ch. 17 — reviewfaculty.chas.uni.edu/~groves/ehch17lecturept2.pdf · – diversification of...
TRANSCRIPT
![Page 1: Ch. 17 — Reviewfaculty.chas.uni.edu/~groves/EHCh17lecturept2.pdf · – Diversification of diatoms, planktonic forams, calcareous nannoplankton – Diversification of mobile predators](https://reader033.vdocuments.net/reader033/viewer/2022060423/5f19f6a632786214470480df/html5/thumbnails/1.jpg)
Earth History, Ch. 17 1
Ch. 17 — Review
• Life in the Cretaceous
– Diversification of diatoms, planktonic forams, calcareous nannoplankton
– Diversification of mobile predators (especially mollusks and teleost fishes)
– Origin of the angiosperms and co-evolution with insects
– Dinosaur glory days!! Complex dinosaur communities that mimic modern mammal communities
– Mammals still small and inconspicuous (in the dark?)
![Page 2: Ch. 17 — Reviewfaculty.chas.uni.edu/~groves/EHCh17lecturept2.pdf · – Diversification of diatoms, planktonic forams, calcareous nannoplankton – Diversification of mobile predators](https://reader033.vdocuments.net/reader033/viewer/2022060423/5f19f6a632786214470480df/html5/thumbnails/2.jpg)
Earth History, Ch. 17 2
Today’s outline
• Cretaceous paleogeography
• End-Cretaceous mass extinction
• Cretaceous geology of North America
![Page 3: Ch. 17 — Reviewfaculty.chas.uni.edu/~groves/EHCh17lecturept2.pdf · – Diversification of diatoms, planktonic forams, calcareous nannoplankton – Diversification of mobile predators](https://reader033.vdocuments.net/reader033/viewer/2022060423/5f19f6a632786214470480df/html5/thumbnails/3.jpg)
Earth History, Ch. 17 3
Cretaceous paleogeography
• Remember: Pangaea began to break up
during early Mesozoic
– Triassic rifting between N. Africa and S.
Europe
– Jurassic rifting between N. America and S.
America; between N. America and Africa
– But, Gondwanaland remained intact
![Page 4: Ch. 17 — Reviewfaculty.chas.uni.edu/~groves/EHCh17lecturept2.pdf · – Diversification of diatoms, planktonic forams, calcareous nannoplankton – Diversification of mobile predators](https://reader033.vdocuments.net/reader033/viewer/2022060423/5f19f6a632786214470480df/html5/thumbnails/4.jpg)
Earth History, Ch. 17 4
Cretaceous paleogeography
• By late Cretaceous time:
– South America, Africa and India had become
discrete entities
– Only Australia and Antarctica remained
attached to one another
– Greenland split from North America
![Page 5: Ch. 17 — Reviewfaculty.chas.uni.edu/~groves/EHCh17lecturept2.pdf · – Diversification of diatoms, planktonic forams, calcareous nannoplankton – Diversification of mobile predators](https://reader033.vdocuments.net/reader033/viewer/2022060423/5f19f6a632786214470480df/html5/thumbnails/5.jpg)
Earth History, Ch. 17 5
![Page 6: Ch. 17 — Reviewfaculty.chas.uni.edu/~groves/EHCh17lecturept2.pdf · – Diversification of diatoms, planktonic forams, calcareous nannoplankton – Diversification of mobile predators](https://reader033.vdocuments.net/reader033/viewer/2022060423/5f19f6a632786214470480df/html5/thumbnails/6.jpg)
Earth History, Ch. 17 6
Cretaceous paleogeography
• Large Tethys ocean was tropical and
probably accounted for warm climate and
gentle latitudinal climatic gradients
– Dinosaurs and warm-adapted plants lived
within 15º of the south pole
• High rates of seafloor spreading caused
mid-ocean ridges to rise � highest sea
level in Phanerozoic history
![Page 7: Ch. 17 — Reviewfaculty.chas.uni.edu/~groves/EHCh17lecturept2.pdf · – Diversification of diatoms, planktonic forams, calcareous nannoplankton – Diversification of mobile predators](https://reader033.vdocuments.net/reader033/viewer/2022060423/5f19f6a632786214470480df/html5/thumbnails/7.jpg)
Earth History, Ch. 17 7
![Page 8: Ch. 17 — Reviewfaculty.chas.uni.edu/~groves/EHCh17lecturept2.pdf · – Diversification of diatoms, planktonic forams, calcareous nannoplankton – Diversification of mobile predators](https://reader033.vdocuments.net/reader033/viewer/2022060423/5f19f6a632786214470480df/html5/thumbnails/8.jpg)
Earth History, Ch. 17 8
End-Cretaceous mass extinction
• Dinosaurs, mosasaurs, plesiosaurs,
rudists and ammonoids were totally
eliminated
• Angiosperms and gymnosperms suffered
big hits
