{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/37846"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/37846","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"High Resolution Stratigraphy of Ordovician Carbonates, Kentucky: Evidence for a Greenhouse to Glacial Transition","abstract":"Early Ordovician Knox Group carbonates consist of meter-scale dolomite cycles deposited on a passive margin. The meter-scale cycles were deposited under warm, semi-arid conditions, under low amplitude sea level fluctuations on a relatively ice-free earth. The overlying Knox unconformity (~10 m.y. duration), formed by global eustatic sea level fall and tectonic uplift of the subducting margin at the onset of Taconic orogenesis. Middle Ordovician carbonates were deposited on a ramp peripheral to a foredeep in Tennessee. The Middle Ordovician High Bridge Group consists of a 2nd-order supersequence with three 3rd-order sequences (each 30 to 100 m thick), which record a long term change from humid conditions in TST's into more arid conditions during HST's. Peritidal cycles formed under low-amplitude eustatic fluctuations. The late Middle to Late Ordovician carbonates and clastics comprise a 2nd-order supersequence deposited on a ramp peripheral to the Taconic foredeep. The supersequence is composed of four 3rd-order sequences (each 40 to 80 m thick), which contain 11 parasequence sets (2 to 20 m thick). The small sequences are composed of stacked, predominantly subtidal meter-scale cycles (parasequences). Meter-scale subtidal cycles contain facies that suggest they formed under moderate amplitude (20 to 40 m) sea level fluctuations, likely produced by glacio-eustasy. However, peritidal cycles in the HST's indicate they formed under low-amplitude sea level fluctuations, thus suggesting the amplitude of sea level fluctuations decreased during 3rd-order sea level falls. The facies in the supersequence indicate they formed under cool, humid conditions during the 2nd-order TST and became more arid during the 2nd-order HST. The unconformity at the top of the supersequence formed during eustatic sea level drawdown associated with extensive Latest Ordovician glaciation.","abstract_html":"Early Ordovician Knox Group carbonates consist of meter-scale dolomite cycles deposited on a passive margin. The meter-scale cycles were deposited under warm, semi-arid conditions, under low amplitude sea level fluctuations on a relatively ice-free earth. The overlying Knox unconformity (~10 m.y. duration), formed by global eustatic sea level fall and tectonic uplift of the subducting margin at the onset of Taconic orogenesis. Middle Ordovician carbonates were deposited on a ramp peripheral to a foredeep in Tennessee. The Middle Ordovician High Bridge Group consists of a 2nd-order supersequence with three 3rd-order sequences (each 30 to 100 m thick), which record a long term change from humid conditions in TST's into more arid conditions during HST's. Peritidal cycles formed under low-amplitude eustatic fluctuations. The late Middle to Late Ordovician carbonates and clastics comprise a 2nd-order supersequence deposited on a ramp peripheral to the Taconic foredeep. The supersequence is composed of four 3rd-order sequences (each 40 to 80 m thick), which contain 11 parasequence sets (2 to 20 m thick). The small sequences are composed of stacked, predominantly subtidal meter-scale cycles (parasequences). Meter-scale subtidal cycles contain facies that suggest they formed under moderate amplitude (20 to 40 m) sea level fluctuations, likely produced by glacio-eustasy. However, peritidal cycles in the HST's indicate they formed under low-amplitude sea level fluctuations, thus suggesting the amplitude of sea level fluctuations decreased during 3rd-order sea level falls. The facies in the supersequence indicate they formed under cool, humid conditions during the 2nd-order TST and became more arid during the 2nd-order HST. The unconformity at the top of the supersequence formed during eustatic sea level drawdown associated with extensive Latest Ordovician glaciation.","abstract_has_math":false,"creators":["Pope, Michael C."],"institution":"Virginia Tech","degree_name":"Ph. D.","degree_level":"doctoral","degree_discipline":"Geosciences","degree_department":"Geosciences","school":null,"contributors":[],"advisors":[],"committee_chairs":["Read, J. Frederick"],"committee_members":["Eriksson, Kenneth A.","McLean, Dewey M.","Bambach, Richard K.","Coruh, Cahit"],"year":1995,"date_issued":"1995-12-01","date_published":"1995-12-01","updated_at":"2026-07-22T22:19:18Z","subjects":["dolomite cycles"],"languages":["en"],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["etd-05202008-111414"],"render_values":[{"text":"etd-05202008-111414","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/10919/37846","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.committeechair","label":"Committee Chair","values":["Read, J. 