Download - Cenozoic History
• At only 66 million years long, – the Cenozoic is
only 1.4% of all geologic time
– or only 20 minutes
– on our hypothetical 24-hour clock for geologic time
Cenozoic History
• In this class we use – the term Tertiary
Period – rather than
Paleogene and Neogene Periods
Cenozoic Time Scale
Late CretaceousRifts separate Africa and South America and then India, Australia, Antarctica. North America rifts from Europe.
Old Gondwana (Africa, India, Australia) move north toward Eurasia, closing the Tethys Ocean and forming the Alpine-Himalayan mountains.
The Atlantic lengthens / widens, the Sevier orogeny continues, and the Caribbean arc forms.
Texas 65-144 Ma: continuing shallow limestone and shale deposition to the southeast (from Rockies).
http://vishnu.glg.nau.edu/rcb/globaltext.html
Paleocene / Eocene
Himalayan Orogeny. Alps and Pyrenees form.
The modern patterns of geography appear.
Atlantic continues to open. Rocky Mountains grow.
Texas 65 - 35 Ma: shale and sandstone in southeast region prograde shoreline (from the Rockies). Volcanic activity in Panhandle.http://vishnu.glg.nau.edu/rcb/globaltext.html
• By Eocene time, – the Americas had completely separated – from Europe and Africa– but India had not yet collided with Eurasia
Cenozoic Plate Tectonics
Oligocene and Miocene
Orogeny continues inthe Mediterranean region and India nears its junction with southern Asia.
Antarctica isolated.
Southwestern North America intercepts the East Pacific Rise and a great extensional event, the Basin and Range orogeny begins.
Texas 35-5 Ma: continued sandstone/shale deposition and progradation of shoreline (erosion of Rockies)
http://vishnu.glg.nau.edu/rcb/globaltext.html
• During Miocene time, – the Atlantic Ocean basin continued to
widen– and India had collided with Eurasia
• The Tethys Sea between Africa and Eurasia – was mostly closed by this time
Cenozoic Plate Tectonics
http://vishnu.glg.nau.edu/rcb/globaltext.html
Age of Ocean Basins
• A triple junction – joins the East African
Rift System – to the Gulf of Aden – and the Red Sea– Oceanic crust began
forming • in the Gulf of Aden
about 10 million years ago
– Red Sea rifting began later and oceanic crust is now forming
East African Rift
• Circum-Pacific orogenic belt and the Alpine-Himalayan orogenic belt are the sites of most recent geologic and orogenic activity
Orogenic Belts
• Remember that during Mesozoic time – the Tethys Sea separated much of Gondwana – from Eurasia
• Closure of this sea – took place during the Cenozoic – as the African and Indian plates – collided with the huge landmass to the north
Closure of the Tethys Sea
• Eocene timeCenozoic Plate Tectonics
• Miocene timeCenozoic Plate Tectonics
• During the Early Cretaceous, – India broke away from Gondwana – and began moving north, – and oceanic lithosphere was consumed – at a subduction zone – along the southern margin of Asia
The Himalayas
• Oceanic lithosphere – subducted beneath southern Tibet – as India approached Asianorthern margin of India
Before India Collided with Asia
southern margin of Tibet
• About 40 to 50 million years ago• India collided with Asia,
– but because India was to light to subduct, – it thrust under Asia
India Collided with Asia
• Thrusting of Asian rocks – onto the Indian subcontinent – accompanied continued convergence
Continued Convergence
• Since about 10 million years ago, – India has moved beneath Asia – along the main boundary fault
India Moved beneath Asia
– Shallow marine sedimentary rocks • that were deposited along India’s
northern margin • now form the higher parts of the Himalayas
The Circum-Pacific Orogenic Belt
• Prior to 200 million years ago, – the west coast of South America – was a passive continental margin – where huge quantities of sediment were
deposited
Evolution of the Andes Mountains
• Orogeny began when this area – became an active continental margin – as South America moved to the west – and collided with oceanic lithosphere
Evolution of the Andes Mountains
• Deformation, volcanism and plutonism continued
Evolution of the Andes Mountains
• The North American Cordillera – is one large segment of the circum-
Pacific orogenic belt – extending from Alaska to central Mexico
• In the United States it widens to 1200 km – stretching east-west – from the eastern flank of the Rocky
Mountains – to the Pacific Ocean
The North American Cordillera
• North American Cordillera – and the
major provinces
– of the United States and Canada
Cordillera
• Locations of Proterozoic sedimentary Basins – in the western United
States and Canada• Belt Basin• Uinta Basin• Apache Basin
Sedimentary Basins in the
West
Cordilleran Mobile Belt
Antler Orogeny in Devonian
• After Laramide deformation, Cordillera continued to evolve – large-scale block-faulting – extensive volcanism – vertical uplift and deep erosion
– Basin and Range• During about the first half of the Cenozoic
Era, a subduction zone was present – along the entire western margin of the
Cordillera, – but now most of it is a transform plate
boundary– ???
