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A cratonic sequence (also known as megasequence, Sloss sequence or supersequence) in geology is a very large-scale lithostratigraphic sequence in the rock record that represents a complete cycle of marine transgression and regression on a craton (block of continental crust) over geologic time.
The sequence dates from the late Proterozoic through the early Ordovician periods, though the marine transgression did not begin in earnest until the middle Cambrian. [2] It is one of the most striking cratonic sequences in the geological record, spreading sheets of sandstone across basement rock deep into the interiors of many continents.
Cratons of South America and Africa during the Triassic Period when the two continents were joined as part of the Pangea supercontinent. A craton (/ ˈ k r eɪ t ɒ n / KRAYT-on, / ˈ k r æ t ɒ n / KRAT-on, or / ˈ k r eɪ t ən / KRAY-tən; [1] [2] [3] from Ancient Greek: κράτος kratos "strength") is an old and stable part of the continental lithosphere, which consists of Earth's two ...
The Tippecanoe sequence was the cratonic sequence or the marine transgression following the Sauk sequence; it extended from roughly the Middle Ordovician to the Early Devonian. The Tippecanoe is bound by two Unconformities , at the base by the Knox Unconformity, and at its top the Wallbridge Unconformity.
Laurentia basement rocks. Laurentia or the North American Craton is a large continental craton that forms the ancient geological core of North America.Many times in its past, Laurentia has been a separate continent, as it is now in the form of North America, although originally it also included the cratonic areas of Greenland and the Hebridean terrane in northwest Scotland.
Approximate location of Mesoproterozoic (older than 1.3 Ga) cratons in South America and Africa. The São Luís and Luís Alves cratonic fragments are shown. Gondwana and the Kuungan orogen. Listed by modern continent and Gondwana, include:
On a map showing only volcanic rocks, the west coast of North America shows a striking continuous north–south structure, the American Cordillera. The North American Cordillera extends up and down the coast of North America and roughly from the Great Plains westward to the Pacific Ocean , narrowing somewhat from north to south.
The Absaroka sequence was a cratonic sequence that extended from the end of the Mississippian through the Permian periods. There is an unconformity between the Absaroka and the lower Kaskaskia sequence. This unconformity divides the Carboniferous into the Mississippian and Pennsylvanian periods in North America.