recall that:
- the Grenville orogeny apparently resulted in assembly of the supercontinent "Rodinia" about 1 b.y. ago
- Laurentia (ancestral North America) broke out of Rodinia about 600 to 700 m.y.; breakout apparently left behind and assembled the southern supercontinent "Gondwana" containing the cores of Africa, South America, Antarctica, India, and Australia
- passive margin subsidence yielded thick sequence of Upper Proterozoic and Lower Paleozoic sedimentary strata along the present day western Canada and the US east coast
but the entire continent was also being flooded during this time…
- Sauk Sequence: rising sea level in the Cambrian and Ordovician (probably due to fast seafloor spreading) flooded the Laurentian craton resulting in shallow marine deposition; sandstones gave way to shales then carbonates as the shoreline transgressed into the middle of the craton
- the transcontinental arch, running approximately from New Mexico to Greenland, probably remained a chain of islands above the maximum transgression
- the continents have been flooded periodically throughout the Phanerozoic. Transgressions yield thick sequences (Sauk, Tippecanoe, etc.) of shallow marine sediments on the craton and probably result from periods of fast seafloor spreading. Regressions cause major unconformities in the sedimentary record on the craton and probably occur when seafloor spreading is slow.
- the Taconic Orogeny in the Late Ordovician (deformation seen from New York to New Foundland) was probably caused by collision of an island arc or microcontinent
- immature sediments shed westward from the Taconic highlands resulted in a clastic wedge deposited in the Taconic foreland basin, thickest and coarsest near the source
- The Devonian Acadian Orogeny was the result of collision of Europe with northern portions of Laurentia (Greenland and Newfoundland) and added another permanent terrane to the eastern cratonic margin (the Avalon Terrane added portions of New England and Maritime Canada)
- this collision:
- Appalachian orogeny (also called Alleghenian orogeny) - Pennsylvanian-Permian collision of Africa and North America, as part of the collision of Laurussia and Gondwana, resulted in the emplacement of massive thrust sheets and widespread folding; this was the final phase of compressional deformation in the Appalachian region
Formation of Pangea
The upper Paleozoic (Penn-Perm) saw the collisions of
The collision between these three continental masses formed the supercontinent Pangea
These collisions resulted in the formation of several major mountain ranges:
- of course great clastic wedges were shed from the flanks of these mountain ranges