• 90% of the species of calcareous
nannoplankton and planktonic
foraminifers were wiped out
![Page 9: Ch. 17 — Reviewfaculty.chas.uni.edu/~groves/EHCh17lecturept2.pdf · – Diversification of diatoms, planktonic forams, calcareous nannoplankton – Diversification of mobile predators](https://reader033.vdocuments.net/reader033/viewer/2022060423/5f19f6a632786214470480df/html5/thumbnails/9.jpg)
Earth History, Ch. 17 9
Familial
diversity
record
![Page 10: Ch. 17 — Reviewfaculty.chas.uni.edu/~groves/EHCh17lecturept2.pdf · – Diversification of diatoms, planktonic forams, calcareous nannoplankton – Diversification of mobile predators](https://reader033.vdocuments.net/reader033/viewer/2022060423/5f19f6a632786214470480df/html5/thumbnails/10.jpg)
Earth History, Ch. 17 10
End-Cretaceous mass extinction
• Possible causes include asteroid impact, volcanism, climate change, or combination of all
• Mineral evidence for asteroid impact:
– Iridium anomaly at top of Cretaceous in both marine and terrestrial rocks
• Iridium is rare on Earth, but abundant in meteorites
– Shocked quartz grains
• Welded fractures due to enormous pressure
– Microspherules
• Liquefied droplets of molten rock that cool rapidly
– Microscopic diamonds
• Again, high pressure minerals
![Page 11: Ch. 17 — Reviewfaculty.chas.uni.edu/~groves/EHCh17lecturept2.pdf · – Diversification of diatoms, planktonic forams, calcareous nannoplankton – Diversification of mobile predators](https://reader033.vdocuments.net/reader033/viewer/2022060423/5f19f6a632786214470480df/html5/thumbnails/11.jpg)
Earth History, Ch. 17 11
![Page 12: Ch. 17 — Reviewfaculty.chas.uni.edu/~groves/EHCh17lecturept2.pdf · – Diversification of diatoms, planktonic forams, calcareous nannoplankton – Diversification of mobile predators](https://reader033.vdocuments.net/reader033/viewer/2022060423/5f19f6a632786214470480df/html5/thumbnails/12.jpg)
Earth History, Ch. 17 12
Iridium layer at Gubbio, Italy
![Page 13: Ch. 17 — Reviewfaculty.chas.uni.edu/~groves/EHCh17lecturept2.pdf · – Diversification of diatoms, planktonic forams, calcareous nannoplankton – Diversification of mobile predators](https://reader033.vdocuments.net/reader033/viewer/2022060423/5f19f6a632786214470480df/html5/thumbnails/13.jpg)
Earth History, Ch. 17 13
Mineral evidenceIridium layer near
Drumheller in
southern Alberta,
Canada
![Page 14: Ch. 17 — Reviewfaculty.chas.uni.edu/~groves/EHCh17lecturept2.pdf · – Diversification of diatoms, planktonic forams, calcareous nannoplankton – Diversification of mobile predators](https://reader033.vdocuments.net/reader033/viewer/2022060423/5f19f6a632786214470480df/html5/thumbnails/14.jpg)
Earth History, Ch. 17 14
Mineral evidence
microspherulesshocked quartz
![Page 15: Ch. 17 — Reviewfaculty.chas.uni.edu/~groves/EHCh17lecturept2.pdf · – Diversification of diatoms, planktonic forams, calcareous nannoplankton – Diversification of mobile predators](https://reader033.vdocuments.net/reader033/viewer/2022060423/5f19f6a632786214470480df/html5/thumbnails/15.jpg)
Earth History, Ch. 17 15
End-Cretaceous mass extinction
• Further evidence for asteroid impact:
– The crater itself has been discovered in the Gulf of Mexico, just offshore Yucatan Peninsula
• Chicxulub crater
– Central cavity (60 miles in diameter)
– Outer ring (120 miles in diameter)
– Magma that cooled after impact is dated at 65 ±0.4 Ma, exactly same as end-Cretaceous boundary
![Page 16: Ch. 17 — Reviewfaculty.chas.uni.edu/~groves/EHCh17lecturept2.pdf · – Diversification of diatoms, planktonic forams, calcareous nannoplankton – Diversification of mobile predators](https://reader033.vdocuments.net/reader033/viewer/2022060423/5f19f6a632786214470480df/html5/thumbnails/16.jpg)
Earth History, Ch. 17 16
Chicxulub crater
Impact
trajectory
![Page 17: Ch. 17 — Reviewfaculty.chas.uni.edu/~groves/EHCh17lecturept2.pdf · – Diversification of diatoms, planktonic forams, calcareous nannoplankton – Diversification of mobile predators](https://reader033.vdocuments.net/reader033/viewer/2022060423/5f19f6a632786214470480df/html5/thumbnails/17.jpg)
Earth History, Ch. 17 17
Chicxulub crater
• Trajectory of asteroid was at a low angle
(20-30°) and from southeast to northwest
