A stable isotope study of the Kaap Valley Tonalite, Barberton Mountain Land, South Africa

Bibliography: pages 100-109.The Kaap Valley Tonalite (KVT) was a homogenous hornblende+ biotite tonalite that had been subjected to overail propylitic and potassic alteration. Petrographic studies reveal that carbonate alteration and increased proportions of hydrous minerals occur along the KVT and Barberton greenstone belt contact zone, and along major shear zones within the KVT

Deep Circulation in the Eastern South Pacific Ocean

We use an inverse method to compute the deep circulation in the eastern South Pacific Ocean, on isopycnal layers within the depth range of 1,000–3,000 m. The method gives probability density functions of the isopycnal and diapycnal velocities and diffusivities on a grid with a realistic eastern boundary, based on tracer fields. An oxygen consumption rate, assumed spatially constant, controls the solution effectiveness (minimum value of the model cost function) and the magnitude of the diffusivities. The isopycnal circulation is, by contrast, less dependent on the consumption rate. Direct deep float displacement data is used as a check on our solutions rather than a constraint. The model circulation agrees broadly with this independent data. Where the computed circulation does not agree, we argue that it is mainly because of different sampling, model resolution and model assumptions. The isopycnal circulation below 1,000 dbar is dominated by zonal flows and topographically controlled structures. A westward helium plume at 15°S seen on δ3He maps is reproduced by the model but is less intense than expected by the β-plume theory. The model did not find correlations between the diapycnal forcing and the known volcanically active part of the EPR, suggesting that the net large-scale effect of heating along the ridge on the circulation is small over the basin as a whole. Eastern boundary flow along the coast of South America appears as a main exit route for deep water, but the flow shows broader scales than suggested in previous studies, possibly due to the resolution of the model. The deep outflow of the southeastern Pacific is associated in the model with isopycnal PV stretching, rather than a Stommel-Arons (diapycnal) balance

The importance of talc and chlorite "hybrid” rocks for volatile recycling through subduction zones; evidence from the high-pressure subduction mélange of New Caledonia

The transfer of fluid and trace elements from the slab to the mantle wedge cannot be adequately explained by simple models of slab devolatilization. The eclogite-facies mélange belt of northern New Caledonia represents previously subducted oceanic crust and contains a significant proportion of talc and chlorite schists associated with serpentinite. These rocks host large quantities of H2O and CO2 and may transport volatiles to deep levels in subduction zones. The bulk-rock and stable isotope compositions of talc and chlorite schist and serpentinite indicate that the serpentinite was formed by seawater alteration of oceanic lithosphere prior to subduction, whereas the talc and chlorite schists were formed by fluid-induced metasomatism of a mélange of mafic, ultramafic and metasedimentary rocks during subduction. In subduction zones, dehydration of talc and chlorite schists should occur at sub-arc depths and at significantly higher temperatures (∼ 800°C) than other lithologies (400-650°C). Fluids released under these conditions could carry high trace-element contents and may trigger partial melting of adjacent pelitic and mafic rocks, and hence may be vital for transferring volatile and trace elements to the source regions of arc magmas. In contrast, these hybrid rocks are unlikely to undergo significant decarbonation during subduction and so may be important for recycling carbon into the deep mantl

Methane seepage along the Hikurangi Margin of New Zealand : geochemical and physical data from the water column, sea surface and atmosphere

The concentration and carbon isotope values of dissolved methane were measured in the water column at Rock Garden, Omakere Ridge and Wairarapa areas in the first dedicated cold seep investigation along the Hikurangi Margin of New Zealand. These measurements provide a high resolution impression of the methane distribution in the water column and show that these seep sites are actively venting methane with varying intensity. The highest concentrations (up to 3500 nM) measured in water samples obtained from Conductivity–Temperature–Depth (CTD) operations were at Faure Site of Rock Garden. Here, seafloor bubble release was observed by ROV. The Omakere Ridge area is actively venting over almost its entire length (not, vert, similar 25 km), in particular at Bear's Paw, a newly discovered seep site. In the Wairarapa area another new seep site called Tui was discovered, where methane measurements often exceeded 500 nM. No evidence was obtained from water column or sea surface measurements along the Hikurangi Margin to indicate that methane from seeps is reaching the sea surface. In fact, a consistent upper boundary was observed at a density of 26.85 kg/m3, which occurs at about 500 m below sea surface, above which methane decreased to background concentrations. No obvious oceanographic feature is associated with this 500 m CH4 boundary. Bubble dissolution calculations show that about 500 m was also the model-derived maximum bubble rise height. A wide range of δ13CCH4 values from − 71 to − 19‰ (VPDB) were measured, with the highest CH4 concentrations having the lowest δ13CCH4 values of about − 71 to − 68‰. Simple mixing and isotope fractionation calculations show that changes of δ13CCH4 values are predominantly caused by the dilution of seep fluids with the seawater, with some anaerobic oxidation also occurring

