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Steve Matthes U.S. Department of Energy National Energy Technology Laboratory Albany, Oregon.

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Presentation on theme: "Steve Matthes U.S. Department of Energy National Energy Technology Laboratory Albany, Oregon."— Presentation transcript:

1 Steve Matthes U.S. Department of Energy National Energy Technology Laboratory Albany, Oregon

2 1. Introduction to Oregon Geology

3 Cartoon by Sidney Harris

4 Oregon’s Geographic Regions Correspond to Oregon’s Geology USGS Geological Map of Oregon Various colors represent surface rock of varying types and ages.

5 Metasequoia – Oregon’s State Fossil Sun Stone – Oregon’s State Gemstone Thunderegg – Oregon’s State Rock

6 Paleozoic sedimentary rock (frequently metamorphosed) (300MYA) Permian and Triassic sedimentary and volcanic rocks (250 – 200 MYA) Mezozoic sedimentary and volcanic rocks Mezozoic granitic rocks (150 MYA) Permian and Triassic sedimentary and volcanic rocks (250 – 200 MYA) Mezozoic sedimentary and volcanic rocks Eocene and Oligocene marine sediments (50MYA) Old Cenozoic marine basalt and andesite (50 MYA) Oregon’s Oldest Surface Rocks (more than 50MYA)

7 Paleozoic sedimentary rock (frequently metamorphosed) (300MYA) Permian and Triassic sedimentary and volcanic rocks (250 – 200 MYA) Mezozoic sedimentary and volcanic rocks Permian and Triassic sedimentary and volcanic rocks (250 – 200 MYA) Mezozoic sedimentary and volcanic rocks Eocene and Oligocene marine sediments (50MYA) Triassic Jurassic Pennsylvanian Eocene Cretaceous Oligocene Jurassic Mississippian

8 Oldest Oregon Rocks 360 MYA rocks from the Mississippian epoch of the Paleozoic era. Most surface rocks in Oregon are younger than 25 million years

9 Older Cenozoic non-marine sedimentary rock- ash-flow tuffs, banded rhyolite (20-5 MYA) Recent alluvial lake deposits and pumice (1 MYA or younger) High Cascades andesite and basalt (less than 10 MYA) Columbia River Basalts (20 MYA) Recent alluvial deposits including deposits from Missoula Floods (15,000 YA or younger) Younger Cenozoic ( less than 5 MYA) Western Cascades andesite and basalt (25 MYA) Miocene marine sediment (5 MYA) Recent basalt and andesite (less than 1 MYA) Oregon’s Youngest Surface Rocks (less than 50MYA)

10 Older Cenozoic non-marine sedimentary rock- ash-flow tuffs, banded rhyolite (20-5 MYA) Recent alluvial lake deposits and pumice (1 MYA or younger) Recent alluvial deposits including deposits from Missoula Floods (15,000 YA or younger) Younger Cenozoic ( less than 5 MYA) Miocene marine sediment (5 MYA)

11 Paleozoic sedimentary rock (frequently metamorphosed) (300MYA) Permian and Triassic sedimentary and volcanic rocks (250 – 200 MYA) Mezozoic sedimentary and volcanic rocks Mezozoic granitic rocks (150 MYA) Permian and Triassic sedimentary and volcanic rocks (250 – 200 MYA) Mezozoic sedimentary and volcanic rocks Eocene and Oligocene marine sediments (50MYA) Older Cenozoic non-marine sedimentary rock- ash-flow tuffs, banded rhyolite (20-5 MYA) Recent alluvial lake deposits and pumice (1 MYA or younger) High Cascades andesite and basalt (less than 10 MYA) Columbia River Basalts (20 MYA) Recent alluvial deposits including deposits from Missoula Floods (15,000 YA or younger) Younger Cenozoic ( less than 5 MYA) Western Cascades andesite and basalt (25 MYA) Old Cenozoic marine basalt and andesite (50 MYA) Miocene marine sediment (5 MYA) Recent basalt and andesite (less than 1 MYA)

12 Cartoon by Sidney Harris

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14 Corvallis, Oregon Siletz River volcanics – Ancient undersea volcanoes uplifted by collision of tectonic plates Corvallis Fault

15 Corvallis

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17 2. How geologists figure out the geologic past.

18 How do geologists know what the earth’s geologic history looks like? Wells from oil and gas exploration- rocks from drill core (geologic column) Water wells Type of rock (igneous, sedimentary) Fossils Chemical composition of rocks Dating Methods (radioactive decay, dendrochronology, ice cores, varves, coral clocks) Plate tectonics

19 CORE SAMPLES

20 Tertiary Ft. Union Fm ……… feet Cretaceous Greenhorn Fm … feet Cretaceous Mowry Fm …..… feet Cretaceous Inyan Kara Fm … feet Jurassic Rierdon Fm …… feet Triassic Spearfish Fm …… feet Permian Opeche Fm …… feet Pennsylvanian Amsden Fm feet Pennsylvanian Tyler Fm … feet Mississippian Otter Fm …… feet Mississippian Kibbey Lm … feet Mississippian Charles Fm … feet Mississippian Mission Canyon Fm feet Mississippian Lodgepole Fm feet Devonian Bakken Fm … feet Devonian Birdbear Fm … feet Devonian Duperow Fm … feet Devonian Souris River Fm … feet Devonian Dawson Bay Fm feet Devonian Prairie Fm …… feet Devonian Winnipegosis Grp feet Silurian Interlake Fm …… feet Ordovician Stonewall Fm … feet Ordovician Red River Dolomite feet Ordovician Winnipeg Grp … feet Ordovician Black Island Fm … feet Cambrian Deadwood Fm feet Precambrian ……… feet Complete Geologic Column in North Dakota- discovered by an oil exploration well drilled 15,000 feet deep!

