ESCI 536 - Rocky Mountains FT Precambrian-Cambrian Stratigraphy & Paleogeography: North American...
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Transcript of ESCI 536 - Rocky Mountains FT Precambrian-Cambrian Stratigraphy & Paleogeography: North American...
ESCI 536 - Rocky Mountains FT
Precambrian-Cambrian Stratigraphy & Paleogeography:
North American Cordillera
February 3, 2010J. 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