Evidence for long residence times of rhyolitic magma in the Long Valley magmatic system; the isotopic record in precaldera lavas of Glass Mountain

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doi: 10.1016/0012-821X(89)90146-5
Authors:Halliday, A. N.; Mahood, G. A.; Holden, P.; Metz, J. M.; Dempster, T. J.; Davidson, J. P.
Author Affiliations:Primary:
Univ. Mich., Dep. Geol. Sci., Ann Arbor, MI, United States
Other:
Stanford Univ., United States
Scott. Univ. Res. and React. Cent., United Kingdom
Volume Title:Earth and Planetary Science Letters
Source:Earth and Planetary Science Letters, 94(3-4), p.274-290. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0012-821X
Publication Date:1989
Note:In English. 48 refs.; illus. incl. 1 table, geol. sketch map
Summary:These rhyolite lavas provide a record of the evolution of the system during the 1.4 m.y. prior to the eruption of the Bishop tuff 0.73 m.y. ago. The older lavas (erupted at 2.1-1.2 m.y.) are extremely evolved, whereas the younger lavas (erupted at 1.2-0.7 m.y.) are less evolved. It is suggested that the older lavas may have been derived from an evolved roof zone of a differentiated magma chamber present in the Long Valley region at 2.1 m.y. The isotopic compositions of the younger Glass Mountain lavas and the Bishop tuff, as well as the isochronous relationship of most of the younger lavas, indicate that the chamber containing the magma later to erupt as the younger lavas of Glass Mountain and the Bishop tuff was already formed, isotopically homogenized, and had developed an evolved roof zone by approx 1.1 m.y. There is no evidence for significant assimilation of crustal rocks or input of mantle-derived magma into the upper reaches of the system after this time. [R.E.S.]
Subjects:Absolute age; Acidic magmas; Alkaline earth metals; Cenozoic; Data; Dates; Eruptions; Fractional crystallization; Geochemistry; Igneous rocks; Isotopes; Lava; Magma chambers; Magmas; Metals; Nd-144/Nd-143; Neodymium; Quaternary; Rare earths; Rb/Sr; Rhyolites; Sr-87/Sr-86; Stable isotopes; Strontium; Volcanic rocks; Volcanoes; Volcanology; California; Long Valley Caldera; Mono County California; United States; East-central California; Evolution; Glass Mountain
Coordinates:N374100 N374600 W1184300 W1185200
Abstract Numbers:90M/3147
Record ID:1989080082
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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