Northwestern Edge Research Articles

Middle East Caridina (Decapoda: Atyidae): Redescription of C. fossarum Heller, 1862, description of three new species, and remarks on the status of C. syriaca Bouvier, 1904 and C. babaulti basrensis Al-Adhub & Hamzah, 1987

The most species-rich genus, Caridina, of the shrimp family Atyidae is broadly distributed throughout five biogeographic realms, with the Indo-Malayan realm being the centre of its distributional range. Due to the scarcity of studies, very little is known regarding the Middle East species, which are placed on the north-western edge of the genus’ distribution. Numerous museum specimens from across the entire range of Caridina in the Middle East were thus analysed using morphological characters and mitochondrial sequences (16S) in order to gain insight into the biodiversity of the genus in the region. Consequently, the present study describes three new atyid species of the genus Caridina H. Milne Edwards, 1837, Caridina enbilului sp. nov., Caridina enkii sp. nov. and Caridina shahrazadae sp. nov. from freshwater habitats of Syria, Iraq and Iran respectively. Furthermore, Caridina fossarum Heller, 1862 is redescribed, while the taxonomic status of Caridina syriaca Bouvier, 1904 and Caridina babaulti basrensis Al-Adhub & Hamzah, 1987 is discussed and the latter synonymized with Caridina fernandoi Arudpragasam & Costa, 1962. C. shahrazadae sp. nov. differs from its congener C. fossarum by the reduced branchial formula of the latter species, the absence of an appendix interna at the endopod of the male's first pleopod, and the lack of a prominent sexual dimorphism on the propodus of the third and fourth pereiopods. C. enbilului sp. nov. differs from C. fossarum in the same characters as C. shahrazadae sp. nov., while from the latter species C. enbilului sp. nov. is different in showing a distinct tooth on the pterygostomial margin of the carapace, by a well-developed arthrobranch on the first pereiopod, a well-developed podobranch on the second maxilliped and a more slender endopod of the male's first pleopod. C. enkii sp. nov. can be distinguished from C. fossarum by the more developed sexual appendages of male specimens as well as more slender pereiopods. In addition, the genetic analysis supports the existence of multiple species in the Middle East, while their phylogenetic relationships and their geographic distribution are described.

Petrogenesis of ultramafic-mafic clasts in the Dos Hermanos Mélange, Ilocos Norte: Insights to the evolution of western Luzon, Philippines

The clasts of ophiolitic mélanges formed in orogenic margins reflect the tectonomagmatic history of a region and record the petrological signatures of oceanic lithospheres that interacted in the past. Exposed at the northwestern edge of Luzon, Philippines, the highly deformed Dos Hermanos Mélange (DHM) provides new insights on the complex history of western Luzon island. The DHM is a tectonic mélange composed predominantly of ultramafic-mafic clasts set in a sheared serpentinite matrix. The ultramafic clasts are mostly harzburgites with rare occurrences of lherzolite, dunite and chromitite. Petrographic (e.g. protogranular to equigranular texture) and geochemical characteristics (e.g. spinel Cr# = 0.17–0.60, olivine Fo content = 87–91) of the peridotites typify residual mantle peridotites which underwent low to moderately high degrees of partial melting. Mineral chemistry of some dunite and harzburgite samples (e.g. high spinel TiO2 = 0.01–0.64 wt%) further record subsequent modification of the depleted mantle material by arc-related processes (e.g. metasomatism). Most of the mafic clasts classify as gabbros and are composed of highly anorthitic plagioclase (An88–99) and Ti-poor pyroxenes which suggest derivation from arc-related melts. One troctolite clast, however, records the distinct petrographic (e.g. ophitic texture) and geochemical (e.g. low An content of plagioclase = 73–80) signatures of primitive MOR-related magma. These contrasting petrologic signatures in the ultramafic-mafic clasts of the DHM are similar to those observed in the crustal and mantle sections of the Eocene Zambales Ophiolite Complex (ZOC). This suggests that the DHM, like the ZOC, records the complex history of the convergence and emplacement of an ancient oceanic crust onto the Philippine Mobile Belt. Later tectonic processes in the region, which occurred after the emplacement of the ZOC, resulted to the extensive dissection and translation of ophiolitic blocks northwards transforming them into the DHM.

