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Chapter 11 . Late Paleozoic Earth History. Tully Monster. Tullimonstrum gregarium , also known as the Tully Monster, is Illinois’s official state fossil Specimen from Pennsylvanian rocks, Mazon Creek Locality, Illinois. Reconstruction of the Tully Monster about 30 cm long.

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Chapter 11

Late Paleozoic Earth History

tully monster
Tully Monster
  • Tullimonstrum gregarium, also known as the Tully Monster, is Illinois’s official state fossil
    • Specimen from Pennsylvanian rocks, Mazon Creek Locality, Illinois
  • Reconstruction of the Tully Monster
    • about 30 cm long
mazon creek fossils
Mazon Creek Fossils
  • Approximately 300 million years ago
    • in the region of present-day Illinois,
    • sluggish rivers flowed southwestward through swamps,
    • and built large deltas that extended outward into a subtropical shallow sea
  • These rivers deposited high quantities of mud
    • that entombed many of the plants and animals living in the area
  • Rapid burial
    • and the formation of ironstone concretions
    • preserved many of the plants and animals of the area
exceptional preservation
Exceptional Preservation
  • The resulting fossils,
    • known as the Mazon Creek fossils
      • for the area in northeastern Illinois
      • where most specimens are found,
    • provide us with significant insights about the soft-part anatomy of the region\'s biota
  • Because of the exceptional preservation of this ancient biota,
    • Mazon Creek fossils are known throughout the world
    • and many museums have extensive collections from the area
pennsylvanian delta organisms
Pennsylvanian Delta Organisms
  • During Pennsylvanian time, two major habitats existed in northeastern Illinois
    • One was a swampy forested lowland of the subaerial delta,
    • and the other was the shallow marine environment of the actively prograding delta
  • Living in the warm, shallow waters
    • of the delta front were numerous
      • cnidarians,
      • mollusks,
      • echinoderms,
  • arthropods,
  • worms,
  • and fish
swampy lowlands
Swampy Lowlands
  • The swampy lowlands surrounding the delta were home to more than 400 plant species,
    • numerous insects and spiders,
    • and other animals such as
      • scorpions and amphibians
    • In the ponds, lakes, and rivers were many
      • fish, shrimp, and ostracods
    • Almost all of the plants were
      • seedless vascular plants,
      • typical of the kinds that lived in the coal-forming swamps
      • during the Pennsylvanian Period
tully monster7
Tully Monster
  • One of the more interesting Mazon Creek fossils is the Tully Monster,
    • which is not only unique to Illinois,
    • but also is its official state fossil
  • Named for Francis Tully,
    • who first discovered it in 1958,
    • Tullimonstrum gregarium
    • was a small
      • up to 30 cm long
    • soft-bodied animal that lived in the warm, shallow seas
    • covering Illinois about 300 million years ago
tully monster8
Tully Monster
  • The Tully Monster had a relatively long proboscis
    • that contained a "claw" with small teeth in it
    • The round-to-oval shaped body was segmented
    • and contained a cross-bar,
    • whose ends were swollen,
    • and are interpreted by some to be the animals sense organs
    • The tail had two horizontal fins
  • It probably swam like an eel
    • with most of the undulatory movement occurring behind the two sense organs
tully monster9
Tully Monster
  • There presently is no consensus
    • as to what phylum the Tully Monster belongs
    • or to what animals it might be related
late paleozoic paleogeography
Late Paleozoic Paleogeography
  • The Late Paleozoic was a time of
    • evolutionary innovations,
    • continental collisions,
    • mountain building,
    • fluctuating seas levels,
    • and varied climates
  • Coals, evaporites, and tillites
    • testify to the variety of climatic conditions
    • experienced by the different continents during the Late Paleozoic
gondwana continental glaciers
Gondwana Continental Glaciers
  • Major glacial-interglacial intervals
    • occurred throughout much of Gondwana
    • as it continued moving over the South Pole
      • during the Late Mississippian to Early Permian
  • The growth and retreat of continental glaciers
    • during this time
    • profoundly affected the world\'s biota
    • as well as contributing to global sea level changes
continental collisions
Continental Collisions
  • Collisions between continents
    • not only led to the formation of the supercontinent Pangaea
    • by the end of the Permian,
    • but resulted in mountain building
    • that strongly influenced oceanic and atmospheric circulation patterns
  • By the end of the Paleozoic,
    • widespread arid and semiarid conditions prevailed over much of Pangaea
the devonian period
The Devonian Period
  • During the Silurian,
    • Laurentia and Baltica collided along a convergent plate boundary
    • to form the larger continent of Laurasia
  • This collision,
    • which closed the northern Iapetus Ocean,
    • is marked by the Caledonian orogeny
  • During the Devonian,
    • as the southern Iapetus Ocean narrowed
    • between Laurasia and Gondwana,
    • mountain building continued along the eastern margin of Laurasia
    • with the Acadian orogeny
paleogeography of the world
Paleogeography of the World
  • For the Late Devonian Period
paleogeography of the world15
Paleogeography of the World
  • For the Early Carboniferous Period
paleogeography of the world16
Paleogeography of the World
  • For the Late Carboniferous Period
paleogeography of the world17
Paleogeography of the World
  • For the Late Permian Period
reddish fluvial sediments
Reddish Fluvial Sediments
  • The erosion of the resulting highlands
    • provided vast amounts of reddish fluvial sediments
    • that covered large areas of northern Europe
      • Old Red Sandstone
    • and eastern North America
      • the Catskill Delta
collision of laurentia and baltica
Collision of Laurentia and Baltica
  • Other Devonian tectonic events include,
    • the Cordilleran Antler orogeny,
    • the Ellesmere orogeny along the northern margin of Laurentia
      • which may reflect the collision of Laurentia with Siberia
    • and the change from a passive continental margin to an active convergent plate boundary
      • in the Uralian mobile belt of eastern Baltica
uniform global climate
Uniform Global Climate
  • The distribution of
      • reefs,
      • evaporites,
      • and red beds,
    • as well as the existence of similar floras throughout the world,
    • suggests a rather uniform global climate during the Devonian Period
the carboniferous period
The Carboniferous Period
  • During the Carboniferous Period
    • southern Gondwana moved over the South Pole,
    • resulting in extensive continental glaciation
  • The advance and retreat of these glaciers
