GEOLOGICAL MARVELS: The Colorado Plateau and the Grand Canyon SC 204 January 9, 2013
Gil Brenner John Bush Gary Oberts
RIO GRANDE RIVER WEST OF TAOS NEW MEXICO RIO GRANDE RIVER ISLETA PUEBLO-NEAR ALBUQUERQUE RIO GRANDE RIFT WEST OF GRANTS NEW MEXICO
CONTINENTAL DIVIDE CENTRAL COLORADO
CONTINENTAL DIVIDE I-40 WESTERN NEW MEXICO
CONTINENTAL DIVIDE I-40 WESTERN NEW MEXICO RED ROCK STATE PARK NEAR GALLUP NEW MEXICO
PETRIFIED FOREST NEAR HOLBROOK ARIZONA PETRIFIED FOREST NEAR HOLBROOK ARIZONA PAINTED DESERT NEAR WINSLOW ARIZONA BARRINGER CRATER NEAR FLAGSTAFF ARIZONA BARRINGER CRATER
SAN FRANCISCO MOUNTAINS NEAR FLAGSTAFF ARIZONA SAN FRANCISCO MOUNTAINS FLAGSTAFF ARIZONA SUNSET CRATER SAN FRANCISCO VOLCANIC FIELD SEDONA ARIZONA COCONINO PLATEAU WEST OF SELIGMAN ARIZONA HURRICANE FAULT EAST OF KINGMAN ARIZONA COLORADO RIVER NEAR NEEDLES CALIFORNIA
GRAND CANYON FROM NAVAJO POINT
LAKE POWELL GLEN CANYON DAM LEE’S FERRY/NAVAJO BRIDGE MARBLE CANYON BELOW LEE’S FERRY GRAND WASH CLIFFS PEARCE FERRY RAPID
LAKE MEAD HOOVER DAM HELICOPTER TOUR OF GRAND CANYON Geologic Time Scale GRAND CANYON GRAND CANYON PRECAMBRIAN GEOLOGIC COLUMN • Elves Chasm Pluton (gneisses) 1840 Ma • Granite Gorge Metamorphic Suite 1750- 1730 Ma – Rama & Brahma Metavolcanics – Vishnu Schist Metasediments – Zoroaster Granite • The “Greatest Unconformity” 480 myrs • Grand Canyon Supergroup 1250 Ma- 750 Ma – Unkar Group LS, SH, SS – Nankoweap Formation SS, MS – Chuar Group DO, LS, SH, SS – Sixtymile Formation BR, SS • The Great Unconformity 200 myrs
GRAND CANYON GRAND CANYON SUPERGROUP TONTO PLATFORM TAPEATS SS, BRIGHT ANGEL SH, MUAV LS REDWALL LIMESTONE SUPAI GROUP KAIBAB LIMESTONE
UINKARET VOLCANIC FIELD GEOLOGIC MAP OF GRAND CANYON USGS G. H. BILLINGSLEY 2000
HERITAGE SQUARE FLAGSTAFF ARIZONA
PALEOGEOGRAPHIC MAPS
Ron Blakey Colorado Plateau Geosystems, Inc PRESENT PRESENT Geologic Time Scale LATE CAMBRIAN (500 Ma)
Iapetus Ocean Greenland
Panthalassa Ocean
North America GRAND CANYON PRECAMBRIAN GEOLOGIC COLUMN • Elves Chasm Pluton (gneisses) 1840 Ma • Granite Gorge Metamorphic Suite 1750- 1730 Ma – Rama & Brahma Metavolcanics – Vishnu Schist Metasediments – Zoroaster Granite • The “Greatest Unconformity” 480 myrs • Grand Canyon Supergroup 1250 Ma- 750 Ma – Unkar Group LS, SH, SS, LA – Nankoweap Formation SS, MS – Chuar Group DO, LS, SH, SS – Sixtymile Formation BR, SS • The Great Unconformity 200 myrs
EARLY CAMBRIAN 525 Ma
Tonto Group Tapeats SS Bright Angel SH Muav LS Geologic Time Scale MID MISSISSIPPIAN (340 Ma)
Arctica Baltica North Slope Greenland Panthalassa Ocean Laurussia
North America Africa
Florida Yucatan Hunic terrane Gondwana South America MID MISSISSIPPIAN 340 MA
Temple Butte Fm (D) DO Redwall Limestone LS Surprise Canyon Fm CO SS LS MS Geologic Time Scale LATE PENNSYLVANIAN (300 Ma) Baltica North Slope Greenland Panthalassa Ocean
North America Africa
Yucatan Florida
Hunic terrane Gondwana South America LATE PENNSYLVANIAN 304 Ma
Supai Group Watahomigi Fm LS MS DO Manakacha Fm SS MS Wescogame Fm SS
Geologic Time Scale EARLY PERMIAN (280 Ma)
Baltica North Slope Greenland Panthalassa Ocean
North America Africa
Yucatan Florida Gondwana
Hunic terrane South America 295 Ma EARLY PERMIAN
Esplanade Sandstone SS Hermit Fm MS SS Coconino Sandstone SS Toroweap Fm East SS West GY DO LS SS MID PERMIAN 270 Ma
Kaibab Fm -Fossil Mountain West LS East LS SS -Harrisburg GY SS MS LS
Geologic Time Scale THAT’S ALL THAT SURVIVES* BUT ELSEWHERE ON THE PLATEAU
• There are places where rocks date from 250 Ma to Recent • At Grand Canyon weathering and erosion has stripped away the rest— “unroofing” – When did unroofing happen? – How did unroofing happen? – How much rock was removed? – Where did all that rock go? *Except for some lava flows
FOCAL QUESTIONS FOR THIS CLASS
• GRAND CANYON – WHEN WAS IT FORMED? – HOW WAS IT FORMED? • COLORADO PLATEAU – WHAT LIFTED IT? – WHEN WAS IT LIFTED? – WHAT HOLDS IT UP? THESE ARE CONTROVERSIAL TOPICS • Answering them requires integrating loosely connected technical specialities – Sedimentary geology – Igneous geology – Tectonics – Geomorphology-weathering, erosion, deposition – Life sciences- ichthyology, botany, genetics – Atmospheric sciences-climatology • The facts keep growing as new techniques are devised and the theories keep changing partially as a consequence