A first phylogenetic study on stoloniferous octocorals off the coast of Kota Kinabalu, Sabah, Malaysia, with the description of two new genera and five new species.

Sabah, Malaysia, is well known for its extensive and diverse coral reefs. It is located on the northwestern edge of the Coral Triangle, the region with the highest marine biodiversity. Much of the marine fauna here is still unknown, especially inconspicuous animals, such as small stoloniferous octocorals, which are common on coral reefs. Here, we describe two new monospecific genera of the family Arulidae found off the coast of Kota Kinabalu, Sabah, East Malaysia; Bunga payunggen. nov. et sp. nov. and Laeta waheedaegen. nov. et sp. nov. As well, the stoloniferan genus Phenganax Alderslade & McFadden, 2011 belonging to the family Clavulariidae is expanded with three new species, P. marumisp. nov., P. subtilissp. nov., and P. stokvisisp. nov., which are all sclerite-free. Additionally, we report a possibly undescribed species, closely related to the clavulariid genera Azoriella Lopez-Gonzalez & Gili, 2001 and Cervera Lopez-Gonzalez et al., 1995. As this and other recent studies have shown, discoveries of small stoloniferous octocorals are helping to fill gaps in our knowledge of the overall systematics of Octocorallia.

Geochemical constraints on the origin and tectonic setting of the serpentinized peridotites from the Paleoproterozoic Nyong series, Eseka area, SW Cameroon

Serpentinized rocks closely associated with Paleoproterozoic eclogitic metabasites were recently discovered at Eseka area in the northwestern edge of the Congo craton in southern Cameroon. Here, we present new field data, petrography, and first comprehensible whole-rock geochemistry data and discuss the protolith and tectonic significance of these serpentinites in the region. The studied rock samples are characterized by pseudomorphic textures, including mesh microstructure formed by serpentine intergrowths with cores of olivine, bastites after pyroxene. Antigorite constitutes almost the whole bulk of the rocks and is associated (to the less amount) with tremolite, talc, spinel, and magnetite. Whole-rock chemistry of the Eseka serpentinites led to the distinction of two types. Type 1 has high MgO (> 40 wt%) content and high Mg# values (88.80) whereas Type 2 serpentinite samples display relatively low MgO concentration and Mg# values ( 50 ppm). This similarity, associated with the high Cr contents, spinel-peridotite protolith compositions and Mg/Si and Al/Si ratios imply that the studied serpentinites were formed in a subduction-related environment. The U-shaped chondrite normalized-REE patterns of serpentinized peridotites, coupled with similar enrichments in LREE and HFSE, suggest the refertilized nature due to melt/rock interaction prior to serpentinization. Based on the results, we suggest that the Eseka serpentinized peridotites are mantle residues that suffered a high degree of partial melting in a subduction-related environment, especially in Supra Subduction Zone setting. These new findings suggest that the Nyong series in Cameroon represents an uncontested Paleoproterozoic suture zone between the Congo craton and the Sao Francisco craton in Brazil.

Analysis of the effectiveness of ecological protection work in Dujiangyan area after 5.12 earthquake

Dujiangyan, a county-level city in Chengdu, is located at the outskirts of the Minjiang River on the northwestern edge of the Chengdu Plain. As a national health city, the ecological protection status of Dujiangyan City has received much attention. From the five aspects of ecological economy, ecological environment, ecological awareness, ecological governance and landscape maintenance, we will make a comprehensive consideration and evaluation of the ecological protection status of Dujiangyan area, so that the area can make more obvious achievements in ecological aspects.