    • produced global changes in sea level
    • that affected sedimentation pattern on the cratons
  • As Gondwana continued moving northward,
    • it first collided with Laurasia
      • during the Early Carboniferous
    • and continued suturing with it during the rest of the Carboniferous
gondwana laurasia collision
Gondwana/Laurasia Collision
  • Because Gondwana rotated clockwise relative to Laurasia,
    • deformation of the two continents generally progressed in a northeast-to-southwest direction along
      • the Hercynian,
      • Appalachian,
      • and Ouachita mobile belts
  • The final phase of collision between Gondwana and Laurasia
    • is indicated by the Ouachita Mountains of Oklahoma
    • which were formed by thrusting
    • during the Late Carboniferous and Early Permian
pangaea began taking shape
Pangaea Began Taking Shape
  • Elsewhere, Siberia collided with Kazakhstania
    • and moved toward the Uralian margin of Laurasia (Baltica),
    • colliding with it during the Early Permian
  • By the end of the Carboniferous,
    • the various continental landmasses were fairly close together
    • as Pangaea began taking shape
coal basins in equatorial zone
Coal Basins in Equatorial Zone
  • The Carboniferous coal basins of
    • eastern North America,
    • western Europe,
    • and the Donets Basin of Ukraine
  • all lay in the equatorial zone,
    • where rainfall was high and temperatures were consistently warm
  • The absence of strong seasonal growth rings
    • in fossil plants from these coal basins
    • is indicative of such a climate
fossil plants of siberia
Fossil Plants of Siberia
  • The fossil plants found in the coals of Siberia,
    • however, show well-developed growth rings,
    • signifying seasonal growth
    • with abundant rainfall
    • and distinct seasons
    • such as occur in the temperate zones
      • at latitudes 40 degrees to 60 degrees north
continental ice sheets
Continental Ice Sheets
  • Glacial condition
    • and the movement of large continental ice sheets
    • in the high southern latitudes
    • are indicated by widespread tillites
    • and glacial striations in southern Gondwana
  • These ice sheets spread toward the equator and,
      • at their maximum growth,
    • extended well into the middle temperate latitudes
the permian period
The Permian Period
  • The assembly of Pangaea
    • was essentially completed during the Permian
    • as a result of the many continental collisions
      • that began during the Carboniferous
  • Although geologists generally agree
    • on the configuration and locations
    • of the western half of the supercontinent,
  • no consensus exists
    • on the number or configuration of the various terranes
    • and continental blocks that composed the eastern half of Pangaea
pangaea surrounded
Pangaea Surrounded
  • Regardless of the exact configuration
    • of the eastern portion of Pangaea,
    • geologists know that the supercontinent
    • was surrounded by various subduction zones
    • and moved steadily northward during the Permian
  • Furthermore, an enormous single ocean,
    • Panthalassa,
    • surrounded Pangaea and
    • spanned Earth from pole to pole
climatic consequences
Climatic Consequences
  • The formation of a single large landmass
    • had climatic consequences for the continent
    • Terrestrial Permian sediments indicate
    • that arid and semiarid conditions were widespread over Pangaea
  • The mountain ranges produced by
    • the Hercynian, Alleghenian, and Ouachita orogenies
    • were high enough to create rain shadows
    • that blocked the moist, subtropical, easterly winds
      • much as the southern Andes Mountains do in western South America today
mountains influenced climate
Mountains Influenced Climate
  • The mountains’ influence produced very dry conditions in North America and Europe,
    • as evident from the extensive
    • Permian red beds and evaporites
    • found in western North America, central Europe, and parts of Russia
  • Permian coals,
      • indicative of abundant rainfall,
    • were mostly limited to the northern temperate belts
      • latitude 40 degrees to 60 degrees north
    • while the last remnants of the Carboniferous ice sheets retreated
late paleozoic history of north america
Late Paleozoic History of North America
  • The Late Paleozoic cratonic history of North America included periods
    • of extensive shallow-marine carbonate deposition
    • and large coal-forming swamps
    • as well as dry, evaporite-forming terrestrial conditions
  • Cratonic events largely resulted from changes in sea level because of
    • Gondwanan glaciation
    • and tectonic events related to the joining of Pangaea
mountain building
Mountain Building
  • Mountain building
    • that began with the Ordovician Taconic orogeny
    • continued with the
      • Caledonian,
      • Acadian,
      • Alleghenian,
      • and Ouachita orogenies
  • These orogenies were part of the global tectonic process
    • that resulted in the formation of Pangaea by the end of the Paleozoic Era
the kaskaskia sequence
The Kaskaskia Sequence
  • The boundary between
    • the Tippecanoe sequence
    • and the overlying Kaskaskia sequence
      • Middle Devonian-Late Mississippian
    • is marked by a major unconformity
  • As the Kaskaskia Sea transgressed
    • over the low-relief landscape of the craton,
    • the majority of the basal beds deposited
      • consisted of clean, well-sorted quartz sandstones
oriskany sandstone
Oriskany Sandstone
  • A good example is the Oriskany Sandstone
    • of New York and Pennsylvania
    • and its lateral equivalents
  • The Oriskany Sandstone,
    • like the basal Tippecanoe St. Peter Sandstone,
    • is an important glass sand
    • as well as a good gas-reservoir rock
basal kaskaskia sandstones
Basal Kaskaskia Sandstones
  • Extent of the basal units of the Kaskaskia sequence in the eastern and north-central United States
source areas
Source Areas
  • The source areas for the basal Kaskaskia sandstones
    • were primarily the eroding highlands of the Appalachian mobile belt area,
    • exhumed Cambrian and Ordovician sandstones cropping out along the flanks of the Ozark Dome,
    • and exposures of the Canadian Shield in the Wisconsin area
devonian period
Devonian Period
  • Paleogeography of North America during the Devonian Period
sediment sources
Sediment Sources
  • The earlier Silurian carbonate beds
      • below the Tippecanoe-Kaskaskia unconformity
    • lacked Kaskaskia-like sands
  • The absence of such sands indicates
    • that the source areas for the basal Kaskaskia
    • had still been submerged and not yet exposed at the time the Tippecanoe sequence was deposited
  • Stratigraphic studies indicate
    • that these source areas were uplifted
    • and the Tippecanoe carbonates removed by erosion
    • prior to the Kaskaskia transgression
kaskaskian rocks
Kaskaskian Rocks
