GEOLOGICAL MARVELS: The Colorado Plateau and the Grand Canyon

SC 204 January 16, 2013

Gil Brenner

John Bush

Gary Oberts

THE HUALAPAI OVERLOOK

GLOBAL CHANGES OF SEA LEVEL

FORMATION OF THE THE GRAND CANYON

A YOUNG CANYON

OR

AN ANCIENT ONE ?

CLARENCE E DUTTON JOHN WESLEY POWELL

THE PHYSICAL GEOLOGY OF THE GRAND CANYON DISTRICT 1882

THE EXPLORATION OF THE COLORADO RIVER AND ITS CANYONS 1875

Antecedent Rivers “The Great Denudation”

SAN JUAN RIVER GOOSENECKS NEAR BLUFF UTAH

GRAND CANYON: LATER HYPOTHESES

• At least 8 major theories with minor variations

• New techniques, new evidence and new concepts were responsible

• The newer hypotheses had to incorporate validated evidence of the prior theories

James Lawrence Powell, Grand Canyon: Solving

Earth’s Grandest Puzzle Pi Press 2005

THE YOUNG CANYON HYPOTHESIS

• Grand Canyon was cut in the last 6 million years

• It was cut by the Colorado River

• This is the consensus position

THE 2010 CONSENSUS

VIDEO

“HOW THE EARTH WAS MADE—GRAND CANYON”

A YOUNG CANYON-- SUMMARY

• Calcium content of garnets

• Presence of marine fossils

• Alignment of pebbles in Hindu Canyon

• Muddy Creek formation

• Lake Bidahochi- fossils and green rocks

• Rapid down-cutting at Lee’s Ferry

• Rapids focus energy of the river

• Canyon widening processes

• Volcanoes yield lava flows into the Canyon

AN ANCIENT CANYON

• Western Grand Canyon was cut close to its present depth by 60-70 Ma

• The Colorado River did not create Grand Canyon

Brian Wernecke The California River and its role in carving Grand Canyon Geological Society of America Bulletin 123 1288-1316, 2011

SUPPORTERS OF THE ANCIENT CANYON THEORY

• Rebecca Flowers—U Colorado

• Kenneth A Farley– CalTech

R. M. Flowers and K. A. Farley Apatite 4He/3He

and (U-Th)/He Evidence for an Ancient

Grand Canyon Science, 338 1616 2012

ADVOCATES OF THE YOUNG CANYON HYPOTHESIS

• Karl E Karlstrom University of New Mexico

• Richard A Young State University of New York Geneseo

• Joel Pederson Utah State University

• Many other geologists

W.R. Dickinson & G.E. Gehrels American Journal of Science 2008

Location of the Kaibab Uplift in the west-central

Colorado Plateau, near the margin of the Sevier thrust

belt.

Tindall S et al. Lithosphere 2 221-231 2010

SOUTHWESTERN COLORADO PLATEAU

LATE CRETACEOUS—75 Ma

CRETACEOUS AMERICAN SOUTHWEST 80 MA

UNROOFING, INCISION, AND UPLIFT HISTORY OF THE SOUTHWESTERN COLORADO PLATEAU FROM APATITE (U-Th)/He THERMOCHRONOMETRY RM Flowers, BP Wernecke, and KA Farley Geological Society of America

Bulletin 120 571 (2008)

• Thermochronometry

– Based on decay of uranium and thorium to helium

– Retention of helium depends on the thermal history of the mineral (apatite) which traps it

– Helium ages record time since cooling

• Results and interpretation

Wayne Ranney Arizona Geology Magazine Fall/Winter 2012

Wayne Ranney Arizona Geology magazine Fall/Winter 2012

WHAT THEY CONCLUDED

Wayne Ranney Arizona Geology Magazine Fall/Winter 2012

LOCATION OF CROSSSECTION FLOWERS ET AL 2008

Reconstructed cross sections through the study area at (A) 80 Ma, (B) 50–35 Ma, (C) 28 Ma,

(D) 16 Ma, and (E) present day.

Based on Apatite (U-Th)He Thermochronometry

Flowers R et al. Geological Society of America Bulletin 120

571 2008

©2008 by Geological Society of America

Reconstructed sedimentary thicknesses at the selected times depicted in the cross sections

in Figure 9, relative to the horizontal Kaibab limestone datum.

