Geology, geochemistry and Sr–Nd constraints of selected metavolcanic rocks from the eastern boundary of the Saharan Metacraton, southern Sudan : a possible revision of the eastern boundary

Neoproterozoic, Pan-African low-grade metavolcanic rocks and associated mafic and ultramafic rocks of ophiolitic origin have long been identified within the pre-Neoproterozoic Saharan Metacraton (SMC). These low-grade rocks within generally high-grade (upper amphibolite facies) gneiss and schist have not yet been fully investigated, and their geological and geotectonic significance have been recognised only in a very few localities: (1) the Delgo–Atmur ophiolite and low-grade volcano-sedimentary belt, (2) the Rahib ophiolite and low-grade sedimentary fold and thrust belt, both in northern Sudan along the eastern boundary of the Saharan Metacraton and (3) the low-grade volcano-sedimentary rocks in the Central African Republic. Dismembered and low-grade metamorphosed occurrences of mafic extrusive and intrusive and minor ultramafic rocks, grouped as the Arid unit, similar to those of the Arabian Nubian Shield (ANS), are reported here for the first time in the westernmost part of the Nuba Mountains, southeastern Sudan. These occurrences are interpreted to represent part of an ophiolite sequence with a lower cumulate layer composed of layered gabbro and minor cumulate hornblendite and a top layer of thick massive gabbro, pillowed basalt and basaltic andesite. The Arid unit is structurally underlain by basaltic-andesite and andesite and a metasedimentary sequence identified as turbidite and both grouped as the Abutulu unit. All of the rocks are slightly sheared, deformed and metamorphosed under low-grade greenschist facies to epidote amphibolite sub-facies. New geochemical and Sr–Nd isotope data reveal that the low-grade metavolcanic rocks of the westernmost Nuba Mountains represent a Neoproterozoic oceanic arc/backarc assemblage. The massive gabbro and pillowed basalt of the Arid unit show the geochemical characteristics of HFSE-depleted tholeiitic basalt while the co-genetic and more evolved meta-andesite of Abutulu unit show a calc-alkaline signature. Both units display a REE pattern characterized by LILE enrichment indicating formation in an arc/back-arc environment. This arc was active at around 778 ± 90 Ma (Sm– Nd 12 WR isochron) that is similar in age to the arc magmatism in the ANS. The close interval between the TDM Nd model age (average of 10 metavolcanic samples is 814 Ma) and the crystallization age (778 ± 90 Ma) is indicative of little or no involvement of older material. The western Nuba Mountains metavolcanic rocks have eNd values of +5.9 at 778 Ma (average of 12 samples) indicating a depleted mantle source similar to that of the ANS (published range from +6.5 to +8.4). The eNd values of the metavolcanic rocks are different from previously published ages of high-grade basement rocks that occupy the area west of the Kabus suture and east of Abutulu (+2.2 and +3.5 for the Rashad and Abbassyia). It is proposed that the metavolcanic and associated plutonic mafic rocks represent a unique Neoproterozoic entity named the Abutulu terrane that developed in a marginal back-arc basin west of the medium-grade gneiss of the Nuba Mountains. If the Abutulu terrane is included as a part of the ANS, then the eastern boundary of the SMC is adjacent to the western edge of the ANS along the Abutulu suture.http://www.elsevier.com/locate/precamres2017-08-31hb2016Geolog

Exploring South Africa's southern frontier : a 20-year vision for polar research through the South African National Antarctic Programme

Antarctica, the sub-Antarctic islands and surrounding Southern Ocean are regarded as one of the planet’s last remaining wildernesses, ‘insulated from threat by [their] remoteness and protection under the Antarctic Treaty System’. Antarctica encompasses some of the coldest, windiest and driest habitats on earth. Within the Southern Ocean, sub-Antarctic islands are found between the Sub-Antarctic Front to the north and the Polar Front to the south. Lying in a transition zone between warmer subtropical and cooler Antarctic waters, these islands are important sentinels from which to study climate change. A growing body of evidence now suggests that climatically driven changes in the latitudinal boundaries of these two fronts define the islands’ short- and long-term atmospheric and oceanic circulation patterns. Consequently, sub-Antarctic islands and their associated terrestrial and marine ecosystems offer ideal natural laboratories for studying ecosystem response to change. For example, a recent study indicates that the shift in the geographical position of the oceanic fronts has disrupted inshore marine ecosystems, with a possible impact on top predators. Importantly, biotic responses are variable as indicated by different population trends of these top predators. When studied collectively, these variations in species’ demographic patterns point to complex spatial and temporal changes within the broader sub-Antarctic ecosystem, and invite further examination of the interplay between extrinsic and intrinsic drivers.http://www.sajs.co.zaam2017GeneticsMammal Research InstituteZoology and Entomolog

The place of peripheral neurectomy in the management of trigeminal neuralgia.

One hundred and forty-six patients with trigeminal neuralgia were studied. Of 49 patients ultimately maintained pain-free by non-medical means, 26 underwent peripheral neurectomy. Twenty of these achieved excellent pain control in the longer term and 5 of the remaining 6 became more responsive to carbamazepine after operation. Seven patients required repeat neurectomies. Peripheral neurectomy is a useful and simple method of pain control in trigeminal neuralgia

'Save the North Sea' Fulmar Study 2002-2004: a regional pilot project for the Fulmar-Litter-EcoQO in the OSPAR area

North Sea Ministers at the Bergen Conference in 2002 decided that monitoring of marine plastic litter in stomachs of seabirds should become one of the 'Ecological Quality Objectives for the North Sea (EcoQO's)'. The task of implementation was delegated to OSPAR, which covers the wider northeast Atlantic Ocean. OSPAR has requested to expand Dutch studies using the Fulmar (Fulmarus glacialis) as a marine litter monitor to the wider North Sea, considering such a project as a pilot study for the introduction of a Fulmar-Litter-EcoQO in the wider OSPAR area. A North Sea international study of Fulmar stomach contents became possible as a part of the 'Save the North Sea (SNS)' project. SNS is an international and interdisciplinary initiative to reduce marine litter which received cofunding from EU Interreg IIIB program for the North Sea over the years 2002-2004. The Fulmar is used as the symbol of the SNS campaign. The SNS Fulmar study established a research network in all countries around the North Sea. Combined results from Dutch long-term work and the 2002-2004 North Sea study show the Fulmar to be a sensitive and robust monitoring tool for spatial and temporal trends in the marine litter situation that will be of use for EcoQO implementation by OSPAR and the European Marine Strateg