DOĞU KARADENİZ BÖLGESİ KİL MİNERALLEŞMELERİNİN OLUŞUMU VE KÖKENİ

Widespread and intensive hydrothermal alteration is associated with volcanogenic massive sulfide and vein type sulfide deposits are generally observed thought the Eastern Black Sea province. Samples were collected from many localities in the province for bulk-rock and clay fraction X-ray diffraction (XRD), scanning electron microscopy and energy dispersive X-ray (SEM-EDX), dry chemical analyses were made. Clay mineral assemblages are observed in and around of Late Cretaceous volcanic rocks composed of basaltic, andesitic, dacitic, rhyodacitic and rhyolitic lavas and pyroclastics are often spatially associated with Late Cretaceous-Paleocene granitoid intrusion. Hydrothermal alteration of the volcanic rocks resulted in the formation of propylitic, phyllitic (seritic) and, argillic alteration along with hematite, silica polymorphs and, alunite mineralization. Alunite, kaolinite, gypsum, pyrite and native sulfur are abundant in high sulfidation zones, kaolinite and silica are abundant in the argillic alteration and sericite (illite) dominates in the phyllic alteration. Some of kaolinite occurrences are composed of kaolinite, silica polymorpps and partly illite. Other kaolinites were seen as veins and their thickness are between 5 to 30 cm and white to light green in color. Illite minerals are generally 2M polytype and their crystalinity are good. Oxygen isotope values of illite minerals range between 6 and 8 ‰ (V-SMOW) and suggest deposition from seawater at elevatedtemperatures (200-300 oC). Oxygen isotope values of the kaolinite veins range between 16 and 17 ‰. The veins were most likely formed at temperatures of 75 to 100 oC in equilibrium with water that has values similar to those of seawater (0 ‰). Two type of bentonite occurrences in the alteration were defined zones and generally contain Ca-montmorillonite. First type of the bentonite deposits which are greenish yellow colored consists of nearly pure montmorillonite whereas second type which is white to purple ones contain minor amounts of silica polymorphs (% 5-10) besides to Ca-montmorillonite. Oxygen isotope values of montmorillonite from the bentonite deposits range between 23 and 29 ‰ clear evidence of formation by halmyrolysis. Na and K are found in Ca-montmorillonites in generally all of bentonite occurrences.Doğu Karadeniz provensi boyunca volkanojenik masif ve damar tip sülfit yatakları ile ilişkili durumda yaygın ve yoğun hidrotermal alterasyon gözlenmektedir. İnceleme alanından derlenen numuneler üzerinde tüm kaya ve kil numunelerinin X-ışınları difraksiyonu (XRD), taramalı elektron mikroskop (SEM) ve enerji dispersiv spektrometre (EDS) çalışmaları ve kimyasal analizler yapılmıştır. Kil mineral toplulukları Geç Kretase volkanik kayaçları (bazaltik, andezitik, dasitik, riyodasitik ve riyolitik lavlar ve piroklastikler) içerisinde gözlenmiştir ve özellikle de Geç Kretase-Paleosen intrüzyonları ile ilişkilidir. Geç Kretase volkanizması den oluşmuştur. Volkanik kayaçların hidrotermal alterasyonu; propillitik, fillitik (serisitik) alterasyonlar, hematitleşme, silisleşme ve alunitleşme şeklinde gelişmiştir. Alunit, kaolinit, jips ve nabit sülfür yüksek sülfitleşme zonlarında, kaolinit ve silis polimorfları killeşme zonlarında ve serisit (illit) ise fillitik zonda gözlenmiştir. Bazı kaolinit oluşumları silis polimorfları ve kısmen illit içerirken, bazıları kaolinitler saf olup 5-30 cm lik bantlar halinde, beyaz-açık yeşil renklidirler. İllit genellikle 2M politipinde olup kristalinitesi iyidir. İllitlerin oksijen izotop değerleri ‰ 6-8 (V-SMOW) arasında olup, deniz suyundan yüksek sıcaklıklarda (200-300oC) oluştuğunu göstermektedir. Volkanik kayaçları içinde gözlenen, bindirme fayına paralel olarak gelişmiş 1-2 m genişlikteki bir zonda gözlenen hidrotermal, beyazımsı- çık yeşil renkli kaolinitin oksijen izotop değerleri ‰ 16-17 arasındadır ve bu değerlere göre muhtemelen deniz suyunun benzer değerleri ile denge halindeki 75-100oC arasındaki sıcaklıklarda oluşmuştur. Alterasyon zonlarında genellikle Ca-montmorillonitten oluşan iki tür bentonit oluşumu belirlenmiştir. Yeşilimsi-sarımsı yeşil renkli olan birinci tür bentonit oluşumu hemen hemen saf montmorillonitten oluşurken, ikinci tür beyazımsı-pembe renkli olanlar az miktarda (%5-10) silis polimorfları içerir. Her iki tür bentonit oluşumunun oksijen izotop değerleri (‰ 23-29), bu bentonitlerin halmrolizle oluştuğunu gösterir. Ca-montmorillonit türü simektitlerde tabaka aralarında Na veya K bulunmasında bölgeler arasında bir farklılık gözlenmemiştir