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The meter-scale cycles were deposited under warm, semi-arid conditions, under low amplitude sea level fluctuations on a relatively ice-free earth. The overlying Knox unconformity (~10 m.y. duration), formed by global eustatic sea level fall and tectonic uplift of the subducting margin at the onset of Taconic orogenesis. Middle Ordovician carbonates were deposited on a ramp peripheral to a foredeep in Tennessee. The Middle Ordovician High Bridge Group consists of a 2nd-order supersequence with three 3rd-order sequences (each 30 to 100 m thick), which record a long term change from humid conditions in TST's into more arid conditions during HST's. Peritidal cycles formed under low-amplitude eustatic fluctuations. The late Middle to Late Ordovician carbonates and clastics comprise a 2nd-order supersequence deposited on a ramp peripheral to the Taconic foredeep. The supersequence is composed of four 3rd-order sequences (each 40 to 80 m thick), which contain 11 parasequence sets (2 to 20 m thick). The small sequences are composed of stacked, predominantly subtidal meter-scale cycles (parasequences). Meter-scale subtidal cycles contain facies that suggest they formed under moderate amplitude (20 to 40 m) sea level fluctuations, likely produced by glacio-eustasy. However, peritidal cycles in the HST's indicate they formed under low-amplitude sea level fluctuations, thus suggesting the amplitude of sea level fluctuations decreased during 3rd-order sea level falls. The facies in the supersequence indicate they formed under cool, humid conditions during the 2nd-order TST and became more arid during the 2nd-order HST. The unconformity at the top of the supersequence formed during eustatic sea level drawdown associated with extensive Latest Ordovician glaciation."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Ph. D."]},{"key":"dc:format.mimetype","label":"Dc Format Mimetype","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["High Resolution Stratigraphy of Ordovician Carbonates, Kentucky: Evidence for a Greenhouse to Glacial Transition"]}]}],"canonical_facts":{"dc:contributor.committeechair":["Read, J. Frederick"],"dc:contributor.committeemember":["Eriksson, Kenneth A.","McLean, Dewey M.","Bambach, Richard K.","Coruh, Cahit"],"dc:contributor.department":["Geosciences"],"dc:creator":["Pope, Michael C."],"dc:date.accessioned":["2014-03-14T21:11:14Z"],"dc:date.available":["2014-03-14T21:11:14Z","2008-05-20"],"dc:date.issued":["1995-12-01"],"dc:description.abstract":["Early Ordovician Knox Group carbonates consist of meter-scale dolomite cycles deposited on a passive margin. The meter-scale cycles were deposited under warm, semi-arid conditions, under low amplitude sea level fluctuations on a relatively ice-free earth. The overlying Knox unconformity (~10 m.y. duration), formed by global eustatic sea level fall and tectonic uplift of the subducting margin at the onset of Taconic orogenesis. Middle Ordovician carbonates were deposited on a ramp peripheral to a foredeep in Tennessee. The Middle Ordovician High Bridge Group consists of a 2nd-order supersequence with three 3rd-order sequences (each 30 to 100 m thick), which record a long term change from humid conditions in TST's into more arid conditions during HST's. Peritidal cycles formed under low-amplitude eustatic fluctuations. The late Middle to Late Ordovician carbonates and clastics comprise a 2nd-order supersequence deposited on a ramp peripheral to the Taconic foredeep. The supersequence is composed of four 3rd-order sequences (each 40 to 80 m thick), which contain 11 parasequence sets (2 to 20 m thick). The small sequences are composed of stacked, predominantly subtidal meter-scale cycles (parasequences). Meter-scale subtidal cycles contain facies that suggest they formed under moderate amplitude (20 to 40 m) sea level fluctuations, likely produced by glacio-eustasy. However, peritidal cycles in the HST's indicate they formed under low-amplitude sea level fluctuations, thus suggesting the amplitude of sea level fluctuations decreased during 3rd-order sea level falls. The facies in the supersequence indicate they formed under cool, humid conditions during the 2nd-order TST and became more arid during the 2nd-order HST. The unconformity at the top of the supersequence formed during eustatic sea level drawdown associated with extensive Latest Ordovician glaciation."],"dc:description.degree":["Ph. D."],"dc:format.mimetype":["application/pdf"],"dc:identifier.other":["etd-05202008-111414"],"dc:identifier.uri":["http://hdl.handle.net/10919/37846"],"dc:language.iso":["en"],"dc:publisher":["Virginia Tech"],"dc:rights":["In Copyright"],"dc:rights.uri":["http://rightsstatements.org/vocab/InC/1.0/"],"dc:subject":["dolomite cycles"],"dc:title":["High Resolution Stratigraphy of Ordovician Carbonates, Kentucky: Evidence for a Greenhouse to Glacial Transition"],"dc:type":["Dissertation"],"dc:type.dcmitype":["Text"],"thesis:degree_discipline":["Geosciences"],"thesis:degree_level":["doctoral"],"thesis:degree_name":["Ph. D."],"thesis:institution_name":["Virginia Polytechnic Institute and State University"]},"updated_at":"2026-07-22T22:19:18Z"}