Tectonic Framework of New York State Kurt Hollocher Union College Geology Department Talk given for the UCALL program Union College, Schenectady, NY April 3, 2007
New York State Geological Highway Map. Educational Leaflet No. 33
Outline for the talk Review of common rocks in NY Processes Sedimentary Igneous Metamorphic Review of rock age dating Review of plate tectonics Geologic historical outline of NY Summary
Processes that make rocks Sedimentary rocks Erosion Transport (rivers, wind, glaciers) Deposition Igneous rocks Melting to make liquid rock Transport of the liquid (dikes) Solidification (below ground, on the surface, in the air) Metamorphic rocks Change at high temperature and pressure New minerals grow Rock deforms
Sedimentary Conglomerate Sandstone Shale Limestone Igneous Volcanic Plutonic Metamorphic Rocks Metamorphosed sediments Metamorphosed igneous rocks
Conglomerate: rivers, beaches
Sandstone: rivers, beaches, dunes
Shale: river flood plains, quiet or deep ocean
Limestone: warm, shallow oceans
Sedimentary Conglomerate Sandstone Shale Limestone Igneous Volcanic Plutonic Metamorphic Rocks Metamorphosed sediments Metamorphosed igneous rocks
Explosive volcanics
Volcanic ash
Granite
Quieter eruptions
Lava flows
Gabbro
Anorthosite
Sedimentary Conglomerate SandstoneShale Limestone Igneous Volcanic Plutonic Metamorphic Rocks Metamorphosed sediments Metamorphosed igneous rocks
Quartzite from sandstone
Schist from shale
Marble from limestone
Gneiss from granite
Recrystallized anorthosite from anorthosite
Amphibolite from basalt
Metamorphic reactions: garnet around pyroxene in anorthosite
Metamorphic reactions: garnet in partially melted gneiss
Metamorphic reactions: garnet and other minerals from gabbro
Folds
Geologic time How do you tell how old things are? Sedimentary and volcanic rock layering. Crosscutting relationships. Radiometric age dating.
Relative geologic age from stacked layers
Crosscutting relationship: basalt dike cutting quartzite
Crosscutting relationship: faults cutting sandstones
Crosscutting relationship: erosion surface cutting gneiss
Absolute age from various radiometric clocks
Adirondacks Geology
Plate tectonics Mid-ocean ridges: new ocean crust formed Subduction zones: old ocean crust destroyed Transform faults
World earthquakes, volcanoes, and plate boundaries Source: NASA
Mid-ocean ridges and subduction zones Source: NOAA
Source: NASA Tibet India Continental collisions typically raise the highest mountains
New York State At last
Taconics, Berkshires, Green Mtns. Adirondacks Coastal plains Folded Appalachians Canadian Shield Sedimentary lowlands RV RV Appalachian Plateau Base map Andrew Birrell: http://birrell.org/andrew/reliefmaps/
New York State geologic map New York State Geological Highway Map. Educational Leaflet No. 33 Adirondacks Sedimentary lowlands Appalachian Plateau T a c o n i c s Folded Appalachians Coastal Plain Rift valley
Summary
New York State geologic map New York State Geological Highway Map. Educational Leaflet No. 33
Earthquakes 1990-2001 Map source: USGS
Map source: NOAA
Map source: NOAA 50% chance of volcanoes off the eastern seaboard Trench
References For this talk I used several references, including: Hamilton, M.A., McLelland, J., and Selleck, B., 2004, SHRIMP U-Pb zircon geochronology of the anorthosite-mangerite-charnockite-granite suite, Adirondack Mountains, New York: Ages of emplacement and metamorphism. Geological Society of America, Memoir 197, p. 337-355. Isachsen, Y.W., T.D. Mock, R.E. Nyahay, and W.B. Rogers, 1990, New York State Geological Highway Map. Educational Leaflet No. 33. 1:1,000,000, four-plate color sheet. Isachsen, Y.W., E. Landing, J.M. Lauber, L.V. Rickard, and W.B. Rogers, Editors, 2000, Geology of New York: A Simplified Account, Second Edition. Educational Leaflet No. 28., 284 p., 4 plates. Jaffe, H.W. and Jaffe, E.B., 1986, Geology of the Adirondack High Peaks Region: a Hiker s Guide. Adirondack Mountain Club, 201 p. McLelland, J.M., Bickford, M.E., Hill, B.M., Clechenko, C.C., Valley, J.W., and Hamilton, M.A., 2004, Direct dating of Adirondack massif anorthosite by U-Pb SHRIMP analysis of igneous zircon: Implications for AMCG complexes. Geological Society of America Bulletin, v. 116, p. 1299-1317. Van Diver, B., 1985, Roadside Geology of New York. Mountain Press Publishing Company, 411 p. I had to use my memory and experience for a lot of the material in this talk. Quite frankly, my fertile imagination filled in many parts. Constructive suggestions for improvement are welcome. Contact Kurt Hollocher, Union College Geology Department, Schenectady, NY, 12308, U.S.A.