HR: 0800h
AN: GP11D-0866    [Abstracts]
TI: Investigating the Timing and Extent of Early Yellowstone Hotspot Volcanism While Expanding the Steens Mountain Magnetic Reversal Record.
AU: * Jarboe, N A
EM: njarboe@es.ucsc.edu
AF: University of California, Earth Sciences Department, Santa Cruz, CA 95064 United States
AU: Coe, R S
EM: rcoe@es.ucsc.edu
AF: University of California, Earth Sciences Department, Santa Cruz, CA 95064 United States
AU: Glen, J M
EM: jglen@usgs.gov
AF: US Geological Survey, MS989 345 Middlefield Rd., Menlo Park, CA 94025 United States
AU: Renne, P R
EM: prenne@bgc.org
AF: Berkeley Geochronology Center, 2455 Ridge Road, Berkeley, CA 94709 United States
AB: The lower Steens Basalt flows of the Oregon Plateau appears to have been erupted earlier than the oldest Columbia River Basalt flows (Hooper et al., 2002), although some contest this conclusion (Baksi, 2004). The extent and timing of the Steens Basalt eruptions are not well understood and knowledge gained in this area will enhance understanding of the Yellowstone Hotspot and Large Igneous Provinces. Volcanic flow stacks in this area show at most one reversal and when present always show a reversed to normal change. This fact suggests that the lavas all record the same reversal and, consequently, that the eruptions occurred over a short period of time. By using high precision Ar/Ar dating and the path of the VGP during the transition, we can test whether the reversals recorded in this area are contemporaneous. At the same time, we hope to find new transitional directions of the well documented Steens Mountain reversal. VGP paths that we have obtained from Summit Springs suggest that this section is indeed Steens equivalent. In addition, we have dated two flows from the transition found at Steens Mountain to 16.69 +- 0.19 Ma and 16.48 +- 0.18 Ma using Ar/Ar dating techniques. Initial portable fluxgate analysis at Catlow Peak show around 30 transitional flows present. We will present paleomagnetic results from this section and several others in the area.
DE: 1520 Magnetostratigraphy
DE: 1525 Paleomagnetism applied to tectonics (regional, global)
DE: 1527 Paleomagnetism applied to geologic processes
DE: 1535 Reversals (process, timescale, magnetostratigraphy)
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2004 AGU Fall Meeting