ESAS-Derived Earth Departure Stage Design for Human Mars Exploration

The Vision for Space Exploration has set the nation on a course to have humans on Mars as early as 2030. To reduce the cost and risk associated with human Mars exploration, NASA is planning for the Mars architecture to leverage the lunar architecture as fully as possible. This study takes the defined launch vehicles and system capabilities from ESAS and extends their application to DRM 3.0 to design an Earth Departure Stage suitable for the cargo and crew missions to Mars. The impact of a propellant depot in LEO was assessed and sLzed for use with the EDS. To quantitatively assess and compare the effectiveness of alternative designs, an initial baseline architecture was defined using the ESAS launch vehicles and DRM 3.0. The baseline architecture uses three NTR engines, LH2 propellant, no propellant depot in LEO, and launches on the Ares I and Ares V. The Mars transfer and surface elements from DRM 3.0 were considered to be fixed payloads in the design of the EDS. Feasible architecture alternatives were identified from previous architecture studies and anticipated capabilities and compiled in a morphological matrix. ESAS FOMs were used to determine the most critical design attributes for the effectiveness of the EDS. The ESAS-derived FOMs used in this study to assess alternative designs are effectiveness and performance, affordability, reliability, and risk. The individual FOMs were prioritized using the AHP, a method for pairwise comparison. All trades performed were evaluated with respect to the weighted FOMs, creating a Pareto frontier of equivalently ideal solutions. Additionally, each design on the frontier was evaluated based on its fulfillment of the weighted FOMs using TOPSIS, a quantitative method for ordinal ranking of the alternatives. The designs were assessed in an integrated environment using physics-based models for subsystem analysis where possible. However, for certain attributes such as engine type, historical, performance-based mass estimating relations were more easily employed. The elements from the design process were integrated into a single loop, allowing for rapid iteration of subsystem analyses and compilation of resulting designs

Submarine Hydrothermal Activity on the Aeolian Arc: New evidence from Helium Isotopes

In November 2007 we conducted a water-column and seafloor mapping study of the submarine volcanoes of the Aeolian Arc in the southern Tyrrhenian Sea aboard the R/V Urania. A total of 26 CTD casts were completed, 13 vertical casts and 13 tows. In addition to in situ measurements of temperature, conductivity, pressure and suspended particles, we also collected discrete samples for helium isotopes, methane, and trace metals. The helium isotope ratio, which is known to be an unambiguous indicator of hydrothermal input, showed a clear excess above background at 5 out of the 10 submarine volcanoes surveyed. We found the strongest helium anomaly over Marsili seamount, where the 3He/4He ratio reached maximum values of 3He = 23% at 610 m depth compared with background values of ~ 7%. We also found smaller but distinct 3He anomalies over Enerato, Eolo, Palinuro, and Secca del Capo. We interpret these results as indicating the presence of hydrothermal activity on these 5 seamounts. Hydrothermal venting has been documented at subsea vents offshore of the islands of Panarea, Stromboli, and Vulcano (Dando et al., 1999; Di Roberto et al., 2008), and hydrothermal deposits have been sampled on many of the submarine volcanoes of the Aeolian Arc (Dekov and Savelli, 2004). However, as far as we know this is the first evidence of present day hydrothermal activity on Marsili, Enerato, and Eolo. Samples collected over Filicudi, Glabro, Lamentini, Sisifo, and Alcioni had 3He very close to the regional background values, suggesting either absence of or very weak hydrothermal activity on these seamounts. Helium isotope measurements from the background hydrocasts positioned between the volcanoes revealed the presence of an excess in 3He throughout the SE Tyrrhenian Sea. These background profiles reach a consistent maximum of about 3He = 11% at 2300 m depth. Historical helium profiles collected in the central and northern Tyrrhenian Sea in 1987 and 1997 do not show this deep 3He maximum (W. Roether and B. Klein, private comm.). Furthermore, the maximum is too deep to be attributed to the volcanoes of the Aeolian Arc, which are active at <1000 m depth. We are currently conducting additional measurements to determine whether this deep 3He maximum is from a local hydrothermal source or is somehow related to the deep water mass transient which occurred in the eastern Mediterranean in the 1990’s

