Magmatische und metasomatische Prozesse in Graniten,insbesondere Zweiglimmergraniten

Ohne Zusammenfassung     

Electrical properties of seafloor massive sulfides

Seafloor massive sulfide (SMS) deposits are increasingly seen as important marine metal resources for the future. A growing number of industrialized nations are involved in the surveying and sampling of such deposits by drilling. Drill ships are expensive and their availability can be limited; seabed drill rigs are a cost-effective alternative and more suitable for obtaining cores for resource evaluation. In order to achieve the objectives of resource evaluations, details are required of the geological, mineralogical, and physical properties of the polymetallic deposits and their host rocks. Electrical properties of the deposits and their ore minerals are distinct from their unmineralized host rocks. Therefore, the use of electrical methods to detect SMS while drilling and recovering drill cores could decrease the costs and accelerate offshore operations by limiting the amount of drilling in unmineralized material. This paper presents new data regarding the electrical properties of SMS cores that can be used in that assessment. Frequency-dependent complex electrical resistivity in the frequency range between 0.002 and 100 Hz was examined in order to potentially discriminate between different types of fresh rocks, alteration and mineralization. Forty mini-cores of SMS and unmineralized host rocks were tested in the laboratory, originating from different tectonic settings such as the intermediate-spreading ridges of the Galapagos and Axial Seamount, and the Pacmanus back-arc basin. The results indicate that there is a clear potential to distinguish between mineralized and non-mineralized samples, with some evidence that even different types of mineralization can be discriminated. This could be achieved using resistivity magnitude alone with appropriate rig-mounted electrical sensors. Exploiting the frequency-dependent behavior of resistivity might amplify the differences and further improve the rock characterization.     

Locational and socio-economic variation in public perceptions of economics and the environment

Government policies for the use of publicly owned environmental resources in Australia are often justified as being for the economic good of the nation. Yet there has been little enquiry about how Australians perceive economic good in the context of the use of environmental resources. The residents of five State government electorates of Perth and one in regional south west Western Australia were surveyed. Their perceptions of economics, the environment and resources in relation to public policy were assessed. The differences in the responses were greater between the different electorates, than between the different socio-economic strata within the same electorate. This paper examines the spatial variability of the results and raises the possibility of developing a socio-locational indicator of attitudes which could provide a tool for policy implementation.     

Restored Eelgrass (<Emphasis Type="Italic">Zostera marina</Emphasis> L.) as a Refuge for Epifaunal Biodiversity in Mid-Western Atlantic Coastal Bays

As nearshore ecosystems are increasingly degraded by human activities, active restoration is a critical strategy in ensuring the continued provision of goods and services by coastal habitats. After being absent for nearly six decades, over 1800 ha of the foundational species eelgrass (Zostera marina L.) has been successfully re-established in the coastal bays of the mid-western Atlantic, USA, but nothing is known about the recovery of associated animal communities in this region. Here, we determine the patterns and drivers of functional recovery in epifaunal invertebrates associated with the restored eelgrass habitat from 2001 to 2013. After less than a decade, the invertebrate community in the restored bed was richer, more even, and exhibited greater variation in functional traits than a nearby reference bed. Analysis of a suite of environmental and physical variables using random forests revealed these differences were primarily due to the increasing area and density of eelgrass, a direct consequence of ongoing restoration efforts. Based on analysis of functional traits, we propose that the rapid life histories of constituent organisms may have played a key role in their successful recovery. We also speculate that diverse epifaunal communities may have contributed to the restoration success through a well-described mutualism with eelgrass. Given that restored eelgrass now make up 32 % of total seagrass cover in the mid-Atlantic coastal bays, this restoration may conserve regional biodiversity by providing new and pristine habitat, particularly given the general decline of existing eelgrass in this region.     

Nitrile,Latex, Neoprene and Vinyl Gloves: A Primary Source of Contamination for Trace Element and Zn Isotopic Analyses in Geological and Biological Samples

Exogenic contamination is of primary concern for geochemical and biological clean laboratories working with sample sizes at the nanogram or even subpicogram level. Here, we determined sixty trace elements in fifteen different types of gloves from major suppliers world‐wide to evaluate whether gloves could be potential sources of contamination for routine trace element and isotope measurements. We found that all gloves contain some trace elements that can be easily mobilised in significant amounts. In weak acid at room temperature, the tested gloves released up to 17 mg of Zn, more than 1 μg of Mg, Ti, Mn, Fe, Rb, Sr, Zr, Sn, Hf and Pb and between 100 and 1000 ng of Li, Sc, V, Cr, Ni, Cu, Ga, As, Se, Y, Ag, Ba, La, Ce, Nd, Tl and Th. Vinyl gloves released lower quantities of biologically and geologically important elements, with the exception of In and Sn. Isotopic analyses indicate that all gloves share roughly the same Zn isotopic composition (average δ⁶⁶Zn = +0.10 ± 0.32‰ (2s)). A single contact between glove and labware releases an average of ~ 6 ng of Zn and hence can significantly shift δ⁶⁶Zn above the precision level when the amount of Zn determined is below 500 ng.     

SIESTA, a time domain, general purpose simulation program for the VIRGO experiment

In this paper we present the simulation program that has been developed for the VIRGO gravitational wave detection experiment. Although this program — SIESTA — is still evolving, it has reached a stage where the design requirements have been largely fulfilled. We first remind the needs and the choices which have steered the program design and led to the present structure. The contents of the program is then reviewed, the performances are discussed, and some typical applications are briefly described.     

A first application of a marine inductive source electromagnetic configuration with remote electric dipole receivers: Palinuro Seamount,Tyrrhenian Sea

We study a new marine electromagnetic configuration that consists of a ship‐towed inductive source transmitter and a series of remote electric dipole receivers placed on the seafloor. The approach was tested at the Palinuro Seamount in the southern Tyrrhenian Sea, at a site where massive sulphide mineralization has been previously identified by shallow drilling. A 3D model of the Palinuro study area was created using bathymetry data, and forward modelling of the electric field diffusion was carried out using a finite volume method. These numerical results suggest that the remote receivers can theoretically detect a block of shallowly buried conductive material at up to ～100 m away when the transmitter is located directly above the target. We also compared the sensitivity of the method using either a horizontal loop transmitter or a vertical loop transmitter and found that when either transmitter is located directly above the mineralized zone, the vertical loop transmitter has sensitivity to the target at a farther distance than the horizontal loop transmitter in the broadside direction by a few tens of metres. Furthermore, the vertical loop transmitter is more effective at distinguishing the seafloor conductivity structure when the vertical separation between transmitter and receiver is large due to the bathymetry. As a horizontal transmitter is logistically easier to deploy, we conducted a first test of the method with a horizontal transmitter. Apparent conductivities are calculated from the electric field transients recorded at the remote receivers. The analysis indicates higher apparent seafloor conductivities when the transmitter is located near the mineralized zone. Forward modelling suggests that the best match to the apparent conductivity data is obtained when the mineralized zone is extended southward by 40 m beyond the zone of previous drilling. Our results demonstrate that the method adds value to the exploration and characterization of seafloor massive sulphide deposits.