A Rapid Drawdown Event Related to Quarry Operations in a Dolomite Aquifer

Two active quarries are mining stone from the Silurian dolomite aquifer in Waukesha County in southeastern Wisconsin. The village in which the quarries are located uses local zoning to control the depth of mining and to institute a long-term water level monitoring program and well guarantee/one with the quarry owners. Water levels dropped as much as 40 feet in at least 24 residential wells surrounding the quarries over a period of a few hours to days. The rapid decline in head was caused by a single boring drilled lo a depth of 75 feel he low the floor of one quarry. The borehole penetrated a localized fracture zone under confined artesian head. Water levels recovered to previous static levels within nine days after grouting the borehole. The rapid drawdown event demonstrates the potential impact of mining in fractured aquifers. The apparent complete recovery of the aquifer demonstrates that quick response can sometimes restore an aquifer. However, the potential for blasting into a similar zone illustrates the need for a well-thought-out aquifer monitoring program and emergency response plan. The experience of the village is a good example of managing conflicting uses of a finite resource and collecting baseline data needed to make informed decisions.     

Cloud Structure And Composition Of Jupiter's Atmosphere

The understanding of the composition and cloudstructure has advanced greatly in the last few yearsand in particular was greatly improved upon followingthe highly successful Pioneer and Voyager missions tothat planet. Recently the Galileo spacecraft has goneinto orbit about Jupiter and its remote sensinginstruments, including the Near Infrared MappingSpectrometer (NIMS) and the Solid State Imager (SSI),have yielded exciting new details of the spatial andvertical structure of the Jovian clouds and volatiles.At the same time Galileo's entry probe has made thefirst ever in situ measurements of conditions inthe atmosphere. Recent ground-based observations havealso added to the body of evidence from whichconditions in the Jovian atmosphere may be inferred.This paper aims to review the current understanding ofthe composition and cloud structure of Jupiter'satmosphere in the light of the new Galileo results andrecent ground-based, and earth-orbiting telescopeobservations.     

Mineralogy of the sources for magnetic anomalies on Mars

Abstract— Recent discovery of intense magnetic anomalies on Mars, which are due to remanent magnetization, requires some explanation for the possible minerals responsible for the anomalous signature. Thermoremanent magnetization (TRM) in single domain (SD) and multidomain (MD) sized magnetite, hematite, and pyrrhotite, all potential minerals, are considered. The intensity of TRM (in 0.05 mT) is in descending order: SD‐sized magnetite, SD‐sized pyrrhotite, MD‐sized hematite, MD‐sized pyrrhotite, MD‐sized magnetite, SD‐sized hematite. The TRM intensity is <4% of the saturation isothermal remanence (SIRM) for all but the MD hematite, which may have >50% of the SIRM. Each of these minerals and estimated concentrations of magnetic remanence carriers (assumed to be titanomagnetite) in the Shergotty‐Nakhla‐Chassigny martian meteorites are used in a thin sheet approximation model to reveal the concentration of each mineral required for the generation of an observed magnetic anomaly (1500 nT at 100 km altitude) assuming TRM acquisition in a 0.05 mT magnetic field.     

Deep‐water Corallium rubrum (L., 1758) from the Mediterranean Sea: preliminary genetic characterisation

The precious red coral Corallium rubrum (L., 1758) lives in the Mediterranean Sea and adjacent Eastern Atlantic Ocean on subtidal hard substrates. Corallium rubrum is a long‐lived gorgonian coral that has been commercially harvested since ancient times for its red axial calcitic skeleton and which, at present, is thought to be in decline because of overexploitation. The depth distribution of C. rubrum is known to range from c. 15 to 300 m. Recently, live red coral colonies have been observed in the Strait of Sicily at depths of c. 600–800 m. This record sheds new light on the ecology, biology, biogeography and dispersal mechanism of this species and calls for an evaluation of the genetic divergence occurring among highly fragmented populations. A genetic characterization of the deep‐sea red coral colonies has been done to investigate biological processes affecting dispersal and population resilience, as well as to define the level of isolation/differentiation between shallow‐ and deep‐water populations of the Mediterranean Sea. Deep‐water C. rubrum colonies were collected at two sites (south of Malta and off Linosa Island) during the cruise MARCOS of the R/V Urania. Collected colonies were genotyped using a set of molecular markers differing in their level of polymorphism. Microsatellites have been confirmed to be useful markers for individual genotyping of C. rubrum colonies. ITS‐1 and mtMSH sequences of deep‐water red coral colonies were found to be different from those found in shallow water colonies, suggesting the possible occurrence of genetic isolation among shallow‐ and deep‐water populations. These findings suggest that genetic diversity of red coral over its actual range of depth distribution is shaped by complex interactions among geological, historical, biological and ecological processes.     

The Rockall Bank Mass Flow: Collapse of a moated contourite drift onlapping the eastern flank of Rockall Bank,west of Ireland

The Rockall Bank Mass Flow (RBMF) is a large, multi-phase submarine slope failure and mass flow complex. It is located in an area where the Feni Drift impinges upon the eastern flank of the Rockall Bank in the NE Atlantic. A 6100 km² region of slope failure scarps, extending over a wide water depth range and with individual scarps reaching up to 22 km long and 150 m high, lies upslope of a series of mass flow lobes that cover at least 18,000 km² of the base of slope and floor of the Rockall Trough. The downslope lobe complex has a negative topographic relief along much of its northern boundary, being inset below the level of the undisplaced contourite drift at the base of slope. The southern margin is topographically more subtle but is marked by the sharp termination of sediment waves outside the lobe. Within the lobe complex the southern margin of the largest lobe shows a positive relief along its southern margin. The initial failure is suggested to have occurred along coherent layer-parallel detachment surfaces at depths of up to 100 m and this promoted initial downslope block sliding which in turn transformed into debris flows which moved out into the basin. The remains of a deep erosional moat linked to the onlapping contourite complex bisects the region of failed slope, and post-failure thermohaline currents have continued to modify the mass flow in this area. Differential sedimentation and erosion associated with the moat may have promoted slope instability. Following the major failure phase, continuous readjustments of the slope occurred and resulted in small-volume turbidites found in shallow gravity cores collected on the lobes. The short term trigger for the failure remains uncertain but earthquake events associated with a deep-seated tectonic lineament to the north of the mass flow may have been important. A Late Pleistocene age for the slope failure is likely. The RBMF is unusual in that it records large-scale collapse of a contourite body that impinged on a sediment-undersupplied slope system. Unlike many other large slope failure complexes along the NE Atlantic margin, the RBMF occurs in a region where there was little overloading by glacial sediment.