Geology 102 - Outline for Lecture 11
THE PALEOZOIC IN AMERICA
Paleozoic Paleogeography of the World (revisited)
Reading p. 305 – 312; 332-339; 362 - 371:
APPALACHIANS
EARLY PALEOZOIC - Cambrian, Ordovician
p. 305 - 307 then 310, 311
rifting with the opening of the Iapetus Ocean
rock types -
The formation of Pangea begins with Subduction (three orogenies)
By end of ORDOVICIAN - the Taconic orogeny (#1)
Accretion of volcanic island arc and other pieces of continental crust
(p. 207)
EVIDENCE
carbonate platform
sea deepened
Flysch and molasse and melange
FLYSCH - shales and turbidites that accumulated in deep water
within a foreland basin associated with an active plate margin.
MOLASSE - non marine and shallow marine sediments
(alluvial fans, rivers, barrier island, lagoon)
accumulated after sediments from the mountains have changed the environment
from deep marine (flysch) to shallow. i.e. the basin is filled in
MELANGE - a chaotic, deformed, mixture of rocks associated with sibduction and a deep-sea trench
EXOTIC TERRANE - a block of lithosphere that has been sutured to a larger continent
EXOTIC TERRANE - the Piedmont of VA
CLASTIC WEDGE - a wedge shaped body of Molasse
e.g., The QUEENSTON CLASTIC WEDGE
West of the Taconic highlands
MIDDLE PALEOZOIC - Silurian Devonian
p. 332, 333, 336, 337, 338
SILURIAN - end of Taconic
then carbonates returned - passive margin
associated Caledonian orogeny in Europe
DEVONIAN - Acadian orogeny (#2)
Laurentia - Baltica
orogenesis
cont - cont
and - Laurentia - Avalonia
ALL creates EURAMERICA
NY - Catskill clastic wedge
LATE PALEOZOIC - Carboniferous (Miss, Penn), Permian
p. 362 - 364.
MISSISSIPPIAN
quiet period
PENNSYLVANIAN - PERMIAN
Alleghenian orogeny(#3)
Collision of Euramerica with Gondwana
cont - cont collision.
Pangea is formed
CONTINENTAL INTERIOR & GRAND CANYON
EARLY PALEOZOIC - Cambrian, Ordovician
310, 311
transgression began - flooding of the continent - early Cambrian
Laurentia - core above water - surrounded by clastic sedimnets,
then carbonate platform then deep water deposits
Grand Canyon
in Precambrian
then transgression in Cambrian - rock sequences -
Center of the Continent
sandstone - shale - limestone
ORDOVICIAN
Sea began to regress.
what was our climate?
what would the weathering have been like?
then - a new transgression - first sandstone - ultrapure!
now forming a major unconformity.
Center of the Continent
St. Peters sandstone - Missouri, Wisconsin
MIDDLE PALEOZOIC - Silurian Devonian
p. 338
SILURIAN
still covered by seas
Silurian - we had abundant reef and evaporite deposits
End of the Silurian -regression -
get many evaporites - halite and gypsum
Grand Canyon - oops - no sequences -- why?
DEVONIAN
Little accumulation in center of continent - above water
West-center dominated by Limestones again
Evaporites in mid continent
Widespread black shales
what is happening world wide??
Grand Canyon
typical Muav - Temple Butte - Redwall
L'st on L'st ??
LATE PALEOZOIC - Carboniferous (Miss, Penn), Permian
p. 364 - 370
MISSISSIPPIAN
Limestone
Coal
PENNSYLVANIAN
Ouachita Mountains in Oklahoma and Texas
c-c collision associated with formation of Pangea
microplates involved
Four corners area
Basins and uplifts
Ancestral Rockies
Mid continent Final transgression and regression sequence in the Paleozoic
cyclotherms
PERMIAN
Seas retreated much more slowly than the other cycles
restricted areas, evaporite deposits, continental red beds.
Pangea is formed
Delaware Basin
Carbonate Banks and Reefs
shallow marine - then deep marine
finally evaporites - death of the reef
Grand Canyon
SUPAI group is considered deltaic
Coconino sandstone is Aeolian so....same as in Zion
end of the sequence Toroweap Formation; Kaibab
red beds, limestone and gypsum - a transgression
Western North America in Paleozoic
EARLY PALEOZOIC - Cambrian, Ordovician
p. 312
Passive Margin
5 orogenies total - 2 in Paleozoic
An island arc was created off the West Coast - subduction - o-o
MIDDLE PALEOZOIC - Silurian Devonian
p. 339
ANTLER OROGENY (#1) - Devonian –Pennsylvanian
Formed Klamath Mountains
LATE PALEOZOIC - Carboniferous (Miss, Penn), Permian
p. 370 - 371
A second island arc was created off the West Coast - subduction - o-o
SONOMA OROGENY (#2) - Permian and into Triassic
Formed Mountains in Nevada