José A. Rodríguez-Losada

The volcanism-related multistage hydrothermal system of El Jaroso (SE Spain): Implications for the exploration of Mars

The SE Mediterranean margin of Spain is an extremely interesting area of synchronous interaction of tectonic, volcanic, evaporitic and mineralizing hydrothermal processes. This works tackles the multiple relations among these processes by the study of a specific and representative case: the ‘Jaroso Hydrothermal System’. The hydrothermal fluids were genetically linked with the late episodes of the Upper Miocene calc-alkaline and shoshonitic volcanism of the area. The ascent of the fluids was mainly controlled by the Palomares fault in Sierra Almagrera. In the shallow-marine basin of Las Herrerias, the movement of the acid solutions was controlled by both NNE-SSW and N150E normal faults and WNW-ESE wrench reverse faults. At least three mineralising stages were identified, although the particular formation of jarosite could be associated with both hypogenic and supergenic processes. We suggest that the multistage hydrothermal system of El Jaroso (Sierra Almagrera, Almería province, SE Spain), which is responsible for both the Jaroso ores (especially rich in jarosite) and the Las Herrerias sulfate-rich, shallowmarine laminites, could be exploited as a potential model with important implications for the exploration of Mars.

The hydrothermally altered ankaramite basalts of Punta Poyata (Tenerife, Canary Islands)

The features of hydrothermal mineral phases hosted in ankaramite basalts from the lower part of the Taganana area (northside Anaga, Tenerife) are studied in this work. This area, known as “Arco de Taganana”, constitutes a volcanic rift zone that is overturned to the northwest and now identified by a dense NE‐SW striking dyke swarm with a distinct SE dip. The most recent K‐Ar data indicate a mid-upper Miocene age for the emplacement of the dykes. The rocks are intensely altered, usually brecciated, and are deeply eroded. This allows us to look at the roots of a volcanic edifice that has almost disappeared. Basaltic pyroclastic deposits and lava flows, as well as salic breccias, associated to the emplacement of salic domes, unconformably overly these rocks. Mineralogical and geochemical characteristics of the mineralization as well as isotopic data are reported in this paper. Some mineral paragenesis and isotopic data reflect submarine conditions of alteration. Mineralogy was studied by transmitted and reflected light microscopy, XRD, SEM and electron microprobe. In general terms, the mineralization consists of major jasper (quartz and opal) and celadonite, in association with minor hematite, magnetite, Fe ^ Ca, Mg carbonates, Kaersutite, calcite and traces of ilmenite, which is always associated with magnetite. Four paragenetic stages were recognized in the studied area; two of them exhibit hydrothermal mineralization. q 2000 Elsevier Science B.V. All rights reserved.

Atmospheric Megacryometeor Events versus Small Meteorite Impacts: Scientific and Human Perspective of a Potential Natural Hazard

It is important to differentiate between a natural hazard and a natural disaster. A natural hazard is an unexpected or uncontrollable natural event of unusual magnitude that threatens the activities of people or people themselves (NHERC 2004). A natural disaster is a natural hazard event that actually results in widespread destruction of property or causes injury and/or death. Only a very small fraction of the actual meteorite events are observed as falls in any given year. It has been predicted that 5800 meteorite events (with ground masses greater than 0.1 kg) should occur per year on the total land mass of the Earth. In a recent work, Cockell (2003) emphasizes the scientific and social importance of giving a coordinated and multidisciplinary response to events related with the entrance of small asteroidal bodies that could potentially collide with the Earth. In fact, it can be said that the recovery of small meteorites between 1 kg to 200 kg is relatively common; in Spain alone there are four meteorites in the collection of the National Museum of Natural History, weighing more than 30 kg (e.g. Colomera iron meteorite). But what would happen if the impact bodies, despite weighing up to 200 kg, would melt?

Comparative analysis of the impact of geological activity on the structural design of telescope facilities in the Canary Islands, Hawaii and Chile

An analysis of the impact of seismic and volcanic activity has been carried out at selected astronomical sites, namely the observatories of El Teide (Tenerife, Canary Islands), Roque de los Muchachos (La Palma, Canary Islands), Mauna Kea (Hawaii) and Paranal (Chile), and the candidate site of Cerro Ventarrones (Chile). Hazard associated with volcanic activity is low or negligible at all sites, whereas seismic hazard is very high in Chile and Hawaii. The lowest geological hazard in both seismic and volcanic activity is found at Roque de los Muchachos observatory, on the island of La Palma.

Comparative analysis of the impact of geological activity on the structural design of telescope facilities in the Canary Islands, Hawaii and Chile: Geological activity at astronomical sites

An analysis of the impact of seismic and volcanic activity has been carried out at selected astronomical sites, namely the observatories of El Teide (Tenerife, Canary Islands), Roque de los Muchachos (La Palma, Canary Islands), Mauna Kea (Hawaii) and Paranal (Chile), and the candidate site of Cerro Ventarrones (Chile). Hazard associated with volcanic activity is low or negligible at all sites, whereas seismic hazard is very high in Chile and Hawaii. The lowest geological hazard in both seismic and volcanic activity is found at Roque de los Muchachos observatory, on the island of La Palma.

Monitoring of geological activity on astronomical sites of the Canary Islands, Hawaii and Chile

Future large and extremely large ground-based telescopes will demand stable geological settings.Remote sensing could be an unvaluable tool to analyse the impact of geological activity at selected astronomical sites, namely the observatories of El Teide (Tenerife, Canary Islands), Roque de los Muchachos (La Palma, Canary Islands), Mauna Kea (Hawaii) and Paranal (Chile) and the candidate site of Cerro Ventarrones (Chile). In this sense, the extent of lava flows, eruptive clouds or ground deformation associated to seismic and/or volcanic activity could be analysed and characterised through remote sensing.

Comparative analysis of the impact of geological activity on astronomical sites of the Canary Islands, Hawaii and Chile

An analysis of the impact of seismic and volcanic activity has been carried out at selected astronomical sites, namely the observatories of El Teide (Tenerife, Canary Islands), Roque de los Muchachos (La Palma, Canary Islands), Mauna Kea (Hawaii) and Paranal (Chile), and the candidate site of Cerro Ventarrones (Chile). Hazard associated with volcanic activity is low or negligible at all sites, whereas seismic hazard is very high in Chile and Hawaii. The lowest geological hazard in both seismic and volcanic activity is found at Roque de los Muchachos observatory, on the island of La Palma.

The impact of seismicity on high angular resolution astronomy: the case of El Teide Observatory, Canary Islands

Seismicity induces ground vertical and horizontal displacements that could affect the image quality obtained by telescopes in a similar fashion than atmospheric turbulence. In this work, we study the effect of local seismicity relative to atmospheric turbulence upon the image quality of astronomical observations at El Teide observatory, Canary Islands. Three different aspects of seismicity are studied, namely regional seismicity (that is compared with other astronomical sites), seismic noise and possible resonances between seismic noise and the structure of telescopes.