Paleozoic Era. Continents in late Proterozoic Eon

Paleozoic Era

Continents in late Proterozoic Eon

Rodinia began breaking apart sometime during the late Proterozoic

By the beginning of the Paleozoic Era, six major continents were present

Each continent can be divided into two major components a craton and one or more mobile belts

Cratons and Mobile Belts

Transgressing and regressing shallow seas called epeiric seas Common feature of most Paleozoic cratonic

histories Cause unconformities

Continental glaciation as well as plate movement caused changes in sea level

Epeiric Seas

Four mobile belts formed around the margin of the North American craton during the Paleozoic

Franklin mobile belt Cordilleran mobile belt Ouachita mobile belt Appalachian mobile belt

Each was the site of mountain building in response to compressional forces convergent plate boundary formed such mountain ranges as the Appalachians

and Ouachitas

Four Mobile Belts

Paleozoic North America

• Mobile belts

At the beginning of the Paleozoic, six major continents were present Baltica - Russia west of the Ural Mountains and

the major part of northern Europe China - a complex area consisting of at least

three Paleozoic continents that were not widely separated and are here considered to include China, Indochina, and the Malay Peninsula

Gondwana - Africa, Antarctica, Australia, Florida, India, Madagascar, and parts of the Middle East and southern Europe

Six Major Paleozoic Continents

Kazakhstan - a triangular continent centered on Kazakhstan, but considered by some to be an extension of the Paleozoic Siberian continent

Laurentia - most of present North America, Greenland, northwestern Ireland, and Scotland

Siberia - Russia east of the Ural Mountains and Asia north of Kazakhstan and south Mongolia

Besides these large landmasses, geologists have also identified numerous small microcontinents and island arcs associated with various microplates

Six Major Paleozoic Continents

Major extinctions during Paleozoic

OrdovicianSilurianDevonianPermian

For the Late Cambrian Period

Paleogeography of the World

M&W, Fig. 21.1a

EARTH HISTORY PALEOZOIC LIFE

M&W, Fig. 21.1b

M&W, Fig. 21.1c

• In the earliest part of the Cambrian, a few small (several millimeters in size) shelly fossils are found, but then shortly afterwards life really “takes off” with larger animals with hard skeletons and shells.

Lapworthella, Australia.

Archaeooides, Northwest Territories, Canada.

An anabaritid, Northwest Territories, Canada.

M&W, Fig. 21.1a

EARTH HISTORY PALEOZOIC LIFE

• What advantages do SHELLS provide?

Lapworthella, Australia.

-Protection from predators

-Protection from UV light (allowing animals to move into shallower water)

-When the tide goes out, shelled organisms don’t dry out

-Shells provide structural support for larger and larger organisms to evolve

Early History—Paleozoic Era

Cambrian Period 543-490 mya

Trilobites, sponges, brachiopods live in oceans


Cambrian Period 543-490 mya

Global warming as Rodinia breaks up

Laurentia, Kazahkstan, Siberia move toward equator

Sea level rises as ice melts

Deposition of limestone common


Cambrian Period Ordovician Period

490-443 mya

Trilobites, corals, algae, brachiopods, molluscs, in complex reef systems

First lichens and bryophytes on land

Major extinction at end of period due to ice age


Cambrian Period Ordovician Period

490-443 mya

Laurentia begins to collide with Europe (mountain building)

Gondwana moves over pole

Land is cold and barren, warm tropical shallow marine near equator

Ice age toward end of Ordovician

For the Late Ordovician Period



Cambrian Period Ordovician Period Silurian Period 443-417 mya

Abundant life in ocean, coral reefs in shallow marine near equator

Jawless fish common Echinoderms and

molluscs flourish, trilobites begin to decline

First plants on land First terrestrial

arthropods


Cambrian Period Ordovician Period Silurian Period 443-417 mya

Gondwana moves more across south pole

Laurentia, Siberia, Baltica move toward each other at equator

Early Silurian glaciers melt and sea level rises toward end of Silurian (greenhouse effect)

For the Middle Silurian Period



Devonian Period 417-354 mya Many mountain building

events

Abundant marine life including bony fish

First sharks First ferns on land as

well as tree-like plants First tetrapods and

first terrestrial arthropods

Late Devonian extinction: 70% of invertebrate species (especially marine)

Map


Devonian Period 417-354 mya Many mountain building

events

Two supercontinents: Gondwana and Euramerica

Both continents slowly drift north

Map Map


Carboniferous Period 354-290 mya Missisippian (354-318

mya) Pennsylvanian (318-290

mya)

Fish expand in oceans, many molluscs, corals, few trilobites.

Forests and swamps with seed plants on land

Winged insects Early amphibians on

land.


Carboniferous Period 354-290 mya Many episodes of

mountain building

Inland seas reduced due to beginning collision of continents to form Pangaea

Ice develops over Gondwana due to climate change

Land dries due to changes in glaciation and Pangaea


Permian Period 290-248 mya

Life in oceans diminishes Predatory ammonites First vertebrate

herbivores on land. Reptiles common on

land Many insects on land Many gymnosperm

plants 90% of marine species

experience extinction at end of period (Pangaea, flood basalts in Siberia, impact)


Permian Period 290-248 mya Climate becomes dryer

Pangaea assembled, with only Chinas and Kazahkstan separated

Warming climate, dry interior of continent

Pangaea!

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Paleozoic Era. Continents in late Proterozoic Eon