– Fiery vapor cloud was driven across west-
central North America
• Western North American floras were hardest his
– Microspherule layers are thickest in Mexico
(~ 1m), thinner in Texas (~10cm), thinner still
in New Jersey (~5cm)
![Page 18: Ch. 17 — Reviewfaculty.chas.uni.edu/~groves/EHCh17lecturept2.pdf · – Diversification of diatoms, planktonic forams, calcareous nannoplankton – Diversification of mobile predators](https://reader033.vdocuments.net/reader033/viewer/2022060423/5f19f6a632786214470480df/html5/thumbnails/18.jpg)
Earth History, Ch. 17 18
Radar image of Chicxulub crater
![Page 19: Ch. 17 — Reviewfaculty.chas.uni.edu/~groves/EHCh17lecturept2.pdf · – Diversification of diatoms, planktonic forams, calcareous nannoplankton – Diversification of mobile predators](https://reader033.vdocuments.net/reader033/viewer/2022060423/5f19f6a632786214470480df/html5/thumbnails/19.jpg)
Earth History, Ch. 17 19
Chicxulub crater
Gravity survey
data
![Page 20: Ch. 17 — Reviewfaculty.chas.uni.edu/~groves/EHCh17lecturept2.pdf · – Diversification of diatoms, planktonic forams, calcareous nannoplankton – Diversification of mobile predators](https://reader033.vdocuments.net/reader033/viewer/2022060423/5f19f6a632786214470480df/html5/thumbnails/20.jpg)
Earth History, Ch. 17 20
Impact of the impact
• Perpetual darkness from atmospheric dust
– Months in duration? No photosynthesis?
• Short-term global refrigeration from dust and aerosol particles (like “nuclear winter”)
• Acid rain from sulfur dioxide and water in atmosphere
• Wildfires, especially in North America
• Long-term global warming from aerosols that stayed in atmosphere
![Page 21: Ch. 17 — Reviewfaculty.chas.uni.edu/~groves/EHCh17lecturept2.pdf · – Diversification of diatoms, planktonic forams, calcareous nannoplankton – Diversification of mobile predators](https://reader033.vdocuments.net/reader033/viewer/2022060423/5f19f6a632786214470480df/html5/thumbnails/21.jpg)
Earth History, Ch. 17 21
Aftermath
• Although angiosperms suffered loss of
diversity, they recovered to become the
dominant flora
• With dinosaurs out of the way, mammals
diversified spectacularly in post-extinction
Cenozoic Era
![Page 22: Ch. 17 — Reviewfaculty.chas.uni.edu/~groves/EHCh17lecturept2.pdf · – Diversification of diatoms, planktonic forams, calcareous nannoplankton – Diversification of mobile predators](https://reader033.vdocuments.net/reader033/viewer/2022060423/5f19f6a632786214470480df/html5/thumbnails/22.jpg)
Earth History, Ch. 17 22
Cretaceous geology of
North America
• East coast, now a passive continental
margin, was mostly quiet
• West coast, a convergent margin, continued
to experience mountain building
– Sevier orogeny produced folding and thrusting
as far east as Wyoming; igneous activity in
California, Nevada, Idaho, and farther north
![Page 23: Ch. 17 — Reviewfaculty.chas.uni.edu/~groves/EHCh17lecturept2.pdf · – Diversification of diatoms, planktonic forams, calcareous nannoplankton – Diversification of mobile predators](https://reader033.vdocuments.net/reader033/viewer/2022060423/5f19f6a632786214470480df/html5/thumbnails/23.jpg)
Earth History, Ch. 17 23
Sevier Orogeny
![Page 24: Ch. 17 — Reviewfaculty.chas.uni.edu/~groves/EHCh17lecturept2.pdf · – Diversification of diatoms, planktonic forams, calcareous nannoplankton – Diversification of mobile predators](https://reader033.vdocuments.net/reader033/viewer/2022060423/5f19f6a632786214470480df/html5/thumbnails/24.jpg)
Earth History, Ch. 17 24
Cretaceous geology of
North America
• Interior seaway developed when continent was
flooded: northern Arctic Ocean joined with Gulf
of Mexico
• Late Cretaceous rocks of interior seaway are
cyclic deposits produced by oscillation of
shoreline
– Nearshore sand facies
– Shallow marine shale facies
– Offshore chalk facies
![Page 25: Ch. 17 — Reviewfaculty.chas.uni.edu/~groves/EHCh17lecturept2.pdf · – Diversification of diatoms, planktonic forams, calcareous nannoplankton – Diversification of mobile predators](https://reader033.vdocuments.net/reader033/viewer/2022060423/5f19f6a632786214470480df/html5/thumbnails/25.jpg)
Earth History, Ch. 17 25
Late Cretaceous cyclic deposits