  • Kaskaskian basal rocks
    • elsewhere on the craton
    • consist of carbonates
    • that are frequently difficult to differentiate
    • from the underlying Tippecanoe carbonates
    • unless they are fossiliferous
  • The majority of Kaskaskian rocks are
    • carbonates, including reefs, and associated evaporite deposits
    • except for widespread Upper Devonian and Lower Mississippian black shales
other parts of the world
Other Parts of the World
  • In many other parts of the world, such as
      • southern England,
      • Belgium,
      • Central Europe,
      • Australia,
      • and Russia,
    • the Middle and early Late Devonian epochs were times of major reef building
reef development in western canada
Reef Development in Western Canada
  • The Middle and Late Devonian-age reefs of western Canada
    • contain large reserves of petroleum
    • and have been widely studied from outcrops and in the subsurface
  • These reefs began forming
    • as the Kaskaskia Sea transgressed southward
    • into western Canada
middle devonian reefs and evaporites
Middle Devonian Reefs and Evaporites
  • By the end of the Middle Devonian,
    • the reefs had coalesced into a large barrier-reef system
    • that restricted the flow of oceanic water into the back-reef platform,
    • thus creating conditions for evaporite precipitation
  • In the back-reef area, up to 300 m of evaporites
    • were precipitated in much the same way as in the Michigan Basin during the Silurian
devonian reef complex
Devonian Reef Complex
  • Reconstruction of the extensive Devonian Reef complex of western Canada
  • These reefs controlled the regional facies of the Devonian epeiric seas
potash from evaporites
Potash from Evaporites
  • More than half of the world\'s potash,
    • which is used in fertilizers,
    • comes from these Devonian evaporites
  • By the middle of the Late Devonian,
    • reef growth stopped in the western Canada region,
    • although nonreef carbonate deposition continued
black shales
Black Shales
  • In North America, many areas of carbonate-evaporite deposition
    • gave way to a greater proportion of shales
    • and coarser detrital rocks
      • beginning in the Middle Devonian and continuing into the Late Devonian
  • This change to detrital deposition
    • resulted from the formation of new source areas
    • brought on by the mountain-building activity
    • associated with the Acadian orogeny in North America
increased detrital deposition
Increased Detrital Deposition
  • Deposition of black shales
  • was brought on by the the Acadian orogeny
widespread black shales
Widespread Black Shales
  • As the Devonian Period ended,
    • a conspicuous change in sedimentation took place over the North American craton
    • with the appearance of widespread black shales
  • These Upper Devonian-Lower Mississippian black shales are typically
    • noncalcareous,
    • thinly bedded,
    • and usually less than 10 m thick
extent of black shales
Extent of Black Shales
  • The extent of the upper Devonian and Lower Mississippian Chattanooga Shale and its equivalent units
  • such as the Antrim Shale and the Albany Shale
new albany shale
New Albany Shale
  • Upper Devonian New Albany Shale,
  • Button Mold Knob Quarry, Kentucky
dating black shales
Dating Black Shales
  • Because most black shales lack body fossils,
    • they are difficult to date and correlate
  • However, microfossils, such as
    • conodonts
      • microscopic animals
    • acritarchs
      • microscopic algae
    • or plant spores
    • indicate that the lower beds are Late Devonian,
    • and the upper beds are Early Mississippian in age
origin debated
Origin Debated
  • Although the origin of these extensive black shales is still being debated,
    • the essential features required to produced them include
      • undisturbed anaerobic bottom water,
      • a reduced supply of coarser detrital sediment,
      • and high organic productivity in the overlying oxygenated waters
  • High productivity in the surface waters leads to a shower of organic material,
    • which decomposes on the undisturbed seafloor
    • and depletes the dissolved oxygen at the sediment-water interface
puzzling origin
Puzzling Origin
  • The wide extent in North America
    • of such apparently shallow-water black shales
    • remains puzzling
  • Nonetheless, these shales
    • are rich in uranium
    • and are an important source rock of oil and gas
    • in the Appalachian region
the late kaskaskia
The Late Kaskaskia
  • Following deposition of the black shales,
    • carbonate sedimentation on the craton dominated the remainder of the Mississippian Period
  • During this time, a variety of carbonate sediments was deposited in the epeiric seas
    • as indicated by the extensive deposits of
    • crinoidal limestones
      • rich in crinoid fragments
    • oolitic limestones,
    • and various other limestones and dolostones
mississippian period
Mississippian Period
  • Paleogeography of North America during the Mississippian Period
mississippian carbonates
Mississippian Carbonates
  • These Mississippian carbonates display
      • cross-bedding, ripple marks, and well-sorted fossil fragments,
    • all of which are indicative of a shallow-water environment
    • Analogous features can be observed on the present-day Bahama Banks
  • In addition, numerous small organic reefs
    • occurred throughout the craton during the Mississippian
    • These were all much smaller than the large barrier-reef complexes
      • that dominated the earlier Paleozoic seas
regression of the kaskaskia sea
Regression of the Kaskaskia Sea
  • During the Late Mississippian regression
    • of the Kaskaskia Sea from the craton,
    • carbonate deposition was replaced
    • by vast quantities of detrital sediments
  • The resulting sandstones,
      • particularly in the Illinois Basin,
    • have been studied in great detail
    • because they are excellent petroleum reservoirs
cratonwide unconformity
Cratonwide Unconformity
  • Prior to the end of the Mississippian,
    • the epeiric sea had retreated
      • to the craton margin,
    • once again exposing the craton
    • to widespread weathering and erosion
  • This resulted in a cratonwide unconformity
    • when the Absaroka Sea began transgressing
    • back over the craton
the absaroka sequence
The Absaroka Sequence
  • The Absaroka sequence
    • includes rocks deposited
      • during the Pennsylvanian
      • through Early Jurassic
    • At this point, we will only discuss the Paleozoic rocks of the Absaroka sequence
  • The extensive unconformity
    • separating the Kaskaskia and Absaroka sequences
    • essentially divides the strata
    • into the North American
    • Mississippian and Pennsylvanian systems
mississippian and pennsylvanian versus carboniferous
Mississippian and Pennsylvanian Versus Carboniferous
  • The Mississippian and Pennsylvanian systems of North America
