Ore deposits and epithermal evidences associated with intra-magmatic faults at Aïn El Araâr-Oued Belif ring structure (NW of Tunisia)

International Journal of Earth Sciences - Hydrothermal ore deposits at Aïn El Araâr-Oued Belif location are classified as epithermal deposits type. The ore bodies are hosted by upper...     

Climate extremes: an observation and projection of its impacts on food production in ASEAN

Climate change alters global food systems, especially agriculture and fisheries—significant aspects of the livelihoods and food security of populations. The 2014 IPCC Fifth Assessment Report identified Southeast Asia as the most vulnerable coastal region in the world, and highlighted the potential distribution of impacts and risks of climate change in the region. While climate hazards may differ across geographical regions, the impact of climate extremes on food production will affect marginal farmers, fishers and poor urban consumers disproportionately, as they have limited capacities to adapt to and recover from extreme weather events. Governments and other stakeholders need to respond to climate extremes and incorporate adaptation into national development plans. Unfortunately, there is still limited peer-review publication on the subject matter. This paper presents some findings from research on observed and projected loss and damage inflicted by climate extremes on agricultural crops in Southeast Asia.     

Manifestations tectono-diapiriques synsédimentaires et polyphasées d'âge Crétacé supérieur–Quaternaire dans la région de Zag Et Tir (Tunisie centre-nord)

The geodynamic evolution of the diapir of Zag Et Tir is the result of the coexistence of the diapiric and tectonic activity from the Upper Cretaceous until the Quaternary. The interference of the tectonic and diapiric phenomena is at the origin of the basin individualization with differential sedimentation during the Miocene. This explains the current distribution of the Neogene deposits on both sides of Zag Et Tir Triassic structure. The submeridian faults that subdivide our sector played a significant role during the Atlasic compression, inducing an unequal distribution of the folds on both sides of these accidents, as well in kind as in number, showing the anteriority of the faults compared to the folds. To cite this article: R.A. Gharbi et al., C. R. Geoscience 337 (2005).     

Assessment of heavy metal contamination status in sediments and identification of pollution source in Ichkeul Lake and rivers ecosystem,northern Tunisia

The aim of this study was to determine the concentration of Pb, Zn, Cu, Cd, Cr, and Fe in sediments of the Ichkeul Lake and rivers ecosystem in northern Tunisia; their comparison with international sediment quality criteria was also proposed to assess the extent of metal pollution and their origin using various pollution indicators. For this purpose, sediment samples were collected in thirteen locations and characterized for metal content (Pb, Cr, Zn, Cu, Cd, and Fe) using the total digestion technique. Pollution level was assessed via the geoaccumulation index (Igeo), enrichment factor (EF), contamination factor (C ), potential ecological risk (PER), and pollution load index (PLI). Our results showed that all metals were lower than the threshold effect levels (TEL), the effect range low (ERL), the probable effect level (PEL), the effect range median (ERM), and the probable effect concentration (PEC) value, except Pb and Cr (higher than TEL), the threshold effect concentration (TEC), and the toxicity reference value (TRV). The geoaccumulation index (Igeo) indicated no pollution for Cr, Cu, Zn, and Fe, but moderate pollution for Pb. The enrichment factor showed no enrichment for most of the studied metals. This was further confirmed by the contamination factor that indicated low contamination levels, with the exception of Pb. The pollution load index (PLI) showed moderate pollution status in all the studied stations in the Ichkeul Lake and rivers ecosystem. The statistical results presented similar trends of Zn and Pb probably due to their similar pollution sources. It was found that the Ichkeul Lake and river ecosystems are characterized by moderate pollution status in all the studied sites except for that of a feeder river drained from an old lead mine which had relatively high metallic concentrations of Pb and Cd. It can be argued that effective remediation strategies and environmental management plans are required to control and reduce the input of environmentally hazardous toxic pollutants (Cd and Pb). This study may serve as a useful reference tool pertinent to approaches to the remediation of the old lead mine area surrounding the Ichkeul Lake as well as other areas under similar ecological conditions..     

Climate extremes: an observation and projection of its impacts on food production in ASEAN

Multifractal behaviour of interevent time sequences is investigated for the earthquake events in the NW Himalaya, which is one of the most seismically active zones of India and experienced moderate to large damaging earthquakes in the past. In the present study, the multifractal detrended fluctuation analysis (MF-DFA) is used to understand the multifractal behaviour of the earthquake data. For this purpose, a complete and homogeneous earthquake catalogue of the period 1965–2013 with a magnitude of completeness M _w 4.3 is used. The analysis revealed the presence of multifractal behaviour and sharp changes near the occurrence of three earthquakes of magnitude (M _w ) greater than 6.6 including the October 2005, Muzaffarabad–Kashmir earthquake. The multifractal spectrum and related parameters are explored to understand the time dynamics and clustering of the events.