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NARROW
GeoRef Subject
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all geography including DSDP/ODP Sites and Legs
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Canada
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Ontario
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Invertebrata
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Articulata
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Vermes (1)
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Tertiary
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Paleozoic
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lower Paleozoic
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Cape Phillips Formation (1)
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Ordovician
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Beekmantown Group (1)
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Prairie du Chien Group (2)
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Middle Ordovician
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Bromide Formation (1)
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Chazy Group (1)
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Platteville Formation (1)
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Trenton Group (3)
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Upper Ordovician
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Maquoketa Formation (1)
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Neda Formation (1)
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Queenston Shale (1)
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Trentonian (2)
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Utica Shale (1)
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Silurian
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Bainbridge Formation (4)
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Lockport Formation (32)
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Lower Silurian
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Alexandrian (1)
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Brassfield Formation (1)
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Grimsby Sandstone (1)
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Llandovery (4)
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Clinton Group (5)
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Guelph Formation (2)
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Keefer Sandstone (2)
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McKenzie Formation (1)
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Racine Dolomite (16)
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Rochester Formation (2)
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Waldron Shale (3)
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Niagaran (105)
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Upper Silurian
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Cayugan (3)
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upper Paleozoic
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minerals
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sulfates
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Primary terms
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bibliography (1)
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Canada
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Ontario
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Quebec
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Nunavut
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Queen Elizabeth Islands
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Western Canada
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Northwest Territories (2)
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carbon
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C-13/C-12 (3)
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organic carbon (1)
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Cenozoic
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Quaternary
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Pleistocene
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upper Pleistocene
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Wisconsinan (1)
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Tertiary
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Paleogene
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upper Eocene
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coal deposits (1)
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Graptolithina
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Invertebrata
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Phacopida (2)
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Brachiopoda
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Articulata
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Pentamerida
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Pentameracea (1)
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Bryozoa
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Trepostomata (1)
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Cnidaria
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Anthozoa (8)
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Hydrozoa (1)
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Echinodermata
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Crinozoa
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Crinoidea (10)
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Cystoidea (1)
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Mollusca
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Bivalvia
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Cyrtodontida (1)
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Cephalopoda (2)
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Gastropoda (2)
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Porifera
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Stromatoporoidea (6)
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Protista
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Foraminifera (3)
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Vermes (1)
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isostasy (1)
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isotopes
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stable isotopes
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C-13/C-12 (3)
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O-18/O-16 (2)
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Pb-206/Pb-204 (1)
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Pb-208/Pb-204 (1)
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North America
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Great Lakes region (12)
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Michigan Basin (25)
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Niagara Escarpment (1)
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oceanography (1)
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oil and gas fields (10)
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orogeny (1)
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oxygen
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O-18/O-16 (2)
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paleobotany (1)
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paleoclimatology (1)
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paleoecology (14)
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paleogeography (9)
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paleomagnetism (1)
