Holocene tephrochronology of the southernmost part (42°30'-45°S) of the Andean Southern Volcanic Zone

Naranjo, José A.; Stern, Charles R.

doi:10.4067/s0716-02082004000200003

Cited by 129 publications

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“…[20] Bulk ash compositional analyses, undertaken on four ash samples by X-ray fluorescence spectroscopy, and glass analyses on 219 points of fifteen ash samples by electron microprobe (Table 2), have been combined with compositional data on the recent and previous eruptions of Chaitén [Naranjo and Stern, 2004;Horwell et al, 2008]. With calculated CIPW norm compositions [Kelsey, 1965] and examination of particles by scanning electron microscope, this shows the eruption involved a weakly peraluminous rhyolitic melt, lacking phenocrysts, with minor proportions of plagioclase and rarer biotite microlites, and a mean glass silica content of 74.5 wt % (Figure 6).…”

Section: Ash Chemistry and Potential Impactsmentioning

confidence: 99%

“…Ash composition was relatively uniform, with subtle chemical differences between eruptive phases suggested by discrete domains within the overall compositional range occupied by samples from specific depositional lobes (Figure 6b). The ash has similar silica content to, but is more sodic and less potassic than, the $10 ka Chaitén (Cha1) ash [López-Escobar et al, 1993;Naranjo and Stern, 2004]. Rhyolites are rare in this portion of the southern Andean volcanic arc, the only regional tephra of comparable composition being the eastward dispersed Mic2 unit (Figure 6), identified as originating from Minchinmá-vida, 20 km east of Chaitén [Naranjo and Stern, 2004].…”

Section: Ash Chemistry and Potential Impactsmentioning

confidence: 99%

“…The ash has similar silica content to, but is more sodic and less potassic than, the $10 ka Chaitén (Cha1) ash [López-Escobar et al, 1993;Naranjo and Stern, 2004]. Rhyolites are rare in this portion of the southern Andean volcanic arc, the only regional tephra of comparable composition being the eastward dispersed Mic2 unit (Figure 6), identified as originating from Minchinmá-vida, 20 km east of Chaitén [Naranjo and Stern, 2004]. However, this rock composition is not typical of that produced by Minchinmávida, and the identification of the source volcano, based on a lack of the Mic2 tephra outcropping west of Minchinmávida, may not be correct, with Chaitén as the alternative.…”

Section: Ash Chemistry and Potential Impactsmentioning

confidence: 99%

“…Prior to this, the volcano comprised a rhyolitic lava dome within a 2.5 km diameter caldera, last thought to have erupted at 9370 14 C years B.P. [Naranjo and Stern, 2004]. The event had immediate social and economic impacts across southern Chile and Argentina, with more than 5000 people evacuated from settlements up to 75 km from the volcano, and extensive ash deposition leading to regional disruption of agriculture and aviation.…”

Section: Introductionmentioning

confidence: 99%

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Fallout and distribution of volcanic ash over Argentina following the May 2008 explosive eruption of Chaitén, Chile

et al. 2009

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[1] The major explosive eruption of Chaitén volcano, Chile, in May 2008 provided a rare opportunity to track the long-range dispersal and deposition of fine volcanic ash. The eruption followed $10,000 years of quiescence, was the largest explosive eruption globally since Hudson, Chile, in 1991, and was the first explosive rhyolitic eruption since Novarupta, Alaska, in 1912. Field examination of distal ashfall indicates that $1.6 Â 10 11 kg of ash (dense rock equivalent volume of $0.07 km 3 ) was deposited over $2 Â 10 5 km 2 of Argentina during the first week of eruption. The minimum eruption magnitude, estimated from the mass of the tephra deposit, is 4.2. Several discrete ashfall units are identifiable from their distribution and grain size characteristics, with more energetic phases showing a bimodal size distribution and evidence of cloud aggregation processes. Ash chemistry was uniform throughout the early stages of eruption and is consistent with magma storage prior to eruption at depths of 3-6 km. Deposition of ash over a continental region allowed the tracking of eruption development and demonstrates the potential complexity of tephra dispersal from a single eruption, which in this case comprised several phases over a week-long period of intense activity.

