Intermediate Depth Drilling of the Snake River Plain: Tracking the Yellowstone Hotspot Through Space

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Intermediate Depth Drilling of the Snake River
Plain Tracking the Yellowstone HotspotThrough
Space and Time
John W. Shervais, Utah State University Dennis
Geist, University of Idaho Barry B. Hanan, San
Diego State University Scott S. Hughes, Idaho
State University Michael Branney, University of
Leicester Douglas F. Williams, University of
South Carolina Alexander Prokopenko University of
South Carolina
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Digital Topography of the USA
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Digital Topography of the USA
Snake River Plain
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Sr 0.706 Line
?
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Yellowstone Plume Geoid Anomaly
Velocity at 100 km depth
Humphreys Deuker
Smith Braile, 1994
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Theoretical Model of Mantle Plume
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Theoretical Model of Mantle Plume
Head entrains cooler asthenosphere
Plume Head Flood Basalts and Oceanic Plateaux
Plume Tail Hotspot track Ocean Island chains
and Snake River Plain
Start at Core-Mantle Boundary?
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Cenozoic Volcanism in Western US
Christiansen, Foulger Evans, 2002, Geological
Society of America Bulletin, v.114, 1245-1256.
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Seismic Tomography of Snake River PlainDerek
Schutt and Eugene Humphreys
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Plume roll-over model
Humphreys et al., 2000, GSA Today
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Seismic Tomography
Christiansen, Foulger Evans, 2002, Geological
Society of America Bulletin, v.114, 1245-1256.
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Montelli et al 2003
Another view of the Seismic tomography
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Mantle Counter-flow model
Humphreys et al., 2000, GSA Today
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Existing Deep Core
INEL
MH
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Eastern Snake River Plain Basalts as Young as
2000 years
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INEL Deep Core WO-2/NPR-E
Surface
3000 Feet
3220-3230
Basalt
BASALT ENDS 3750 feet
710-760
3750 Feet
880-910
Rhyolite
1570-1580
1680-1700
1730-1810
2000-2040
5000
Feet
Bottom
2280-2290
2580-2590
2620-2630
3000 Feet
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INEL Deep Core 15 Flow Groups
Surface
3000 Feet
Flow Groups Separated by Sediment Intercalations
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15
3220-3230
3 2 1
Basalt
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710-760
13
3750 Feet
880-910
Rhyolite
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11
1570-1580
10
1680-1700
1730-1810
9
2000-2040
8
5000
Feet
Bottom
7
2280-2290
2580-2590
6
2620-2630
5
3000 Feet
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Upward Fractionation cycles
Cr Super cycles
TiO2
Mg
Cr Ni
INEL site only deep core ESRP
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DMM
EM 2
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Western SRP Young Basalts (2 Ma) on 1-3 km of
Pliocene Lake Sediments
All underlain by basaltic basement (7-9 Ma)
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Western SRP Pillow deltas formed on top of Lake
sediments
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Mountain Home AFB Deep Core
Surface
1927 Feet
0 Feet
Dense Subaerial Basalt Flows with
Intercalated Sediments
WAB 1988 to 2022
WAB 2178 to 2405
532 Feet
Ash 2627 to 2639
Lacustrine Sediment
WAB 3187 to 3329
Sandy Silt and Clay with Calcareous matrix
Dense Subaerial Basalt Flows with Intercalated
hyaloclastites
1927 Feet
Bottom of Hole
4403 Feet
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Mountain Home AFB Core
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Existing Deep Core
INEL
MH
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Proposed Core
Existing Core
INEL
MH
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Major Science Issues for SRP Drilling Project

• How Do Mantle Plumes Interact with Continental
  Lithosphere/Crust?
• What Does This Tell Us About Fundamental
  Processes of Continental Dynamics and Geochemical
  Evolution of the Earth?
• Baseline What We Know About Plumes From Oceanic
  Settings (e.g., Hawaii Deep Drilling Project)

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Major Science Issues for SRP Drilling Project

• What is the time integrated flux of magma in the
  Yellowstone plume system?
• Has magma flux varied through time?
• What is the proportion of basalt to rhyolite?
  Does it vary along strike? Why or why not?
• Origin of the SRP Rhyolites Crustal melting or
  Fractional crystallization of mantle derived
  basalt? Both? Proportions?

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Major Science Issues for SRP Drilling Project

• Origin and Evolution of the Basalts
• Lithosphere vs Asthenosphere vs Plume?
• Change in magma composition/flux thru time? Super
  cycles in volcanic chemo-stratigraphy.
• Interactions between primary melts and crust or
  lithosphere?
• Location dependent variation in chemistry?
  Age/Composition of crust/lithosphere?

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Major Science Issues for SRP Drilling Project

• Origin of the Western SRP
• How/Why do Rhyolites and Basalts of western SRP
  differ from those of ESRP?
• Comparison of crust/mantle structure WSRP vs
  ESRP.

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Additional Science Issues Paleoclimate of
intra-continental North America during the
Pliocene

• Western SRP provides complete section of lake
  sediments deposited during the Pliocene and early
  Pleistocene from extinct Lake Idaho.
• Sediments contain calcareous fossils suitable for
  oxygen isotope paleothermometry intercalated
  tuffs suitable for radiometric age
  determinations.
• Lake Idaho sediments offer advantage that
  drilling would not involve an existing lake, and
  can be drilled with standard landbased
  technology.

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Additional Science Issues Hydrology of the
Snake River Aquifer

• Shallow sections of each hole will provide
  constraints on the stratigraphy, conductivity,
  and chemical transport of the Snake River
  aquifer, the principal aquifer in southern Idaho,
  which recharges on the INEEL reactor site in the
  Lost River sink and feeds springs along the Snake
  River canyon NW of Twin Falls.

Additional Science Issues Deep Biosphere
Studies
Extremophiles bacteria and archaea within the
core life in extreme environments. Analogue
for possible life in deep lava flows on Mars,
other planetary bodies.
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EarthScope

• Ground Truth for Big Foot array.
• Flex-array More Data on Crust-Mantle Structure,
  plume-lithosphere interactions.
• How is strain accommodated within the SRP?
  Down-hole strain meters, seismometers.
• Volcanic hazard assessment Future volcanic
  eruptions from Yellowstone system.

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CONCLUSIONS
The SRP-Yellowstone System Best Example of
Plume-Continent Interaction
Major Questions that can Only be answered by
Drilling
Also Significant Collateral Questions Addressed
by Drilling (Paleoclimate, Hydrology, Deep
Biosphere)
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Time Line for Drilling
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Time Line for Drilling
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Time Line for Drilling