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paleontology (24)
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Paleozoic
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Cambrian
-
Upper Cambrian
-
Eau Claire Formation (1)
-
-
-
Devonian
-
Lower Devonian (1)
-
Middle Devonian
-
Detroit River Group (1)
-
Onondaga Limestone (2)
-
Sylvania Formation (1)
-
Tully Limestone (1)
-
-
-
lower Paleozoic
-
Cape Phillips Formation (1)
-
-
Ordovician
-
Lower Ordovician
-
Beekmantown Group (1)
-
Prairie du Chien Group (2)
-
-
Middle Ordovician
-
Bromide Formation (1)
-
Chazy Group (1)
-
Platteville Formation (1)
-
-
Trenton Group (3)
-
Upper Ordovician
-
Maquoketa Formation (1)
-
Neda Formation (1)
-
Queenston Shale (1)
-
Trentonian (2)
-
-
Utica Shale (1)
-
-
Silurian
-
Bainbridge Formation (4)
-
Lockport Formation (32)
-
Lower Silurian
-
Alexandrian (1)
-
Brassfield Formation (1)
-
Grimsby Sandstone (1)
-
Llandovery (4)
-
Wenlock (12)
-
-
Middle Silurian
-
Clinton Group (5)
-
Guelph Formation (2)
-
Keefer Sandstone (2)
-
McKenzie Formation (1)
-
Racine Dolomite (16)
-
Rochester Formation (2)
-
Waldron Shale (3)
-
-
Niagaran (105)
-
Upper Silurian
-
Cayugan (3)
-
Ludlow (7)
-
Salina Group (5)
-
-
-
upper Paleozoic
-
Antrim Shale (1)
-
-
-
paragenesis (1)
-
petroleum
-
natural gas (18)
-
-
petrology (1)
-
Phanerozoic (1)
-
Plantae
-
algae
-
Chlorophyta
-
Chlorophyceae
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Dasycladaceae (2)
-
-
-
-
-
problematic fossils (1)
-
reefs (43)
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sea-level changes (5)
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sedimentary petrology (19)
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sedimentary rocks
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boundstone (2)
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dolostone (15)
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limestone
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micrite (1)
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microbialite (1)
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chemically precipitated rocks
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clastic rocks
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shale (2)
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coal (1)
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sedimentary structures
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bedding plane irregularities (1)
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biogenic structures
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bioherms (3)
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bioturbation (1)
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stromatolites (4)
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soft sediment deformation (1)
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sedimentation (11)
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sediments
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clastic sediments
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silicon (1)
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slope stability (1)
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stratigraphy (13)
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structural analysis (2)
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structural geology (4)
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sulfur
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S-34/S-32 (1)
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tectonics (3)
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thallophytes (4)
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tunnels (1)
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United States
-
Allegheny Plateau (1)
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Cincinnati Arch (2)
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Eastern U.S. (2)
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Florida
-
Florida Keys
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Key Largo (1)
-
-
Monroe County Florida
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Key Largo (1)
-
-
-
Hudson River (1)
-
Illinois
-
Cook County Illinois
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Chicago Illinois (1)
-
-
DuPage County Illinois (1)
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Jersey County Illinois (1)
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Kankakee County Illinois (1)
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Will County Illinois (2)
-
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Indiana (11)
-
Kentucky
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Johnson County Kentucky (1)
-
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Michigan
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Michigan Lower Peninsula
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Benzie County Michigan (1)
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Grand Traverse County Michigan (1)
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Kalkaska County Michigan (1)
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Macomb County Michigan (4)
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Manistee County Michigan (1)
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Otsego County Michigan (2)
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Saint Clair County Michigan (1)
-
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Michigan Upper Peninsula
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Chippewa County Michigan (1)
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Delta County Michigan (1)
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Mackinac County Michigan (1)
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Schoolcraft County Michigan (1)
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Midwest (3)
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Mississippi
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Hinds County Mississippi (1)
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Missouri
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Perry County Missouri (1)
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New Jersey
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Mercer County New Jersey
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Trenton New Jersey (1)
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New York
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Cattaraugus County New York (1)
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Chautauqua County New York (1)
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Monroe County New York (2)
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Niagara County New York (7)
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Oneida County New York (2)
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Orleans County New York (1)
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Wayne County New York (1)
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Ohio
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Mercer County Ohio (1)
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Oklahoma (1)
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Tennessee
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West Virginia
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Wisconsin
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Grant County Wisconsin (1)
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Wyoming (1)
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USSR (1)
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well-logging (5)
