The Kharapeh orogenic gold deposit: geological,structural, and geochemical controls on epizonal ore formation in West Azerbaijan Province,Northwestern Iran

The Kharapeh gold deposit is located along the northwestern margin of the Sanandaj–Sirjan Zone (SSZ) in the West Azerbaijan province, Iran. It is an epizonal orogenic gold deposit formed within the deformed zone between central Iran and the Arabian plate during the Cretaceous–Tertiary Zagros orogeny. The deposit area is underlain by Cretaceous schist and marble, as well as altered andesite and dacite dikes. Structural analysis indicates that the rocks underwent tight to isoclinal recumbent folding and were subsequently co-axially refolded to upright open folds during a second deformation. Late- to post-tectonic Cenozoic granites and granodiorites occur northeast of the deposit area. Mineralization mainly is recognized within NW-trending extensional structures as veins and breccia zones. Normal faults, intermediate dikes, and quartz veins, oriented subparallel to the axial surface of the Kharapeh antiform, indicate synchronous extension perpendicular to the fold axis during the second folding event. The gold-bearing quartz veins are >1 km in length and average about 6 m in width; breccia zones are 10–50 m in length and ≤1 m in width. Hydrothermal alteration mainly consists of silicification, sulfidation, chloritization, sericitization, and carbonatization. Paragenetic relationships indicate three distinct stages—replacement and silicification, brecciation and fracture filling, and cataclastic brecciation—with the latter two being gold-rich. Fluid inclusion data suggest mineral deposition at temperatures of at least 220–255°C and depths of at least 1.4–1.8 km, from a H₂O–CO₂±CH₄ fluid of relatively high salinity (12–14 wt.% NaCl equiv.), which may reflect metamorphism of passive margin carbonate sequences. Ore fluid δ¹⁸O values between about 7‰ and 9‰ suggest no significant meteoric water input, despite gold deposition in a relatively shallow epizonal environment. Similarities to other deposits in the SSZ suggest that the deposit formed as part of a diachronous gold event during the middle to late Tertiary throughout the SSZ and during the final stages of the Zagros orogeny. The proximity of Kharapeh to the main tectonic suture of the orogen, well-developed regional fold systems with superimposed complex fracture geometries, and recognition of nearby volcanogenic massive sulfide systems that suggest a region characterized by sulfur- and metal-rich crustal rocks, collectively indicate an area of the SSZ with high favorability for undiscovered gold resources.     

Spatio-temporal occurrences and mineralogical–geochemical characteristics of airborne dusts in Khuzestan Province (southwestern Iran)

Dust storms in Khuzestan province (Iran) are causing problems in industries and human health. To mitigate the impact of those phenomena, it is vital to know the physical and chemical characteristics of airborne dusts. In this paper, we give an overview of the spatio-temporal occurrences and geochemical characteristics of airborne dusts in Khuzestan. Meteorological data from 10 stations in Khuzestan during 1996–2009 indicate (a) an average of 47 dust storm days per year, (b) a lowest annual average of 13 dust storm days in 1998, (c) a highest annual average of 104 dust storm days in 2008, and (d) an average increase of two dust storm days per year. Above-average number of dust storm days usually occurred in the cities of Dezful, Ahvaz, Masjed-e-Soleiman, Abadan and Bostan, whereas below-average number of dust storm days usually occurred in the cities of Mahshahr, Ramhormoz, Behbahan, Shoushtar and Izeh. XRD analyses of airborne dust samples collected in 2008 and 2009 show that the mineralogy of airborne dusts is dominated by calcite, followed by quartz and then kaolinite, with minor gypsum. SEM analyses of the samples indicate that airborne dusts have rounded irregular, prismatic and rhombic shapes. The sizes of airborne dusts vary from 2 to 52 μm, but 10 to 22 μm are the dominant sizes. The smallest and largest dust particles are clays, sulfates or carbonates. XRF and ICP analyses of the samples show that the most important oxide compositions of airborne dusts are SiO₂, Al₂O₃, Fe₂O₃, CaO and MgO. Estimates of enrichment factors (EF) for all studied elements show that Mn, Hf, U, Sc, K, V and Sr, with EF < 10, are of natural origin, whereas Na, Ni, Co, Ba and Cr, with EF > 10, are of anthropogenic origin. Flat REE patterns with depletion in Th, V, Nb, Zr and enrichment in Al, Rb, Sr and Mn indicate that airborne dusts in Khuzestan come from the same source, which is likely an eroded sedimentary environment outside Iran. In general, airborne dusts in Khuzestan are geochemically similar to airborne dusts elsewhere in the world.     

