Transcript Cenozoic Earth History

Cenozoic Earth History
The Cenozoic Era
• Spans the time from 66
Ma until now
• Is sub-divided into the
periods and epochs
• Experienced 1 marine
transgression, the Tejas
• Another transgression
began ~ 16,000 years
ago
Geologic Provinces of North America
Rift Basins
and Magnetic
Highs along
the East
Coast of
North
America
What do the
two ridges of
magnetic highs
represent?
The eastern margin of North America is
presently a passive continental margin
But ultimately oceanic crust will break along the continental
margin and subduction of Atlantic basin crust will begin
What geologic events would suggest subduction has begun?
Geologic Provinces of the Southern Appalachians
Fall Zone
The Atlantic Coastal Plain
• Comprises a thick sequence of
sediments deposited on top of the
Appalachian crystalline rocks by the
Zuni (Cretaceous) and Tejas
(Eocene) transgressions
• The Cretaceous and Eocene strata
crop out the farthest inland
• The ACP strata are progressively
younger and thicker toward the
coast
Evolution of the Atlantic Coastal Plain Following
Maximum Advance of the Tejas Transgression
• The Tejas Transgression began in the Paleocene, peaked
in the Eocene, having advanced as far inland as where
Augusta, Columbia, Raleigh, Richmond, and Philadelphia
are now located
• As sea level receded following maximum transgression:
– Erosion began sculpting a stair-step series of
• scarps (paleo-shorelines) and
• terraces (wave-scoured sea floor)
– Acidic groundwater began forming numerous caves and
sinkholes in the Santee limestone
– Thousands of Carolina Bays were formed on the
Middle and Lower coastal plains
The ACP
Sandhills
The Atlantic
Coastal Plain
Scarps and
Terraces
Peachtree Rock
A remnant of tidal inlet sands deposited near Columbia
during maximum advance of the Tejas Transgression
Santee
Limestone
was deposited
in deeper
water on the
continental
shelf as sands
that formed
Peachtree
Rock were
deposited at
the coast
The core (a)
Was drilled
at Pregnall
Sinkholes (irregularly-shaped depressions) formed in
Santee Limestone near Eutaw Springs, SC
Sinkhole and Cave at Santee State Park, SC
A cave forms as acidic water slowly dissolves limestone
A sinkhole forms when the roof of the cave collapses
Atlantic Coastal Plain
Arches and
Embayments
Fall Zone
The eastern margin of
North America has been
folded into a series of
NW-SE-trending arches
and embayments by
tectonism associated
with formation of the
Caribbean plate and
persistent northward
movement of Cuba
Carolina Bays near Orangeburg, SC
Carolina Bays are NW-trending oval depressions surrounded
by a sand rim. They are found only on the Middle and Lower
Coastal Atlantic Plain
The Western Margin of North America
Continued subduction of the Farallon Plate yielded the:
• Juan de Fuca and Cocos plates (its Cenozoic remnants)
• San Andreas fault system
• Numerous Cordilleran accreted terranes
Accreted
Cordilleran
Volcanic
Island Arc
Terranes
An eastward-advancing wave of hot mantle caused...
Extension that
formed the
Basin and Range
Wind River Range,
a Laramide uplift
Cretaceous-Tertiary
Laramide uplift
of Archean crust
that formed the
Rocky Mountains
Uplift of the
Colorado Plateau
E-dipping Permian (left), Triassic (red) and Jurassic (tan)
sandstone beds (right) on the E Flank of the Wind River
Range (a Laramide Archean basement uplift). View toward
the NW from Red Canyon Overlook near Lander, Wyoming
Oregon Trail
Cascade
Range
Centers of
Cenozoic
Cordilleran
Volcanism
Columbia plateau
flood basalts
Yellowstone
hot spot
Snake River
Plain
Arizona
volcanic
field
San Juan
volcanic
field
Columbia Plateau, Snake River Plain, and Yellowstone:
Products of the Yellowstone Mantle Plume Hot Spot
Columbia River Plateau
Northwestward movement of N. A. over the hot spot in the
Mid Tertiary caused eruption of the Columbia Plateau flood
basalts. Then N. A. began moving toward the SW, forming
the hook-like shape of the Snake River Plain flood basalts
Yellowstone
Calderas
Island Park Caldera
Erupted the Huckleberry
Ridge tuff 2 Ma
Henry’s Fork Caldera
Erupted the Mesa Falls
tuff 1.3 Ma
Yellowstone Caldera
Erupted the Lava Creek
tuff 0.6 Ma