An Assessment of the Geographic Distribution and Status of a Rare Dragonfly, Rhionaeschna mutata, at the Northwestern Edge of Its Range

Rhionaeschna mutata (Hagen) (Spatterdock Darner) is a rare North American dragonfly, most widely distributed in the eastern US. In 2009, a reproductive population was found in 2 ponds in eastern Minnesota, establishing a substantial northwestern range expansion. We assessed the geographic distribution of the Spatterdock Darner in the region to inform conservation planning for this species. Using previously defined habitat criteria, we identified potential reproductive ponds in the ecoregion with GIS. In 2015 and 2016, we used multiple methods to survey 25 ponds for Spatterdock Darner nymphs, adults, and exuviae. We found no Spatterdock Darners in the region, despite intensive survey efforts targeted at ponds that met the habitat criteria. The Spatterdock Darner may be present in this water-rich region, but was undetected by our efforts, or a local extirpation may have occurred, possibly linked to recent fish colonization in one of the original reproductive ponds.

The Xiaoqinling metamorphic core complex: A record of Early Cretaceous backarc extension along the southern part of the North China Craton

AbstractMany metamorphic core complexes (MCCs) of Early Cretaceous age are documented in the northern part of the North China Craton (NCC), which formed in a backarc extensional setting. However, whether or not the MCCs are also present in the southern part of the NCC, and where the western boundary of backarc extension lies, remain unclear. We present new structural and geochronological data to show that Early Cretaceous structures in the Xiaoqinling region (China) lying in the southern part of the central NCC represent a Cordilleran-type MCC. The NW-dipping detachment zone on the northwestern edge of the Xiaoqinling MCC is a ductile extensional shear zone that is overprinted by a later brittle detachment fault. The footwall (lower plate) consists of Archean metamorphic rocks and Mesozoic plutonic rocks, and was cut by a series of ductile normal sense shear belts and later brittle normal faults that strike predominantly NE-SW. Both the ductile and brittle structures indicate that NW-SE extension was responsible for the development of the MCC. Geochronological data suggest that the MCC initiated at 138 Ma and lasted until 100 Ma, recording a protracted extensional history. The MCC experienced an early phase of crustal-scale normal faulting (138–126 Ma) and later isostatic doming (125–100 Ma), consistent with the “rolling-hinge” model. The Xiaoqinling MCC shows similar features and a similar evolution to other intraplate MCCs in the northern and southeastern parts of the NCC, and shows that the southern part of the NCC was also involved in intense backarc extension and magmatism. Distribution of these intraplate MCCs indicates synchronous backarc extension over a length of around 1800 km. Delamination of a flat oceanic slab during roll-back is consistent with such large-scale, synchronous extension in the overriding plate.

Extreme Lake Level Changes on the Tibetan Plateau Associated With the 2015/2016 El Niño

AbstractAlthough the impact of El Niño–Southern Oscillation on the Tibetan Plateau (TP) is reflected through stable isotopes of precipitation and ice cores, the hydroclimate response of TP lakes to El Niño–Southern Oscillation is seldom investigated. Here we show that significant lake water deficit occurred on the central TP (CTP) due to a dramatic decrease in precipitation 2016 El Ni/2016 El Niño event, followed by extreme lake water surplus in 2016 and 2017 over most of the TP (except the eastern CTP). Similar but weaker lake shrinkage and afterward expansion can also be found during historical El Niño events. Further exploration reveals that the CTP dry anomaly during El Niño events tends to bridge the dry anomalies over India and northern China, thereby forming a dry zone along the northwestern edge of the Asian monsoon domain. This study may shed light on the prediction of lake level changes on the TP.