    • are equivalent to the European Lower and Upper Carboniferous systems:
      • Mississippian = Lower Carboniferous
      • Pennsylvanian = Upper Carboniferous
absaroka rocks
Absaroka Rocks
  • The rocks of the Absaroka sequence
    • are not only different from those of the Kaskaskia sequence,
    • but they are also the result of different tectonic regimes
  • The lowermost sediments of the Absaroka sequence
    • are confined to the margins of the craton
lowermost absaroka
Lowermost Absaroka
  • These lowermost deposits
    • are generally thickest in the east and southeast,
      • near the emerging highlands of the Appalachian and Ouachita mobile belts,
    • and thin westward onto the craton
  • The lithologies also reveal lateral changes
    • from nonmarine detrital rocks and coals in the east,
    • through transitional marine-nonmarine beds,
    • to largely marine detrital rocks and limestones farther west
pennsylvanian period
Pennsylvanian Period
  • Paleogeography of North America during the Pennsylvanian Period
what are cyclothems
What Are Cyclothems?
  • A cyclical pattern of alternating marine and nonmarine strata
    • is one of the characteristic features of Pennsylvanian rocks
  • Such rhythmically repetitive sedimentary sequences are known as cyclothems
  • They result from repeated alternations
    • of marine
    • and nonmarine environments,
    • usually in areas of low relief
delicate interplay
Delicate Interplay
  • Though seemingly simple,
  • cyclothems reflect a delicate interplay between
    • nonmarine deltaic environments
    • shallow-marine interdeltaic environments
    • and shelf environments
  • For example,
    • a typical coal-bearing cyclothem from the Illinois Basin contains
      • nonmarine units,
      • capped by a coal unit
      • and overlain by marine units
nonmarine units of a cyclothem
Nonmarine Units of a Cyclothem
  • The initial units represent
    • deltaic deposits
    • and fluvial deposits
  • Above them is an underclay
    • that frequently contains roots from the plants and trees
    • that comprise the overlying coal
  • The coal bed
    • results from accumulations of plant material
    • and is overlain by marine units
cyclothem
Cyclothem
  • Columnar section of a complete cyclothem
pennsylvanian coal bed
Pennsylvanian Coal Bed
  • Pennsylvanian coal bed, West Virginia
  • part of a cyclothem
coal forming swamp
Coal-Forming Swamp
  • Reconstruction of the environment of a Pennsylvanian coal-forming swamp
the okefenokee swamp
The Okefenokee Swamp
  • similar to those occurring during the Pennsylvanian Period
  • in Georgia, is a modern coal-forming environment,
marine units of a cyclothem
Marine Units of a Cyclothem
  • Next the marine units consist of alternating
    • limestones and shales,
    • usually with an abundant marine invertebrate fauna
  • The marine cycle ends with an erosion surface
  • A new cyclothem begins with a nonmarine deltaic sandstone
  • All the beds illustrated in the idealized cyclothems are not always preserved because of
    • abrupt changes from marine to nonmarine conditions
    • or removal of some units by erosion
why are cyclothems important
Why Are Cyclothems Important?
  • Cyclothems represent
    • transgressive
    • and regressive sequences
    • with an erosional surface separating one cyclothem from another
  • Thus, an idealized cyclothem
    • passes upward from fluvial-deltaic deposits,
    • through coals,
    • to detrital shallow-water marine sediments,
    • and finally to limestones typical of an open marine environment
modern analogues
Modern Analogues
  • Such places as
      • the Mississippi delta,
      • the Okefenokee Swamp, Georgia
      • the Florida Everglades,
      • and the Dutch lowlands
    • represent modern coal forming environments
    • similar to those that existed during the Pennsylvanian Period
  • By studying these modern analogues,
    • geologists can make reasonable deductions
    • about conditions existing in the geologic past
sea level changes
Sea Level Changes
  • The Pennsylvanian coal swamps
    • must have been large lowland areas neighboring the sea
  • In such cases,
    • a very slight rise in sea level
      • would have flooded large areas,
    • while slight drops
      • would have exposed large areas,
    • resulting in alternating marine and nonmarine environments
  • The same result could have been caused by
    • rising sea level and progradation of a large delta, such as occurs today in Louisiana
explaining cyclicity
Explaining Cyclicity
  • Such regularity and cyclicity in sedimentation
    • over a large area requires an explanation
  • In most cases, local cyclothems of limited extent can be explained for
    • by rapid but slight changes in sea level
    • in a swamp-delta complex of low relief near the sea
    • such as progradation or by localized crustal movement
  • Explaining widespread cyclothems is more difficult
favored hypothesis
Favored Hypothesis
  • The hypothesis currently favored
      • by most geologists
      • for explaining widespread cyclothems
    • is a rise and fall of sea level
    • related to advances and retreats of Gondwanan continental glaciers
  • When the Gondwanan ice sheets advanced,
      • sea level dropped,
    • and when they melted,
      • sea level rose
  • Late Paleozoic cyclothem activity on all cratons
    • closely corresponds to Gondwana glacial-interglacial cycles
cratonic uplift
Cratonic Uplift
  • Recall that cratons are stable areas,
    • and when they do experience deformation, it is usually mild
  • The Pennsylvanian Period, however, was a time of unusually severe cratonic deformation,
    • resulting in uplifts of sufficient magnitude to expose Precambrian basement rocks
  • In addition to newly formed highlands and basins,
    • many previously formed arches and domes,
    • such as the Cincinnati Arch, Nashville Dome, and Ozark Dome,
    • were also reactivated
ancestral rockies
Ancestral Rockies
  • During the Pennsylvanian Period,
    • the area of greatest deformation occurred in the southwestern part of the North American craton
    • where a series of fault-bounded uplifted blocks formed the Ancestral Rockies
  • Uplift of these mountains,
    • some of which were elevated more than 2 km along near-vertical faults,
    • resulted in the erosion of the overlying Paleozoic sediments
    • and exposure of the Precambrian igneous and metamorphic basement rocks
pennsylvanian highlands
Pennsylvanian Highlands
  • Location of the principal Pennsylvanian highland areas and basins of the southwestern part of the craton
ancestral rockies80
Ancestral Rockies
  • Erosion of these mountains produced
  • coarse red sediments
  • that were deposited in the adjacent basins
  • Block diagram of the Ancestral Rockies, which were elevated by faulting during the Pennsylvanian Period
red basin sediment
Red Basin Sediment
  • As the Ancestral Rocky mountains eroded,
    • tremendous quantities of
