Chapter 10

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Chapter 10 Early Paleozoic Events
The beginning of the Phanerozoic - 542 million
years before present Paleozoic - Ancient
Life Mesozoic - Middle Life Cenozoic - Late
Life Rodina has broken up into Laurentia,
Baltica, Kazakhstania, Siberia, China, and
Gondwana
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Early Paleozoic Timeline
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Dance of the Continents
Laurentia - North America, and parts of
Greenland, northwestern Ireland and
Scotland. Baltica - Russia west of Urals and
most of northern Europe. Kazakhstania - region
between the Caspian Sea and China Siberia -
Russia east of Urals and north of Mongolia
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Dance of the Continents continues
China - China, Indochina and the Malay
Peninsula. Gondwana - South America, Africa,
India, Australia, and Antarctica
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Neoproterozoic Plates
Most continents in southern hemi-sphere. Africa
traverses South Pole.
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Some Regions Tranquil, Others Active
Many shallow, warm, well-lite seas allowed for
diversification of life. These are rare
today. Cambrian equator was N-S across North
America. Large-scale folding with development of
broad domes and basins. Also rare today.
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North America During the Cambrian
East
West
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North America Basins and Domes
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Michigan Basin and Cincinnati Arch
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Identifying the Base of the Cambrian
Used to be easy. First shell-bearing
multicellular organisms. Trilobites. Then older
fossils were found. Oh no! Now defined
as Trichophycus
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Trichophycus
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Early Paleozoic Events
We know little of the ancient ocean basins. They
are all subducted. Sedimentary rocks demonstrate
that oceans spilled out of their basins and
covered much of the continents.
Limestone. Advance and retreat of the oceans are
the most important part of the Paleozoic
landscape and evolution of life.
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Cratonic Sequences The Seas Come In, The Seas Go
Out
Four major marine transgressions and regressions
define the Paleozoic. Sauk - Neoproterozoic to
Lower Ordovician Tippecanoe - Middle Ordovician
to Upper Silurian Kaskaskia - Lower Devonian
to Upper Mississippian Absaroka - Lower
Pennsylvanian to Jurassic
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Cratonic Sequences of North America
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The Sauk and Tippecanoe Sequences
Beginning of Sauk Transgression Sedimentation
restricted to continental margins. Continen
tal interiors are above sealevel and eroding.
No living organisms on land. Erosion rate
difference? Begins with deposition of broad
beach sand deposits. Grand Canyon
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Grand Canyon Rocks
Tapeats Sandstone Bright Angel Shale? ?
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Grand Canyon Transgression
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The Second Transgression
Close of Sauk Transgression resulted in much land
above sea-level and eroding. Disconformity. Tippe
canoe Transgression Ordovician-Silurian Deposit
ion of beach sands St. Peter
Sandstone Ultra-mature quartz ss Glass
manufacturing Many rock cycles Eroded
Sauk rocks
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St. Peter Sandstone
Pacific, Missouri 99.44 quartz
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Evaporites Mark the Seas Last Stand
Michigan Basin Silurian in age Halite and
gypsum Salina Group Up to 750 m
thick! Barred basin restricts sea water
input Organic reefs Raised
sill Submerged bar
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Barred Basin Model
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Michigan Basin Salt Face
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Way Out West Events in the Cordillera
Cordillera (N.A.) Nearly parallel mountain
ranges that extend from the Rockies to the
California Coast Ranges. Passive margin during
Paleozoic with much sedimentation. Continents
edge near Owens Valley. Burgess
Shale Unusual organisms Discussed in next
chapter
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Unusual Organism
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Orogeny Begins Out West
Pacific Plate begins to collide with North
America plate. Graywakes and volcanic
rocks. Silica rich volcanic ash results in
cherts. North Sierra Nevada overturned thrust
belt
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Paleozoic Cordillera
Pacific Plate North America Plate
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Deposition In the Far North
Thick Silurian limestones indicate tropic
climate.
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Dynamic Events in the East
Passive plate margin with broad continental shelf
gives way to active subduction zone (with
volcanoes) during Middle Ordovician. The
Taconic Orogeny begins. Partial closure of the
Iapetus Ocean (precursor to Atlantic) Various
terranes are sutured onto eastern North America.
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Taconic Orogeny
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Caledonian Orogenic Belt
Caledonia is the ancient name for Scotland. Part
of the Appalachian-Caledonian system. Extends
from Stone Mountain in the south to Spitzbergen
in the north. Sheds vast quantities of sediment
to the west to form the Queenston Wedge.
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Aspects of Early Paleozoic Climate
During Early Paleozoic time, Earth had similar
climate to today. Differences Earth spins
faster and had shorter days. Tidal effects were
stronger. No vascular plants on land. Higher
albedo