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Late Paleozoic Earth History


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Title: Late Paleozoic Earth History

Chapter 11
Late Paleozoic Earth History
Tully Monster
  • Tullimonstrum gregarium, also known as the Tully
    Monster is Illinoiss official state fossil
  • Specimen from Pensylvanian rocks, Mazon Cree
    Locality, Illinois
  • Reconstruction of the Tully Monster
  • about 30 cm long

Mazon Creek Fossils
  • Approximately 300 million years ago
  • in the region of present-day Illinois,
  • sluggish rivers flowed southwestward through
  • 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

Exceptional Preservation
  • The resulting fossils,
  • known as the Maxon 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
  • and many museums have extensive collections from
    the area

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
  • The swampy lowlands surrounding the delta were
    home to more than 400 plant species,
  • numerous insects,
  • including millipedes and centipedes, as well as
  • and other animals such as
  • scorpions and amphibians
  • In the ponds, lakes, and rivers were many
  • fish, shrimp, and ostracodes
  • 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 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
  • its scientific name
  • 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 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 Monster
  • There presently is no consensus
  • as to what phylum the Tully Monster belongs
  • or to what animals it might be related

Tully Monster
  • Tullimonstrum gregarium, also known as the Tully
    Monster is Illinoiss official state fossil
  • Specimen from Pensylvanian rocks, Mazon Cree
    Locality, Illinois
  • Reconstruction of the Tully Monster
  • about 30 cm long

Late Paleozoic Paleogeography
  • The Late Paleozoic was a time of
  • 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
  • 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

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
  • 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
  • For the Late Devonian Period

Paleogeography of the World
  • For the Early Carboniferous Period

Paleogeography of the World
  • For the Late Carboniferous Period

Paleogeography of the World
  • For the Late Permian Period

Reddish Fluvial Sediments
  • The erosion of the resulting highlands
  • provided vast amounts of reddish fluvial
  • that covered large areas of northern Europe
  • Old Red Sandstone
  • and eastern North America
  • the Catskill Delta

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
  • and the change from a passive continental margin
    to an active convergent plate boundary
  • in the Uralian mobile belt of eastern Baltica
  • These are probably related to the collision of
    Laurentia and Baltica

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
  • 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
  • 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
  • Because Gondwana rotated clockwise relative to
  • deformation of the two continents generally
    progressed in a northeast-to-southwest direction
  • the Hercynian,
  • Appalachian,
  • and Ouachita mobile belts
  • The final phase of collision between Gondwana and
  • is indicated by the Ouachita Mountains of
  • which were formed by thrusting
  • during the Late Carboniferous and Early Permian

Pangaea Began Taking Shape
  • Elsewhere, Siberia collided with Kazakhstania
  • and moved toward the Uralian margin of Laurasia
  • colliding with it during the Early Permian
  • The northwestern margin of China may have
  • collided with the southwestern margin of Siberia
  • during the Late Carboniferous
  • By the end of the Carboniferous,
  • the various continental landmasses were fairly
    close together
  • as Pangaea began taking shape

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
  • 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
  • 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 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
  • and continental blocks that composed the eastern
    half of Pangaea

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
  • 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
  • were high enough to create rain shadows
  • that blocked the moist, subtropical, easterly
  • much as the southern Andes Mountains do in
    western South America today

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
  • latitude 40 degrees to 60 degrees north
  • while the last remnants of the Carboniferous ice
    sheets retreated

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
  • Cratonic events largely resulted from changes in
    sea level due to
  • Gondwanan glaciation
  • and tectonic events related to the joining of

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
  • that resulted in the formation of Pangaea by the
    end of the Paleozoic Era

The Kaskaskia Sequence
  • The boundary between
  • the Tippecanoe sequence (discussed previously)
  • and the overlying Kaskaskia sequence
  • Middle Devonian-Middle 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
  • 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
  • Extent of the basal units of the Kaskaskia
    sequence in the eastern and north-central
    United States

Source Areas
  • The source areas for the basal Kaskaskia
  • 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
  • Paleogeography of North America during the
    Devonian Period

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 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
  • 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
  • The Middle and Late Devonian-age reefs of western
  • 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
  • By the end of the Middle Devonian,
  • the reefs had coalesced into a large barrier-reef
  • that restricted the flow of oceanic water into
    the back-reef platform,
  • thus creating conditions for evaporite
  • 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
  • Reconstruction of the extensive Devonian Reef
    complex of western Canada
  • These reefs controlled the regional facies of the
    Devonian epeiric seas

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
  • 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