    • coarse, red arkosic sand and conglomerate
    • were deposited in the surrounding basins
  • These sediments are preserved in many areas
    • including the rocks of the Garden of the Gods near Colorado Springs
    • and at the Red Rocks Amphitheater near Morrison, Colorado
garden of the gods
Garden of the Gods
  • Storm-sky view of Garden of the Gods from Near Hidden Inn, Colorado Springs, Colorado
intracratonic mountain ranges
Intracratonic Mountain Ranges
  • Intracratonic mountain ranges are unusual,
    • and their cause has long been debated
    • It is thought that the collision of Gondwana with Laurasia along the Ouachita mobile belt
    • produced great stresses in the southwestern region of the North American craton
  • These crustal stresses were relieved by faulting
    • that resulted in uplift of cratonic blocks
    • and downwarp of adjacent basins,
    • forming a series of ranges and basins
the middle absaroka
The Middle Absaroka

More Evaporite Deposits and Reefs

  • While the various intracratonic basins
    • were filling with sediment
      • during the Late Pennsylvanian,
    • the epeiric sea slowly began retreating from the craton
  • During the Early Permian,
    • the Absaroka Sea occupied a narrow region
    • from Nebraska through west Texas
permian period
Permian Period
  • Paleogeography of North America during the Permian Period
middle permian absaroka sea
Middle Permian Absaroka Sea
  • By the Middle Permian,
    • the sea had retreated to west Texas
    • and southern New Mexico
  • The thick evaporite deposits
    • in Kansas and Oklahoma
    • show the restricted nature of the Absaroka Sea
      • during the Early and Middle Permian
    • and its southwestward retreat from the central craton
restricted absaroka sea
Restricted Absaroka Sea
  • During the Middle and Late Permian,
    • the Absaroka Sea was restricted to
    • west Texas and southern New Mexico,
    • forming an interrelated complex of
      • lagoonal environments,
      • reef environments,
      • and open-shelf environments
  • Three basins separated by two submerged platforms
    • formed in this area during the Permian
permian reefs and basins
Permian Reefs and Basins
  • Location of the west Texas Permian basins and surrounding reefs
massive reefs
Massive Reefs
  • Massive reefs grew around the basin margins
    • while limestones, evaporites, and red beds were deposited
      • in the lagoonal areas behind the reefs
  • As the barrier reefs grew and the passageways between the basins became more restricted,
    • Late Permian evaporites gradually filled the individual basins
capitan limestone reef reconstruction
Capitan Limestone Reef Reconstruction
  • Reconstruction of the Middle Permian Capitan Limestone reef environment
  • Shown are brachiopods, corals, bryozoans and large glass sponges
capitan limestone
Capitan Limestone
  • Spectacular deposits representing the geologic history of this region
    • can be seen today in the Guadalupe Mountains of Texas and New Mexico
    • where the Capitan Limestone forms the caprock of these mountains
  • These reefs have been extensively studied
    • because of the tremendous oil production that comes from this region
  • By the end of the Permian Period,
    • the Absaroka Sea had retreated from the craton
    • exposing continental red beds
    • over most of the southwestern and eastern region
late paleozoic mobile belts
Late Paleozoic Mobile Belts
  • Having examined the Kaskaskia and Absarokian history of the craton,
    • we now turn our attention to the orogenic activity in the mobile belts
  • The mountain building that occurred during this time
    • profoundly influenced the climatic and sedimentary history of the craton
  • In addition it was part
    • of the global tectonic regime that formed Pangaea
cordilleran mobile belt
Cordilleran Mobile Belt
  • During the Neoproterozoic and Early Paleozoic,
    • the Cordilleran area was a passive continental margin
    • along which extensive continental shelf sediments were deposited
  • Thick sections of marine sediments
    • graded laterally into thin cratonic units
    • as the Sauk Sea transgressed onto the craton
  • Beginning in the Middle Paleozoic,
    • an island arc formed off the western margin of the craton
antler orogeny
Antler orogeny
  • A collision between
    • this eastward-moving island arc
    • and the western border of the craton
    • took place during the Late Devonian and Early Mississippian,
    • resulting in a highland area
  • This orogenic event,
    • the Antler orogeny,
    • was caused by subduction
    • and resulted in the closing of the narrow ocean basin
      • that separated the island arc from the craton
antler highlands
Antler Highlands
  • in which deep-water continental slope deposits
  • Reconstruction of the Cordilleran mobile belt during the Early Mississippian
  • were thrust eastward
  • over shallow-water continental shelf carbonates
  • forming the Antler Highlands
erosion of the antler highlands
Erosion of the Antler Highlands
  • Erosion of the resulting Antler Highlands
    • produced large quantities of sediment
    • that were deposited to the east in the epeiric sea covering the craton
    • and to the west in the deep sea
major tectonic activity
Major Tectonic Activity
  • The Antler orogeny was the first in a series
    • of orogenic events to affect the Cordilleran mobile belt
  • During the Mesozoic and Cenozoic,
    • this area was the site of major tectonic activity
    • caused by oceanic-continental convergence
    • and accretion of various terranes
ouachita mobile belt
Ouachita Mobile Belt
  • The Ouachita mobile belt
    • extends for approximately 2100 km
    • from the subsurface of Mississippi
    • to the Marathon region of Texas
  • Approximately 80% of the former mobile belt
    • is buried beneath a Mesozoic and Cenozoic sedimentary cover
  • The two major exposed areas in this region are
    • the Ouachita Mountains of Oklahoma and Arkansas
    • and the Marathon Mountains of Texas
beginning of the ouachita orogeny
Beginning of the Ouachita Orogeny
  • During the Neoproterozoic to Early Mississippian,
    • shallow-water detrital and carbonate sediments
    • were deposited on a broad continental shelf,
    • while in the deeper-water portion of the adjoining mobile belt,
    • bedded cherts and shales were accumulating
  • Beginning in the Mississippian Period,
    • the rate of sedimentation increased dramatically
    • as the region changed from a passive continental margin to an active convergent plate boundary,
    • marking the beginning of the Ouachita orogeny
ouachita mobile belt100
Ouachita Mobile Belt
  • Plate Tectonic model for the deformation of the Ouachita mobile belt
  • Depositional environment prior to the beginning of orogenic activity
ouachita mobile belt101
Ouachita Mobile Belt
  • Incipient continental collision between North America and Gondwana began during the Mississippian Period.
