Topographic constraints on magma accumulation below the actively uplifting Uturuncu and Lazufre volcanic centers in the Central Andes

Perkins, J. P.; Finnegan, N. J.; Henderson, S. T.; Rittenour, Tammy M.

doi:10.1130/ges01278.1

Cited by 24 publications

(47 citation statements)

References 57 publications

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“…The development of a diapir, its ascent, and ultimately its cessation occur on time scales operating over 10 4 -10 5 yr (e.g., Burov et al, 2003) and are inconsistent with the geomorphological evidence (Perkins et al, 2016).…”

Section: Best-fit Model and Relation To Existing Modelsmentioning

confidence: 95%

“…Geomorphological investigations of shorelines and river terraces reveal an absence of sustained residual long-term and long-wavelength deformation at the geodetically observed rates (Perkins et al, 2016), and identify the onset of Uturuncu's present deformation phase as no more than 100 yr ago. These observations indicate that the recent deformation is a transient pulse.…”

Section: Geomorphologymentioning

confidence: 99%

“…15). That is to show that in our model all residual stresses and strains can be relaxed by the time-dependent mechanical response of the crust over time scales consistent with a transient episode of deformation at Uturuncu (Perkins et al, 2016). Because no observational constraints are available, we do not discuss further the implications of depressurization.…”

Section: Deformation History-depressurizationmentioning

confidence: 99%

“…Considering that there is no long-term (>100 yr) record of residual uplift from the Uturuncu deformation pattern (Perkins et al, 2016), we also test whether uplift is reversible in our model; i.e. ; whether the ground uplift trigger by pressurization can be reversed by an equal amount of depressurization.…”

Section: Data Modeling Time-dependent Pressure Historiesmentioning

confidence: 99%

“…Andesitic and basaltic andesitic enclaves in Uturuncu lavas and in silicic ignimbrites of the APVC (Michelfelder et al, 2014) are interpreted as aliquots of the least evolved resident magmas in the APMB entrained into the volumetrically dominant, silica-rich dacite magmas (Sparks et al, 2008). The mafic magmas have less radiogenic strontium and more radiogenic neodymium isotopes than associated dacites (Michelfelder et al, 2014) and are thought to be Size and geometry of anomalous structures Schilling et al (2006); Comeau et al (2015Comeau et al ( , 2016 Gravimetry A pproximately 12-24 km wide, vertically elongated (8-12 km high), low-density structures rooted at the top of the APMB at ~15 km below sea level Surface velocity and spatiotemporal evolution of deformation Fialko and Pearse (2012); Henderson and Pritchard (2013);del Potro et al (2013a); Blewitt et al (2016) Geomorphology Absence of sustained residual long-term deformation Null result for residual ground deformation at time, t > 100 yr Perkins et al (2016) Note: See text for details on numerical model. APMB-Altiplano-Puna magma body.…”

Section: Petrologymentioning

confidence: 99%

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Thermomechanical modeling of the Altiplano-Puna deformation anomaly: Multiparameter insights into magma mush reorganization

et al. 2017

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A 150-km-wide ground deformation anomaly in the Altiplano-Puna volcanic complex (APVC) of the Central Andes, with uplift centered on Uturuncu volcano and peripheral subsidence, alludes to complex subsurface stress changes. In particular, the role of a large, geophysically anomalous and partially molten reservoir (the Altiplano-Puna magma body, APMB), located ~20 km beneath the deforming surface, is still poorly understood. To explain the observed spatiotemporal ground deformation pattern, we integrate geophysical and petrological data and develop a numerical model that accounts for a mechanically heterogeneous and viscoelastic crust. Best-fit models imply subsurface stress changes due to the episodic reorganization of an interconnected vertically extended mid-crustal plumbing system composed of the APMB and a domed bulge and column structure. Measured gravity-height gradient data point toward low-density fluid migration as the dominant process behind these stress changes. We calculate a mean annual flux of ~2 × 10 7 m 3 of water-rich andesitic melt and/or magmatic water from the APMB into the bulge and column structure accompanied by modest pressure changes of <0.006 MPa/yr. Two configurations of the column fit the observations equally well: (1) a magmatic (igneous mush) column that extends to a depth of 6 km below sea level and contains trapped volatiles, or (2) a volatile-bearing hybrid column composed of an igneous mush below a solidified and permeable body that extends to sea level. Volatile loss from the bulge and column structure reverses the deformation, and explains the absence of broad (tens of kilometers) and long-term (>100 yr) residual deformation at Uturuncu. Episodic mush reorganization may be a ubiquitous characteristic of the magmatic evolution of the APVC.

