Rights statement: An edited version of this paper was published by AGU. Copyright 2019 American Geophysical Union. This is the peer reviewed version of the following article:which has been published in final form at Heap, M. J., Tuffen, H., Wadsworth, F. B., Reuschlé, T., Castro, J. M., & Schipper, C. I. ( 2019). The permeability evolution of tuffisites and implications for outgassing through dense rhyolitic magma. Journal of Geophysical Research: Solid Earth, 124, 8281– 8299. https://doi.org/10.1029/2018JB017035 which has been published in final form at https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018JB017035 ©2019. American Geophysical Union. All Rights Reserved.
Accepted author manuscript, 501 KB, PDF document
Available under license: CC BY-NC: Creative Commons Attribution-NonCommercial 4.0 International License
Final published version
Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
}
TY - JOUR
T1 - The Permeability Evolution of Tuffisites and Implications for Outgassing Through Dense Rhyolitic Magma
AU - Heap, Michael J.
AU - Tuffen, Hugh
AU - Wadsworth, Fabian B.
AU - Reuschlé, Thierry
AU - Castro, Jonathan M.
AU - Schipper, C. Ian
N1 - An edited version of this paper was published by AGU. Copyright 2019 American Geophysical Union. This is the peer reviewed version of the following article:which has been published in final form at Heap, M. J., Tuffen, H., Wadsworth, F. B., Reuschlé, T., Castro, J. M., & Schipper, C. I. ( 2019). The permeability evolution of tuffisites and implications for outgassing through dense rhyolitic magma. Journal of Geophysical Research: Solid Earth, 124, 8281– 8299. https://doi.org/10.1029/2018JB017035 which has been published in final form at https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018JB017035 ©2019. American Geophysical Union. All Rights Reserved.
PY - 2019/8/31
Y1 - 2019/8/31
N2 - There is growing evidence that outgassing through transient fracture networks exerts an important control on conduit processes and explosive-effusive activity during silicic eruptions. Indeed, the first modern observations of rhyolitic eruptions have revealed that degassed lava effusion may depend upon outgassing during simultaneous pyroclastic venting. The outgassing is thought to occur as gas and pyroclastic debris are discharged through shallow fracture networks within otherwise low-permeability, conduit-plugging lava domes. However, this discharge is only transient, as these fractures become clogged and eventually blocked by the accumulation and sintering of hot, melt-rich pyroclastic debris, drastically reducing their permeability and creating particle-filled tuffisites. In this study we present the first published permeability measurements for rhyolitic tuffisites, using samples from the recent rhyolitic eruptions at Chaitén (2008–2009) and Cordón Caulle (2011–2012) in Chile. To place constraints on tuffisite permeability evolution, we combine (1) laboratory measurements of the porosity and permeability of tuffisites that preserve different degrees of sintering, (2) theoretical estimates on grainsize- and temperature-dependent sintering timescales, and (3) H2O diffusion constraints on pressure-time paths. The inferred timescales of sintering-driven tuffisite compaction and permeability loss, spanning seconds (in the case of compaction-driven sintering) to hours (surface tension-driven sintering), coincide with timescales of diffusive degassing into tuffisites, observed vent pulsations during hybrid rhyolitic activity (extrusive behavior coincident with intermittent explosions), and more broadly, timescales of pressurization accompanying silicic lava dome extrusion. We discuss herein the complex feedbacks between fracture opening, closing, and sintering and their role in outgassing rhyolite lavas and mediating hybrid explosive-effusive activity.
AB - There is growing evidence that outgassing through transient fracture networks exerts an important control on conduit processes and explosive-effusive activity during silicic eruptions. Indeed, the first modern observations of rhyolitic eruptions have revealed that degassed lava effusion may depend upon outgassing during simultaneous pyroclastic venting. The outgassing is thought to occur as gas and pyroclastic debris are discharged through shallow fracture networks within otherwise low-permeability, conduit-plugging lava domes. However, this discharge is only transient, as these fractures become clogged and eventually blocked by the accumulation and sintering of hot, melt-rich pyroclastic debris, drastically reducing their permeability and creating particle-filled tuffisites. In this study we present the first published permeability measurements for rhyolitic tuffisites, using samples from the recent rhyolitic eruptions at Chaitén (2008–2009) and Cordón Caulle (2011–2012) in Chile. To place constraints on tuffisite permeability evolution, we combine (1) laboratory measurements of the porosity and permeability of tuffisites that preserve different degrees of sintering, (2) theoretical estimates on grainsize- and temperature-dependent sintering timescales, and (3) H2O diffusion constraints on pressure-time paths. The inferred timescales of sintering-driven tuffisite compaction and permeability loss, spanning seconds (in the case of compaction-driven sintering) to hours (surface tension-driven sintering), coincide with timescales of diffusive degassing into tuffisites, observed vent pulsations during hybrid rhyolitic activity (extrusive behavior coincident with intermittent explosions), and more broadly, timescales of pressurization accompanying silicic lava dome extrusion. We discuss herein the complex feedbacks between fracture opening, closing, and sintering and their role in outgassing rhyolite lavas and mediating hybrid explosive-effusive activity.
KW - HO diffusion
KW - lava dome
KW - permeability
KW - rhyolite
KW - sintering
KW - tuffisite
U2 - 10.1029/2018JB017035
DO - 10.1029/2018JB017035
M3 - Journal article
AN - SCOPUS:85070835508
VL - 124
SP - 8281
EP - 8299
JO - Journal of Geophysical Research: Solid Earth
JF - Journal of Geophysical Research: Solid Earth
SN - 2169-9313
IS - 8
ER -