for mineral exploration purposes given the good quality of the final section and fast seismic surveys employing a simple cost-effective and easily available impact-type seismic source.     

Scale considerations in using diatoms as indicators of sea‐level change: lessons from Alaska

This paper assesses variations in quantitative reconstructions of late Holocene relative sea‐level (RSL) change arising from using modern diatom datasets from different spatial scales, applied to case studies from Alaska. We investigate the implications of model choice in transfer functions using local‐, sub‐regional‐ and regional‐scale modern training sets, and produce recommendations on the creation and selection of modern datasets for reconstructing RSL change over Holocene timescales in tidal marsh environments comparable with those in Alaska. We show that regional modern training sets perform best in terms of providing fossil samples with good modern analogues, and in producing reconstructions that most closely match observations, where these are available. Local training sets are frequently insufficient to provide fossil samples with good modern analogues and may over‐estimate the precision of RSL reconstructions. This is particularly apparent when reconstructing RSL change for periods beyond the last century. For reconstructing RSL change we recommend using regional modern training sets enhanced by local samples. Copyright © 2012 John Wiley & Sons, Ltd.     

Historical water resources in South Asia: the hydrological background

Abstract

The development of historical water resources in the South Asian subcontinent has been largely dependent on the hydrological background. The runoff patterns are derived from climate statistics and the historical developments in different areas are related to these patterns.

Citation Sutcliffe, J., Shaw, J. & Brown, E. (2011) Historical water resources in South Asia: the hydrological background. Hydrol. Sci. J. 56(5), 775–788.     

The Tornquist Sea and Baltica–Avalonia docking

Early Ordovician (Late Arenig) limestones from the SW margin of Baltica (Scania–Bornholm) have multicomponent magnetic signatures, but high unblocking components predating folding, and the corresponding palaeomagnetic pole (latitude=19°N, LONGITUDE=051°E) compares well with Arenig reference poles from Baltica. Collectively, the Arenig poles demonstrate a midsoutherly latitudinal position for Baltica, then separated from Avalonia by the Tornquist Sea.Tornquist Sea closure and the Baltica–Avalonia convergence history are evidenced from faunal mixing and increased resemblance in palaeomagnetically determined palaeolatitudes for Avalonia and Baltica during the Mid-Late Ordovician. By the Caradoc, Avalonia had drifted to palaeolatitudes compatible with those of SW Baltica, and subduction beneath Eastern Avalonia was taking place. We propose that explosive vents associated with this subduction and related to Andean-type magmatism in Avalonia were the source for the gigantic Mid-Caradoc (c. 455 Ma) ash fall in Baltica (i.e. the Kinnekulle bentonite). Avalonia was located south of the subtropical high during most of the Ordovician, and this would have provided an optimum palaeoposition to supply Baltica with large ash falls governed by westerly winds.In Scania, we observe a persistent palaeomagnetic overprint of Late Ordovician (Ashgill) age (pole: LATITUDE=4°S, LONGITUDE=012°E). The remagnetisation was probably spurred by tectonic-derived fluids since burial alone is inadequate to explain this remagnetisation event. This is the first record of a Late Ordovician event in Scania, but it is comparable with the Shelveian event in Avalonia, low-grade metamorphism in the North Sea basement of NE Germany (440–450 Ma), and sheds new light on the Baltica–Avalonia docking.     

Total organic carbon fluxes of the Red River system (Vietnam)

Riverine transport of organic carbon from terrestrial ecosystems to the oceans plays an important role in the global carbon cycle. The Red River is located in Southeast Asia where river discharge, sediment loads and fluxes of elements (carbon, nitrogen and phosphorus) associated with suspended solids have been dramatically altered over past decades as a result of reservoir impoundment and land use, population, and climate change. Dissolved organic carbon (DOC) and particulate organic carbon (POC) concentrations were measured monthly at four stations of the Red River system from January 2008 to December 2010. The results reveal that POC changed synchronically with total suspended solids (TSS) concentration and with the river discharge, whereas no clear trend was observed for DOC concentration. The mean value of total organic carbon (TOC = DOC + POC) flux in the delta of the Red River was 31.5 × 10¹³ ± 4.0 × 10¹³ MgC.yr^?1 (range 27.9–35.8 × 10¹³ MgC.yr^?1 which leads to a specific TOC flux of 2012 ± 255 kgC.km^?2.yr^?1 during this 2008–2010 period. About 80% of the TOC flux was transferred to the estuary during the rainy season as a consequence of the higher river water discharge. The high mean value of the POC:Chl‐a ratio (1585 ± 870 mgC.mgChl‐a^?1) and the moderate C:N ratio (7.3 ± 0.1) in the water column system suggest that organic carbon in the Red River system is mainly derived from erosion and soil leaching in the basin. The effect of two new dam impoundments in the Red River was also observable with lower TOC fluxes in 2010 compared with 2008. Copyright © 2017 John Wiley & Sons, Ltd.     

