Mafic magma recharge supplies high CO2 and SO2 gas fluxes from Popocatépetl volcano, Mexico

Roberge, Julie; Delgado-Granados, Hugo; Wallace, Paul

doi:10.1130/g25242a.1

Cited by 92 publications

(58 citation statements)

References 19 publications

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“…5). While in 1974 H 2 O and CO 2 concentrations are high, in 1999 and 2003 similarly high CO 2 concentrations (up to 1,500 ppm CO 2 ) can be observed, but without high 1974 melt inclusions: Roggensack, 2000Sadofsky et al, 20071999& 2003: Sisson and Layne, 1993Harris et al, 1984 groundmass glass in clusters, this study this study melt inclusions, this study Roggensack, unpublished (Rust et al 2004) and Popocatepetl (Roberge et al 2009). The gas phase with which such melt inclusions are in contact has to be very rich in CO 2 ; for Fuego, the gas composition should contain >90 mol% CO 2 .…”

Section: High Co 2 Low H 2 O Melt Inclusionsmentioning

confidence: 78%

A tale of two magmas, Fuego, Guatemala

et al. 2011

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Fuego volcano in Guatemala erupted in 1974 in a basaltic sub-Plinian event, which has been well documented and studied. In 1999, after a period of quiescence lasting 20 years, Fuego erupted again, this time less violently, but with persistent low-level activity. This study investigates the link between these episodes. Previous melt inclusion studies have shown magma erupted in 1974 to have been a volatile-rich hybrid tapped from a vertically extensive system. By contrast, magma erupted in 1999 and 2003 is similar in composition to that erupted in 1974, but melt inclusions are more evolved. Although melt inclusions from the later period are CO 2 rich (up to ∼1,500 ppm), they have low H 2 O concentration (max 1.5 wt.%, compared to ∼6 wt.% in 1974). These melt inclusions have a modified H 2 O concentration due to diffusive re-equilibration at shallow pressures. Despite this diffusive exchange, both eruptions show evidence of recent mingling of the same low and higher K melts, one of which was slightly cooler than the other and as a result traversed the amphibole stability field. ( 210 Pb/ 226 Ra) data on selected bulk rock samples from 1974 suggest that whereas the cooler, more evolved end-member may have been degassing since the last major eruption in the 1930s, the warmer end-member intruded at most a decade prior to the 1974 eruption. The two end-members are thus batches of the same magma emplaced shallowly ∼30 years apart during which time the older batch was cooled and differentiated before mixing with the younger influx. The presence of the same two melts in the later eruptions suggests that magma in 1999 and 2003 is partly residual from 1974. The current eruptive activity is clearing the system of this residual magma prior to an expected new magma batch.

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Section: High Co 2 Low H 2 O Melt Inclusionsmentioning

confidence: 78%

A tale of two magmas, Fuego, Guatemala

et al. 2011

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“…Important observations at Popocatepetl volcano in Mexico have recently placed constraints on the contribution to the volatile budget from mafic magma and the mechanism by which gases are transported from deep-seated levels in the volcanic system to the surface, without needing to invoke conduit convection (Roberge et al 2009). Popocatepetl erupts dacite magma that contains evidence for mixing with mafic magmas in the form of euhedral Mg-rich olivines, which contain basaltic to basaltic-andesite melt inclusions.…”

Section: "Excess Sulfur" or More Accurately "Excess Volatiles" Problemmentioning

confidence: 99%

The Sulfur Budget in Magmas: Evidence from Melt Inclusions, Submarine Glasses, and Volcanic Gas Emissions

Wallace

Edmonds

2011

Reviews in Mineralogy and Geochemistry

236

145

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“…We conclude that this significant amount of H 2 O released through Vol. 168, (2011) Flat-Slab Thermal Structure and Evolution Beneath Central Mexico slab deserpentinization can induce partial melting of the mantle above the slab and explain the volcanic productivity and the reasonably high H 2 O found in the erupted mafic magmas, similar to magmas from other arcs (ROBERGE et al, 2009;CERVANTES and WALLACE, 2003). …”

Section: Peridotite-water Systemmentioning

confidence: 99%

Flat-Slab Thermal Structure and Evolution Beneath Central Mexico

Manea

2010

Pure Appl. Geophys.

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Recent seismic and magnetotelluric experiments, aimed at better characterizing the shape and state of the subducting slab and continental crust beneath Central Mexico, exposed significant differences with conclusions of previous studies. A new slab geometry is revealed in which the subducting Cocos slab is perfectly flat between 120 to 290 km from the trench, after which it plunges into the asthenosphere at a dip angle of *65°, in sharp contrast with the previously proposed *20°dip angle. Seismic tomography studies show negative P-wave velocity anomalies (-2 to -4%) in the mantle wedge beneath the Mexican Volcanic Belt, and positive anomalies (?2 to ?3%) for the subducted Cocos slab. Magnetotelluric experiments exposed a very low-resistivity area (1-10 Xm) located within the continental crust just below the Mexican Volcanic Arc. Finally, several spots of non-volcanic tremors (NVTs) have been recorded inside the continental crust above the flat-slab segment. While all these experiments provide a better picture of the subduction system beneath Central Mexico, several key processes need further investigation. In this study, we take advantage of these new observations to better constrain the thermal structure beneath Central Mexico. Two different thermal models are computed for a mantle potential temperature (T p ) of 1,350 and 1,450°C, respectively. The new thermal structures are then converted into P-wave velocity anomalies and compared with the observed V p anomalies. We found that a T p of 1,450°C produced larger V p anomalies that do not fit the observations. However, using a T p of only 1,350°C, our predicted V p anomalies are positive (?2 to ?3%) for the cold slab and negative (-2 to -4%) in the mantle wedge. These V p estimates are consistent with the observed seismic tomography from P-wave arrivals, and therefore we conclude that a T p of 1,350°C is a better estimate for the mantle potential temperature beneath Central Mexico. The new thermal model, in conjunction with phase diagrams for sediments, hydrated basalt and lithospheric mantle, have been used to estimate the amount and location of fluids released from the subducting Cocos slab. Several dehydration pulses have been identified along the slab interface where most of the fluids stored in sediments and oceanic crust are released into the overlying continental crust above the flat-slab. We found a good correlation between the pattern of these dehydration pulses and the location of NVTs, suggesting that slab dehydration is responsible for triggering the tremors. We suggest that NVT bursts localized above the flat slab segment represent the manifestation of ongoing continental crust hydration and weakening, a process that has been going on since 15 Ma ago when the Cocos slab entered into a flat-slab regime. Such continuous weakening would have reduced the suction forces that kept the slab in a flat regime in the last 15 Ma, allowing the slab to easily roll back. The continuous low-resistivity region recorded beneath the volcanic front in Central Mexico mi...

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Mafic magma recharge supplies high CO2 and SO2 gas fluxes from Popocatépetl volcano, Mexico

Cited by 92 publications

References 19 publications

A tale of two magmas, Fuego, Guatemala

A tale of two magmas, Fuego, Guatemala

The Sulfur Budget in Magmas: Evidence from Melt Inclusions, Submarine Glasses, and Volcanic Gas Emissions

Flat-Slab Thermal Structure and Evolution Beneath Central Mexico

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