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Section: Ash Chemistry and Potential Impactsmentioning

confidence: 99%

Section: Ash Chemistry and Potential Impactsmentioning

confidence: 99%

Section: Ash Chemistry and Potential Impactsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Fallout and distribution of volcanic ash over Argentina following the May 2008 explosive eruption of Chaitén, Chile

et al. 2009

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“…AP. (Naranjo y Stern 2004). Este segmento estratigráfi co es muy friable, aunque con un límite inferior neto.…”

Section: El Contexto De Hallazgounclassified

Comentario Sobre Una Edad 14c en El Límite Pleistoceno/ Holoceno De Alero El Toro, Bosque Siempreverde De Aisén

Méndez¹,

Reyes

M³

et al. 2010

Magallania

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RESUMENComentamos una edad radiocarbónica situada en la transición Pleistoceno/Holoceno obtenida en un contexto estratigráfi co -sin asociación humana-ubicado en el bosque siempreverde de Aisén, Chile (~44° S). Discutimos las implicancias de este inesperado resultado en el marco de las dinámicas poblacionales de Patagonia. Para ello describimos el contexto espacial y estratigráfi co del sitio alero El Toro, lugar de recuperación de la muestra. Se señalan las posibles explicaciones y proponemos una interpretación parsimoniosa a la luz de otros resultados obtenidos a lo largo del valle del río Cisnes.PALABRAS CLAVES: transición Pleistoceno/Holoceno, bosque siempre verde, procesos de formación de sitio. COMMENTS ON A PLEISTOCENE/HOLOCENE BOUNDARY 14 C AGE FROM EL TORO ROCKSHELTER, AISÉN'S EVERGREEN FOREST. ABSTRACTWe comment on a transitional Pleistocene/Holocene radiocarbon age obtained from a stratigraphic context -without human association-located in the evergreen forest of Aisén, Chile (~44° S). We discuss the implications of this unexpected result in frame of peopling dynamics of Patagonia. In order to do so, we describe the spatial and stratigraphic contexts of El Toro rockshelter site, location where the sample was recovered. We point out possible explanations and propose a parsimonious interpretation in light of other results obtained along Cisnes river basin.

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Soluble iron inputs to the Southern Ocean through recent andesitic to rhyolitic volcanic ash eruptions from the Patagonian Andes

Simonella

Palomeque

Croot

et al. 2015

Global Biogeochemical Cycles

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Patagonia, due to its geographic position and the dominance of westerly winds, is a key area that contributes to the supply of nutrients to the Southern Ocean, both through mineral dust and through the periodic deposits of volcanic ash. Here we evaluate the characteristics of Fe dissolved (into soluble and colloidal species) from volcanic ash for three recent southern Andes volcanic eruptions having contrasting features and chemical compositions. Contact between cloud waters (wet deposition) and end-members of andesitic (Hudson volcano) and rhyolitic (Chaitén volcano) materials was simulated. Results indicate higher Fe release and faster liberation rates in the andesitic material. Fe release during particle-seawater interaction (dry deposition) has higher rates in rhyolitic-type ashes. Rhyolitic ashes under acidic conditions release Fe in higher amounts and at a slower rate, while in those samples containing mostly glass shards, Fe release was lower and faster. The 2011 Puyehue eruption was observed by a dust monitoring station. Puyehue-type eruptions can contribute soluble Fe to the ocean via dry or wet deposition, nearly reaching the limit required for phytoplankton growth. In contrast, the input of Fe after processing by an acidic eruption plume could raise the amount of dissolved Fe in surface ocean waters several times, above the threshold required to initiate phytoplankton blooms. A single eruption like the Puyehue one represents more than half of the yearly Fe flux contributed by dust.

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Holocene tephrochronology of the southernmost part (42°30'-45°S) of the Andean Southern Volcanic Zone

Cited by 129 publications

References 0 publications

Fallout and distribution of volcanic ash over Argentina following the May 2008 explosive eruption of Chaitén, Chile

Fallout and distribution of volcanic ash over Argentina following the May 2008 explosive eruption of Chaitén, Chile

Comentario Sobre Una Edad 14c en El Límite Pleistoceno/ Holoceno De Alero El Toro, Bosque Siempreverde De Aisén

Soluble iron inputs to the Southern Ocean through recent andesitic to rhyolitic volcanic ash eruptions from the Patagonian Andes

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