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dc.contributor.authorMcFadden, Kathleen Anneen_US
dc.date.accessioned2014-03-14T20:17:15Z
dc.date.available2014-03-14T20:17:15Z
dc.date.issued2008-09-26en_US
dc.identifier.otheretd-10092008-224350en_US
dc.identifier.urihttp://hdl.handle.net/10919/29230
dc.description.abstractThe Ediacaran Period (635-542 Ma) just preceded the radiation of animals, yet witnessed profound changes in biological innovation, including the first appearance of large spiny acritarchs called the acanthomorphic acritarch, followed by the radiation of the Ediacara biota (575-542 Ma), and earliest recognizable bilaterally symmetrical animals (~550 Ma). It has been proposed that key environmental events, such as the termination of the Cryogenian glaciations, the Neoproterozoic Acraman impact event, and oxygenation of the deep oceans may have played an integral role in the evolution of Ediacara organisms and early animals. However, the extent to which these events shaped biological evolution remains elusive. The Doushantuo Formation in South China, radiometrically constrained between 635.2±0.6 and 551.1±0.7 Ma, is ideal for high-resolution interdisciplinary research, and has the potential to clarify the relationship between environmental and biological events. Research in this dissertation aims to address the following questions: (1) was the Doushantuo Formation deposited in an open marine or a (partially) restricted basin; (2) are Doushantuo paleoenvironmental and biostratigraphic proxies consistent with an Ediacaran oxidation event; and (3) can the Doushantuo acanthomorphic acritarchs be useful biostratigraphic tools for the Ediacaran Period? Detailed (sub-meter) sampling of six sections in the Doushantuo Formation in the Yangtze Gorges area of South China reveal a complex depositional history. Eight broad lithostratigraphic facies and 6 cycles packaged into 3 sequences can be identified and potentially traced into basinal sections. It is likely that the deposition of the Doushantuo Formation occurred under open marine conditions and became increasingly restricted with the development of thick carbonate accumulations at the platform margin. Geochemical analysis shows extreme isotopic variability in the Doushantuo Formation that may be the result of pulsed oxidation of a deep oceanic organic carbon reservoir. Oxidation events may have had further implications on the radiation of early animals. Distinct assemblage biozonation of the Doushantuo acanthomorphic acritarchs is concurrent with isotopic variability, suggesting an ecological and/or evolutionary response during the early Ediacaran. Further efforts in refining the internal geochronology of the Doushantuo Formation is needed in order to test competing hypotheses on the radiation of important taxonomic groups.en_US
dc.publisherVirginia Techen_US
dc.relation.haspartPNAS_Permission.pdfen_US
dc.relation.haspartMcFadden_Dissertation_2008_ETDEdits.pdfen_US
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectCarbonen_US
dc.subjectStratigraphyen_US
dc.subjectOxygenen_US
dc.subjectEdiacaranen_US
dc.subjectDoushantuo Formationen_US
dc.titleIntegrated High-resolution Stratigraphy of the Doushantuo Formation, South Chinaen_US
dc.typeDissertationen_US
dc.contributor.departmentGeosciencesen_US
dc.description.degreePh. D.en_US
thesis.degree.namePh. D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen_US
thesis.degree.disciplineGeosciencesen_US
dc.contributor.committeechairXiao, Shuhaien_US
dc.contributor.committeememberEriksson, Kenneth A.en_US
dc.contributor.committeememberJiang, Ganqingen_US
dc.contributor.committeememberKaufman, Alan J.en_US
dc.contributor.committeememberRead, James Fredricken_US
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-10092008-224350/en_US
dc.date.sdate2008-10-09en_US
dc.date.rdate2008-11-17
dc.date.adate2008-11-17en_US


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