Comparison of Volumes of Pyroclastic Eruptions
Cenozoic
Volcanism
in the
Cascade
Range
Subduction of the Juan de Fuca plate along the Cascadia
subduction zone is responsible for the Late Tertiary to
recent volcanism of the Cascade Range volcanoes
San Francisco Mountains, Arizona
Late Cenozoic volcanism formed the San Francisco Mountains
Volcanism ceased ~ 1200 years ago
They are remnants of a stratovolcano that blew its top
Earth’s Major Orogenic Belts
The Circum-Pacific and Alpine-Himalayan orogenic belts,
Earth’s present-day major mountain building belts
The Alpine-Himalayan Orogenic Belt
• Volcanism, seismicity, and deformation in the AlpineHimalayan orogenic belt extends eastward from Spain
through the Mediterranean region into Southeast Asia
• The tectonism, due to collision of the Arabian, African
and Indo-Australian plates with the Eurasian plate,
caused closure of
the Tethys sea
Eocene (50–40 Ma
Miocene (25–15 Ma
The Alpine Orogeny
• Is occurring in response to northward movement of the
African and Arabian plates toward southern Europe
• The convergence is causing deformation along a linear zone
from Spain eastward through Greece and Turkey and along
Africa's northwest coast
Products of the Alpine Orogeny
• Alps (France, Germany, Switzerland)
• Pyrenees (Spain and France)
• Apennines (Italy)
The Alps in
Southern Germany
Italy and Greece
• Subduction of Mediterranean crust under Italy, Greece,
and Turkey continues to cause volcanism and seismicity
• In 1999 an earthquake killed 17,000 people in Turkey
Mount Vesuvius, Italy, has erupted
80 times since it destroyed Pompeii
in A.D. 79
Mount Etna, Sicily, is
Earth’s most active volcano
The Mediterranean Basin
Most of the water flows into the Mediterranean Sea from
the Atlantic Ocean through the Strait of Gibraltar
Northward advance of the African plate ~ 6 Ma closed
the Strait of Gibraltar, caused the Sea to dry up
When the dam broke, a colossal flood from the Atlantic
ocean rushed into the basin and re-filled the sea
The Circum-Pacific Orogenic Belt
• Subduction of the Cocos plate under western Central
America is causing mountain-building and volcanism
• Subduction of the Nazca plate under western South
America is causing mountain-building and volcanism
• Subduction of the Pacific plate under western Asia is
causing mountain-building and volcanism in Japan and
the Philippians
Global Cooling and Warming Since the Archean
Paleogeography
during the
Permian Ice Age
Global Cooling and Warming Since the Cretaceous
The Pleistocene
“Ice Age”
Changes in
Sea Surface
Temperatures
Since the
Eocene High
Pleistocene Ice Ages and Interglacial Intervals
• The Pleistocene began 1.6 Ma, ended 10,000 years ago
• Four major periods of widespread glaciation occurred, were
separated by warmer interglacial periods
Two Notable Pleistocene Terminal Moraines
End moraines
Cape Cod
Long Island
Glacial and Pluvial
Lakes
Wave-cut shore lines cut
by Glacial Lake Missoula
Channeled Scablands formed
by the Missoula flood
Glacial Lake
Missoula
Great Salt
Lake
Pluvial Lake
Bonneville
Pleistocene Glaciation of the Northern Hemisphere
Maximum Extent of glaciation
in the Northern Hemisphere
Climate Belts
Sea Level Change during the Past 20,000 Years
Global warming has been
occurring for 17,000 years
Positions of the coastline of North America
during the Ice Age and if the ice sheets melt
What is thought to...
...have caused the Pleistocene Ice Age?
• Formation of Central America deflected the Gulf Stream
and moist air northward, produce more snow
• Northward movement of North America and Eurasia
provided more surface for snow accumulation
...also cause/contribute to occurrence of ice ages?
• Milankovitch cycles, natural periodic changes in
• Earth’s orbital eccentricity
• Tilt of Earth’s axis
• Precession of Earth’s axis, of the equinoxes
– Cause periodic changes in the amount of sunlight at
high latitudes
– Lead to natural periods of global cooling and warming
• Excessive volcanism, etc.
Milankovitch Cycles
A change in Earth’s orbital eccentricity
occurs every 100,000 years
A 2° change in tilt of Earth’s
axis occurs every 41,000 years
A precession of Earth’s
axis occurs every
23,000 years