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rock formations
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Medina Formation (1)
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sedimentary rocks
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sedimentary rocks
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carbonate rocks
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boundstone (2)
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dolostone (15)
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limestone
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micrite (1)
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microbialite (1)
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wackestone (3)
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chemically precipitated rocks
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chert (2)
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evaporites (7)
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Niagaran
A comparison of carbon dioxide storage resource estimate methodologies for a regional assessment of the Northern Niagaran Pinnacle Reef Trend in the Michigan Basin
A new sequence stratigraphic model for the Silurian A-1 Carbonate (Ruff Formation) of the Michigan Basin
ABSTRACT The A-1 Carbonate is the primary hydrocarbon source rock and an important reservoir component of the Silurian (Niagaran) pinnacle reef complexes in the Michigan Basin. The geology of the A-1 Carbonate, however, is not widely known because the majority of published research about this hydrocarbon system focuses on the pinnacle reefs. To gain a better understanding of the sedimentology and stratigraphy of the A-1 Carbonate, we integrated data from slabbed core, thin section petrography, gamma-ray logs, and energy-dispersive X-ray fluorescence spectrometry (ED-XRF). Thirteen distinct lithofacies within the A-1 Carbonate are recognized, with inferred depositional environments ranging from intertidal-sabkha to deep basin. The recognition of deep-water lithofacies contrasts significantly with previous interpretations of the A-1 Carbonate as a shallow, peritidal deposit. Lithofacies stacking patterns and ED-XRF elemental trends within the A-1 Carbonate are consistent with basinwide sea-level fluctuations that resulted in deposition of three major stratigraphic units, called the Lower A-1 Carbonate, Rabbit Ear Anhydrite, and Upper A-1 Carbonate. The basal part of the Lower A-1 Carbonate was deposited during a basinwide transgression, as evidenced by deep-water pelagic carbonate accumulation in the basin center, lithofacies that become progressively muddier from bottom to top, and higher concentrations of Si, Al, and K upward, which are interpreted to reflect the influx of continental sediments. The subsequent highstand deposits of the upper part of the Lower A-1 Carbonate are characterized by a decrease in Si, Al, and K, coupled with a shallowing-upward facies succession consistent with increased carbonate production rates. The Rabbit Ear Anhydrite, which bifurcates the Upper and Lower A-1 Carbonate units, exhibits a variety of anhydrite fabrics across a wide range of paleotopographic settings within the basin. The Rabbit Ear Anhydrite is interpreted to reflect a time-correlative sea-level drawdown, which caused basin restriction, gypsum deposition, and elevated concentrations of redox-sensitive elements, such as Mo and Ni. The Upper A-1 Carbonate represents sedimentation during another major basinwide transgression that culminated in the deposition of shallow-water microbialites on the crests of previously exposed Niagara reef complexes. Similar to the Lower A-1 Carbonate, the base of the Upper A-1 Carbonate exhibits elemental signatures indicative of continental influence, whereas the overlying highstand deposits are characterized by more normal marine conditions and lower concentrations of Si, Al, and K.
Utilizing sequence stratigraphy to develop a depositional model for Silurian (Niagaran) reefs in the Michigan Basin
ABSTRACT Based upon the construction of a high-resolution sequence stratigraphic framework, this paper interprets the evolution of Niagaran (Silurian) reefs in the Michigan Basin as being characterized by episodic reef growth in response to three distinct, third-order-scale, eustatic sea-level fluctuations. The fluctuations are observed in both the northern and southern reef trends and are interpreted to coincide with Silurian eustatic sea-level fluctuations defined at a global scale. The resulting episodic reef growth model, based upon subsurface core and wireline log analysis, is characterized by at least two orders of stratigraphic cyclicity (probably third and fourth order) that likely formed in response to eustatic sea-level change as well as relative sea-level variations. A detailed sequence stratigraphic analysis of the reefs utilizing facies stacking patterns and identification of key surfaces highlights the punctuated growth of these reefs and provides insight into the lateral and vertical facies variability observed in the subsurface. The sequence hierarchy is manifested by thicker (third- and fourth-order) sequences (tens of meters thick) controlled by globally recognized sea-level changes, and thinner (fifth-order) cycles (few meters thick) driven by relative sea-level variations. Local changes in relative sea level were likely controlled by the combination of higher-frequency eustatic variations along with subsidence and autocyclic mechanisms related to reef growth. The higher-frequency (fourth-order) cyclicity, likely due to eustatic sea-level change, played a major role in controlling the lateral and vertical heterogeneity of reservoir facies in these reefs. Understanding of the growth of these reefs utilizing a modern sequence stratigraphic approach provides new insight into the development of the Niagaran reefs while providing evidence for a complex and episodic depositional model that explains the variability observed in the stratigraphic architecture of these reefs.
ABSTRACT Silurian-age (Niagaran) reefs in the Michigan Basin have long been interpreted as relatively homogeneous units, despite production histories that strongly suggest the reefs are heterogeneous in both lateral and vertical dimensions. In an attempt to better illustrate reservoir heterogeneity in these reefs, a three-dimensional (3-D) sequence stratigraphic model was produced for the Ray Reef field. The resulting 3-D Petrel model incorporates 28 wells in the field using a combination of gamma-ray and neutron logs, porosity and permeability data from whole-core analysis, and facies descriptions from eight cores evenly distributed within the reef complex. Comparison of porosity and permeability values within the diverse depositional facies clearly shows trends related to the individual facies and positioning within the sequence hierarchy. Incorporation of the sequence stratigraphic framework into the 3-D model illustrates the episodic nature of reef growth as exhibited by the stacked nature of reef and capping grainstones, often separated by well-developed exposure horizons. The model also suggests a distinct difference between windward and leeward margins in both the geometry of the reef complex and the distribution of reservoir-prone facies. Windward margins are steeper due to higher rates of aggradational growth, and they typically contain higher percentages of reservoir-quality rock in both the reef core and forereef facies. Utilization of the sequence stratigraphic approach illustrates that the vertical reservoir heterogeneity often predicted from production in these reefs may be controlled in large part by the combination of vertical stacking patterns of facies within third- and fourth-order sequences.
