scholarly journals New Perspectives on Prolific and Voluminous Rhyolite Volcanism of the Mahogany Mountain--Three Fingers Rhyolite Field, Eastern Oregon

2021 ◽  
Author(s):  
◽  
Robert Jackson
Keyword(s):  
Rhyolite Volcanism

Igneous history of the Andean Cordillera and Patagonian plateau around latitude 46°S

1981 ◽  
Vol 303 (1474) ◽  
pp. 105-149 ◽  
Keyword(s):  
Calc Alkaline ◽  
Alkali Basalts ◽  
Cinder Cones ◽  
Andean Cordillera ◽  
The Pacific ◽  
Igneous Activity ◽  
History Of ◽  
Pacific Margin ◽  
Rhyolite Volcanism ◽  
Back Arc

From the Middle Jurassic onwards persistent igneous activity in the southern Andes around 46 °S was controlled by easterly dipping subduction along the Pacific margin. Cogenetic plutonic rocks belonging to the Patagonian batholith, and calc-alkaline volcanics ranging from basaltic andesites to rhyolitic tuffs and ignimbrites are the principal products. Erosion of the primary volcanics has led at various times to the development of thick volcaniclastic sequences, for example in the Cretaceous-Lower Tertiary Divisadero formation. The Coyhaique region marks the northerly extension of a narrow back-arc basin in which the marine Neocomian successions accumulated. Volcaniclastics from the island arc, which presumably lay to the west, are intercalated with the sediments. Although the marine basin was short-lived a mildly extensional back-arc regime may have existed through much of Mesozoic-Recent times. Widespread basalt-rhyolite volcanism on the eastern side of the cordillera seems to have been associated with this tectonic environment. Remnants of the Patagonian basalt plateau at latitude 45-47 °S extend from the Argentine-Chile frontier to Lago Colhue Huapi. Four principal age and compositional groups have been distinguished in the lavas, (i) The oldest, which are about 80 Ma, occur in sections at Senguerr and Morro Negro. They are almost exclusively tholeiitic, but show some calc-alkaline affinities and resemble in other respects basalts from marginal basins, (ii) The second group (57-43 Ma) occur in the lower part of the Chile Chico section with a compositional spread from olivine tholeiites through alkali basalts to one occurrence of a basanite. (iii) The upper part of the main plateau sequence, where the flows are in the range 25-9 Ma, are dominantly of alkali basalt composition, (iv) Post-plateau flows from small cinder cones on the surface of the plateau range in age from ca. 4 Ma to 0.2 Ma or less. They are mostly highly undersaturated basanites, with occasional leucite basanites, enriched in incompatible elements. A few of the earlier tholeiites with calc-alkali traits may have been closely associated with subduction or marginal basin processes. The younger lavas are more alkalic intraplate types generated in the remote back-arc extensional zone.

scholarly journals First Results from HOTSPOT: The Snake River Plain Scientific Drilling Project, Idaho, U.S.A.

2013 ◽  
Vol 15 ◽  
pp. 36-45 ◽  
Author(s):  
J. W. Shervais ◽  
D. R. Schmitt ◽  
D. Nielson ◽  
J. P. Evans ◽  
E. H. Christiansen ◽  
...  
Keyword(s):  
Thermal Anomaly ◽  
Surface Expression ◽  
Snake River Plain ◽  
Snake River ◽  
Scientific Drilling ◽  
Geophysical Logging ◽  
First Results ◽  
History Of ◽  
Rhyolite Volcanism ◽  
River Plain

HOTSPOT is an international collaborative effort to understand the volcanic history of the Snake River Plain (SRP). The SRP overlies a thermal anomaly, the Yellowstone-Snake River hotspot, that is thought to represent a deep-seated mantle plume under North America. The primary goal of this project is to document the volcanic and stratigraphic history of the SRP, which represents the surface expression of this hotspot, and to understand how it affected the evolution of continental crust and mantle. An additional goal is to evaluate the geothermal potential of southern Idaho. <br><br> Project HOTSPOT has completed three drill holes. (1) The Kimama site is located along the central volcanic axis of the SRP; our goal here was to sample a long-term record of basaltic volcanism in the wake of the SRP hotspot. (2) The Kimberly site is located near the margin of the plain; our goal here was to sample a record of high-temperature rhyolite volcanism associated with the underlying plume. This site was chosen to form a nominally continuous record of volcanism when paired with the Kimama site. (3) The Mountain Home site is located in the western plain; our goal here was to sample the Pliocene-Pleistocene transition in lake sediments at this site and to sample older basalts that underlie the sediments. <br><br> We report here on our initial results for each site, and on some of the geophysical logging studies carried out as part of this project. <br><br> doi:<a href="http://dx.doi.org/10.2204/iodp.sd.15.06.2013" target="_blank">10.2204/iodp.sd.15.06.2013</a>

scholarly journals Piggy-back Supervolcanoes—Long-Lived, Voluminous, Juvenile Rhyolite Volcanism in Mesoproterozoic Central Australia

2015 ◽  
Vol 56 (4) ◽  
pp. 735-763 ◽  
Author(s):  
R. H. Smithies ◽  
H. M. Howard ◽  
C. L. Kirkland ◽  
F. J. Korhonen ◽  
C. C. Medlin ◽  
...  
Keyword(s):  
Central Australia ◽  
Rhyolite Volcanism

scholarly journals K-bentonites in the Argentine Precordillera contemporaneous with rhyolite volcanism in the Famatinian Arc

2004 ◽  
Vol 161 (5) ◽  
pp. 747-756 ◽  
Author(s):  
C.M. Fanning ◽  
R.J. Pankhurst ◽  
C.W. Rapela ◽  
E.G. Baldo ◽  
C. Casquet ◽  
...  
Keyword(s):  
Argentine Precordillera ◽  
Rhyolite Volcanism
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