Fine-scale genetic structure and conservation status of American badgers at their northwestern range periphery

Peripheral populations are often characterized by small population size and low genetic diversity, with many at risk of extirpation. These characteristics may be even more pronounced in human-modified landscapes that further reduce the resiliency of populations to environmental change. Situated at the northwestern edge of the species’ range, the western American badger (Taxidea taxus jeffersonii) is an endangered mammal in Canada, where it inhabits the interior grassland and open forest ecosystems of British Columbia (BC) and continues to be threatened by severe vehicle-induced mortality rates and other anthropogenic factors. Here, we collected mitochondrial DNA haplotypic and microsatellite genotypic data to investigate the extent and distribution of American badger genetic variation within and among sites in British Columbia, and relative to adjacent populations in the USA, including in Washington state. From these data, we reconstructed population structure and connectivity, and examined current designatable unit status. Patterns of genetic variation for American badgers in British Columbia were as expected for peripheral populations, including reduced genetic diversity, increased population differentiation, and evidence of demographic contraction. Furthermore, we found limited connectivity between regional populations in our study area and identified significant substructure isolating the most northwestern sampling unit (Cariboo), findings that starkly contrast with the high levels of gene flow observed between populations across the species’ range core. These results have important implications for current designatable unit status for western American badgers in British Columbia and emphasize the need for further population monitoring and mitigation of potential barriers to gene flow.

Uninvited citizens: violence, spatiality and urban ruination in postwar and postsocialist Bosnia and Herzegovina

ABSTRACTIn this article I analyze the lived, violent effects of post war and postsocialist transformations through the prism of one urban ruin in Bihać, a city located on the northwestern edge of Bosnia and Herzegovina. The building is Dom penzionera—never completed socialist retirement home. This urban ruin remains eerie, semi-empty and skeleton-like, a shadow and a symbol of the unmaterialized socialist modernity and the perpetually transitioning postwar present. Ethnographic focus on the urban ruin, and not on a ‘place’ or a ‘population,’ is conscious, and it reflects the importance of material objects in the context of regional transformations and global dispossessions. More specifically, I show how over the last 25 years this ruin, instead of its imagined inhabitants—elderly socialist workers who were going to age and die in it peacefully—has been housing multiple uninvited citizens. These inhabitants include disillusioned Bosnian youth and, more recently, refugees and ‘migrants’ from the Middle East, South Asia and North Africa. Highlighting the ruination of the build environment and the ‘wasted lives’ of those who occupy it, provides a powerful critique of the current geopolitical violences, and of confident and arrogant theories of transition in the Balkans and beyond.

Geology of the Gouap iron deposit, Congo craton, southern Cameroon: Implications for iron ore exploration

The Ntem Complex represents the northwestern edge of the Archean Congo craton in southern Cameroon where numerous banded iron formation (BIF)-hosted iron deposits have been discovered. The Gouap iron deposit, which is located on the western edge of the Ntem Complex, is one of the recent discoveries of iron deposits in this area. In this study, geological mapping, detailed drillcore logging and petrographical studies reveal that the Gouap iron deposit comprises of two lithostratigraphic units, namely the BIF and the Country rocks. The BIF unit consists of amphibole BIF and amphibole-pyrite BIF, whereas the Country rocks unit is made up of gneisses (garnet, amphibole–magnetite and amphibole–garnet–pyrite gneiss), schists (amphibole–magnetite and garnet–magnetite micaschist), quartzites and dolerite sills.The BIFs are well interlayered and observed to be in sharp or gradational contacts to their associated country rocks. The mineral assemblages of the BIFs and wallrocks (except the dolerites) indicate that both units have been metamorphosed under amphibole facies conditions. Two main iron mineralization types are identified in the Gouap deposit: the soft iron type which is mainly located in the western and northern parts and the hard iron type mostly confined to the southern sector of the deposit.The structural controls of the Gouap iron deposit are better observed in drillcore samples other than on the outcrop-scale. There are three principal deformation events (D1, D2 and D3) that led to the development of foliation, folding and faulting respectively. The iron mineralization are mostly concentrated on the F2 fold hinge zones and fractures that acted as passage ways for the circulation of meteoric water at surface. We suggest that the following three major processes that led to the formation of the Gouap deposit: (i) the chemical precipitation of chert and iron-oxide followed by sedimentation and diagenesis that formed chert–magnetite BIFs; (ii) secondly, the amphibolite facies metamorphism and deformation that formed quartz–magnetite BIFs, which constitute the main iron ridge located on thicker zones of fold noses; and (iii) finally, the Gouap BIFs have been upgraded to medium-grade iron ore due to supergene enrichment processes, which are restricted to the modern land surface and locally reached deeper levels through fault and fracture zones. The western and northern parts of the Gouap deposit have been identified as potential exploration target areas for iron mineralization. Even though the iron formation processes of the Gouap deposit are not yet completely understood and many questions remain unanswered regarding the genesis of the soft and hard iron mineralization, these new insights have important implications on the exploration drilling strategies of this deposit.