Cordillera Evolved
Plate Interactions Continue
http://earth.geol.ksu.edu/sgao/research/data/
seiswus/example1.gif
• Third in a series of deformational events – in the Cordillera beginning during the
Late Jurassic• Late Cretaceous to Eocene • Differed from the previous orogenies
in important ways
The Laramide Orogeny
– took place as the Farallon plate, – buoyed up by a mantle plume– subducted beneath North America – at a decreasing angle– and igneous activity shifted inland
Laramide orogeny
???
• By Early Tertiary time, – the westward-moving North American plate – had overridden the part of the Farallon plate, – above the head of the mantle plume
• The lithosphere – immediately above this plume – was buoyed up, – accounting for a change – from steep to shallow subduction
Change to Shallow Subduction
• With nearly horizontal subduction, – igneous activity ceased – and the continental crust – was deformed mostly by vertical uplift
Igneous Activity Ceased
• Disruption of the oceanic plate – by the mantle plume– marked the onset – of renewed igneous activity
Renewed Igneous Activity
• The vast batholiths in • Idaho • British Columbia• Sierra Nevada of California
– were emplaced during the Mesozoic Era
– intrusive activity continued into Tertiary
Cordilleran Igneous Activity
http://www.bhc.edu/academics/science/harwoodr/GEOL102/Study/Images/
BatholithsNA.gif
Tertiary Volcanism– more or less
continuous in the Cordillera
– varied in intensity, eruptive style, and location
– ceased temporarily in the area of the Laramide orogen
– an aggregate thickness of about 2500 m – well exposed in the walls of the deep gorges – cut by the Columbia and Snake rivers– Some of the individual flows were truly
phenomenal• Roza flow alone covers 40,000 km2 and has been
traced about 300 km from its source
Columbia River Basalts
~ 20 lava flows of the Columbia River basalts exposed in the canyon of the
Grand Ronde River in Washington
• Some of the highest mountains in the Cordillera are the Cascades– California, Oregon, Washington, British
Columbia • Thousands of volcanic vents are present
– dozen large volcanoes – Lassen Peak in California
• world's largest lava dome• Related to subduction of the Juan de Fuca
plate
Cascade Range
http://www.cr.nps.gov/history/online_books/resedu/resedu2a.htm
Basin and Range
• Generalized cross section of the Basin and Range Province– ranges are bounded by faults
Basin and Range Province
Colorado Plateau
– Paleozoic rocks exposed in the Grand Canyon, Arizona
Colorado Plateau
– Mesozoic sedimentary rocks in the Valley of the Gods, Utah
Colorado Plateau– Mesozoic sedimentary rocks at Colorado
National Monument, Colorado
• Before the Eocene, – the entire Pacific
Coast was a convergent plate boundary
– Farallon plate was consumed at a subduction zone
– stretched from Mexico to Alaska
Pacific Coast
• As the North American Plate – overrode the Pacific–
Farallon Ridge,– its margin became
transform faults• the San Andreas• and the Queen
Charlotte– alternating with
subduction zones
Change from Subduction
• Further overriding of the ridge – extended the San
Andreas Fault– and diminished the
size of the Farallon–Plate remnants
• Now only two small remnants – of the Farallon
plate exist– the Juan de Fuca
and Cocos plates
Extending the San Andreas Fault
• A vast area called the Interior Lowlands
– the Great Plains
– and the Central Lowlands
The Continental Interior
• Deformation in the Appalachians has a long history– began during the Late Proterozoic
Cenozoic History of the Appalachian Mountains
– during Late Triassic time, the entire region experienced faulting as Pangaea fragmented
• By the end of the Mesozoic– erosion had reduced the mountains to a
plain across which streams flowed eastward to the ocean
Reduced to Plains
• Streams developed across the plains during the Tertiary
Appalachians in the Tertiary
• Although these mountains have a long history – their present topographic expression resulted
mainly from Cenozoic uplift and erosion
Present Appalachian Topography
• The Atlantic Coastal Plain and the Gulf Coastal Plain – form a
continuous belt
– from the Northeastern United States to Texas
The Southern and Eastern Continental Margins
• Both areas have – horizontal or gently seaward-dipping strata – deposited mostly by streams flowing across
them• Seaward of the coastal plains
– lie the continental shelf, slope and rise, – also areas of notable Mesozoic and Cenozoic
deposition
Coastal Plain Similarities
http://www.missgeo.com/directors%20-%20mail.htm
• The overall Gulf Coast sedimentation pattern – was established during the Jurassic – and persists today
• Sediments derived from• Cordillera • western Appalachians • Interior Lowlands
– were transported toward the Gulf of Mexico– where they were deposited in terrestrial,
transitional, and marine environments
Gulf Coast Sedimentation Pattern
• Cenozoic Deposition on the Gulf Coastal Plain
Gulf-Coastal-Plain Deposition
– Depositional provinces and surface geology
Cross section of Eocene Claiborne Group
Showing facies changes and seaward thickening
• Many sedimentary rocks in the Gulf Coastal Plain – are either source rocks – or reservoirs for hydrocarbons
Reservoirs for Hydrocarbons
http://www.spe.org/specma/binary/images/1257473world_oil_production.gif