Proterozoic

Making the Modern World

2500-543 Myrs

Era Age (Myrs) Epoch

0.01Holocene

1.8Pleistocene

5.3Pliocene

23.8Miocene

33.6Oligocene

54.8Eocene

65Paleocene

144

206

248

290

323

354

417

443

490

543

2500

3800

Precambrian

Phanerozoic

Eon

Proterozoic

Archean

Hadean

Period

Quaternary

Tertiary

Neogene

Paleocene

Mississippian

Cenozoic

Mesozoic

Paleozoic

Cretaceous

Jurassic

Age of the Earth 4600 Myrs (4.6 Byrs)Source: Geological Society of America (1999)

Geologic Time Scale

Devonian

Silurian

Ordivician

Cambrian

Triassic

Permian

Pennsylvanian

2500 Myr

1600 Myr

1000 Myr

Precambrian

Rocks of the Proterozoic& the Stories They Tell

Anatomy of a Continent

Orogenic(Mobile) Belt

Basement Rock

Precambrian Cratons:Shields and Platforms

CratonsShields

AndPlatforms

Canadian Shield

Orogenic (Mobile)

Belts

Orogenies= Mountian Building Events

Caused by:1. Collision - Fold and Thrust Mountains

Orogenies= Mountian Building Events

Caused by:2. Subduction - Volcanic (Arc) Mountains

Provinces of the NA

CratonA.K.A.

“The United Plates of

America”

Archean Basement

Proterozoic Basement

Orogenic (Mobile) Belts

Continental Growth

Proterozoic

Radioactive Heat Flow

Proterozoic

Grenville Orogony

(The building of Rodinia)

Archean Basement

Proterozoic Basement

Orogenic Belts

Rocks of the Grenville Orogeny1.2-1.0 Gyrs

Rodinia“Motherland”

Forms1.2-1.0 Grs

Montana

New York

Belt Supergroup, Montana West Coast of Laurasia

Mid Continental

Rift(1.3-1.0 Gyr)

Origin of aFailed Rift

Continental Rift

Keweenawan Supergroup, MIMesoproterozoic Rift Rocks

RodiniaRifts

(750 Myrs)

Montana

New York

Rifts to form the (pre-Pacific) PanthalassaOcean

Rifts to form the (pre-Atlantic) Iapetus Ocean

Rifting of Rodinia

Gondwana & Laurentia

About 500 Myr

Wilson Cycle

Atmospheric ChangesOxygen Increases: Carbon Dioxide Decreases

Proterozoic

Thanks to…

BIF’s(3.5-1.8 Gyrs)

Banded Iron Formation

92% Between2.5-2.0 Gyrs

Iron Source:Hydrothermal Vents

QuickTime™ and aVideo decompressor

are needed to see this picture.

Carol Lake Iron

Mine, Canada

Red Beds<1.8 Gyrs

After iron in the ocean was used up, it started to

accumulate in the atmosphere.

Oxygen Buildup occurs at the Same

Time as First Eukaryotes Appear

Atmospheric Changes:UV Protection

Reduced Amounts of Carbon Dioxide Made it Possible for…

Paleoproterozoic (2.2 Gyr)Gowganda Fm, Canada

Tillite

VarvesThe First Ice Age

Major“Ice Ages”

in Earth History

1

2

3

4

5

Glacial Evidence from Neoproterozoic Rock for Varangian Ice Age

NeoproterozoicSnowball Earth

Carbon Storage

Where Did All the Atmospheric Carbon Dioxide Go?

The Carbon Thermostat

Neoproterozoic (Varangian)Ice Age (800-600 Myr)

Tillite

Carbonates &

Ironstones

Snowball Earth

12C Signature

in Snowball Deposits

Carbon Isotopes & Snowball Earth

Why Banded Iron

Formations?

Ice Age Ends at the Same Time the First Multi-Celled Animals

Appear

Coincidence or not?