Increased Detrital Deposition
  • Deposition of black shales
  • was brought on by the the Acadian orogeny

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
  • The extent of the upper Devonian and Lower
    Mississippian Chattanooga Shale and its
    equivalent units
  • such as the Antrion Shale and the Albany Shale

New Albany Shale
  • Upper Devonian New Albany Shale,
  • Button Mold Knob Quarry, Kentucky

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
  • Although the origin of these extensive black
    shales is still being debated,
  • the essential features required to produced them
  • 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
  • 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
  • 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 were 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
  • Paleogeography of North America during the
    Mississippian Period

Mississippian Carbonates
  • These Mississippian carbonates display
  • cross-bedding, ripple marks, and well-sorted
    fossil fragments,
  • all of which are indicative of a shallow-water
  • Analogous features can be observed on the
    present-day Bahama Banks
  • In addition, numerous small organic reefs
  • occurred throughout the craton during the
  • These were all much smaller than the large
    barrier-reef complexes
  • that dominated the earlier Paleozoic seas

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
  • Prior to the end of the Mississippian,
  • the Kaskaskia 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
  • includes rocks deposited
  • during the latest Mississippian
  • 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
  • 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
  • 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
  • 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
  • through transitional marine-nonmarine beds,
  • to largely marine detrital rocks and limestones
    farther west

Pennsylvanian Period
  • Paleogeography of North America during the
    Pennsylvanian Period

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
  • 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
  • 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

  • Columnar section of a complete cyclothem

Pennsylvanian Coal Bed
  • Pennsylvanian coal bed, West Virginia
  • part of a cyclothem

Coal-Forming Swamp
  • Reconstruction of the environment of a
    Pennsylvanian coal-forming swamp

The Okefenokee Swamp
  • in Georgia, is a modern coal-forming environment,

similar to those occurring during the
Pennsylvanian Period
Marine Units of a Cyclothem
  • Next the marine units consist of alternating
  • limestones and shales,
  • usually with an abundant marine invertebrate
  • The marine cycle ends with an erosion surface
  • A new cyclothem begins with a nonmarine deltaic
  • All the beds illustrated in the idealized
    cyclothems are not always preserved because of
  • abrupt changes from marine to nonmarine
  • or removal of some units by erosion

  • Columnar section of a complete cyclothem

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
  • 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
  • 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
  • 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
  • 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
  • a swamp-delta complex of low relief near the sea
  • by
  • rapid but slight changes in sea level
  • or by localized crustal movement
  • Explaining widespread cyclothems is more difficult

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
  • 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
  • During the Late Absaroka (Pennsylvania),
  • 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
  • Location of the principal Pennsylvanian highland
    areas and basins of the southwestern part of the

Ancestral Rockies
  • Block diagram of the Ancestral Rockies, which
    were elevated by faulting during the
    Pennsylvanian Period
  • Erosion of these mountains produced
  • coarse red sediments
  • that were deposited in the adjacent basins

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,

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 are unusual,
  • and their cause has long been debated
  • It is thought that the collision of Gondwana with
  • 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 Late Absaroka
  • More Evaporite Deposits and Reefs
  • While the various intracratonic basins
  • were filling with sediment
  • during the Late Pennsylvanian,
  • the Absaroka Sea slowly began retreating from the
  • During the Early Permian,
  • the Absaroka Sea occupied a narrow region
  • from Nebraska through west Texas

Permian Period
  • Paleogeography of North America during the
    Permian Period

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
  • provide evidence of the restricted nature of the
    Absaroka Sea
  • during the Early and Middle Permian
  • and its southwestward retreat from the central

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
  • Location of the west Texas Permian basins and
    surrounding reefs

Massive Reefs
  • Massive reefs grew around the basin margins
  • while limestones, evaporites, and red beds were
  • 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
  • Reconstruction of the Middle Permian Capitan
    Limestone reef environment
  • Shown are brachiopods, corals, bryozoans and
    large glass sponges

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
  • 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
  • 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
  • During the Late Proterozoic and Early Paleozoic,
  • the Cordilleran area was a passive continental
  • 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
  • A collision between
  • this eastward-moving island arc
  • and the western border of the craton
  • took place during the Late Devonian and early
  • resulting in a highland area
  • This orogenic event,
  • the Antler orogeny,
  • was caused by subduction
  • and resulted in the closing of the narrow ocean
  • that separated the island arc from the craton