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Section: Best-fit Model and Relation To Existing Modelsmentioning

confidence: 95%

Section: Geomorphologymentioning

confidence: 99%

Section: Deformation History-depressurizationmentioning

confidence: 99%

Section: Data Modeling Time-dependent Pressure Historiesmentioning

confidence: 99%

Section: Petrologymentioning

confidence: 99%

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Thermomechanical modeling of the Altiplano-Puna deformation anomaly: Multiparameter insights into magma mush reorganization

et al. 2017

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Gypsum‐lined degassing holes in tumuli

Hofmann,

Hinman,

Phillips

et al. 2023

Earth Surf Processes Landf

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Small, circular holes, lined with a thin gypsum veneer, and closely associated with gypsum tumuli (domes), occur at Salar de Pajonales, a salt flat in the northern Andes, Chile. We propose a model in which the formation of the gypsum‐lined holes, and less commonly the formation of the tumuli itself, is controlled by the unique juxtaposition of physiographic, geologic and hydrologic conditions. On a regional scale, Salar de Pajonales is unusual compared to other salars, as it is located close to a large magmatic inflation centre (Lazufre), lies along strike of major regional structural trends, is a large ephemeral lake and contains high salt concentrations. On a basin scale, the lined holes are only present along strike of lineaments that are directly linked to the local stress regime. In turn, these lineaments control the location of degassing and subsequently the formation of the lined holes in the gypsum tumuli and, in part, the tumuli themselves.

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Dissecting a Zombie: Joint analysis of density and resistivity models reveals shallow structure and possible sulfide deposition at Uturuncu Volcano, Bolivia

MacQueen

Gottsmann

Pritchard

et al. 2021

Preprint

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The recent identification of unrest at multiple volcanoes that have not erupted in over 10 kyr presents an intriguing scientific problem. How can we distinguish between unrest signaling impending eruption after kyr of repose and non-magmatic unrest at a waning volcanic system? After ca. 250 kyr without a known eruption, in recent decades Uturuncu volcano in Bolivia has exhibited multiple signs of unrest, making the classification of this system as "active", "dormant", or "extinct" a complex question. Previous work identified anomalous low resistivity zones at <10 km depth with ambiguous interpretations. We investigate subsurface structure at Uturuncu with new gravity data and analysis, and compare these data with existing geophysical data sets. We collected new gravity data on the edifice in November 2018 with 1.5 km spacing, ±15 μGal precision, and ±5 cm positioning precision, improving the resolution of existing gravity data at Uturuncu. This high quality data set permitted both gradient analysis and full 3-D geophysical inversion, revealing a 5 km diameter, positive density anomaly beneath the summit of Uturuncu (1.5-3.5 km depth) and a 20 km diameter arc-shaped negative density anomaly around the volcano (0.5-7.5 depth). These structures often align with resistivity anomalies previously detected beneath Uturuncu, although the relationship is complex, with the two models highlighting different components of a common structure. Based on a joint analysis of the density and resistivity models, we interpret the positive density anomaly as a zone of sulfide deposition with connected brines, and the negative density arc as a surrounding zone of hydrothermal alteration. Based on this analysis we suggest that the unrest at Uturuncu is unlikely to be pre-eruptive. This study shows the value of joint analysis of multiple types of geophysical data in evaluating volcanic subsurface structure at a waning volcanic center.

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Topographic constraints on magma accumulation below the actively uplifting Uturuncu and Lazufre volcanic centers in the Central Andes

Cited by 24 publications

References 57 publications

Thermomechanical modeling of the Altiplano-Puna deformation anomaly: Multiparameter insights into magma mush reorganization

Thermomechanical modeling of the Altiplano-Puna deformation anomaly: Multiparameter insights into magma mush reorganization

Gypsum‐lined degassing holes in tumuli

Dissecting a Zombie: Joint analysis of density and resistivity models reveals shallow structure and possible sulfide deposition at Uturuncu Volcano, Bolivia

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