Volcanism and structure of southwestern Bolivia

Kussmaul, Siegfried; Hörmann, P. K.; Ploskonka, E.; Subieta, T.

doi:10.1016/0377-0273(77)90016-6

Cited by 45 publications

(17 citation statements)

References 20 publications

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“…Also, two active sulfur-producing fumarole fields have been documented near the summit (e.g. Kussmaul et al 1977;Sparks et al 2008). In May 2003 and May 2009, the temperature of these fumaroles was measured to be slightly below 80°C (Sunagua 2004;Sparks et al 2008;J.…”

Section: Introductionmentioning

confidence: 99%

Shallow seismicity, triggered seismicity, and ambient noise tomography at the long-dormant Uturuncu Volcano, Bolivia

et al. 2011

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Using a network of 15 seismometers around the inflating Uturuncu Volcano from April 2009 to 2010, we find an average rate of about three local volcano-tectonic earthquakes per day, and swarms of 5-60 events a few times per month with local magnitudes ranging from −1.2 to 3.7. The earthquake depths are near sea level, more than 10 km above the geodetically inferred inflation source and the Altiplano Puna Magma Body. The Mw 8.8 Maule earthquake on 27 February 2010 triggered hundreds of earthquakes at Uturuncu with the onset of the Love and Rayleigh waves and again with the passage of the X2/X3 overtone phases of Rayleigh waves. This is one of the first incidences in which triggering has been observed from multiple surface wave trains. The earthquakes are oriented NW-SE similar to the regional faults and lineaments. The b value of the catalog is 0.49, consistent with a tectonic origin of the earthquakes. We perform ambient noise tomography using Love wave cross-correlations to image a low-velocity zone at 1.9 to 3.9 km depth below the surface centered slightly north of the summit. The low velocities are perhaps related to the hydrothermal system and the low-velocity zone is spatially correlated with earthquake locations. The earthquake rate appears to vary with time-a seismic deployment from 1996 to 1997 reveals 1-5 earthquakes per day, whereas 60 events/day were seen during 5 days using one seismometer in 2003. However, differences in analysis methods and magnitudes of completeness do not allow direct comparison of these seismicity rates. The rate of seismic activity at Uturuncu is higher than at other wellmonitored inflating volcanoes during periods of repose. The frequent swarms and triggered earthquakes suggest the hydrothermal system is metastable.

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Section: Introductionmentioning

confidence: 99%

Shallow seismicity, triggered seismicity, and ambient noise tomography at the long-dormant Uturuncu Volcano, Bolivia

et al. 2011

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“…Using data from multiple centers representing a "zone" would require additional analyses and comparison of the centers. Ferná ndez et al [42], Kussmaul et al [44], Avila-Salinas [38], and Feeley [41] demonstrated that rocks with the highest K 2 O contents also have the highest 87 Sr/ 86 Sr ratios. These authors proposed that the eastward enrichments of incompatible trace elements require the involvement of some form of crustal melting or contamination.…”

Section: Discussion: Origin Of Across-arc Geochemical Variations In Tmentioning

confidence: 96%

“…Overtime, this contribution diminishes and compositions become increasingly controlled by mantle source compositions. Ferná ndez et al [42] and Kussmaul et al [44] suggested that the observed compositional trends may reflect crustal melting or contamination of more mafic magmas at increasingly shallower depths eastward. These conclusions were reached without comprehensive trace element data, which was later suggested to play key roles in modeling the mineralogies and source compositions during magma differentiation and migration [41,97,98].…”

Section: Discussion: Origin Of Across-arc Geochemical Variations In Tmentioning

confidence: 97%

“…For example, Ferná ndez et al [42] and Kussmaul et al [44] suggested the trends may reflect crustal melting or contamination of more mafic magmas at increasingly shallower depths eastward. This hypothesis is unlikely because Y and Yb contents, although high in Uturuncu rocks, probably as a result of assimilation of more incompatible element-enriched silicic crustal source rocks, decrease with increasing SiO 2 contents for rocks from all centers ( Figure 5).…”

Section: Discussion: Origin Of Across-arc Geochemical Variations In Tmentioning

confidence: 97%

“…These restrictions allow for a more focused examination relative to larger regional studies (i.e., [22,36,37]). Previous regional-scale studies of magmatism in the southern Altiplano region documented eastward increases in K 2 O and related incompatible trace elements virtually identical to across-strike geochemical trends observed at many oceanic island arcs and continental arcs constructed on thin crust [38][39][40][41][42][43][44][45]. [30,32,33,46]; stippled region illustrates distribution of Quaternary volcanic rocks.…”

Section: Introductionmentioning

confidence: 95%

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Modification of the Continental Crust by Subduction Zone Magmatism and Vice-Versa: Across-Strike Geochemical Variations of Silicic Lavas from Individual Eruptive Centers in the Andean Central Volcanic Zone

et al. 2013

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To better understand the origin of across-strike K 2 O enrichments in silicic volcanic rocks from the Andean Central Volcanic Zone, we compare geochemical data for Quaternary volcanic rocks erupted from three well-characterized composite volcanoes situated along a southeast striking transect between 21° and 22° S latitude (Aucanquilcha, Ollagüe, and Uturuncu). At a given SiO 2 content, lavas erupted with increasing distance from the arc front display systematically higher K 2 O, Rb, Th, Y, REE and HFSE contents; Rb/Sr ratios; and Sr isotopic ratios. In contrast, the lavas display systematically lower Al 2 O 3 , Na 2 O, Sr, and Ba contents; Ba/La, Ba/Zr, K/Rb, and Sr/Y ratios; Nd isotopic ratios; and more negative Eu anomalies toward the east. We suggest that silicic magmas along the arc front reflect melting of relatively young, mafic composition amphibolitic source rocks and that the mid-to deep-crust becomes increasingly older with a more felsic bulk composition in which residual mineralogies are progressively more feldspar-rich toward the east. Collectively, these data suggest the continental crust becomes strongly hybridized beneath frontal arc localities due to protracted intrusion of primary, mantle-derived basaltic OPEN ACCESSGeosciences 2013, 3 634 magmas with a diminishing effect behind the arc front because of smaller degrees of mantle partial melting and primary melt generation.

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Iwawi and Tiwanaku

Isbell¹,

Burkholder²

2002

Andean Archaeology I

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Volcanism and structure of southwestern Bolivia

Cited by 45 publications

References 20 publications

Shallow seismicity, triggered seismicity, and ambient noise tomography at the long-dormant Uturuncu Volcano, Bolivia

Shallow seismicity, triggered seismicity, and ambient noise tomography at the long-dormant Uturuncu Volcano, Bolivia

Modification of the Continental Crust by Subduction Zone Magmatism and Vice-Versa: Across-Strike Geochemical Variations of Silicic Lavas from Individual Eruptive Centers in the Andean Central Volcanic Zone

Iwawi and Tiwanaku

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