Fluid processes in the Tesbihdere base-metal-Au deposit: Implications for epithermal mineralization in the Biga Peninsula,NW Turkey

Tesbihdere is one of a number of spatially close epithermal Cu-Pb-Zn-Ag-Au deposits hosted by andesites and rhyolites, typical of deposits in the Biga peninsula. Microthermometry of fluid inclusions shows a wide range of temperatures, ～360–170°C, and salinities, ～10-0.5 wt.% NaCl, in the different deposits studied. Dilution of a moderately saline magmatic? fluid with meteoric water occurred at constant temperature indicating, the temperature of both fluids was controlled by the geological environment. Boiling was not a major factor, but did occur in very minor amounts. The large range of temperatures within individual samples can only reasonably be explained by variations from near lithostatic to hydrostatic pressure during vein and fracture opening. That this pressure decrease did not produce extensive boiling suggests that vein opening was gradual rather than aggressive, allowing the pressure and temperature decrease to follow a path close to the L-V boiling curve. P-T reconstruction places emplacement of these ore veins at between 300–500 m beneath the surface. Similarities of LA-ICPMS of fluid inclusions from Tesbihdere, Azitepe and Basmakci, supports the conclusion that they were part of the same contemporaneous mineralizing system. The fluids are dominated by Na, with the concentrations of K>Ca>Mg combined equivalent to the concentration of Na. The range of K/Na ratios is not consistent with the fluid inclusion temperatures as the calculated temperatures are significantly higher indicating the fluids were not close to equilibrium with the enclosing rocks. Elevated K concentrations are consistent with acid-sulphate waters in shallow epithermal systems. Ore metals Cu, Zn and Pb are present in significant concentrations ～500, 300 and 200 ppm respectively and the low Fe/Mn ratios are indicative of a relatively oxidising fluid. The negative δ ³⁴S values of sulphides are consistent with boiling and oxidising redox conditions.     

Increasing concentrations of arsenic and vanadium in (southern) Swedish streams

The aim of this study was to investigate temporal trends and controlling factors of As and V in running waters throughout Sweden. For this purpose, data on stream water chemistry from 62 streams of varying catchment size and characteristics, included in the Swedish environmental monitoring programmes were evaluated. The geochemical software Visual MINTEQ was used to model the speciation and trend analyses were performed on total concentrations of As and V as well as modelled fractions (dissolved species as well as arsenate and vanadate adsorbed to ferrihydrite). The trend analyses showed increasing total concentrations of As and V in southern Sweden. Concentrations of As and V correlated significantly to Fe concentrations in 59 and 60 of the 62 streams respectively, indicating that Fe is an important determining factor for As and V concentrations in Swedish streams. This was confirmed by the geochemical modelling that indicated that the adsorbed fraction is the dominant form of As and V and that the concentrations of As and V in Swedish streams are thus highly determined by concentrations of colloidal or particulate Fe. It is therefore suggested that the increasing trends of As and V are to a large extent due to increasing concentrations of colloidal Fe, which is stabilised by increasing concentrations of DOC. Further the geochemical modelling indicates that the dissolved fraction of As and V generally is small, with the exception of a few streams with high pH and/or phosphate concentrations.     

Direct evidence of fluid mixing in the formation of stratabound Pb–Zn–Ba–F mineralisation in the Alston Block, North Pennine Orefield (England)

The North Pennine Orefield Alston Block has produced approximately 4 Mt Pb, 0.3 Mt Zn, 2.1 Mt fluorite, 1.5 Mt barite, 1 Mt witherite, plus a substantial amount of iron ore and copper ore from predominantly vein-hosted mineralisation in Carboniferous limestones. However, a significant proportion of this production (ca. 20%) came from stratabound deposits. Though much is known about the vein mineralisation, the relationship between the veins and the stratabound mineralisation is not well-understood. New petrographic, isotopic and fluid inclusion data derived from samples of stratabound mineralisation allow us to present a unified model that addresses the genesis of both the vein and stratabound styles of mineralisation. The mineralisation can be considered in terms of three episodes:

Using numerical deformation–fluid-flow simulations to understand and target gold mineralisation around basalt domes in the Stawell Zone, Central Victoria, Australia

