Julio Saavedra

Shoshonitic volcanic centres are scarce within the back-arc mafic volcanism of the Puna Plateau in the Central Volcanic Zone of the Andes. San Jerónimo and Negro de Chorrillos volcanoes are two well preserved shoshonitic monogenetic edifices that developed mainly Strombolian activity and lava flows, which extended more than 9 and 4 km from the vent...

Abstract We compare the silicophytolith record of current soils and Holocene palaeosols from two sedimentary sequences in a region between the Chaco-Pampean Plain and the Puna (Tolombón section in Santa María Valley, and Tafí del Valle section in Tafí Valley), NW Argentina. These two geographic areas are separated by the Aconquija-Cumbres Calchaquí...

The eruption of the Cerro Blanco Volcanic Complex, in the southern Puna, NW Argentina dated at 4410–4150 a cal BP, was investigated to produce new information on stratigraphy, geomorphology, physical volcanology, radiocarbon dating, petrography, and geochemistry. Identification of pre–, syn–, and post–caldera products allowed us to estimate the dis...

A systematic study was undertaken to optimize a method to determine S, Cl, Br and I in water by high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS). The sample composition and preparation conditions (the total dissolved solids -TDS-, the total organic compounds -TOC- and the addition of nitric acid) were evaluated to assess the...

The characteristics of rock varnish from the Campo de Piedra Pomez (CPP, Andes Argentina) provides new insights into the development of rock varnish under severe dusty conditions. The CPP varnish has been analysed using SEM‐EDAX and Raman techniques. The rock coating is tens of microns in thickness and under the microscope shows a micro to cryptocr...

We present new data about a major eruption-spreading approx. 110 km3 ashes over 440.000 km2-long thought to have occurred around 4200 years ago in the Cerro Blanco Volcanic Complex (CBVC) in the Central Andes of NW Argentina (Southern Puna, 26 • 45' S, 67 • 45' W). This eruption may be the biggest during the past five millennia in the Central Volca...

We present new data and interpretation about a major eruption -spreading 110 km3 ashes over 440.000 km2- long thought to have occurred around 4200 years ago in the Cerro Blanco Volcanic Complex (CBVC) in NW Argentina. This eruption may be the biggest during the past five millennia in the Central Volcanic Zone of the Andes, and possibly one of the...

The environmental geochemical behaviour of the rhyolitic ashes from the 2008 eruption of Chaitén volcano, Southern Chile, has been studied. After the bulk characterisation, the potential contribution to the regional geochemical fluxes was examined using: i) single batch leaching tests to provide a rapid screening of the implied major and trace elem...

A method to obtain robust information on short term leaching behaviour of volcanic ashes has been developed independently on the sample age. A mixed factorial design (MFD) was employed as a multivariate strategy for the evaluation of the effects of selected control factors and their interactions (amount of sample (A), contact time (B), and liquid t...

Environmental context Explosive volcanic eruptions may have significant environmental repercussions for many Earth system cycles, particularly the water cycle. We investigate the potential contribution to local geochemical fluxes through water of five historical eruptions that occurred over a 20-year period in the Southern Andes. In all five cases,...

Most of the environmentally mobile constituents of volcanic ashes may be detected by one stage batch leaching tests, but the lack of a standardized procedure makes difficult the comparison between different studies. A series of batch tests were conducted using rhyolithic Andean ashes of the Chaiten 2008 eruption (Chile) and an ancient (hundreds of...

Volcanic ashes from the Puna and surrounding Andean areas in northern Argentina show that sometimes volcanic ash deposits are very well preserved (up to several million years) and can remain a potential hazard for the environment in a similar way as current deposits. Eight ashes have been characterized by SEM-EDX and DRX, and their potential releas...

Three techniques for obtaining soil water solutions (gravitational and matrical waters extracted using both in situ tension lysimeters and in vitro pressure chambers) and their later chemical analysis were performed in order to know the evolution of the soil-solution composition when water moves down through the soil, from the Ah soil horizon to th...

Three techniques for obtaining soil water (gravitational waters, with zero-tension lysimeters, and matricial waters extracted with both, in situ tension lysimeters and in vitro pressure chambers) were used to determine the chemical evolution of gravitational and matricial waters, from the Ah and the BwC or C soil horizons. The study was carried out...

Nutrient ion concentrations in soil water were assessed in three deciduous forests in the Sierra de Cata Mountains, central‐western Spain, with annual precipitation ranging between 720 and 1,580 mm. Soil solutions were obtained at incremental depths from 15 to 110 cm with tension lysimeters and analyzed for pH, electrolytic conductivity (EC), disso...

Soil solution composition in Forest soils of ‘Sierra de Gata’ Mountains, Central-Western Spain: Relationship with soil water content Nutrient ion concentration in soil water were assessed in three deciduous forest the ‘Sierra de Gata’ Mountains, Central-Western Spain, with annual precipitation ranging from 720 to 1,580 mm a-1. Soil solution were o...

Geology and soil distribution in Extremadura (Spain) are exposed, indicating the main characteristics.

MENENDEZ I., G. MORENO, J.F. GALLARDO y J. SAAVEDRA: "Soil solution composition in forest soils of 'Sierra de Gata' mountains: Relationship with soil water content". Arid Soil Res. & Rehabil., 9: 495-502 (1995). A study of soil nutrients in three plots of deciduous species from the “Sierra de Gata” Mountains (Western Spain) was performed. The soil...

Geology and Soils of Extremadura, Spain. The main characteristics of the Region of Extremadura (Spain) are firstly described (climate, Geology, geomorphology, etc.). Later, the mains groups of soils are exposed according of the old FAO soil classification (i. e., Leptosols, Regosols, Arenosols, Cambisols, Vertisols, Luvisols, Alisols, Planosols, A...

The trondhjemites of the Cachi Range (24°10′ to 25°07′S latitude and 66°10′ to 66°30′ W longitude) are a group of epizonal stocks that have a minimum Cambrian age. These postkinematic stocks intrude folded slates and graywackes of the crystalline basement of the Cachi Range in the Eastern Cordillera of northwestern Argentina. They are leucocratic r...

Granites not associated with Sn and/or W follow a normal evolutionary trend whereas the mineralized granites deviate from this trend; particularly with respect to alkali feldspars, quartz and muscovite and are water-saturated. -R.A.H.

The Ordovician Famatinian-age magmatic cordierite-andalusite-bearing Capillitas batholith, in the Pampean Ranges of northwestern Argentina, encompasses a coarsely porphyritic to equigranular two-mica monzogranite with equigranular, fine-grained, late leucogranitic muscovite-rich facies. This batholith exhibits sharp, discordant contacts with low-pr...