Site and age-dependent responses of Picea abies growth to climate variability

Knowledge about spatiotemporal variability of climate change effect on tree-ring width (TRW) and crown condition is essential to optimize the modelling of future forest ecosystem responses to the changing climate. Geographical differences in the climate–growth relationship are a reflection of the regional climatic conditions mainly. In this study, 175 Picea abies trees from the north-western edge of its geographical distribution in Central Norway were evaluated with respect to geographical and age-dependent differences during the common period of 1950–2015. The results showed that the most significant positive correlations between TRW and the current June temperature were unstable although the temperature increased. The correlations suddenly started to decrease (regardless of the site placement and tree age) at the beginning of the 1990s, but subsequently unexpectedly increased in the 2010s. The superposed epoch analysis revealed longer TRW regeneration of the southern plots (except over-mature trees) after negative pointer years compared to the northern plots. Previous summer temperature and related physiological processes (cone crops, storage of nutrients, etc.) significantly negatively affected P. abies growth in the current year. Additionally, our results showed that the selection of the chronology version (standard or residual) significantly affects the resulting correlations and thus must be carefully considered in dendroclimatological studies. Our main outputs can contribute to better understanding of the climate–growth relationship variability and general prediction of the radial growth.

Petrogenesis of an Eocene syenitic intrusion from south-central British Columbia: Evidence for increasing influence of cratonic Laurentia on alkaline magmatism of western North America

The Allendale Lake stock is a representative intrusion of the Eocene alkaline igneous province in south-central British Columbia (Canada), which forms the northwestern edge of the Montana-Wyoming alkaline province. The shallow-seated intrusion (~53 Ma), about 4.5 km long and 2 km wide, is composed predominately of feldspar-phyric biotite-clinopyroxene-amphibole-bearing monzonitic/syenitic rocks. The feldspar forms distinct rhomb-shaped phenocrysts, which contain abundant exsolution of perthite and antiperthite. The Allendale Lake rocks are silica-undersaturated with SiO2 ranging from 52 to 63 wt% and high contents of alkalis, particularly K2O (4.5–6.5 wt%), typical of shoshonitic rocks. The rocks show a distinct enrichment of large-ion-lithophile elements relative to heavy rare earth elements and high-field strength elements. Their isotopic compositions are highlighted by high negative ƐNd(t) values (−4.5 to −5.5), Neoproterozoic Nd model ages (750–900 Ma) and high but relatively uniform initial 87Sr/86Sr ratios (~0.706). The rocks were generated by fractional crystallization under oxidizing conditions. The parent magma, a hydrous alkaline basaltic melt, was formed by partial melting of an amphibole-phlogopite-bearing peridotite of the subduction-modified subcontinental lithospheric mantle. The mantle source underwent Neoproterozoic and subsequently Cenozoic metasomatic enrichment events. The alkaline volcanic rocks of the Penticton Group (Marron Formation) from the nearby Eocene Challis-Kamloops volcanic belt are volcanic correlatives of these intrusions. The Eocene alkaline rocks in the south-central part of the British Columbia are related to continental arc rifting.