Antler Highlands
  • Reconstruction of the Cordilleran mobile belt
    during the Early Mississippian
  • in which deep-water continental slope deposits
  • were thrust eastward
  • over shallow-water continental shelf carbonates
  • forming 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
  • 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
  • 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
  • During the Late Proterozoic to Early
  • 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 Belt
  • Plate Tectonic model for the deformation of the
    Ouachita mobile belt
  • Depositional environment prior to the beginning
    of orogenic activity

Ouachita Mobile Belt
  • Incipient continental collision between
    North America and Gondwana began during
    the Mississippian to Pennsylvanian

Ouachita Mobile Belt
  • Continental collision continued during the
    Pennsylvanian Period

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
  • most of which was eroded during the Mesozoic Era
  • Only the rejuvenated Ouchita and Marathon
    Mountains remain of this once lofty mountain range

Three Continuous Mobile Belts
  • The Ouachita deformation
  • was part of the general worldwide tectonic
  • 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
  • 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 between the
  • 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
  • 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
  • off the east coast of Laurentia (North America)

Caledonian Orogeny
  • The culmination of the Caledonian orogeny
  • occurred during the Late Silurian and Early
  • with the formation of a mountain range
  • along the western margin of Baltica

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
  • As with the preceding Taconic and Caledonian
  • 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
  • As the increased metamorphic and igneous activity
  • 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
  • And, just as with the Taconic orogeny,
  • deep-water sediments
  • were folded and thrust northwestward,
  • producing angular unconformities
  • separating Upper Silurian from Mississippian rocks

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
  • contains nearly three times as much sediment as
    the Queenston Delta

Catskill Delta Clastic Wedge
  • Area of collision between Laurentia and Baltica
  • The Catskill Delta clastic wedge
  • and the Old Red Sand-stone
  • are bilaterally symmetrical
  • and derived their sediments
  • from the Acadian and Caledonian Highlands

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
  • to Ohio,
  • where the deltaic facies are only about 100 m
  • and consist of cratonic shales and carbonates

Catskill Delta Red Beds
  • The red beds of the Catskill Delta
  • derive their color from the hematite found in the
  • Plant fossils and oxidation of the hematite
  • that the beds were deposited in a continental

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
  • contains numerous fossils of
  • freshwater fish,
  • early amphibians,
  • and land plants

Old Red Sandstone
  • Old Red Sandstone on one side
  • and the Catskill Delta on the other

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
  • The Taconic, Caledonian, and Arcadian 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
  • 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
  • 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
  • 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

  • These three Late Paleozoic orogenies
  • Hercynian,
  • Alleghenian,
  • and Ouachita
  • represent the final joining of Laurasia and
  • into the supercontinent Pangaea
  • during the Permian

What Role Did Microplates Play 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
  • However, accretion along the continental margins
  • is more complicated than the somewhat simple,
  • large-scale plate interactions discussed here

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
  • In this chapter and the previous one,
  • 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

  • For example, the small continent 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
  • The Avalon microplate
  • existed as a separate continent
  • during the Ordovician
  • and began to collide with Baltica
  • during the Silurian
  • and Laurentia
  • as part of Baltica
  • during the Devonian

Numerous Microplates
  • Florida and parts of the eastern seaboard of
    North America
  • make up the Piedmont microplate
  • that was part of the larger Gondwana continent
  • This microplate became sutured to Laurasia
  • during the Pennsylvanian Period
  • Numerous microplates occupied the region between
    Gondwana and Laurasia
  • that eventually became part of Central America
  • during the Pennsylvanian collision between these

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 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-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

  • For example, 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
  • Although Permian-age coal beds
  • are known for 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

U.S. Coal Deposits
  • The age of the coals in the Midwestern states and
  • Appalachian region are mostly Pennsyl-vanian
  • whereas those in the west are mostly Cretaceous
    and Tertiary

Bituminous Coal
  • Much of the coal is characterized as bituminous
  • 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

  • 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

Evaporite and Gas
  • A variety of Late Paleozoic-age evaporite
    deposits are important nonmetallic mineral
  • 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
  • and parts of the North Sea region

More Nonmetal Resources
  • Other important evaporite mineral resources
  • those of the Permian Delaware Basin of west Texas
    and New Mexico
  • and Devonian evaporites in the Elk Point basin of
  • In Michigan, gypsum is mined and used in the
    construction of wallboard
  • 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

Silica Sand
  • For example, silica sand from
  • the Devonian Ridgely Formation is mined in West
    Virginia, Maryland and Pennsylvania
  • and the Devonian Sylvania Sandstone is mined near
    Detroit, Michigan
  • 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
  • and for a variety of other uses

  • 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 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

  • 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
  • resulting in global sea level changes
  • and transgressions and regressions
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