Extending the geographical distribution of Side-striped Jackal, Lupulella adusta (Sundevall, 1847) (Carnivora, Canidae), in South Africa

Side-striped Jackal, Lupulella adusta (Sundevall, 1847), occurs in a vast area within sub-Saharan Africa. In South Africa, the current geographical distribution is limited to eastern coastal regions. Recent sightings from north-central areas of the country suggest a wider geographical distribution. Here we report on 5,130 confirmed, repeated detections of Side-striped Jackal. Of these, 3,625 captures were from 471 new locations not previously recorded in the scientific literature, thereby expanding their current geographical distribution. These new records were captured in 33 vegetation types, including the forest and grassland biomes where they are not commonly detected

Mitochondria-rough-ER contacts in the liver regulate systemic lipid homeostasis

Contacts between organelles create microdomains that play major roles in regulating key intracellular activities and signaling pathways, but whether they also regulate systemic functions remains unknown. Here, we report the ultrastructural organization and dynamics of the inter-organellar contact established by sheets of curved rough endoplasmic reticulum closely wrapped around the mitochondria (wrappER). To elucidate the in vivo function of this contact, mouse liver fractions enriched in wrappER-associated mitochondria are analyzed by transcriptomics, proteomics, and lipidomics. The biochemical signature of the wrappER points to a role in the biogenesis of very-low-density lipoproteins (VLDL). Altering wrappER-mitochondria contacts curtails VLDL secretion and increases hepatic fatty acids, lipid droplets, and neutral lipid content. Conversely, acute liver-specific ablation of Mttp, the most upstream regulator of VLDL biogenesis, recapitulates this hepatic dyslipidemia phenotype and promotes remodeling of the wrappER-mitochondria contact. The discovery that liver wrappER-mitochondria contacts participate in VLDL biology suggests an involvement of inter-organelle contacts in systemic lipid homeostasis.Fil: Anastasia, Irene. Laval University; Canadá. Brain Research Center; CanadáFil: Ilacqua, Nicolò. Laval University; Canadá. Brain Research Center; CanadáFil: Raimondi, Andrea. San Raffaele Scientific Institute; ItaliaFil: Lemieux, Philippe. Brain Research Center; CanadáFil: Ghandehari-Alavijeh, Rana. Brain Research Center; CanadáFil: Faure, Guilhem. Broad Institute of MIT and Harvard; Estados Unidos. National Center For Biotechnology Information; Estados UnidosFil: Mekhedov, Sergei L.. National Center For Biotechnology Information ; Estados UnidosFil: Williams, Kevin J.. University of California at Los Angeles. School of Medicine; Estados UnidosFil: Caicci, Federico. Università di Padova; ItaliaFil: Valle, Giorgio. Università di Padova; ItaliaFil: Giacomello, Marta. Università di Padova; ItaliaFil: Quiroga, Ariel Dario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Fisiología Experimental. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental; Argentina. University of Alberta; CanadáFil: Lehner, Richard. University of Alberta; CanadáFil: Miksis, Michael J.. Northwestern University; Estados UnidosFil: Toth, Katalin. University of Ottawa; CanadáFil: de Aguiar Vallim, Thomas Q.. University of California at Los Angeles. School of Medicine; Estados UnidosFil: Koonin, Eugene V.. National Center For Biotechnology Information ; Estados UnidosFil: Scorrano, Luca. Università di Padova; ItaliaFil: Pellegrini, Luca. Laval University; Canad