ABSTRACT Despite extensive research on Silurian (Niagaran–Wenlockian) reefs, most studies concerning faunal abundance and distribution have been qualitative studies with an emphasis on taxonomy, paleoecology, and evolution. This study is the first quantitative study of relative abundance and distribution of fauna throughout a single Wenlockian reef located in the southern trend of the Michigan Basin. Building on an established sequence stratigraphic framework with wind directions surmised from known paleogeographic location, the purpose of this study was threefold: (1) to quantitatively determine the relative abundances of fauna from subsurface cores of Ray Reef and show how they are tied to the established sequence stratigraphic framework; (2) to determine if the probable wind and current directions, along with water depth, influenced the morphology and distribution of fauna on the reef; and (3) to analyze the influence of wind and current on syndepositional marine cementation. Relative faunal abundance differed among the leeward, windward, and reef crest locations. Overall faunal density was highest in the crest and lowest along the leeward side of the reef complex. Diversity was highest in the crestal portion of the reef complex and in the reef core facies, in general. Changes in faunal morphology and community replacement were seen repeatedly through all cores in association with shallowing-upward conditions, which coincided with third-order stratigraphic and higher-frequency sequence stratigraphic cyclicity. The percentage of syndepositional marine cement was highest on the windward side and lowest on the leeward side. As has been reported in other reef complexes of varying geological ages, results of this study indicate that the core of the Silurian reef was composed mostly of rubble or debris, relative to the smaller proportion of in situ fauna.
Modeling scattering and intrinsic attenuation of crosswell seismic data in the Michigan Basin
A NEW FACIES ARCHITECTURE MODEL FOR THE SILURIAN NIAGARAN PINNACLE REEF COMPLEXES OF THE MICHIGAN BASIN
Abstract The Niagara-Lower Salina reef complex reservoirs of the Michigan Basin host significant hydrocarbon volumes and have recently been identified as promising targets for enhanced oil recovery and carbon sequestration. Although these carbonate buildups have been studied extensively since the late 1960s, there is still wide uncertainty and disagreement concerning their morphology and internal stratigraphic and facies architecture. The prevailing paradigm depicts the reef complexes as tall, symmetric “pinnacles” with heterogeneous internal facies distributions that are patchy and unpredictable. The current study challenges this model of the reefs by examining four Silurian reef reservoirs with abundant core and petrophysical wire-line logs. New and existing subsurface data show that Silurian reefs in the Michigan Basin are highly asymmetric with internal facies distribution patterns that are strongly influenced by east-northeast paleowind direction. Six major depositional environments are identified during the main stage of reef complex growth based on sedimentological characteristics observed in core, as well as the vertical progression (stacking) of facies observed both in core and wire-line log signatures. A central reef core environment is identified based on interspersed coral-stromatoporoid boundstone and skeletal wackestone facies consisting of frame-building organisms such as tabulate corals and stromatoporoids, as well as intrareef faunal assemblages of bryozoans, brachiopods, crinoids, and rugose corals. Environments to the east (windward) of the central reef core are steeply inclined to the east (~40°) with narrow facies belts characterized by coarse reef talus. In contrast, environments to the west (leeward) of the central reef core have shallower slopes that dip to the west (< 15°) and are characterized by wide facies belts composed of carbonate mud and skeletal debris that become finer and thinner in the leeward direction. Application of this new Silurian reef model to reef complexes throughout the basin demonstrates remarkable consistency with respect to the overall asymmetric shape of the reef complexes, as well as the windward-leeward internal facies architecture. The asymmetric architecture and windward-leeward facies distribution patterns described in the new model offer a significant improvement upon preexisting models for Silurian reefs in the Michigan Basin and more accurately reflect our modern understanding of how environmental controls affect reef development and architecture. Furthermore, this new reef model can be used to more accurately predict the shape and internal facies distributions for other Silurian reef complex reservoirs within the Michigan Basin, particularly those that lack abundant well control.