ouachita mobile belt102
Ouachita Mobile Belt
  • Continental collision continued during the Pennsylvanian and Permian periods
gondwana laurasia collision103
Gondwana/Laurasia Collision
  • Thrusting of sediments continued
    • throughout the Pennsylvanian and Early Permian
    • as a result of the compressive forces generated
    • along the zone of subduction
    • as Gondwana collided with Laurasia
  • The collision of Gondwana and Laurasia
    • is marked by the formation of a large mountain range,
    • most of which was eroded during the Mesozoic Era
  • Only the rejuvenated Ouachita and Marathon Mountains remain of this once lofty mountain range
three continuous mobile belts
Three Continuous Mobile Belts
  • The Ouachita deformation
    • was part of the general worldwide tectonic activity
    • that occurred when Gondwana united with Laurasia
  • Three mobile belts
      • the Hercynian,
      • Appalachian,
      • and Ouachita
    • were continuous, and marked the southern boundary of Laurasia
complex tectonic activity
Complex Tectonic Activity
  • The tectonic activity that resulted in the uplift
    • in the Ouachita mobile belt was very complex
      • and involved not only the collision of Laurasia and Gondwana
      • but also several microplates and terranes between the continents
      • that eventually became part of Central America
  • The compressive forces impinging on the Ouachita mobile belt
    • also affected the craton
    • by causing broad uplift of the southwestern part of North America
appalachian mobile belt
Appalachian Mobile Belt

Caledonian Orogeny

  • The Caledonian mobile belt extends
    • along the western border of Baltica
    • and includes the present-day countries of Scotland, Ireland, and Norway
  • During the Middle Ordovician,
    • subduction along the boundary
    • between the Iapetus plate and Baltica began,
    • forming a mirror image of the convergent plate boundary
    • off the east coast of Laurentia (North America)
caledonian orogeny
Caledonian Orogeny
  • The culmination of the Caledonian orogeny
    • occurred during the Late Silurian and Early Devonian
    • with the formation of a mountain range
    • along the western margin of Baltica
acadian orogeny
Acadian Orogeny
  • The third Paleozoic orogeny to affect Laurentia and Baltica
    • began during the Late Silurian
    • and concluded at the end of the Devonian Period
  • The Acadian orogeny affected the Appalachian mobile belt
    • from Newfoundland to Pennsylvania
    • as sedimentary rocks
    • were folded and thrust against the craton
acadian zone of collision
Acadian Zone of Collision
  • As with the preceding Taconic and Caledonian orogenies,
    • the Acadian orogeny occurred along
    • an oceanic-continental convergent plate boundary
  • As the northern Iapetus Ocean continued to close during the Devonian,
    • the plate carrying Baltica
    • finally collided with Laurentia,
    • forming a continental-continental convergent plate boundary along the zone of collision
increased metamorphic and igneous activity
Increased Metamorphic and Igneous Activity
  • As the increased metamorphic and igneous activity indicates,
    • the Acadian orogeny was more intense
    • and of longer duration
    • than the Taconic orogeny
  • Radiometric dates
    • from the metamorphic and igneous rocks
      • associated with the Acadian orogeny
    • cluster between 360 and 410 million years ago
folding and thrusting
Folding and Thrusting
  • Jjust as with the Taconic orogeny,
    • deep-water sediments
    • were folded and thrust northwestward,
    • producing angular unconformities
    • separating Upper Silurian from Mississippian rocks
catskill delta
Catskill Delta
  • Weathering and erosion of the Acadian Highlands
    • produced the Catskill Delta,
    • a thick clastic wedge
      • named for the Catskill Mountains
      • in upstate New York
      • where it is well exposed
  • The Catskill Delta, composed of
    • red, coarse conglomerates, sandstones, and shales,
    • contains nearly three times as much sediment as the Queenston Delta
catskill delta clastic wedge
Catskill Delta Clastic Wedge
  • The Catskill Delta clastic wedge
  • and the Old Red Sand-stone
  • are bilaterally symmetrical
  • and derived their sediments
  • from the Acadian and Caledonian Highlands
  • Area of collision between Laurentia and Baltica
devonian rocks of new york
Devonian Rocks of New York
  • The Devonian rocks of New York are among the best studied on the continent
  • A cross section of the Devonian strata
    • clearly reflects an eastern source for the Catskill facies
      • from the Acadian Highlands
  • These clastic rocks can be traced
    • from eastern Pennsylvania,
      • where the coarse clastics are approximately 3 km thick,
    • to Ohio,
      • where the deltaic facies are only about 100 m thick
      • and consist of cratonic shales and carbonates
catskill delta red beds
Catskill Delta Red Beds
  • The red beds of the Catskill Delta
    • derive their color from the hematite found in the sediments
  • Plant fossils and oxidation of the hematite indicate
    • that the beds were deposited in a continental environment
the old red sandstone
The Old Red Sandstone
  • The red beds of the Catskill Delta
    • have a European counterpart
    • in the Devonian Old Red Sandstone
      • of the British Isles
  • The Old Red Sandstone,
    • just like its North American Catskill counterpart,
    • contains numerous fossils of
      • freshwater fish,
      • early amphibians,
      • and land plants
old red sandstone
Old Red Sandstone
  • is the counterpart to the Catskill Delta clastic wedge
  • The Old Red Sandstone
red beds traced north
Red Beds Traced North
  • By the end of the Devonian Period,
    • Baltica and Laurentia were sutured together,
    • forming Laurasia
  • The red beds of the Catskill Delta
    • can be traced north,
