Columbia River Basalt Flows

Icing the Cake

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Volcanic Episodes

65

55

45

35

25

15

0

5

Age (Myrs)

WesternCascade Arc(37-15 Myrs)

Challis Arc(55-42 Myrs)

High Cascade Arc(5-0 Myrs)

Columbia River Basalts(17-6 Myrs,Most 17-14 Myrs)

Yellowstone Hot Spot(14-0 Myrs)

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Large Igneous Provinces (LIPs)

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Flood basalt Age Volume (mi3 (km3))

Siberian Traps 250 Myrs 950,000 (4,000,000)

Deccan Traps 66 Myrs 475,000 (2,000,000)

CRBs/Steens Mt. 17-6 Myrs 60,000 (250,000)

Columbia River Basalts (CRBs)

F-1

Just the Facts:• 17.5-6 Myrs old

(mostly 16.5-14.5 Myrs)• Over 300 lava flows• Covers 63,200 mi2

(164,000 km2)• Volume = 41,600 mi3

(171,000 km3)

CRB Landmarks

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Haystack Rock, Cannon Beach

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Beacon Rock, Columbia Gorge

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Multnomah Falls

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Dry Falls

Palouse Falls

Relative Volume of the CRBs

Columbia RiverBasalts

(41,600 mi2) YellowstoneEruptions

Tambora, 1815

Krakatoa, 1883

Mt. St. Helens, 1980Crater Lake, 7,000 yrs ago

Mt. Pinatubo, 1991

Basalt Thickness QuickTime™ and a

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QuickTime™ and aTIFF (Uncompressed) decompressor

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Divided into Four Main Formations(Based on chemistry, age, paleomagnetics)

All Basalts

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F-6Age (Myr)

Formation Member # of FLows

Area (mi2)

Volume (mi3)

6

Saddle

Mountain

Lower Monumental 1 170 4

8.5 Ice Harbor 4 830 18

Buford 1 220 5

10.5 Elephant Mtn 2 5,190 105

12 Pamona 1 8,710 180

Esquatzel 1 1,050 17

Weissenfels Ridge 4 470 5

13 Asotin 1 2,490 53

Wilber Creek 2 1,190 17

13.5 Umatilla 2 5,830 170

TOTAL 19 11,800 574

14.5

Wanapum

Priest Rapids 3 22,120 670

Roza 4 15,580 310

15.3 Frenchman Springs 21 26,930 1,540

Eckler Mtn 8 2,350 41

TOTAL 36 37,050 2,561

15.7-15.6

Grande Ronde

7 members (N) 33 44,190 6,690

15.9-15.7 4 members (R) 45 45,450 12,740

16-15.9 2 members (N) 15 39,510 7,530

16.5-16 4 members (R) 27 37,320 8,680

TOTAL 120 57,530 35,640

17.5-17 Imnaha ? Members 26 19,380 2,280

GRAND TOTAL 311 63,200 41,588

6%

86%

7%

1%

Eruptions mostly

finished by14.5 Myrs

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Imnaha Basalts(17.5-17 Mys)

F-7

Grande Ronde Basalts(16.5-15.6 Mys)

F-7

Wanapum Basalts(15.3-14.5 Mys)

F-8

Roza Member Volume

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Roza Member(Wanapum Basalts)1300 km3 / 5-15 yrs

Mauna Loa1859 Eruption0.27 km3 / 10 months

Laki (Iceland)1783 Eruption14.7 km3 / 8 months

Hawaii1986-92 Eruption0.5 km3 / 6 yrs

One Flow in the Roza Member

Volume: 700 km3

Time: 7 daysVelocity: 5-15 km/hrFissure Length: >100 kmRate: 100 km3 per day(1 km3 per day per km of fissure)

For Comparison - 1 Hawaiin Flow(0.001 km3 per day per km of fissure)

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Saddle Mountain Basalts(13-6 Mys)

F-8

Other Flows - Part of CRB’s?Picture Gorge & Steens Mtn Basalts

F-8

Steens Mtn (16.5-15 Myrs)

CRB “Feeder Dikes”F-7

Grande Ronde Feeder Dike

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Photo by Vic Camp

Over 300 Basalt Flows

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Flow AnatomyQuickTime™ and a

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Vesicular Top

Upper Colonnade(not shown)

Entablature

Pillows(if it flowed into water)

Main Colonnade

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Flow AnatomyVesicular Top

Upper Colonnade(not shown)

Entablature

Pillows(if it flowed into water)

Main Colonnade

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Flow Anatomy

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Vesicular Top

Upper Colonnade

Entablature

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Main Colonnade (below pictue)