Abstract Existing subsurface data and data from core and logs in a new CO 2 pilot injection test well drilled in northern lower Michigan were used to evaluate the geological carbon sequestration (GCS) potential in Upper Silurian to Middle Devonian saline reservoir and cap-rock units in the Michigan Basin. The Core Energy-State Charlton #4-30 well, Otsego County, Michigan, was drilled as part of ongoing Midwest Region Carbon Sequestration Partnership (MRCSP) phase II studies to investigate GCS potential in these units in the Michigan Basin. Significant GCS potential is recognized in porous dolomite of the Upper Silurian, Bass Islands Group in the new well. Cherty strata of the Bois Blanc Formation are also present in the #4-30 well but may lack suitable injectivity for consideration of GCS. Argillaceous limestone in parts of the superjacent Amherstburg Formation in the test well contains minimal porosity and permeability and constitutes an excellent cap-rock unit in the area. Regional consideration of the Bass Islands sequestration target interval indicates substantial GCS potential throughout most of the Michigan Basin. Preliminary estimates of regional GCS storage capacity range from 1.34 billion metric tonnes at 2% displacement storage efficiency to 6.7 billion metric tonnes of CO 2 at 10% storage efficiency in the study area. These displacement storage capacities equate to approximately 288–1440 t of CO 2 per hectare (117–583 t/ac) given the regional estimates of average thickness and porosity in the target interval used here. Significant drilling fluid loss into the target injection interval observed during drilling of the State Charlton #4-30 well of about 3.2 m 3 /hr (20 bbl/hr) demonstrates substantial injectivity in the pilot test well. Considering the fluid loss during drilling and measurements of conventional petrophysical properties in the injection target, the proposed CO 2 injection test volume of 10,000 t could fill the target interval in an area of at most 35 ha (86 ac) in the subsurface, depending on displacement storage volume efficiency assumptions. These preliminary assumptions and simple calculations indicate that the CO 2 injection plume for the injection test would extend no more than 600 m (1970 ft) away from the borehole in all directions. Preliminary reservoir simulations, using other assumptions, suggest a substantially less extensive invasion of the target interval during the injection test.
Abstract As oil imports in the United States approach 60% of total daily consumption, more efforts are being expended to maximize recovery from known domestic oil fields. As part of this effort, CO 2 flooding of reservoirs has been proven to be an effective means to increase the recovery of oil bypassed during primary production, albeit commonly at significant cost because of capture, compression, and transportation of adequate CO 2 . At the same time, global and national interest in the viable geological sequestration of anthropogenic CO 2 , a major greenhouse gas when emitted into the atmosphere, is also becoming more significant. In the Michigan Basin, the juxtaposition of the Devonian Antrim Shale natural gas trend, one that contains high levels of associated CO 2 , with the mature Niagaran (Silurian) reef oil play, characterized by reservoirs with high percentages of stranded oil, may provide an economically viable model to combine enhanced oil recovery (EOR) efforts with the geological sequestration of CO 2 . Niagaran pinnacle reefs in the Michigan Basin have produced more than 450 MMBO since the late 1960s. Because of the complex heterogeneity of the reef reservoirs, however, primary production averages only around 30% with secondary waterflood programs typically capturing an additional 12%. The northern reef trend in the Michigan Basin comprises an immense hydrocarbon resource, located in hundreds of closely spaced but highly compartmentalized reef fields in northern lower Michigan. These geologically complex carbonate reef reservoirs present not only significant opportunity for EOR operations because of known traps, quantifiable remaining oil, existing infrastructure, and very few secondary recovery projects to date, but also great challenges to modeling for maximum sweep efficiencies and recovery factors during miscible CO 2 -EOR projects. In the northern reef trend, a local source for subsequent CO 2 flooding is readily available as a by-product of Antrim Shale production. The annual production of CO 2 separated from Antrim gas is approximately 21 bcf, most of which is currently vented directly into the atmosphere. The close proximity of a source of high-quality CO 2 from several gas-processing plants throughout the northern reef trend, a region with more than 800 Niagaran reef fields, provides an economically viable opportunity to combine CO 2 -flood EOR operations with geological sequestration of CO 2 greenhouse gases. Initial results of a pilot project where CO 2 from the Antrim Shale is being injected into several Niagaran reefs are discussed along with reservoir characterization issues associated with these heterogeneous reservoirs. Similar EOR projects throughout the northern reef trend could provide an economic foundation for CO 2 sequestration programs. This is especially the case if they are designed alongside industrial activities that generate easily captured CO 2 emissions streams, such as other gas-processing plants or future ethanol plants planned for the region.