Trace Metals in Groundwater of Kumba and Environs in Cameroon

Kumba and environs situate between longitudes 9.24E - 9.5E and latitudes 4.44N - 4.7N, is the economic capital of the Southwest Region-Cameroon. It is located along the Cameroon Line at northwestern edge of the Douala Basin. The inhabitants depend mostly on groundwater through springs, handdug wells and boreholes. In this area like in most of Cameroon and Africa, water from groundwater sources (springs, wells and boreholes) is not treated. Often, it is given minimal or cosmetic periodic treatment if at all. Although the concentra-tions of trace metals in groundwater affects its safety and acceptability, testing for trace metals is less common and typically occurs mostly when a specific risk has been identified. This could be attributed to the high cost of analysis and lack of technological know-how. In addition to this, testing and monitoring of groundwater is not carried out most of the time and whenever it is done, only major cations and anions are analyzed. Due to the absence of treatment and testing of groundwater before drinking in Kumba and environs, there is a need to evaluate the trace metal content. The study had 21 groundwater samples analyzed using Inductively Coupled Plasma Mass Spectroscopy. Field measurement of physicochemical parameters was determined. R-mode statistical analysis; Pearson’s Correlation Analysis (PCA) together with Hierarchical Cluster Analysis (HCA) between the trace metals and the physico-chemical parameters was carried out. Ten indices were determined: Four trace metal hazard indices: the average daily dose ADD, carcinogenic risks CR and the non-carcinogenic risk hazard quotient HQ which yields the hazard indices HI, and six trace metal pollution indices: Degree of contamination (DC), Enrichment factor (EF), Ecological risk index (Er), Potential ecological risk index (RI), Pollution load index (PLI) and Geo-accu- mulation index (Igeo). The general trend of mean trace metal concentration in the groundwater is in the order of: Mn > Fe > Ba > Sr > Zn > Ni > Cu > Co > Pb > Li > Cr > V > As > Cd. HCA distinguishes two clusters based on spatial similarities and dissimilarities. Cluster one; (01) element Ba; soluble; Cluster two (13) non soluble elements divided into three classes; class one (06) As, Cd, V, Li, Pb, and Cr; less enriched. Class two (03) Co, Cu, Ni and Zn; enriched; Class two (04) Zn, Sr, Fe and Mn; more enriched.

Coastal geology of Iztuzu Spit (Dalyan, Muğla, SW Turkey)

This study was carried out in İztuzu Spit (IS, Muğla-SW Turkey), which is a special environmental protection zone due to the presence of a loggerhead turtle breeding area. The aims of this study are: (1) to determine surface sediment content, (2) to investigate the İztuzu Spit spatial changes using Google-earth images, and (3) to figure out the controlling factors in the spit development. The main shore of the İztuzu Spit is predominantly composed of medium-grained sands that contain dominantly ophiolitic rock fragments. Five types of ostracods, sixteen types of benthic foraminifera, gastropods, mollusc, and bivalve shell fragments were identified from the sediment sample taken from coastal part of the IS. The main coastal area of the İztuzu Spit attached to mainland initially decreased from 67.4 ha (2004) to 56.8 ha (2013) then increased to 58.5 ha in 2016. Significant erosion of the main beach of İztuzu Spit was observed in the north-western edge. A small coastal region separated from the İztuzu Spit by the Dalyan river mouth shows significant change. The northern side of this region acted as a new sedimentation area, while the southern side was affected by erosion. The reason of these changes is variation in the flow direction of the Dalyan River mouth due to the building of piers in the lagoon side of the İztuzu Spit. The main coastal part of the İztuzu Spit has recently been under the effect of waves, tides, and summer tourism clients, while the river flow direction and anthropogenic effects are the main controlling mechanisms in the development of the NW edge. Therefore, the İztuzu Spit must be monitored continuously and protected as this region is the breeding zone of the loggerhead turtle.

