Chapter 11 Late Paleozoic

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Chapter 11 - Late Paleozoic

• Mountain building events that began with the
  Taconic Orogeny continued throughout remainder of
  Paleozoic. Events are preserved in the rock
  record as part of the building of Pangaea.
• Silurian (438 to 408 m.y.) - Laurentia and
  Baltica collided along a convergent plate
  boundary to form the larger continent of
  Laurasia. This collision closed the northern
  Iapetus Ocean the Caledonian orogeny.

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Silurian Period peak of Tippecanoe
inundation, prior to initiation of Caledonia
uplift. Majority of craton covered by
epeiric sea with carbonate bottom conditions.
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Devonian Period The presence of widespread reefs
and evaporite deposits indicate the climate was
uniformly warm and mild
world-wide, and generally dry.
Laurentia/Baltica collision uplift of
Caledonian Highlands Acadian Orogeny
http//www.palaeos.com/Paleozoic/Devonian/Devonian
.htm
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• Devonian Period (408 to 360 m.y.)
• Mountain building continued along the eastern
  margin of Laurentia with the Acadian orogeny
  (Laurentia Baltica collision Laurasia).
• Acadian Orogeny rejuvenation of highlands, more
  active in present NE portion of continent,
  renewed deposition of clastic wedge to NW
  Catskill Delta, similar to Queenston Delta.
• Antler Orogeny marked change in Cordilleran
  (west continent) from a passive to an active
  margin.
• Kaskaskia Sequence deposition began with gradual
  inundation during the early Devonian Period.

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• Kaskaskia Sequence basal sediments include
  clean quartz sands containing heavy mineral
  deposits.
• Clastics derived from Acadian Highlands from two
  source areas 1) Older sedimentary units of east
  and north (tourmaline, zircon rutile) 2)
  Igneous and metamorphic origin from highlands
  (unstable pyroxene, amphibole, biotite garnet)
• Continuing transgression resulted in lime-muds
  and reef complexes. Locally restricted sites
  accumulated salt gypsum.
• Late Devonian Black Shales near "eastern" craton
  (across transcontinental arch) are black shales
  (O2 - deficient waters Chattanooga shale 10 m
  thick).
• Result of orogenic activity (Acadian Orogeny),
  shales contain uranium radiometrically dated at
  350 MY BP.
• Source http//www.colby.edu/personal/r/ragastal/G
  E142/142LatePaleo.htm

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• The extent of the upper Devonian and Lower
  Mississippian Chattanooga Shale and its
  equivalent units such as the Antrion Shale, the
  Albany Shale, the Percha Shale (Franklin Mts.)

Black shales petroleum source rocks elevated
uranium
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Mississippian Period Paleogeography was
controlled by sea-level changes and long-wave
tectonic irregular deformation of topography.
The climate was generally
warm. Williston Basin - restricted circulation
salt gypsum.
http//www.palaeos.com/Paleozoic/Carboniferous/Car
boniferous.htm
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• Mississippian Period -
• Erosion of Acadian Highlands NW growth of
  Catskill Delta with deposition of non-marine
  shales and sandstones (e.g., Pocono Group).
• Reduction in suspended mud results in extensive
  limestone platforms during Mississippian, west of
  the highlands. Platform carbonates present in
  Georgia Valley Ridge, e.g., Bangor Ls., St.
  Genevieve Ls., similar to Bahama Banks
• Western Craton - Limestone, shale, and reef
  deposition, e.g., Miss. Redwall Limestone Grand
  Canyon Lake Valley Limestone New Mexico.
  Antler Highlands yielded clastics.
• Late Mississippian regression associated with
  initiation of Gondwana glaciation.
• Source http//www.colby.edu/personal/r/ragastal/G
  E142/142LatePaleo.htm

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• Late Mississippian regression of the Kaskaskia
  Sea from the craton, carbonate deposition was
  replaced by vast quantities of detrital
  sediments. The resulting sandstones, e.g.,
  Illinois Basin, are excellent petroleum
  reservoirs.
• The widespread disconformity between the
  Kaskaskia and Absaroka sequences reason for
  Mississippian Pennsylvanian divisions of
  Carboniferous Period (European useage).
• Earliest Absaroka clastics deposited from
  re-emerging Appalachian Ouachita highlands,
  thin to northwest. Further northwestward
  marine clastics and carbonates.

