Back to Search
Start Over
Compositional Evolution of Polygenetic Fissure Volcanic Systems: Insights From the Latest Eruptions at Craters of the Moon Volcanic Field.
Compositional Evolution of Polygenetic Fissure Volcanic Systems: Insights From the Latest Eruptions at Craters of the Moon Volcanic Field.
- Source :
- Geochemistry, Geophysics, Geosystems: G3; Apr2023, Vol. 24 Issue 4, p1-15, 15p
- Publication Year :
- 2023
-
Abstract
- The Craters of the Moon (COM) Volcanic Field in Idaho is the largest mostly Holocene lava field in the conterminous U.S. and the site of the most recent volcanism in the Yellowstone‐Snake River Plain province. This prominent example of a polygenetic fissure field has produced over 60 eruptions over the past 15,000 years from the Great Rift fissure system. The eight most recent lava flows, known as Period A, were erupted between about 2,500 and 2,000 years ago. In this study, major and trace element and Pb‐Sr‐Nd isotope data were obtained, with several samples collected from each flow from widely spaced locations to evaluate heterogeneity in their source magmas. The results reveal three previously unrecognized compositional groups that may represent separate magma batches, and that assimilation and fractional crystallization (AFC) controlled the evolution of the entire Period A suite. The three oldest flows were periodic withdrawals from a body of highly evolved and poorly homogenized magma, and four later flows represent successive samplings from a stratified body of more primitive magma. These two flow groups are related via variable AFC modeled with Magma Chamber Simulator software, with Neogene rhyolite as a plausible crustal assimilant. A third compositional type that requires a different parent magma and AFC history is represented by a single flow erupted from vents a few km away from the others. The compositional evolution and variability observed in this sequence of flows provide new insights into how magmas are generated, modified, and delivered in such polygenetic fissure systems. Plain Language Summary: The Craters of the Moon Volcanic Field is a prominent example of a long‐lived eruptive fissure system in a continental setting, where lava flows are produced at the Great Rift, a linear zone of fracturing and extending crust on the Snake River Plain in southern Idaho. Craters of the Moon has produced more than 60 eruptions over the past 15,000 years, including young lavas with high‐silica compositions that are relatively uncommon in the region. The eight most recent lava flows, known as Period A, were erupted between about 2,500 and 2,000 years ago. This sequence of flows provides snapshots of the evolving system over time and constrains processes that modify and feed magmas to this type of volcanic system. New chemical and isotope data with higher precision than in previous studies reveal that the flows fall into three compositional groups, likely reflecting separate magma batches with distinct histories of cooling, crystallization, and contamination by wall rock. These results illuminate the processes that deliver and alter magmas in such long‐lived fissure systems. Key Points: Compositions of the eight most recent Craters of the Moon lava flows elucidate magma evolution in this polygenetic fissure systemThis compositional study revealed the flows were fed by three previously unrecognized magma compositions with distinct petrologic historiesThe magmas were heterogenous, stratified, and culminated in the eruption of increasingly less evolved flows [ABSTRACT FROM AUTHOR]
- Subjects :
- VOLCANIC fields
VOLCANIC craters
LUNAR craters
ALLUVIAL plains
LAVA flows
MAGMAS
Subjects
Details
- Language :
- English
- ISSN :
- 15252027
- Volume :
- 24
- Issue :
- 4
- Database :
- Complementary Index
- Journal :
- Geochemistry, Geophysics, Geosystems: G3
- Publication Type :
- Academic Journal
- Accession number :
- 163336556
- Full Text :
- https://doi.org/10.1029/2022GC010740