First evidence of paleoearthquakes along the Carboneras Fault Zone (SE Iberian Peninsula): Los Trances site

Seismogenic faults that have not produced historical large earthquakes remain unnoticed and, thus, are dangerously left out from seismic hazard analyses. The seismogenic nature of the Carboneras Fault Zone, a left-lateral strikeslip fault in the Eastern Betic Shear Zone (southeastern Spain), has not been fully explored to date in spite of having a morphological expression equivalent to the Alhama de Murcia Fault, a seismogenic fault in the same tectonic system. This study provides the first paleoseismic evidence of the seismogenic nature of the CarbonerasFault Zone, based on the analysis of 3 trenches at Los Trances site, on the northwestern edge of the La Serrata Range. Cross cutting relationships and numerical dating, based on radiocarbon, thermoluminescence and U-series, reveal a minimum of 4 paleoearthquakes: Paleoearthquake1 (the oldest) and Paleoearthquake2 took place after 133ka, Paleoearthquake3 occurred between 83–73ka and Paleoearthquake4 happened after 42.5ka (probably after 30.8ka), resulting in a maximum possible average recurrence of 33ka. This value, based on a minimum amount of paleoearthquakes, is probably overestimated, as it does not scale well with published slip-rates derived from offset channels or GPS geodetical data. The characterization of this fault as seismogenic, implies that it should be considered in the seismic hazard analyses of the SE Iberian Peninsula.

SHRIMP U–Pb zircon geochronology of the granitoids of the Imiter Inlier: Constraints on the Pan-African events in the Saghro massif, Anti-Atlas (Morocco)

This study presents new U–Pb zircon ages for three granitoid bodies in the Imiter inlier at the eastern part of the Moroccan Anti-Atlas chain, which is located in the northwestern edge of the West African Craton (WAC). Analyzes of zircon grains yield the following ages: 538 ± 6 and 575 ± 10 Ma for the Igoudrane massif, 567 ± 6 Ma for the nearby Bou Teglimt granodiorite, and 582 ± 6 Ma for the Bou Fliou granite. These new data reveal that the Igoudrane massif is younger than previously thought (677 Ma), and that all the granitoids in the Imiter area are Ediacaran in age and are related to the Ouarzazate Group. Sm-Nd isotopic data yield negative εNd(t) values (−4.5 to −0.2) and TDM model ages of 1.04–1.82 Ga. These data indicate the presence of an inherited Paleoproterozoic to Archaean component in some zircon grains and show that generation of the parent magmas involved a Neoproterozoic juvenile contribution and recycling of an older crustal component.These new data allow reinterpreting the geochemical and isotopic data of the granitoids, and revisiting the structural significance to the Igoudrane massif, which was assumed until now to be coeval with the major Pan-African event of the Central Anti-Atlas. They also bring significant constraints to discuss the context and age of deposition of the Saghro Group, which is still a matter of debate. All these data provide evidence of an emplacement of the Imiter granitoids in a subduction complex, which affected all of the Anti-Atlas chain during the Late Proterozoic time.

A Morphological Study of the Supernova Remnant Rx J0852.0–4622 (Vela Jr.)

Abstract We conduct a multiwavelength morphological study of the Galactic supernova remnant (SNR) RX J0852.0–4622 (also known as Vela Jr., Vela Z, and G266.2−1.2). RX J0852.0–4622 is coincident with the edge of the larger Vela SNR causing confusion in the attribution of some filamentary structures to either RX J0852.0–4622 or its larger sibling. We find that the RX J0852.0–4622 radio-continuum emission can be characterized by a two-dimensional shell with a radius of 0.°90 ± 0.°01 (or 11.8 ± 0.6 pc at an assumed distance of 750 pc) centered at (l, b) = (133.°08 ± 0.°01,−46.°34 ± 0.°01) (or R.A. = 8h52m19.ˢ2, decl. = −46°20′24.″0, J2000), consistent with X-ray and gamma-ray emission. Although [O iii] emission features are generally associated with the Vela SNR, one particular [O iii] emission feature, which we denote as “the Vela Claw,” morphologically matches a molecular clump that is thought to have been stripped by the stellar progenitor of the RX J0852.0–4622 SNR. We argue that the Vela Claw feature is possibly associated with RX J0852.0–4622. Toward the northwestern edge of RX J0852.0–4622 , we find a flattening of the radio spectral index toward another molecular clump also thought to be associated with RX J0852.0–4622 . It is currently unclear whether this feature and the Vela Claw result from interactions between the RX J0852.0–4622 shock and interstellar medium gas.

