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I. Paleogeography

• North America remained astride the equator during this interval.
• Much of the U.S. would have been under the influence of paleo-tropical trade winds.

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II. Paleoclimate

• Much of North America, particularly the U.S., still had a tropical climate.
• Coal beds, reefs, evaporites, and dune-deposits all attest to a mixture of warm-moist tropical conditions with local areas of aridity.
• Orogenic activity of the Carboniferous and Permian, increased continental aridity (as we will discuss later).
• The south pole was over Gondwana and glaciation influenced global sealevel changes (see Cyclic sedimentation notes).

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III. Sea Level

• The Kaskaskia transgression which began during the Early Devonian continued until the Late Mississippian as the Kaskaskia Sea began to withdraw from the craton.
• During the Late Mississippian-Early Pennsylvanian marine sedimentation became restricted to deeper regions (e.g. basins) of the craton.
• After a period of eperic sea withdrawal, a fourth major flooding episode of the craton began in the Early Pennsylvanian.
• The rise of sea level continued unabated throughout the Pennsylvanian, resulting in deposition of the Absaroka cratonic sequence.

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IV. Surficial Distribution of the Carboniferous in the U.S.

• For much of the preceding Paleozoic, the North America craton was relatively low standing and frequently flooded by epeiric seas.
• Carbonate deposition was formerly widespread, although Ordovician and Devonian eastern orogenies interrupted marine deposition by spreading clastic sediments westward.
• During the Carboniferous and Permian (362-250 m.y.a.), cratonic sedimentation was influenced by orogenies which raised much of the continent above sea level.
• For the last time, widespread carbonates were deposited on the craton (Mississippian).
• As the late Carboniferous unfolded, more non-marine conditions were established and persisted through the remainder of the Paleozoic.

MISSISSIPPIAN

I. North America

A. Limestone Deposition in Kaskaskia Sea

• Quickly replaced shales of latest Devonian. Over much of craton main mass of Miss. is limestone. The last great limestone producing cycle.
1. e.g. Redwall Lmst.- Grand Canyon
2. Salem and Burlington Lmsts.- good building stones
3. Indiana oolite- decorative stone
4. Mission Canyon, Montana- reservoir rock
• barrier reefs absent, evaporites more limited
• platform sea less restricted and well mixed

B. Deltas In the Chester Stage of late period.

• the Kaskaskia Sea was retreating from the mid-continent which largely remained dry thereafter.
• Major rivers drained the Canadian Shield and Acadian highlands, flowing south and southwest.
• Progradation of rivers occurred onto the former shelf (Indiana and Illinois)
• One of these, the Michigan River, is ancestral to the Mississippi River.
• Coal swamps associated with these deltas.

C. Cratonic Margin Tectonics and Sedimentation Ouachita Trend.

• site of deep water sedimentation: flysch and accretionary wedge formation offshore, soon after to be deformed. Antler Orogeny
• coupled imbricated sequence of Cambrian to Upper Devonian continental-margin, slope, and rise sedimentary rocks thrust eastward onto lower Paleozoic shallow-water shelf.
• thrust eastward over a period of 8-10 m.y. in Early Mississippian between S. Idaho and Nevada. -recent evidence suggests Antler deformation did not involve a volcanic collision (as text suggests) but is associated with extension of Klamath
• Sierran Arc which experienced major volcanism between the Late Dev.-Early Mississippian.

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PENNSYLVANIAN

A. The Absaroka Sequence

• Limestones less prevalent,
• greater influence from numerous clastic sources.
• Trans-continental arc no longer evident.
• Numerous clastic sources include: Ouachitas, numerous uplifted blocks trending northwest-southeast (Front Range, Uncompahgre, Defiance, central Kansas)

B. Tectonics

• Basin and Range Formation (Utah, Colorado, Texas, Arizona, New Mexico).
• In Colorado and New Mexico the Uncompahgre, Front Range & Pedernal Uplifts (Front Range sometimes called Ancestral Rocky Mts.). Formed by uplift along steeply-inclined faults.
• Ouachita Orogeny. - mobile belt extending from Mississippi to West Texas and further into Mexico.
• Exposed on in Ouachitas of Arkansas and Oklahoma and in Marathon Uplift of west Texas, elsewhere buried by coastal plain sediments.
• Cause: collision of South America portion of Gondwanaland with southern N. America.
• thrusted Paleozoic rocks that were deformed and metamorphosed during the Middle to Late Pennsylvanian
• Zone of deformation narrower than on eastern margin (only one phase of deformation rather than several), and no suspect terranes.

• Allegheny Orogeny of Southern Appalachians
• cause: collision of western bulge of North Africa with North America.

involves great thrusting of rocks as old as Late PreCambrian and part of the old craton great distances westward (50 to hundreds of kms.) e.g. Great Smoky fault.