Index Catalog // ScholarsArchive@OSU

Creator:: Shrivastava, J. P., Duncan, Robert A., and Kashyap, Mamta
Abstract:: We present new age determinations, derived from ⁴⁰Ar–³⁹Ar incremental heating experiments, for basaltic lava flows from the Mandla lobe, located on the eastern margin of the main Deccan volcanic province, some ~ 1000 km from the Western Ghats escarpment. The most reliable estimates of crystallization ages come from 5 plateau...
Resource Type:: Article
Full Text:: /j.lithos.2015.03.006 Elsevier Accepted Manuscript http://cdss.library.oregonstate.edu/sa-termsofuse

Creator:: Clague, D. A., Paduan, J. B., Duncan, Robert A., Huard, J. J., Davis, A. S., Castillo, P. R., Lonsdale, P., and DeVogelaere
Abstract:: Davidson Seamount, a volcano located about 80 km off the central California coast, has a volume of ~320 km³ and consists of a series of parallel ridges serrated with steep cones. Davidson was sampled and its morphology observed during 27 ROV Tiburon dives. During those dives, 286 samples of lava,...
Resource Type:: Article
Full Text:: ); 8178 Tectonophysics: Tectonics and magmatism. Received 4 June 2009; Revised 17 July 2009; Accepted 15

Creator:: Kruse, Sarah E., Liu, Zhengrong J., Naar, David F., and Duncan, Robert A.
Abstract:: Bathymetry and gravity data collected during Legs 5, 6, and 7 of the 1993 GLORIA Expedition and the recently released 2-min altimetry-derived global gravity grid are used to determine the effective elastic thickness of the lithosphere along the Easter Seamount Chain (ESC). Forward modeling, admittance, and coherence methods yield consistent...
Resource Type:: Article
Full Text:: ., submitted manuscript, 1996)]. A simple hotspot model was initially proposed to explain the origin of this

Creator:: White, William M., McBirney, Alexander R., and Duncan, Robert A.
Abstract:: We report new major element, trace element, isotope ratio, and geochronological data on the Galapagos Archipelago. Magmas erupted from the large western volcanos are generally moderately fractionated tholeiites of uniform composition; those erupted on other islands are compositionally diverse, ranging from tholeiites to picritic basanitoids. While these volcanoes do not...
Resource Type:: Article
Full Text:: manuscript, 1993). Inset shows the regional tectonic setting. GEOLOGICAL BACKGROUND AND PREVIOUS WORK

Creator:: Verplanck, Emily P. and Duncan, Robert A.
Abstract:: New K-Ar age determinations on basalts, basaltic andesites, and ash flow tuffs from the central Western Cascades in Oregon range in age from 32 to 3 Ma. The ages decrease from west to east and with increasing elevation. Volcanism has been continuous throughout the evolution of the Western Cascades, with...
Resource Type:: Article
Full Text:: known from mapping [Smith et al., 1982; G.W. Walker and R.A. Duncan, unpublished manuscript, 1987; N.S

Creator:: Chaytor, Jason D., Keller, Randall A., Duncan, Robert A., and Dziak, Robert P.
Abstract:: Full-coverage multibeam bathymetric mapping of twelve seamounts in the Gulf of Alaska reveals that they are characterized by flat-topped summits (rarely with summit craters) and by terraced, or step-bench, flanks. These summit plateaus contain relict volcanic features (e.g., flow levees, late-stage cones, and collapse craters) and as such must have...
Resource Type:: Article
Full Text:: ; Revised 26 July 2007; Accepted 7 August 2007; Published 29 September 2007. Chaytor, J. D., R. A. Keller

Creator:: Keller, R. A., Graham, David W., Farley, K. A., Duncan, Robert A., and Lupton, J. E.
Abstract:: Helium isotopes are a robust geochemical tracer of a primordial mantle component in hot spot volcanism. The high ³He/⁴He (up to 35 RA, where RA is the atmospheric ³He/⁴He ratio of 1.39 X 10¯⁶) of some Hawaiian Island volcanism is perhaps the classic example. New results for picrites and basalts...
Resource Type:: Article
Full Text:: ; Accepted 26 October 2004; Published 31 December 2004. Keller, R. A., D. W. Graham, K. A. Farley, R. A

Creator:: Jordan, Brennan T., Grunder, Anita L., Duncan, Robert A., and Deino, Alan L.
Abstract:: The High Lava Plains province (HLP) is a late Cenozoic bimodal volcanic field at the northern margin of the Basin and Range province in southeastern Oregon that hosts a westward younging trend of silicic volcanism that crudely mirrors northeastward migration of silicic volcanism along the Yellowstone–Snake River Plain (YSRP) trend....
Resource Type:: Article
Full Text:: ; revised 4 June 2004; accepted 1 July 2004; published 5 October 2004. [1] The High Lava Plains province

Creator:: Duncan, Robert A., Fisk, Martin R., White, William M., and Nielsen, Roger L.
Abstract:: The island of Tahiti, the largest in French Polynesia, comprises two major volcanoes aligned NW-SE, parallel with the general trend of the Society Islands hotspot track. Rocks form this volcanic system are basalts transitional to tholeiites, alkali basalts, basanites, picrites, and evolved lavas. Through K-Ar radiometric dating we have established...
Resource Type:: Article
Full Text:: active volcanism occurs at the southeast end of each of these groups. It is now generally accepted that

Creator:: Konrad, Kevin, Graham, David W., Thornber, Carl R., Duncan, Robert A., Kent, Adam J.R., and Al-Amri, Abdullah M.
Abstract:: Extensive volcanic fields on the western Arabian Plate have erupted intermittently over the last 30 Ma following emplacement of the Afar flood basalts in Ethiopia. In an effort to better understand the origin of this volcanism in western Saudi Arabia, we analyzed ³He/⁴He, and He, CO₂ and trace element concentrations...
Full Text:: l e i n f o Article history: Received 23 October 2015 Accepted 30 January 2016 Available online 10

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