2.2 A BILLION DOLLAR REEFChapter 2: A Tropical Alberta

OBJECTIVES• Learn the geology of the Ordovician, Silurian, and Devonian Periods

Study Alberta when it was submerged under warm, tropical seas

Use the locations of Alberta’s oil and gas to study the surrounding geology

Interpret drill-core data to create diagrams of subsurface rock formations

Learn how geologists use seismic waves to search for petroleum

WEALTH FROM ANCIENT SEASCambrian Period - life on Earth was aquaticOrdovincian Period

life moved from water onto land First fish with backbones First terrestrial plants Most of Alberta was under a tropical sea

that supported LARGE reefs of coral and sponges

o These reefs become the “containers” for the life that becomes our present day petroleum

MAKING PETROLEUMSilurian Period• Sponges and reefs continued to spread on the sea

floor• Primitive plants were colonized• First land-dwelling animals are become part of the

fossil record

Devonian Period• Reef building reached its max

MAKING PETROLEUM• For 200 million years organic matter fell to

the bottom of the sea• When the bacteria decomposed the

organic material, all oxygen and nitrogen was removed and carbon and hydrogen was left behind

• For another 380 million years, as the carbon and hydrogen was covered by sediment and exposed to heat and pressure the carbon and hydrogen matter turned into liquid hydrocarbons and was compressed into the holes of the reefs

MAKING PETROLEUM• The rock layers above

and below the hydrocarbon saturated reef were impermeable shale creating a • “Petroleum Trap”

FINDING PETROLEUM• In Alberta, the Devonian rock

containing petroleum was found 1 km below the surface of Earth• Drill Core Samples

• provided info on the type of rock below the surface

• Age of rocks if fossils are present• Environmental conditions

SEISMIC WAVES

• Waves that can travel through Earth and are reflected off each boundary between the rock layers• Geophones detect the seismic waves and converts them into signals• Seismographs process these signals and make a seismogram• Seismograms are used to identify possible traps that are then verified by

drilling

SUMMARY OF GEOLOGICAL TIME SCALE

1st land dwelling animals1st animals with backbones

1st land plants

Burgess Shale

Cambrian Explosion – aquatic life

Microscopic marine organisms become the source of Alberta’s Petroleum