ZOTINO III: AN EARLY IRON AGE METALLURGICAL CENTER IN THE TRANS-URALS

In 1974 and 1977, an archaeological expedition from the Ural State University excavated part (441 m2 ) of a fortifi ed Early Iron Age manufacturing site on the Bagaryak River near Zotino, in the forest zone of the Trans-Urals foothills. The site, measuring 80 m by 50–66 m (total area, 3800 m2 ), is located on a 40–43 m high cliff. Its northeastern inland side is protected by a low stone and earthen wall, preserved to the height of 0.75 m, and is delimited by a shallow outer drainage ditch. The single entrance is ~2 m wide. Under the wall, there is a thin layer of buried soil with fragments of the Itkul ceramics. Inside the wall, carbonaceous sandy loam, pieces of calx, and charred remains of wooden structures were found. Our reconstruction suggests that the original 2 m wide wall consisted of two rows of logs and a built-in square tower ~3.0 m by 2.6 m. The base of the walls and tower were strengthened with rubble, and its outer face was enforced with limestone slabs. Near the wall and along the northwestern edge of the site’s inner space, remains of three adobe platforms for processing copper and iron were identifi ed, two dug-in ovens, a utility pit and, apparently, remains of an adobe melting furnace. This is the easternmost and latest (400–100 BC) seasonal fortifi ed metallurgical center of Itkul—an autochthonous culture in the forest zone of the eastern Ural Mountains. In the forest-steppe east and south of it, on the lower reaches of the Sinara and Karabolka rivers, the westernmost fortresses built by the Gorokhovo herders (500–100 BC) are situated—the likely source of the Itkul fortifi cation tradition.

Effects of mesoscale eddies on behavior of an oil spill resulting from an accidental deepwater blowout in the Black Sea: an assessment of the environmental impacts.

Because of the environmental sensitivity of the Black Sea, as a semi-enclosed sea, any subsea oil spill can cause destructive impacts on the marine environment and beaches. Employing numerical modeling as a prediction tool is one of the most efficient methods to understand oil spill behavior under various environmental forces. In this regard, a coupled circulation/deepsea oil spill model has been applied to the Black Sea to address the behavior of the oil plume resulting from a representative hypothetical deepwater blowout. With climatological forcing, the hydrodynamic module based on DieCAST ocean circulation model realistically reproduces seasonally-varying circulation from basin-scale dominant structures to meso- and sub-mesoscale elements. The oil spill model utilizes pre-calculated DieCAST thermo-hydrodynamic fields and uses a Lagrangian tracking algorithm for predicting the displacement of a large number of seeded oil droplets, the sum of which forms the rising oil plume resulting from a deepwater blowout. Basic processes affecting the transport, dispersal of oil and its fate in the water column are included in the coupled model. A hypothetical oil source was set at the bottom, at the northwestern edge of the Shatsky Ridge in the area east of the Crimea Peninsula where the oil exploration/development is likely to be planned. Goals of the study are to elucidate the behavior of the subsea oil plume and assess scales of contamination of marine environment and coastlines resulting from potential blowouts. The two 20-day scenarios with the oil released by a hypothetical blowout were examined to reveal combined effects of the basin-scale current, near-shore eddies, and winds on the behavior of the rising oil plume and its spreading on the surface. Special attention is paid to the Caucasian near-shore anticyclonic eddy which is able to trap surfacing oil, detain it and deliver it to shores. The length of contaminated coastlines of vulnerable Crimean and Caucasian coasts are assessed along with amounts of oil beached and deposited.