21 Places where the complete geologic column has been found

22 ParentDaughterHalf-life Uranium-235Lead billion years Uranium-238Lead Potassium-40Argon Rubidium-87Strontium Samarium- 147Neodymium Thorium-232Lead Rhenium- 187Osmium Lutetium- 176Hafnium Radioactive Dating Only 0.01% of the potassium in a rock is K-40!

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24 Select an element = Internet link () Periodic Table of the Elements Potassium 40 (K) has 19 protons and 21 neutrons. It is radioactive and decays to Argon 40 (Ar) which has 18 protons and 22 neutrons.

25 Potassium Argon (K-Ar) Dating o 1250 Million year half-life (works well for mica, amphibole, K-feldspar, volcanic rocks older than 30 million years) o Works best in granitic rocks where the various mineral crystals are large enough for processing. o Based on assumption that Ar will not be present in the crystal structure when the rock forms (good assumption- Ar is Very rare in the crust)

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27 Plate Tectonics The earth’s crust consists of a patchwork of solid plates “floating” on the mantle. These plates are constantly in motion, colliding and rearranging. The drawings at left show how the plates have moved over the last 225 million years.

28 Cartoon by Sidney Harris

29 Age of Ocean Crust New crust Old crust

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31 million years ago, the continents were all connected together in a “super” continent called______________. 1. Answer: Pangea

32 3. Plate tectonics

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34 Plates may Slide by each other. Transform Plates may Separate. Divergent Plates may Collide with each other. Convergent {e.g. San Andreas Fault) (e.g. Juan de Fuca ridge) New Crust forms here

35 Volcanoes form near the collision between two plates New crust is created at the ocean ridge. The seafloor spreading pushes the ocean plate into the continental plate

36 Subduction Upwelling This is where volcanoes form uplift

37 A closer look at subduction

38 Magma Ocean Ridge What causes the two plates to collide? Seafloor Spreading When hot rock gets close to the surface of the ocean crust it may liquefy because of reduced pressure. The liquefied rock solidifies on exposure to the seawater. Solidified rock expands forcing the oceanic crust apart at the ridge. The process repeats resulting in seafloor spreading.

39 Plates are constantly in motion in relation to each other. Average plate speed is 5 cm per year. Southern California coast is on the Pacific Plate and is moving to the NW.

40 California South of San Francisco to Baja California

41 million years from now, parts of California will be an island off of _______________. 5. Answer: Alaska

42 Cartoon by Sidney Harris

43 3. Oregon’s geologic history – Emphasis on Corvallis.

44 Continental shelf 200 million years ago (ya) Pacific Ocean Old continent Klamath Blue Wallowas Subduction zone

45 100 million ya Subduction zone Volcanoes caused by collision of Pacific Plate with North American Plate (Tropical)

46 2. The ____________ zone is where the oceanic plate is forced under the continental plate. 2. Answer: Subduction

47 50 million ya Undersea volcanoes erupt – formation of Siletz River Volcanics (54 million ya) (Tropical)

48 Mary’s Peak was an undersea volcano 54 million years ago!

49 “Pillow Basalt” forms when lava is cooled quickly underwater. “Pillow basalt” is evidence that an area once was underwater. Pillow lava at Axial Seamount Pillow lava on Mauna Loa, Hawaii “Pillow Basalt” on Mary’s Peak 2000 feet above sea level!

50 “Pillow Lava” on Vineyard Mountain

51 The Earth was several degrees warmer in the Eocene (50 million years ago) Today

52 35 million ya Subduction zone (subtropical)

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54 25 million ya Subduction zone Western Cascades erupt Siletz Volcanics covered with thick layer of ocean and river sediments (temperate)

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56 High Cascades Tombstone Pass Santiam Pass

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58 20 million ya Subduction zone FLOOD BASALTS

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61 Flood Basalts on the Columbia River

62 Old Columbia river channel Yaquina Head Coast range had not yet uplifted. This region was a relatively flat plain. 17 million ya

63 Remnants of Flood Basalt flow that filled the Columbia River channel and forced the river to the north.

64 The lava forming Yaquina Head originated in Central Washington!!

65 10 million ya Subduction zone Oregon Coast is near present location. Area west of the Western Cascades is a broad coastal plain. Siletz volcanics are covered with sedimentary rock. As coastal plain is uplifted, sedimentary rock erodes away.

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67 12,000 ya Subduction zone High cascades erupt Sedimentary rock has eroded away exposing older Siletz river volcanics Missoula floods

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69 Cartoon by Sidney Harris

70 Flood waters were 200 feet deep in the Willamette Valley! Icebergs floated boulders from Canada, Idaho, and Montana into the valley and deposited them on hillsides.

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73 Glacial Erratics near McMinnville

74 Erratic rocks “rafted” into the Willamette Valley on icebergs from the melting ice sheet. Erratic rocks came from Washington, Idaho, Montana, and Canada. Flood waters were as deep as 122 meters and extended to Eugene. The famous Willamette meteorite found in Oregon City is an erratic!!

75 We are in a period of cyclic glaciation with glacial maximum occuring every 100,000 years. Significant end-of-ice-age floods occurred at the start of each interglacial period.

76 Cartoon by Sidney Harris

77 today Subduction zone High cascades erupt


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