Flowers R et al. Geological Society of America Bulletin

2008;120:571-587

©2008 by Geological Society of America

ARGUMENT FOR AN ANCIENT CANYON-A SYNTHESIS

The California River and its role in Carving Grand Canyon B. Werneke Geological Society Of America Bulletin 123 1288 2011

TECTONIC BACKGROUND

• 180-140 Ma Nevadan Orogeny—Sierran Arc forms

• 140- 40 Ma Sevier and Laramide (80-40 Ma) Orogenies

________________________________________

• 50-30 Ma Foundering of the Nevadaplano—beginning of the Basin and Range

• 16-6 Ma Foundering of the Mogollon Highlands, disruption of drainage

• 5-6 Ma Opening of Gulf of California, activation of the southern San Andreas Fault

CRETACEOUS AMERICAN SOUTHWEST 80 MA

EVOLUTION OF THE GRAND CANYON-1 BRIAN WERNICKE 2011

TECTONIC BACKGROUND

• 180-140 Ma Nevadan Orogeny—Sierran Arc forms

• 140- 40 Ma Sevier and Laramide (80-40 Ma) Orogenies

• 50-30 Ma Foundering of the Nevadaplano—beginning of the Basin and Range

_________________________________________

• 16-6 Ma Foundering of the Mogollon Highlands, disruption of drainage

• 5-6 Ma Opening of Gulf of California, activation of the southern San Andreas Fault

EOCENE AMERICAN SOUTHWEST 55MA

SEDIMENTS FROM THE “ARIZONA” RIVER J.L. Howard Geology 24 783-786 1996

BOLIVIAN ALTIPLANO

TECTONIC BACKGROUND

• 180-140 Ma Nevadan Orogeny—Sierran Arc forms

• 140- 40 Ma Sevier and Laramide (80-40 Ma)

orogenies

• 50-30 Ma Foundering of the Nevadaplano—beginning of the Basin and Range

• 16-6 Ma Foundering of the Mogollon Highlands, disruption of drainage

___________________________________________

• 5-6 Ma Opening of Gulf of California, activation of the southern San Andreas Fault

EVOLUTION OF THE GRAND CANYON-2 BRIAN WERNICKE 2011

TECTONIC BACKGROUND

• 180-140 Ma Nevadan Orogeny—Sierran Arc forms

• 140- 40 Ma Sevier and Laramide (80-40 Ma)

orogenies

• 50-30 Ma Foundering of the Nevadaplano—beginning of the Basin and Range

• 16-6 Ma Foundering of the Mogollon Highlands, disruption of drainage

• 5-6 Ma Opening of Gulf of California, activation of the southern San Andreas Fault

__________________________________________

EVOLUTION OF THE GRAND CANYON-3 BRIAN WERNICKE 2011

UPLIFT OF THE COLORADO PLATEAU MODEL 1:YOUNG GRAND CANYON

MODEL 2: ANCIENT GRAND CANYON

THE NEW EVIDENCE

• Employed 4He/3He thermochronometry to establish cooling history

• Eastern Grand Canyon

– Verified cooling/incision history

– Two step incision: pre 60 Ma & post 20 Ma

• Western Grand Canyon

– Reached 70-80% of its present depth by 70 Ma

– Data inconsistent with post 6 Ma incision

LOCATIONS OF SAMPLES

THE NEW EVIDENCE EASTERN GRAND CANYON WESTERN GRAND CANYON

THE LAST WORD (?)

“This history supports a model …[that]…has profound implications for the evolution of

topography, landscape, hydrology, and tectonism in the North American Cordillera”

R. M. Flowers and K. A. Farley Apatite 4He/3He and (U-Th)/He Evidence

for an Ancient Grand Canyon Science, 338 1616 2012

BUT THE BATTLE ISN’T OVER • Karl Karlstrom

– “The new data are interesting but they don’t change the big picture.”

– “It is simply ludicrous”

• Richard Young

– “Their calculation is really measuring the fact that the surface is being eroded backward”

– “Why do you have to say it’s the Grand Canyon?”

• Joel Pederson: “It is 6 million years old”

• Brian Wernicke: “Science is a succession of funerals for ideas that have been proven wrong.”

Mantle-driven dynamic uplift of the Rocky Mountains and Colorado Plateau and its surface

response: Toward a unified hypothesis

• Karl E Karlstrom

• Twenty three co-authors

• CREST Working Group

Lithosphere 4 3-22 2012