Title:
Large-volume, low-delta super 18 O rhyolites of the central SnakeRiver plain, Idaho, USA 
Reference Number:
1989 
ISSN:
0091-7613
Publication Year:
2005
GeoREF Number:
2005-074680 (View Original Data File)
Authors:
Boroughs, Scott; Wolff, John; Bonnichsen, Bill; Godchaux, Martha;Larson, Peter
Descriptors:
Bruneau-Jarbridge volcanic field; calderas; Cenozoic; crust;eruptions; feldspar group; framework silicates; geochemistry;hydrothermal alteration; Idaho; Idaho Batholith; igneous rocks;isotope ratios; isotopes; Jacks Creek volcanic field; lava; magmatism;major elements; melting; metasomatism; meteoric water; Miocene;Neogene; O-18/O-16; oxygen; pyroclastics; quartz; rhyolite tuff;rhyolites; silica minerals; silicates; Snake River plain; southwesternIdaho; stable isotopes; Tertiary; trace elements; Twin Falls volcanicfield; United States; volcanic features; volcanic fields; volcanicrocks; volcanism; volume; welded tuff; Yellowstone Hot Spot
Source:
Geology Boulder, vol.33, no.10, pp.821-824, Oct 2005
Abstract:
The Miocene Bruneau-Jarbidge and adjacent volcanic fields of thecentral Snake River Plain, southwest Idaho, are dominated byhigh-temperature rhyolitic tuffs and lavas having an aggregate volumeestimated as 7000 km super 3 . Samples from units representing atleast 50% of this volume are strongly depleted in super 18 O, withmagmatic feldspar delta super 18 O sub VSMOW Vienna standard meanocean water values between -1.4ppm and 3.8 ppm. The magnitude of thesuper 18 O depletion and the complete lack of any rhyolites withnormal values 7 ppm-10 ppm combine to suggest that assimilation ormelting of a caldera block altered by near- contemporaneoushydrothermal activity is unlikely. Instead, we envisage generation ofthe high-temperature rhyolites by shallow melting of Idaho Batholithrocks, under the influence of the Yellowstone hotspot, affected byEocene meteoric-hydrothermal events. The seeming worldwide scarcity ofstrongly super 18 O-depleted rhyolites may simply reflect a similarscarcity of suitable crustal protoliths.
Notes:
With GSA Data Repository Item 2005162
Copyright:
GeoRef, Copyright 2005, American Geological Institute. Referenceincludes data supplied by the Geological Society of America, Boulder,CO, United States

Sample Summary:
Sample ID: Major Data: Trace Data: Isotope Data:
I-3487 No No Yes
I-3488 No No Yes
02SB-39 No No Yes
02SB-40 No No Yes
I-3410 No No Yes
S-487 No No Yes
I-404 No No Yes
I-3388 No No Yes
I-3388 No No Yes
I-1122 Yes Yes Yes
I-1100 Yes Yes Yes
I-841 Yes Yes Yes
X-214 Yes Yes Yes
X-72 Yes Yes No
X-116 Yes Yes No
X-174 Yes Yes Yes
X-20 Yes Yes Yes
X-37 Yes Yes No
I-810 Yes Yes Yes
I-569 No No Yes
I-3868 No No Yes
I-1060 Yes Yes Yes
I-496 Yes Yes Yes
I-529 Yes Yes Yes
I-3843 No No Yes
02SB-45 Yes Yes Yes
02SB-46 Yes Yes Yes
02SB-47 Yes Yes No
02SB-48 Yes Yes Yes
02SB-49 Yes Yes No
02SB-50 Yes Yes No
02SB-51 Yes Yes No
02SB-56 No No Yes
02SB-57 No No Yes
I-2132 No No Yes
I-1143 Yes Yes Yes
01SB-27 Yes Yes No
01SB-28 Yes Yes Yes
01SB-29 Yes Yes No
01SB-30 Yes Yes Yes
01SB-31 Yes Yes No
01SB-32 Yes Yes No
01SB-33 Yes Yes No
01SB-35 Yes Yes No
I-688 Yes Yes Yes
I-1037 Yes Yes Yes
I-1214 Yes Yes Yes
I-1350 No No Yes
I-1260 Yes Yes Yes
02SB-76 No No Yes
I-1056 Yes Yes Yes
01SB-10 Yes Yes No
01SB-6 Yes Yes No
01SB-7 Yes Yes No
01SB-8 Yes Yes No
01SB-05 No No Yes
01SB-1 Yes Yes No
01SB-3 Yes Yes No
01SB-4 Yes Yes Yes
01SB-5 Yes Yes No
02SB-61 No No Yes
02SB-65 No No Yes
I-2863 No No Yes
I-1074 Yes Yes Yes
I-1197 Yes Yes Yes
I-3425 No No Yes
I-1631 No No Yes
I-2207 No No Yes
I-1138 Yes Yes Yes
I-2475 No No Yes
I-1269 Yes Yes No
01SB-11 Yes Yes No
01SB-12 No No Yes
01SB-13 Yes Yes No
01SB-15 Yes Yes No
01SB-19 Yes Yes No
01SB-21 Yes Yes Yes
02SB-85 No No Yes