We present 3-D deformation–fluid-flow numerical models which place constraints on the importance of basalt dome shape and syn-mineralising shortening direction in localising structurally controlled gold mineralisation around basalt domes near Stawell, Victoria, Australia. Gold mineralisation in the Magdala ore-body at the Stawell Mine occurs predominantly within a thin altered unit named the Magdala Facies which blankets the basalt domes. In numerical models of the Magdala Dome models only the east–northeast–west–northwest and east–west shortened models record high fluid-flow rates in areas of known mineralisation which is consistent with the syn-mineralisation shortening directions. In models of the Kewell Dome (a prospect to the north), the position of areas of high fluid-flow rate when shortened in the east–northeast–west–northwest and east–west direction, combined with information from limited drilling indicated the potential for gold mineralisation at the south-west end of the dome. Diamond drill holes in this area yielded significant gold values.     

A framework for reading and unifying heliophysics time series data

We describe a framework designed to simplify the acquisition and integration of data from multiple, diversely formatted, geographically distributed science data sets. Our domain is Heliophysics where measurements of magnetic fields, plasmas, and charged particles are often made in-situ, with the data made available in relatively low volume data sets consisting of time series tables. Data format diversity has proven to be a significant barrier to the type of integrated, multi-mission analysis that is now very important in Heliophysics. Therefore we have developed a Java framework capable of reading, interpreting, and providing uniform access to the science content of any distributed time series data set. The framework exposes data only through fully abstract interfaces that represent data content while hiding all access details such as file format, data file granularity and access protocols. Furthermore, specialized interfaces for representing measurement-specific details are also employed, so that our framework enables data sets to be recast into scientifically interoperable representations. The context of our efforts is an increasingly distributed Heliophysics data environment that employs a collection of discipline-specific Virtual Observatories (VOs), each providing data search and retrieval services for one Heliophysics sub-discipline. Our framework is bundled in a library that ultimately will serve as a universal reader for Heliophysics data, solving the formats problem and serving as key infrastructure for advanced, science-sensitive data manipulation services.     

Hydrology and water quality in two mountain basins of the northeastern US: assessing baseline conditions and effects of ski area development

Mountain regions throughout the world face intense development pressures associated with recreational and tourism uses. Despite these pressures, much of the research on bio‐geophysical impacts of humans in mountain regions has focused on the effects of natural resource extraction. This paper describes findings from the first 3 years of a study examining high elevation watershed processes in a region undergoing alpine resort development. Our study is designed as a paired‐watershed experiment. The Ranch Brook watershed (9·6 km²) is a relatively pristine, forested watershed and serves as the undeveloped ‘control’ basin. West Branch (11·7 km²) encompasses an existing alpine ski resort, with approximately 17% of the basin occupied by ski trails and impervious surfaces, and an additional 7% slated for clearing and development. Here, we report results for water years 2001–2003 of streamflow and water quality dynamics for these watersheds. Precipitation increases significantly with elevation in the watersheds, and winter precipitation represents 36–46% of annual precipitation. Artificial snowmaking from water within West Branch watershed currently augments annual precipitation by only 3–4%. Water yield in the developed basin exceeded that in the control by 18–36%. Suspended sediment yield was more than two and a half times greater and fluxes of all major solutes were higher in the developed basin. Our study is the first to document the effects of existing ski area development on hydrology and water quality in the northeastern US and will serve as an important baseline for evaluating the effects of planned resort expansion activities in this area. Published in 2007 by John Wiley & Sons, Ltd.     

The composition of Saturn's E ring

We present the first in situ direct measurement of the composition of particles in Saturn's rings. The Cassini cosmic dust analyser (CDA) measured the mass spectra of nearly 300 impacting dust particles during the 2004 October E ring crossing. An initial interpretation of the data shows that the particles are predominantly water ice, with minor contributions from possible combinations of silicates, carbon dioxide, ammonia, molecular nitrogen, hydrocarbons and perhaps carbon monoxide. This places constraints on both the composition of Enceladus, the main source of the E ring, as well as the grain formation mechanisms.