UNIVERSITY OF SOUTH ALABAMA Last Time GY 111 Physical Geology Mountain Building 1 A Distribution of mountain belts the return of plate tectonics B Isostasy and the Rock Cycle again C Thrust Faults in the Rockies movie Lecture 31 Mountain Building 2 The Appalachians Mountain Belts Isostasy Isostacy The depression of the asthenosphere beneath mountain belts due to loading followed by rebounding as erosion occurs New Mountains Old Mountains Styrofoam sheets on water The Rock Cycle Faults on Maps There is a special class of reverse fault that is common in mountain belts Thrust Faults 1 Appalachian Mountains Today s Agenda Mountain Building 2 A Appalachian provinces Alabama B Paleozoic time frame orogenies C How to make a mountain belt Web notes 42 Appalachian Mountains Appalachian Provinces Four geological belts are identified We only see the first 3 in Alabama 1 Plateaus undeformed 2 Valley and ridge folded faulted 3 Piedmont Highly metamorphosed 4 Blue Ridge igneous intrusions 1 Plateaus undeformed 2 Valley and ridge folded faulted 3 Piedmont Highly metamorphosed Appalachian Provinces We only see the first 3 in Alabama When Era Period Permian 245 to 286 MA 1 Plateaus undeformed 2 Valley and ridge folded faulted 3 Piedmont Highly metamorphosed Pennsylvanian 286 to 320 MA Mississippian 320 to 362 MA Paleozoic Devonian 362 to 418 MA Time of origin of the Appalachian Mountains Silurian 418 to 441 MA Ordovician 441 to 505 MA Cambrian 505 to 550 MA NeoProterozoic Ediacaran 600 to 550 Ma What happened When did it happen 2 When Period North America Alleghenian Orogeny SE Permian Pensylvannian The Appalachian mountains were produced through the combination of 3 distinct mountain building events or orogenies Mississippian Devonian What Happened We need to consider Paleozoic paleogeography ancient distribution of continents oceans etc Acadian Orogeny E Silurian Ordovician Taconic Orogeny NE Cambrian Paleozoic Paleogeography Paleozoic Paleogeography Laurentia Paleozoic Paleogeography Paleozoic Paleogeography 3 Paleozoic Paleogeography Paleozoic Paleogeography Paleozoic Paleogeography Paleozoic Paleogeography Paleozoic Tectonics Taconic Orogeny Paleozoic Tectonics Taconic Orogeny Early Cambrian Period Permian North America Alleghenian Orogeny SE Laurentia Pennsylvannian Mississippian Devonian Acadian Orogeny E Mid Ordovician Silurian Baltica Ordovician Taconic Orogeny NE Cambrian Middle Ordovician 4 Paleozoic Tectonics Acadian Orogeny Paleozoic Tectonics Acadian Orogeny Silurian Period The next tectonic event the Acadian Orogeny was caused by the approach of Baltica Europe North America Alleghenian Orogeny SE Permian Laurentia Pennsylvannian A Mississippian Acadian Orogeny E Devonian B Silurian Baltica Devonian Taconic Orogeny NE Ordovician Cambrian Su n ctio bdu e zon s B A a Isl nd arc Baltica Baltica Late Ordovician Paleozoic Tectonics Alleghenian Orogeny Paleozoic Tectonics Alleghenian Orogeny Mississippian Period Lastly along comes Gondwanna and North America Alleghenian Orogeny SE Permian Pensylvannian well you get the idea Mississippian A Acadian Orogeny E Devonian B Subduction zone Penn Permian Silurian B Taconic Orogeny NE Ordovician B A Cambrian Mississippian http www jamestown ri info pangaea270 jpg Paleozoic Tectonics Alleghenian Orogeny Paleozoic Tectonics Alleghenian Orogeny Lastly along comes Gondwanna and Lastly along comes Gondwanna and well you get the idea well you get the idea A Su tur ez one B B B A Pennsylvanian B Pennsylvanian Suture zone 5 The End 6
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