    • through Canada and Greenland,
    • to the Old Red Sandstone of the British Isles
    • and into Northern Europe
  • These beds were deposited
    • in similar environments
    • along the flanks of developing mountain chains
    • formed at convergent plate boundaries
closing of the iapetus ocean
Closing of the Iapetus Ocean
  • The Taconic, Caledonian, and Acadian orogenies
    • were all part of the same orogenic event
    • related to the closing of the Iapetus Ocean
  • This event began
    • with paired oceanic-continental convergent plate boundaries
    • during the Taconic and Caledonian orogenies
  • and culminated
    • along a continental-continental plate boundary
    • during the Acadian orogeny
    • as Laurentia and Baltica became sutured
hercynian alleghenian orogeny
Hercynian-Alleghenian Orogeny
  • Following this,
    • the Hercynian-Alleghenian orogeny began,
    • followed by orogenic activity
    • in the Ouachita mobile belt
  • The Hercynian mobile belt
      • of southern Europe
    • and the Appalachian and Ouachita mobile belts
      • of North America
    • mark the zone along which Europe
      • as part of Laurasia
    • collided with Gondwana
eastern laurasia collided with gondwana
Eastern Laurasia Collided with Gondwana
  • While Gondwana and southern Laurasia collided
    • during the Pennsylvanian and Permian
    • in the area of the Ouachita mobile belt,
    • eastern Laurasia
      • Europe and southeastern North America
    • joined together with Gondwana
      • Africa
    • as part of the Hercynian-Alleghenian orogeny
pangaea
Pangaea
  • These three Late Paleozoic orogenies
      • Hercynian,
      • Alleghenian,
      • and Ouachita
    • represent the final joining of Laurasia and Gondwana
    • into the supercontinent Pangaea
    • during the Permian
the role of microplates and terranes in the formation of pangaea
The Role of Microplates and Terranes in the Formation of Pangaea
  • We have discussed the geologic history
    • of the mobile belts
    • bordering the Paleozoic continents
    • in terms of subduction along convergent plate boundaries
  • However, accretion along the continental margins
    • is more complicated than the somewhat simple,
    • large-scale plate interactions discussed here
terranes or microplates
Terranes or Microplates
  • Geologists now recognize
    • that numerous terranes or microplates existed
    • during the Paleozoic
    • and were involved in the orogenic events
    • that occurred during the time
  • We have been concerned only
    • with the six major Paleozoic continents
  • However, microplates of varying size
    • were present during the Paleozoic
    • and participated in the formation of Pangaea
avalonia
Avalonia
  • For example, the microcontinent of Avalonia
    • is composed of
    • some coastal parts of New England,
    • southern New Brunswick,
    • much of Nova Scotia,
    • the Avalon Peninsula of eastern Newfoundland,
    • southeastern Ireland,
    • Wales,
    • England,
    • and parts of Belgium and Northern France
a separate continent
A Separate Continent
  • The Avalon microcontinent
    • existed as a separate continent
    • during the Ordovician
    • and began to collide with Baltica
      • during the Late Ordovician-Early Silurian
    • and then with Laurentia
      • as part of Baltica
      • during the Silurian
numerous microplates
Numerous Microplates
  • Other terranes and microplates include
    • Iberia-Armorica (southern France, Sardinia, Iberian peninsula)
    • Perunica (Bohemia)
    • numerous Alpine fragments
  • Microplates usually developed their own unique faunal and floral assemblages
the basic history remains the same
The Basic History Remains the Same
  • Thus, while the basic history
    • of the formation of Pangaea during the Paleozoic remains the same,
    • geologists now realize that microplates and terranes also played an important role
  • Furthermore, the recognition of terranes
    • within mobile belts helps explain
    • some previously anomalous geologic situations
late paleozoic mineral resources
Late Paleozoic Mineral Resources
  • Late Paleozoic-age rocks contain
    • a variety of important mineral resources
    • including energy resources
    • and metallic and nonmetallic mineral deposits
  • Petroleum and natural gas
    • are recovered in commercial quantities
    • from rocks ranging
    • from the Devonian through Permian
hydrocarbons
Hydrocarbons
  • Devonian-age rocks in
    • the Michigan Basin,
    • Illinois Basin,
    • and the Williston Basin of Montana, South Dakota, and adjacent parts of Alberta, Canada,
    • have yielded considerable amounts of hydrocarbons
  • Permian reefs and other strata in the western United States, particularly Texas,
    • have also been prolific producers
permian age coal beds
Permian-Age Coal Beds
  • Although Permian-age coal beds
    • are known from several areas including Asia, Africa, and Australia,
    • much of the coal in North America and Europe comes from Pennsylvanian deposits
      • Late Carboniferous
  • Large areas in the Appalachian region and the Midwestern United States
    • are underlain by vast coal deposits
    • formed from the lush vegetation
    • that flourished in Pennsylvanian coal-forming swamps
u s coal deposits
U.S. Coal Deposits
  • Appalachian region are mostly Pennsyl-vanian
  • whereas those in the west are mostly Cretaceous and Cenozoic
  • The age of the coals in the midwestern states and the
bituminous coal
Bituminous Coal
  • Much of the coal is characterized as bituminous coal
    • which contains about 80% carbon
  • It is a dense, black coal
    • that has been so thoroughly altered
    • that plant remains can be seen only rarely
  • Bituminous coal is used to make coke,
    • a hard gray substance made up of the fused ash
  • Coke is used to fire blast furnaces during the production of steel
anthracite
