Origin of low oxygen isotopic compositions in alkalic lavas from Erebus volcano, Antarctica

Owens, Lara; Kyle, Philip R.; Sharp, Zachary D.; Campbell, Andrew R.

doi:10.1016/j.gca.2021.06.008

Cited by 3 publications

(4 citation statements)

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“…S20 ). Oxygen isotope trends in the phonolitic lavas can be explained by limited incorporation of this hydrothermally altered rock 9 . We do not discuss this zone further.…”

Section: Resultsmentioning

confidence: 97%

“…For crustal levels, the resistivity of dry phonolite melt at 1000 °C, the interpreted temperature of the magma storage zone in the 4–7.5 km depth range 9 – 11 , is ~1 Ωm 46 . At somewhat higher temperatures with limited water contents that may pertain to greater crustal depths 10 , 11 , resistivities 46 could be as low as 0.3 Ωm for 1050 °C, 1.1 wt % H 2 O.…”

Section: Discussionmentioning

confidence: 99%

“…The alkali-rich Erebus phonolite has been modeled as evolving by fractional crystallization of a parental basanite sourced from an enriched upper mantle through a series of intermediate composition magma reservoirs 3 , 8 , 9 . Simplistic calculations suggest the formation of Erebus volcano requires >4000 km 3 of basanite, which in turn requires low degrees of partial melting of >80,000 km 3 of the upper mantle peridotite 3 .…”

Section: Introductionmentioning

confidence: 99%

“…CO 2 emissions from the Erebus lava lake and fumaroles exceed the rates possible from estimated magmatic solubilities and crystallization, thus requiring deep-sourced, upper mantle CO 2 streaming through the plumbing system. This gas flux is an important heat supply, buffering the conditions of final phonolite differentiation that is modeled to be near 1000 °C in the 4–7.5 km depth range 9 – 12 . Its desiccating effect raises the solidus temperature of the magma promoting crystallization and differentiation.…”

Section: Introductionmentioning

confidence: 99%

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Trans-crustal structural control of CO2-rich extensional magmatic systems revealed at Mount Erebus Antarctica

et al. 2022

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Erebus volcano, Antarctica, with its persistent phonolite lava lake, is a classic example of an evolved, CO2-rich rift volcano. Seismic studies provide limited images of the magmatic system. Here we show using magnetotelluric data that a steep, melt-related conduit of low electrical resistivity originating in the upper mantle undergoes pronounced lateral re-orientation in the deep crust before reaching shallower magmatic storage and the summit lava lake. The lateral turn represents a structural fault-valve controlling episodic flow of magma and CO2 vapour, which replenish and heat the high level phonolite differentiation zone. This magmatic valve lies within an inferred, east-west structural trend forming part of an accommodation zone across the southern termination of the Terror Rift, providing a dilatant magma pathway. Unlike H2O-rich subduction arc volcanoes, CO2-dominated Erebus geophysically shows continuous magmatic structure to shallow crustal depths of < 1 km, as the melt does not experience decompression-related volatile supersaturation and viscous stalling.

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“…S20 ). Oxygen isotope trends in the phonolitic lavas can be explained by limited incorporation of this hydrothermally altered rock 9 . We do not discuss this zone further.…”

Section: Resultsmentioning

confidence: 97%