'Muddy glee': rounding out the picture of women and physical geography fieldwork

Fieldwork in geography has come under close scrutiny from feminist and postcolonial scholars in recent years. In relation to physical geography, commentators have pointed to a range of practices and images (notably the 'heroic', masculinist 'ideal') that have acted to deter and exclude women, from undergraduates to senior academics. For some, fieldwork is one of the key sites of gender discrimination for women in physical geography. This paper starts from a position of agreement with many of these critiques, but also seeks to 'reclaim' some more positive accounts and perspectives on the subject. In doing so, it aims to critique and disrupt the dominant image of physical geography fieldwork as essentially a masculinist endeavour, and encourage a wider view of the challenges and pleasures of fieldwork for women in physical geography.     

The Multiscale TROPIcal CatchmentS critical zone observatory M-TROPICS dataset I: The Nyong River Basin,Cameroon

Simultaneously acquiring time series of climate, hydrology and hydrochemical data over decades on river systems is pivotal to understand the complex interactions involving rock, soil water, air and biota in the Critical Zone, to build integrated modelling and to propose predictive scenarios. Among the Critical Zone Observatories (CZOs) implemented in the past 25 years, only a few are located in the humid Tropics despite the importance of these regions in terms of population density, fast-changing land use, biodiversity hotspots, biomass stock on continents, size of river systems, etc. Since 1994, weathering and erosion processes and fluxes have been investigated at both local (experimental watershed) and regional scales in the Nyong River Basin (Cameroon) which belongs to the Critical Zone Observatories network named Multiscale TROPIcal CatchmentS (M-TROPICS). The data shared by M-TROPICS in Cameroon are: (1) rainfall; (2) air temperature, air relative humidity, wind speed and direction, and global radiation; (3) stream and river water level; (4) pH, electrical conductivity, water temperature and suspended particulate matter (SPM) concentration; (5) major ion, alkalinity and dissolved organic carbon (DOC) concentrations. The dataset already contributed to describe the water partitioning in these tropical humid watersheds, to better understand the factors controlling chemical weathering and physical erosion in tropical ecosystems, particularly the role of organic matter. The dataset also contributed to calculate elemental weathering fluxes and saprolite production rate and to propose denudation rates on tropical cratonic landscapes. Hydrological modelling allowed quantification of the geographical water sources contributing to streamflow. DOC data were used to determine greenhouse-gas emissions and carbon budgets from African inland waters. However, long-term solute concentrations at the outlet of a small tributary of the Nyong River exhibit non-stationary behaviour over the last 26 years. The processes governing those fluctuations are not yet fully understood and might be related to changes in the hydrological regime, land-cover and land-use. The latter highlights the need for longer time-series and continued support for CZOs particularly in the humid tropics.     

Alternative framings of alternative food: A typology of practice

‘Alternative’ food initiatives (AFIs) are often interpreted as political movements, constructed as defiant alternatives to industrial agri‐food relations, and represented by a performance of singular alterity. This understanding of alternative collapses into a mere politics of identity, criticised in the literature for its oversimplification. In this paper, we utilise an established methodological framework that retains AFI diversity, to create a novel typology of AFIs by diverse and embodied practice rather than animating political project. In doing so, we point to the political potential for AFIs to ‘do’ food otherwise and make different worlds.     

Flood insurance: the challenge of the uninsured

Increasing concern about flooding and its potentially socially-devastating effects has reinforced the need for an effective mechanism to deal with the recovery of losses from these events. This paper highlights the problem of uninsurance in the UK and the potentially growing number of people who do not have flood insurance. A dual challenge of uninsurance is emerging: those who have been traditionally excluded from insurance cover due to price and a new phenomenon, those who live in high-risk areas who may become cost-prohibited through the introduction of risk-related premiums.