The Regional Ocean Modeling System (ROMS) 4-dimensional variational data assimilation systems: Part III - Observation impact and observation sensitivity in the California Current System

The critical role played by observations during ocean data assimilation was explored when the Regional Ocean Modeling System (ROMS) 4-dimensional variational (4D-Var) data assimilation system was applied sequentially to the California Current circulation. The adjoint of the 4D-Var gain matrix was used to quantify the impact of individual observations and observation platforms on different aspects of the 4D-Var circulation estimates during both analysis and subsequent forecast cycles. In this study we focus on the alongshore and cross-shore transport of the California Current System associated with wind-induced coastal upwelling along the central California coast. The majority of the observations available during any given analysis cycle are from satellite platforms in the form of SST and SSH, and on average these data exert the largest controlling influence on the analysis increments and forecast skill of coastal transport. However, subsurface in situ observations from Argo floats, CTDs, XBTs and tagged marine mammals often have a considerable impact on analyses and forecasts of coastal transport, even though these observations represent a relatively small fraction of the available data at any particular time.During 4D-Var the observations are used to correct for uncertainties in the model control variables, namely the initial conditions, surface forcing, and open boundary conditions. It is found that correcting for uncertainties in both the initial conditions and surface forcing has the largest impact on the analysis increments in alongshore transport, while the cross-shore transport is controlled mainly by the surface forcing. The memory of the circulation associated with the control variable increments was also explored in relation to 7 day forecasts of the coastal circulation. Despite the importance of correcting for surface forcing uncertainties during analysis cycles, the coastal transport during forecast cycles initialized from the analyses has less memory of the surface forcing corrections, and is controlled primarily by the analysis initial conditions.Using the adjoint of the entire 4D-Var system we have also explored the sensitivity of the coastal transport to changes in the observations and the observation array. A single integration of the adjoint of 4D-Var can be used to predict the change that occurs when observations from different platforms are omitted from the 4D-Var analysis. Thus observing system experiments can be performed for each data assimilation cycle at a fraction of the computational cost that would be required to repeat the 4D-Var analyses when observations are withheld. This is the third part of a three part series describing the ROMS 4D-Var systems.     

Assessing patterns of recreational use in large marine parks: A case study from Ningaloo Marine Park, Australia

Being able to accurately locate and describe recreational use within marine parks is essential for their sustainable management. Given the difficulty in accessing many marine parks, as well as their large size, the surveys to obtain these much-needed data are often logistically challenging and expensive. Aerial surveys are one potential method for obtaining accurate, timely data and this paper details the design for one such survey conducted in the Ningaloo Marine Park, off the northwestern coast of Australia. Ningaloo has been nominated as a world heritage site and the fringing coral reef that forms the centrepiece of the Marine Park extends for 300 km along the coastline. The survey involved 34 temporally stratified flights conducted over a 12-month period. All vessels and people were geo-referenced and where possible, their activities were recorded, providing data that clearly illustrates dramatic expansions and contractions in recreational use. Not only does the spatial extent of use expand in the peak visitor season (April-October), the density of use correspondingly increases. High densities of recreational activity in the Park’s waters were accompanied by increased numbers of vehicles, camps, boat trailers and boats on the adjacent shoreline. Aerial surveys proved to be an effective method for rapidly obtaining recreational data with high spatial accuracy. Such a method has broad applicability to marine parks as it provides comprehensive data to benchmark existing recreational use, as well as monitor future changes in activity patterns, which are essential for the informed management that must underpin sustainability efforts.     

A spectral optimally interpolated mean sea surface from satellite radar altimetry

 A technique is presented for the development of a high-precision and high-resolution mean sea surface model utilising radar altimetric sea surface heights extracted from the geodetic phase of the European Space Agency (ESA) ERS-1 mission. The methodology uses a cubic-spline fit of dual ERS-1 and TOPEX crossovers for the minimisation of radial orbit error. Fourier domain processing techniques are used for spectral optimal interpolation of the mean sea surface in order to reduce residual errors within the initial model. The EGM96 gravity field and sea surface topography models are used as reference fields as part of the determination of spectral components required for the optimal interpolation algorithm. A comparison between the final model and 10 cycles of TOPEX sea surface heights shows differences of between 12.3 and 13.8 cm root mean square (RMS). An un-optimally interpolated surface comparison with TOPEX data gave differences of between 15.7 and 16.2 cm RMS. The methodology results in an approximately 10-cm improvement in accuracy. Further improvement will be attained with the inclusion of stacked altimetry from both current and future missions. Received: 22 December 1999 / Accepted: 6 November 2000     

