Suchergebnisse

Kilauea Volcano's 2018 lower East Rift Zone (LERZ) eruption produced exceptionally high lava effusion rates and record-setting SO2 emissions. The eruption involved a diverse range of magmas, including primitive basalts sourced from Kilauea's summit reservoirs. We analyzed LERZ matrix glasses, melt inclusions, and host minerals to identify melt volatile contents and magma storage depths. The LERZ glasses and melt inclusions span nearly the entire compositional range previously recognized at Kilauea. Melt inclusions in Fo(86-89) olivine from the main eruptive vent (fissure 8) underwent 70-170 degrees C cooling during transport in LERZ carrier melts, causing extensive post-entrapment crystallization and sulfide precipitation. Many of these melt inclusions have low sulfur (400-900 ppm) even after correction for sulfide formation. CO2 and H2O vapor saturation pressures indicate shallow melt inclusion trapping depths (1-5 km), consistent with formation within Kilauea's Halema'uma'u and South Caldera reservoirs. Many of these inclusions also have degassed delta S-34 values (1.5 to -0.5%). Collectively, these results indicate that some primitive melts experienced near-surface degassing before being trapped into melt inclusions. We propose that decades-to-centuries of repeated lava lake activity and lava drain-back during eruptions (e.g., 1959 Kilauea Iki) recycled substantial volumes of degassed magma into Kilauea's shallow reservoir system. Degassing and magma recycling from the 2008-2018 Halema'uma'u lava lake likely reduced the volatile contents of LERZ fissure 8 magmas, resulting in lower fountain heights compared to many prior Kilauea eruptions. The eruption's extreme SO2 emissions were due to high lava effusion rates rather than particularly volatile-rich melts. ; U.S. Geological Survey (USGS) Volcano Science Center; Hawaiian Volcano Observatory (HVO); University of Hawaii-Hilo; HVO volunteer program; Department of Earth Sciences at the University of Oregon; Mineralogical Society of America; Geological Society of America; Mazamas student research grant program; National Science Foundation (NSF) Graduate Research Fellowship ProgramNational Science Foundation (NSF); NSF Graduate Research Internship Program (GRIP) ; Published version ; The authors would like to thank Matthew Loewen, Nicole Metrich, and Matt Patrick for constructive input that significantly improved this manuscript. The authors also thank the U.S. Geological Survey (USGS) Volcano Science Center, Hawaiian Volcano Observatory (HVO), University of Hawaii-Hilo, partner agencies, and the residents of Hawaii for support, field access, data sharing, and for their great care in documenting and responding to the 2018 LERZ eruption crisis. AHL thanks Tina Neal and the HVO volunteer program for support, Mike Zoeller for map assistance, and Carolyn Parcheta for collecting and sharing samples. Geochemical analyses were conducted with the help of John Donovan and Julie Chouinard (EPMA), and Brian Monteleone and Glenn Gaetani (SIMS and MI rehomogenization). AHL thanks Michelle Muth and Madison Myers for discussions on methodology and melt inclusion interpretation. AHL acknowledges funding support from Department of Earth Sciences at the University of Oregon, the Mineralogical Society of America, the Geological Society of America, the Mazamas student research grant program, the National Science Foundation (NSF) Graduate Research Fellowship Program, and the NSF Graduate Research Internship Program (GRIP). Coordination of GRIP at the USGS is through the Youth and Education in Science programs within the Office of Science Quality and Integrity. ; Public domain authored by a U.S. government employee