Influence of preglacial dispersion on geochemical exploration in county Offaly, Central Ireland

Weathering and erosion during the Tertiary period in Ireland gave rise to widespread secondary dispersion in the vicinity of exposed mineralization. Resulting patterns are still partly traceable under the glacial cover and constitute geochemical anomalies that are found to be more revealing than corresponding anomalies in the glacial till.A large near-surface lead and zinc anomaly in northeast County Offaly, Eire, was found to overlie an iron hydroxide-filled Tertiary(?) sinkhole. Tracing the dispersion patterns from this preglacial hydromorphic anomaly led to the discovery, to the north of the sinkhole and under the glacial drift, of two residual anomalies characterized by highly concentrated secondary zinc mineralization (up to 10% Zn). One of these follows a regional structural trend and may be of economic significance.Assessment of the depth of overburden was made using shallow refraction seismic equipment and sampling was carried out with two types of portable drills.     

Off-shore seismological experiments south of Provence in relation to “Glomar Challenger” deep sea drillings (JOIDES-DSDP,Leg 13)

The evaporitic layer located at 35 km south of Toulon, according to compressional-wave velocity measured in samples from JOIDES-DSDP Leg 13 drillings in the Mediterranean Sea, could be constituted by gypsum or anhydrite, halite having been deposited in the most central parts of the basin. These deductions are in favour of the supposed “bull's eye” structure for evaporitic layers in the Mediterranean Sea.     

Unites structurales de la marge continentale sous-marine de Cannes a Menton d'apres la sismique refraction

Offshore seismic refraction profiles permitted us to characterize the extent of the geological formations which prolong the principal units of the Provence and Alpes Maritimes southwards and to establish their respective relationships. The concept of a “Var graben” is confirmed and defined. A magma chamber, probably in relation with the volcanic deposits of the Cap d'Ail, has been disclosed and coincides with the positive magnetic anomaly observed in this area.     

Hydrological field data from a modeller's perspective: Part 1. Diagnostic tests for model structure

Hydrological scientists develop perceptual models of the catchments they study, using field measurements and observations to build an understanding of the dominant processes controlling the hydrological response. However, conceptual and numerical models used to simulate catchment behaviour often fail to take advantage of this knowledge. It is common instead to use a pre‐defined model structure which can only be fitted to the catchment via parameter calibration. In this article, we suggest an alternative approach where different sources of field data are used to build a synthesis of dominant hydrological processes and hence provide recommendations for representing those processes in a time‐stepping simulation model. Using analysis of precipitation, flow and soil moisture data, recommendations are made for a comprehensive set of modelling decisions, including Evapotranspiration (ET) parameterization, vertical drainage threshold and behaviour, depth and water holding capacity of the active soil zone, unsaturated and saturated zone model architecture and deep groundwater flow behaviour. The second article in this two‐part series implements those recommendations and tests the capability of different model sub‐components to represent the observed hydrological processes. Copyright © 2010 John Wiley & Sons, Ltd.