TY - JOUR

T1 - Explosive volcanic eruptions on Mercury

T2 - eruption conditions, magma volatile content, and implications for interior volatile abundances

AU - Kerber, Laura

AU - Head, James

AU - Solomon, Sean

AU - Murchie, Scott

AU - Blewett, David

AU - Wilson, Lionel

PY - 2009/8

Y1 - 2009/8

N2 - Images obtained by the MESSENGER spacecraft have revealed evidence for pyroclastic volcanism on Mercury. Because of the importance of this inference for understanding the interior volatile inventory of Mercury, we focus on one of the best examples determined to date: a shield-volcano-like feature just inside the southwestern rim of the Caloris impact basin characterized by a near-central, irregularly shaped depression surrounded by a bright deposit interpreted to have a pyroclastic origin. This candidate pyroclastic deposit has a mean radius of ~ 24 km, greater in size than the third largest lunar pyroclastic deposit when scaled to lunar gravity conditions. From the extent of the candidate pyroclastic deposit, we characterize the eruption parameters of the event that emplaced it, including vent speed and candidate volatile content. The minimum vent speed is ~ 300 m/s, and the volatile content required to emplace the pyroclasts to this distance is hundreds to several thousands of parts per million (ppm) of the volatiles typically associated with pyroclastic eruptions on other bodies (e.g., CO, CO2, H2O, SO2, H2S). For comparison, measurements of the exsolution of volatiles (H2O, CO2, S) from basaltic eruptive episodes at Kilauea volcano, Hawaii, indicate values of ~ 1300–6500 ppm for the terrestrial mantle source. Evidence for the presence of significant amounts of volatiles in partial melts derived from the interior of Mercury is an unexpected result and provides a new constraint on models for the planet's formation and early evolution.

AB - Images obtained by the MESSENGER spacecraft have revealed evidence for pyroclastic volcanism on Mercury. Because of the importance of this inference for understanding the interior volatile inventory of Mercury, we focus on one of the best examples determined to date: a shield-volcano-like feature just inside the southwestern rim of the Caloris impact basin characterized by a near-central, irregularly shaped depression surrounded by a bright deposit interpreted to have a pyroclastic origin. This candidate pyroclastic deposit has a mean radius of ~ 24 km, greater in size than the third largest lunar pyroclastic deposit when scaled to lunar gravity conditions. From the extent of the candidate pyroclastic deposit, we characterize the eruption parameters of the event that emplaced it, including vent speed and candidate volatile content. The minimum vent speed is ~ 300 m/s, and the volatile content required to emplace the pyroclasts to this distance is hundreds to several thousands of parts per million (ppm) of the volatiles typically associated with pyroclastic eruptions on other bodies (e.g., CO, CO2, H2O, SO2, H2S). For comparison, measurements of the exsolution of volatiles (H2O, CO2, S) from basaltic eruptive episodes at Kilauea volcano, Hawaii, indicate values of ~ 1300–6500 ppm for the terrestrial mantle source. Evidence for the presence of significant amounts of volatiles in partial melts derived from the interior of Mercury is an unexpected result and provides a new constraint on models for the planet's formation and early evolution.

KW - Mercury

KW - pyroclastic

KW - volcanism

KW - volatile

KW - accretion

KW - interior

KW - MESSENGER

U2 - 10.1016/j.epsl.2009.04.037

DO - 10.1016/j.epsl.2009.04.037

M3 - Journal article

VL - 285

SP - 263

EP - 271

JO - Earth and Planetary Science Letters

JF - Earth and Planetary Science Letters

SN - 0012-821X

IS - 3-4

ER -