PALYNOLOGY

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HISTORY OF THE SNAKE RIVER PLAIN HOTSPOT

• PALYNOLOGY
• Environmental Sequence
• Global Climate Change
• Tectonism
• Sierran Rain Shadow
• Local Uplift/Subsidence

• VOLCANOLOGY
• SRP History
• Plume Crust Interactions
• Hotspot Dynamics

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HISTORY OF THE SNAKE RIVER PLAIN HOTSPOT

• PALYNOLOGY
• Environmental Sequence
• Global Climate Change
• Tectonism
• Sierran Rain Shadow
• Local Uplift/Subsidence

Dated Tephra Dated Flows Uplift/Subsidence

• VOLCANOLOGY
• SRP History
• Plume Crust Interactions
• Hotspot Dynamics

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HISTORY OF THE SNAKE RIVER PLAIN HOTSPOT

• PALYNOLOGY
• Environmental Sequence
• Global Climate Change
• Tectonism
• Sierran Rain Shadow
• Local Uplift/Subsidence

Dated Tephra Dated Flows Uplift/Subsidence
Paleoelevation Interbed Ages Correlation

• VOLCANOLOGY
• SRP History
• Plume Crust Interactions
• Hotspot Dynamics

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Strong influence of elevation on vegetation
palynology
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Climatic changes (glacial/interglacial) subtle
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Marked late-Neogene evolution of
vegetation Climate global tectonic
4200 ft
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Trends late Miocene early Pleistocene (means
of dating and correlating flows)
0.7 m.a.
5 m.a.
10 m.a.
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Composite of Bruneau and MHAB-1 cores
4000 ft
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Tentative Chronology (based on correlation)
Pleisto
Pliocene
Terteling Spr 5-6 m.a.
Mio
Dated Lava
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Volcanic Tephra Chronology for palynology,
Before Lake Idaho
8 Ma
11 Ma
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Interbedded Sediments east of Lake Idaho
younger than Lake Idaho
4 Ma
6.25 Ma
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Interbedded Sediments cores wells INEL
(thanks to Linda Davis) Deerflat, Simplot, etc.
1.12 3.16 km 8.2 Ma
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Tentative Sequence
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Preliminary Palynological Results

• Tentative vegetation-climate sequence
• Potential value of long cores
• Apparent ages consistent with HOTSPOT
• Paleoelevation large changes
• INEL-1 km
• Interbedded sediments provide
• Wider coverage (not just Lake Idaho)
• Tephra flow dates for Palynology sequence

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Horseshoe Bend
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Additional INEL, Hagerman Fossil Beds and
Simplot Well samples
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Age Nothing in Lk Idaho older than
mid-Miocene?Elevation big changes high elev.
flora very different
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Sand Spr. 0.095 Ma
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Snake River Plain Cross-section Homedale - Boise
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Surface elevation of Lake Idaho sensu lato
Bruneau Fm.
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Miocene Riparian Vegetation
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