Anthracite
  • Some of the Pennsylvanian coal from North America is anthracite,
    • a metamorphic type of coal
    • containing up to 98% carbon
  • Most anthracite is in the Appalachian region
  • It is an especially desirable type of coal
    • because it burns with a smokeless flame
    • and it yields more heat per unit volume
    • than other types of coal
  • Unfortunately, it is the least common type
    • so that much of the coal used in the U.S. is bituminous
evaporite and gas
Evaporite and Gas
  • A variety of Late Paleozoic-age evaporite deposits are important nonmetallic mineral resources
  • The Zechstein evaporites of Europe extend
    • from Great Britain across the North Sea and into Denmark, the Netherlands, Germany and eastern Poland and Lithuania
  • Besides the evaporites themselves,
    • Zechstein deposits form the caprock
    • for the large reservoirs of the gas fields of the Netherlands
    • and parts of the North Sea region
more nonmetal resources
More Nonmetal Resources
  • Other important evaporite mineral resources include
    • those of the Permian Delaware Basin of west Texas and New Mexico
    • and Devonian evaporites in the Elk Point basin of Canada
  • In Michigan, gypsum is mined and used in the construction of sheetrock
  • The majority of the silica sand
    • mined in the United States comes from east of the Mississippi River
    • and much of this comes from Late Paleozoic-age rocks
silica sand
Silica Sand
  • Silica sand from
    • the Devonian Ridgely Formation is mined in West Virginia, Maryland, and Pennsylvania
    • and the Devonian Sylvania Sandstone is mined near Toledo, Ohio
  • Recall that silica sand is used
    • in the manufacture of glass
    • for refractory bricks in blast furnaces
    • for molds for casting aluminum, iron, and copper alloys
    • and for a variety of other uses
limestones
Limestones
  • Late Paleozoic-age limestones
    • from many areas in North America
    • are used in the manufacture of cement
  • Limestone
    • is also mined and used
    • in blast furnaces
    • when steel is produced
metallic minerals
Metallic Minerals
  • Metallic mineral resources including
    • tin, copper, gold, and silver
    • are also known from Late Paleozoic-age rocks
    • especially those that have been deformed during mountain building
  • Although the precise origin of the Missouri lead and zinc deposits remains unresolved
    • much of the ores of these metals come from Mississippian-age rocks
  • In fact, mines in Missouri account for a substantial amount of all domestic production of lead ores
summary
Summary
  • During the Late Paleozoic, Baltica
    • and Laurentia collided, forming Laurasia
  • Siberia and Kazakhstania collided
    • and finally were sutured to Laurasia
  • Gondwana moved over the South Pole
    • and experienced several glacial-interglacial periods,
    • resulting in global sea level changes
    • and transgressions and regressions
    • along low-lying craton margins
summary141
Summary
  • Laurasia and Gondwana underwent a series
    • of collisions beginning in the Carboniferous
  • During the Permian, the formation
    • of Pangaea was completed
  • Surrounding the supercontinent
    • was a global ocean, Panthalassa
  • The Late Paleozoic history of the North American craton
    • can be deciphered from the rocks
    • of the Kaskaskia and Absaroka sequences
summary142
Summary
  • The basal beds of the Kaskaskia sequence
    • that were deposited on the exposed Tippecanoe surface
    • consisted of either sandstones,
      • derived from the eroding Taconic Highlands,
    • or carbonate rocks
  • Most of the Kaskaskia sequence
    • is dominated by carbonates and associated evaporites
summary143
Summary
  • The Devonian Period was a time of major reef building
    • in western Canada, southern England, Belgium, Australia, and Russia
  • Widespread black shales
    • were deposited over large areas of the craton
    • during the Late Devonian and Early Mississippian
  • The Mississippian Period was dominated for the most part by carbonate deposition
summary144
Summary
  • Transgressions and regressions
    • over the low-lying North American craton,
      • probably caused by advancing and retreating Gondwanan ice sheets,
    • resulted in cyclothems
    • and the formation of coals
    • during the Pennsylvania Period
summary145
Summary
  • Cratonic mountain building
    • specifically the Ancestral Rockies
    • occurred during the Pennsylvanian Period,
    • and resulted in thick nonmarine detrital rocks
    • and evaporites being deposited in the intervening basins
  • By the Early Permian,
    • the Absaroka Sea occupied a narrow zone of the south-central craton
    • Here, several large reefs and associated evaporites developed
summary146
Summary
  • By the end of the Permian Period, the Absaroka Sea had retreated from the craton
  • The Cordilleran mobile belt was the site of the Antler orogeny,
    • a minor Devonian orogeny
    • during which deep-water sediments were thrust eastward over shallow-water sediments
  • During the Pennsylvanian and Early Permian,
    • mountain building occurred in the Ouachita mobile belt
summary147
Summary
  • Ouachita tectonic activity
    • was partly responsible for the cratonic uplift
    • taking place in the southwest
    • resulting in the Ancestral Rockies
  • The Caledonian, Acadian, Hercynian, and Alleghenian orogenies
    • were all part of the global tectonic activity
    • that resulted in the assembly of Pangaea
summary148
Summary
  • During the Paleozoic Era,
    • numerous terranes, such as Avalonia, existed
    • and played an important role in the formation of Pangaea
  • Late Paleozoic-age rocks contain a variety of mineral resources
    • including petroleum, coal, evaporites,
    • silica sand, lead, zinc,
    • and other metallic deposits
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