Earth History GEOL 2110
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Transcript of Earth History GEOL 2110
Earth History GEOL 2110
The Paleozoic EraGeological History of Gondwanaland and
Late Paleozoic Life
Major Concepts
• The continental reconstructions of Gondwana by Werner and DuToit were bang on and confirmed by geologic mapping, paleomagnetism, biostratigraphy, and paleogeography.
• The supercontinent of Gondwana, composed of South America, Africa, Australia, India, and Antarctica, was together for most of the Paleozoic and situated in the high latitudes of the southern hemisphere.
• Floral and faunal assemblages of Gondwana were very distinct from the northern landmasses (Laurasia)
• The Permo-Triassic extinction devastated marine life and to a lesser extent, land-based plants and animals. The cause of this greatest of all extinctions is still unclear.
Events of the Late Paleozoic Era
Making PangeaConvergence of Laurasia and Gondwanaland
Wegner’s Pangea (1927)
Gondwana Reconstruction by DuToit (1927Correlating the Permo-Triassic Gondwana Orogen
Paleomagnetism Confirms Gondwana Continent Reconstructions
From Bullard, 1965
Apparent Polar Wander Paths for SA and Africa
Best-fit of curves imply that SA, Africa & Australia (& Antarctica) have been together near the South Pole since late Cambrian
Current Reconstruction
Late Paleozoic Gondwana Stratigraphy
Dominated by non-marine sediments and tillitesMade it difficult to correlate with European strata based on marine fossilsCapped by Jurassic-Cretaceous basalts – Break-up
Late Paleozoic Glaciation of GondwanaCarboniferousDwyka Tillite
Glacial Striations
Permian Dropstone
Jurassic Basalts Cap Gondwanan SequenceMarking the Break-up
Karoo basalts, South Africa
Ferrar Dolerite Sills, Antarctica
Glossopteris Flora unique to the Gondwanan Continents
Seed fern that liked cool swampy areas compared to the tropical
Lycopsids
The Permo-Triassic Reptiles of GondwanaMesosaur
A freshwater fish-eating reptile
Paleogeography and Paleoclimate of Pangea
Permian ~250 Ma
Paleogeography and Paleoclimate of Pangea
Paleogeography and Paleoclimate of Pangea
Liehl and Shields, 2005, Geology
Strong Latitudinal Zoning of Climate
Tethys Sea
Paleophytic Mesophytic Plant Transition in Mid-Permian
driven by more arid climates
Seedless Vascular Spore-bearing Plants (Silurian-mid Permian)
Seed-bearing Gymnosperm Plants (mid-Permian – mid-Cretaceous)
Late Paleozoic Land AnimalsArthopods, Amphibians and Anthracosaurs, Oh My!
AnthracosaursAmphibian -Reptile Missing Link
Amniotes Arrive in Mid-CarboniferousThe Evolution of Eggs with Amniotic Membrane leads to Reptiles, Birds and
Mammals
Hyolnomus
Dimitrodon
The Great Permo-Triassic Extinction90-95% of all marine species die out, and land life too
Proposed Causes - Global cooling due to Gondwana glaciation- Reduced marine habitat due to the creation of Pangea - Extreme climatic changes- Oxygen depletion due to exposure of coal deposits- Upwelling of CO2 from deep ocean waters – hypercapnia- Intense outpouring of basalt in SerbiaNO EVIDENCE OF A METEOR IMPACT AT LEAST!
Summary of Late Paleozoic Biologic and Geologic Events
Friday
Second Mid-term
Kate will proxy