ESCI 536 - Rocky Mountains FT

Precambrian-Cambrian Stratigraphy & Paleogeography:

North American Cordillera

February 3, 2010

J. Morgan

Precambrian Crystalline

Basement & Belt Supergroup

(Stewart & Suczec, 1977)

2400-1500 m.y.

1500-900 m.y.

Diamictite & Volcanic

Sequences

(Stewart & Suczec, 1977)

900-800 m.y.

2400-1500 m.y.

1500-900m.y.

(Stewart & Suczec, 1977)

900-800m.y.

650-540m.y.

540-500m.y.Shallow water carbonates

Shallow water terrigenous sediments

Local diamictite, volcanics & more

Proterozoic basement

Belt supergroup (correlative)

Stratigraphy• PC: Crystalline rocks• UPC: Discontinuous, locally up

to 3000 m of diamictite, mudstone, sandstone, cgl, & mafic volcanics

• UPC-LC: Westward thickening wedge, locally > 6000 m, of terrigenous detrital rocks

• MC-UC: Predominantly shallow water carbonates, up to 2000 m thick

Belt Supergroup (N Cordielleran)

Precambrian & Cambrian Stratigraphy

(Stewart & Suczec, 1977)

Late Precambrian-Cambrian Evolution, Western NA

(Stewart & Suczec, 1977)

Late Precambrian rifting (850 m.a.)

Stratigraphy• PC: Crystalline rocks• UPC: Discontinuous, locally up

to 3000 m of diamictite, mudstone, sandstone, cgl, & mafic volcanics

• UPC-LC: Westward thickening wedge, locally > 6000 m, of terrigenous detrital rocks

• MC-UC: Predominantly shallow water carbonates, up to 2000 m thick

• Craton• Deposition in

local rift valleys

• Rapid erosion of uplifted rift margins

• Accumulation on subsided shallow-water shelf

Lower Paleozoic

Rifted Margin

Laramide Reactivation of Basement Structures

Inherited Structural Trends

Cotton-woodCanyon