Subsidence of Surtsey volcano, 1967–1991

The Surtsey marine volcano was built on the southern insular shelf of Iceland, along the seaward extension of the east volcanic zone, during episodic explosive and effusive activity from 1963 to 1967. A 1600-m-long, east-west line of 42 bench marks was established across the island shortly after volcanic activity stopped. From 1967 to 1991 a series of leveling surveys measured the relative elevation of the original bench marks, as well as additional bench marks installed in 1979, 1982 and 1985. Concurrent measurements were made of water levels in a pit dug on the north coast, in a drill hole, and along the coastline exposed to the open ocean. These surveys indicate that the dominant vertical movement of Surtsey is a general subsidence of about 1.1±0.3 m during the 24-year period of observations. The rate of subsidence decreased from 15–20 cm/year for 1967–1968 to 1–2 cm/year in 1991. Greatest subsidence is centered about the eastern vent area. Through 1970, subsidence was locally greatest where the lava plain is thinnest, adjacent to the flanks of the eastern tephra cone. From 1982 onward, the region closest to the hydrothermal zone, which is best developed in the vicinity of the eastern vent, began showing less subsidence relative to the rest of the surveyed bench marks. The general subsidence of the island probably results from compaction of the volcanic material comprising Surtsey, compaction of the sea-floor sediments underlying the island, and possibly downwarping of the lithosphere due to the laod of Surtsey. The more localized early downwarping near the eastern tephra cone is apparently due to greater compaction of tephra relative to lava. The later diminished local subsidence near the hydrothermal zone is probably due to a minor volume increase caused by hydrous alteration of glassy tephra. However, this volume increase is concentrated at depth beneath the bottom of the 176-m-deep cased drillhole.     

Contaminant Spread and Flushing in Fractured Rocks Near Oak Ridge, Tennessee

Liquid wastes, including metals dissolved in nitric acid, were discharged into the S-3 Ponds from 1951 to 1983. During this period, contaminants in ground water spread along shallow fracture flow paths toward nearby streams. Also, a high concentration of nitrate in one well at a depth of 110 to 240 in shows that some contaminants may have moved downdip because of differences in fluid density. Neutralization of the ponds in June 1983 caused a dramatic decrease in the contaminant concentrations of Bear Creek about three months later. Since then, the contaminant concentrations of Bear Creek have decreased at a first-order exponential rate. This average rate, which is the same for both more reactive and less reactive constituents, can be interpreted to show that the contaminant reservoir consists of the unfractured rock matrix.
Flushing caused by the natural recharge and discharge of ground water is occurring at all locations, but contaminant concentrations are controlled by the relative rates of molecular diffusion from the rock matrix and advection along the fracture flow paths. Hushing has thus been most effective near the water table. If the exponential decrease in contaminant concentrations continues, water in Bear Creek will meet drinking water standards by 2012: regardless of any remedial action, contaminants will remain in the rocks for many years.     

The 2012 Olympic Learning Legacy Agenda – the intentionalities of mobility for a new London model

This paper investigates the emergence of a Learning Legacy Agenda (LLA) in the wake of the London 2012 Olympic Games as a governmental tool for the dissemination of urban development and infrastructure project delivery best practice. Focusing on the inception, coordination and implementation of the LLA we outline the intentionalities of mobility that underpin its formation and appropriation and suggest how this points to the emergence of a new “London model” of development and governance. Three intentionalities of knowledge capture, public duty and extra-local salience are unpacked to demonstrate the range of ways in which the bureaucratically initiated LLA banner has been used by various development actors and organisations to validate their existing practices. The case study of the LLA as an institutionalised governance apparatus is used to analyse the impact of specific forms of social relations on the ways in which “models” are produced, what their content consists of, how dominant agendas and narratives co-evolve with the priorities of an assemblage of actors and the processes of selective abstraction used to curate particular messages and forms of fixed and potentially mobile knowledge, yet dubious claims of “learning”.     

Passive oil collection device

A novel, efficient, economical oil collection device, which recovers oils from surface waters using physical principles has been demonstrated. This method has never been used in oil skimmers. The device contains a water-filled vessel open at one end that is positioned above the spilled oil so that the oil entrance opening is leveled with the oil layer on the water surface. The oil moves upward into the vessel displacing the water due to the lower density of the oil. The device has no moving parts. Torricelli’s discovery and Pascal’s law govern containment of the liquid in the vessel above the water level, while Archimedes’ buoyancy force moves oil in the vessel. A collection of thick and thin oil layers on calm water has been shown. This device is very durable, environmentally friendly, recovers pure oil, emits no noise, no pollution, and capable of producing a broad economic impact in the oil clean-up industry by protecting health, life, and the environment.