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Chapter 11 – Late Paleozoic Events. 160 million years Three periods Devonian Mississippian Pennsylvanian Permian By the end of the Permian, Pangaea was completely assembled from the six plates that fled Rodina. The Seas Come In, The Seas Go Out.
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Chapter 11 – Late Paleozoic Events 160 million years Three periods Devonian Mississippian Pennsylvanian Permian By the end of the Permian, Pangaea was completely assembled from the six plates that fled Rodina
The Seas Come In, The Seas Go Out The end of the Early Paleozoic had much of North America above sea level and eroding. At the beginning of the Late Paleozoic the seas were advancing again depositing sediment over the old unconformity. Two Transgressions Kaskaskia transgression Absroka transgression
Kaskaskia Sequence – Oriskany Sandstone As sea level rose the Oriskany Sandstone of New York, Pennsylvania, Virginia, and West Virginia are deposited. Important glass sand. South of New York Contains tourmaline, zircon, and rutile and lacks fast weathering minerals. Reworked. New York Contains less resistant minerals Pyroxenes, hornblende, and biotite Derived from igneous or metamorphic minerals; not re-worked sedimentary rocks.
Chattanooga Shale Chattanooga Shale composed of silts and clays from erosion of Acadian highlands. Contains no fossils, but does contain pyrite and disseminated carbon indicating deposition in stagnant, oxygen-poor water. Later a thick deposit of limestones are deposited. Last great Paleozoic flooding of North America
Williston Basin South Dakota and Montana to Canada Arid climate reef-enclosed basins. Rock gypsum Rock salt Petroleum in reef limestones Important Canadian oil source
Paradox Basin Utah and Colorado Flooded by Absaroka Sea Early Pennsylvanian Thick beds of halite, gypsum and anhydrite (waterless gypsum)
To the East: A Clash of Continents Assembly of Pangaea Baltica collides with N.A. to form northern Appalachian Mtns. Avalon microcontinent collides with volcanic arc and then NW Africa to form the southern Appalachian Mtns.
The Catskill Clastic Wedge The tall, ancestral Appalachian Mtn’s are shedding sediments west (Catskill Clastic Wedge) and east (Devonian Old Red Sandstone). Important natural gas deposits in sandstones/shales.