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Southward drift of Gondwana triggers global
cooling (glaciers) low sea level. Collision of
Laurasia Africa Alleghenian
Orogeny, rejuvenation of
highlands clastic wedge.
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Broad clastic wedges tectonic fluctuations
Pennsylvanian Period
different types of deposition from Kaskaskia.
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• In the transition zone between the clastic
  wedge and shallow marine deposits, sea level
  tectonic fluctuations resulted in deposition of
  cyclothems, i.e., local repetitive sedimentary
  sequences.
• A typical coal-bearing cyclothem from the
  Illinois Basin contains (slide 12)
• Nonmarine sandstones, shales
• Capped by a coal unit and
• Overlain by marine units
• Modern coal swamps - the Mississippi Delta, the
  Okefenokee Swamp, the Florida Everglades, and the
  Dutch Lowlands, Mekong Delta.
• Study of modern examples helps understand ancient
  environments.

Deltaic Fluvial conditions
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Columnar section of complete Cyclothem.
Sudden sea level changes or erosion may truncate
sequences.
Deepest water
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Idealized depositional model for cyclothems.
During Stable Sea Level or Regression, sediments
prograde into basin.
Progradation looks like Regression in rock record.
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Principal Pennsylvanian highland areas
basins of the southwestern part of the craton.
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Pennsylvanian Ancestral Rocky Mountains
Erosion of PreCamb. Basement red arkosic
sandstones.
Unusual intra-cratonic compressional event
high-angle reverse vertical faults.
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Permian Period Continental uplift continued
glaciation of Gondwana reduced cratonic seas to
western part of craton. Restricted basin KS
OK deposition of salt gypsum.
http//www.palaeos.com/Paleozoic/Permian/Permian.h
tm
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Cimarron River bluffs, OK Permian-age
gyp-sum overlying continental red beds (shales,
siltstones).
Gypsum beds
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Alabaster Caverns, Woodward, OK Permian
gypsum dissolved by groundwater.
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Permian Basin
Capitan Reef
Reservoir rocks
Absaroka Sea during Permian - formed an
inter-related complex of lagoons, reefs, and
open-shelf environments
Source rocks
Lagoons behind reefs limestones, evaporites,
red beds. Restricted sediments evaporites in
basins.
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• Western craton (Cordilleran) was a passive
  margin Late Proterozoic to Early Paleozoic.
• Beginning in the Middle Paleozoic - an island arc
  formed off the western margin of the craton.
• Antler Orogeny collision of island arc with
  craton Late Devonian/Early Mississippian.

From the Antler Orogeny, the western margin
remains an active margin.
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• The final eastern margin tectonic event
  Ouachita Orogeny. Ouachita Mobile Belt is 80
  covered by Mesozoic Cenozoic sediments, exposed
  in Ouachita Arbuckle Mts. of AR OK and the
  Marathon Mts. of Big Bend area, TX.
• Pre-Mississippian rocks passive margin and deep
  water sediments, including novaculite
  (fine-grained chert) in AR and Marathon Mts. and
  turbidites in the Marathon Mts.
• Orogeny began during Mississippian Period.
• Ouachita, Appalachian, Hercynian Mobile Belts are
  continuous along the eastern margin.
• Microplates caught between continents were
  involved in the collision.

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• Increased metamorphic and igneous activity
  indicates that the Acadian orogeny was more
  intense and of longer duration than the Taconic
  orogeny. Radiometric dates from the meta-morphic
  and igneous rocks associated with the Acadian
  orogeny cluster between 360 and 410 million years
  ago.
• Acadian folding thrusting produced angular
  unconformities separating Upper Silurian from
  Mississippian rocks.
• Catskill Delta rocks consist of red
  conglomerates, sandstones, and shales
  equivalent to the Old Red Sandstone of British
  Isles. Both have similar fossil fish, early
  amphibians, and plants.

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• Taconic, Caledonian, and Arcadian orogenies were
  all part of the same broad orogenic event,
  related to the closing of the Iapetus Ocean.
• This event culminated with a continental-continent
  al collision during the Acadian oro-geny as
  Laurentia and Baltica became sutured.
• Late Paleozoic orogenies - Hercynian,
  Alle-ghenian, and Ouachita represent the final
  joining of Laurasia and Gondwana into the
  supercontinent Pangaea. Granite age-dates in
  Ga., NC range from 325 to 300 m.y..
• Microplates (exotic terranes), e.g., Avalonia,
  Piedmont become part of mobile belts, account for
  some geologic inconsistencies within mountain
  ranges.

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United States Coal Deposits.