Young cumulate complex beneath Veniaminof caldera, Aleutian arc, dated by zircon in erupted plutonic blocks
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Abstract
Mount Veniaminof volcano, Alaska Peninsula, provides an opportunity to relate Quaternary volcanic rocks to a coeval intrusive complex. Veniaminof erupted tholeiitic basalt through dacite in the past ∼260 k.y. Gabbro, diorite, and miarolitic granodiorite blocks, ejected 3700 14C yr B.P. in the most recent caldera-forming eruption, are fragments of a shallow intrusive complex of cumulate mush and segregated vapor-saturated residual melts. Sensitive high-resolution ion microprobe (SHRIMP) analyses define 238U-230Th isochron ages of 17.6 ± 2.7 ka, 5 +11/–10 ka, and 10.2 ± 4.0 ka (2σ) for zircon in two granodiorites and a diorite, respectively. Sparse zircons from two gabbros give 238U-230Th model ages of 36 ± 8 ka and 26 ± 7 ka. Zircons from granodiorite and diorite crystallized in the presence of late magmatic aqueous fluid. Although historic eruptions have been weakly explosive Strombolian fountaining and small lava effusions, the young ages of plutonic blocks, as well as late Holocene dacite pumice, are evidence that the intrusive complex remains active and that evolved magmas can segregate at shallow levels to fuel explosive eruptions.
Study Area
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Young cumulate complex beneath Veniaminof caldera, Aleutian arc, dated by zircon in erupted plutonic blocks |
| Series title | Geology |
| DOI | 10.1130/G23446A.1 |
| Volume | 35 |
| Issue | 6 |
| Year Published | 2007 |
| Language | English |
| Publisher | Geological Society of America |
| Contributing office(s) | Volcano Science Center |
| Description | 4 p. |
| First page | 491 |
| Last page | 494 |
| Country | United States |
| State | Alaska |
| Google Analytic Metrics | Metrics page |