ESR, OSL and TT-OSL dating methods were applied to samples collected from six of the Ancient Coastal Deposits (ACDs) along the southern Georgia Coastline. Samples were collected from the Princess Anne (the youngest and most seaward ACD), Pamlico, Talbot, Penholoway, Wicomico, and Okefenokee ACDs with the goal of determining the age of formation of these features. Ground Penetrating Radar (GPR) was used to determine the subsurface morphology and target lithologies for age determination. OSL and TT-OSL dating was attempted on samples collected from the youngest two ACDs, the Pamlico and Princess Anne, at McMaster Universities AGE Lab. ESR samples collected from all of the ACDs studied were measured at Florida State University as well as Osaka University. ESR analysis measured the Al signal, the Ti-Li signal, measured using two different methods, as well as the Ti-H signal. A number of low additive dose points were added to the ESR dose plan to attempt to create a better dose response curve for the low saturating Ti-H signal in attempt to better utilize the signal. While the geochronological methodology did not prove useful for determining the age of all of the ACDs it did result in depositional age estimates for the Cypresshead Formation at 433-2978 ka and Satilla Formations at 243-417 ka using the Ti-Li ESR signal as a maximum age estimate. The GPR, ESR, and core data all point to the conclusion that the ACDs of the Georgia Coast are geomorphic modifications and not the result of a unique depositional process. Based on the discrepancy between the depositional age of the Cypresshead and Satilla Formations as determined by ESR in this study and the ages of the ACDs published by others from Georgia (Markewich et.al., 2013) or other areas of the Atlantic Coast (Wehmiller, 2004; Willis, 2006) it can be concluded that paleo sea-levels modified the Cypresshead and Satilla Formations in to the morphology seen today at some point after their initial deposition. / Dissertation / Doctor of Philosophy (PhD) / ESR, OSL and TT-OSL dating methods were applied to samples collected from six of the Ancient Coastal Deposits (ACDs) along the southern Georgia Coastline with the goal of determining the age of formation of these features. Ground Penetrating Radar (GPR) was used to determine the subsurface morphology and target lithologies for age determination. A number of low additive dose points were added to the ESR dose plan to attempt to create a better dose response curve for the low-dose saturation of the Ti-H signal in attempt to better utilize the signal. While the geochronological methodology did not prove useful for determining the age of all of the ACDs, it did result in depositional age estimates for the Cypresshead Formation at 433-2978 ka and Satilla Formations at 243-417 ka. The GPR, ESR, and core data all point to the conclusion that the ACDs of the Georgia Coast are geomorphic features without unique depositional events.

Submitted by CARLA MARIA GOULART DE MORAES (carlagm) on 2015-04-01T20:11:18Z No. of bitstreams: 1 RosanaGandiniGeologia.pdf: 4608662 bytes, checksum: 062ac1345c53f4c87b0c0423e27c5022 (MD5) / Made available in DSpace on 2015-04-01T20:11:18Z (GMT). No. of bitstreams: 1 RosanaGandiniGeologia.pdf: 4608662 bytes, checksum: 062ac1345c53f4c87b0c0423e27c5022 (MD5) Previous issue date: 2008-11-04 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Ambientes marginais marinhos são áreas em constante transição que limitam o desenvolvimento das biotas. Fatores ecológicos limitantes da vida bentônica como salinidade, oxigenação, energia e exposição do substrato, condicionam o comportamento dos organismos. A salinidade atua nestes meios como um regulador natural na distribuição da fauna e sua flutuação, combinada aos demais fatores ambientais, resulta em condições fisiologicamente estressantes para muitos organismos. Os depósitos de subsuperfície da sucessão sedimentar Rio Bonito no bloco central da jazida carbonífera de Iruí (Cachoeira do Sul, RS) contêm as icnofábricas de Chondrites, Chondrites-Helmintopsis-Planolites, Cylindrichnus-Thalassinoides, Helminthopsis, Macaronichnus, Ophiomorpha, Palaeophycus, Planolites, Thalassinoides, Thalassinoides-Palaeophycus e Thalassinoides-Palaeophycus-Helminthopsis, distribuídas em associações de fácies representativas de depósitos costeiros e marinhos rasos. As icnofábricas presentes nos depósitos costeiros são caracterizadas pelo baixo índice de bioturbação, pelo tamanho reduzido das escavações e pela baixa icnodiversidade, enquanto que a de depósitos marinhos rasos apresenta moderado a alto índice de bioturbação e maior icnodiversidade. O padrão de cada icnofábrica, sua distribuição estratigráfica e seus vínculos faciológicos permitiram reconhecer quatro assinaturas icnológicas principais, três indicativas de estresse por salinidade e uma substrato-controlada. As icnofábricas de Helmithopsis, Palapeophycus e Planolites presentes na litofácies SiltArg sugerem o domínio de águas oligoalinas a doces. As icnofábricas de Thalassinoides-Palaeophycus e Cylindrichnus-Thalassinoides refletem domínio de águas mesoalinas, representando, respectivamente, uma suíte de ambientes mais estáveis e com menor energia (suíte empobrecida de Icnofácies Cruziana) e uma suíte de ambiente com maior energia (suíte de Icnofácies mista Skolithos-Cruziana). A icnofábrica Thalassinoides-Palaeophycus-Helminthopsis caracteriza uma suíte marinha rasa de Icnofácies Cruziana arquetípica; o tamanho reduzido das escavações, contudo, sugere domínio de águas polialinas, e a ocorrência pontual das icnofábricas, deposição em enseadas, que mimetizariam as condições ambientais encontradas na zona de shoreface inferior/transição ao offshore. A icnofábrica de Thalassinoides é substratocontrolada e ocorre em contexto de Icnofácies Glossifungites, demarcando superfícies estratigráficas autocíclicas nas seqüências C e D e uma superfície estratigráfica alocíclica que separa as seqüências basais da seqüência E. A análise integrada da sedimentologia e da icnologia dos depósitos estudados, em alta resolução, permitiu refinar as interpretações paleoambientais e estratigráficas pré-existentes para a sucessão sedimentar Rio Bonito na área de estudo. / Marginal-marine environments are permanently transitional areas, constraining the biocoenosis development. Ecological features such as salinity gradient, available oxygen content, energy in biotope and substrate consistency and exposure control the animal behavior and impact in the establishment of benthic life. In these environments, the salinity gradient works as a natural regulator of faunal distribution and its fluctuation, combined with the afore mentioned features, results in stressing physiological conditions for many organisms. Thus, the biogenic sedimentary structures produced by the endobenthic fauna in these environments commonly reflect this stress. The subsurface deposits of the Rio Bonito sedimentary succession in the central block of the Iruí coal mine (Cachoeira do Sul, Rio Grande do Sul State, southern Brazil) is composed of sedimentary facies associations that represent deposition in dominantly marginal marine and shallow marine settings, the later in minor scale. Ichnofabrics of Chondrites, Chondrites-Helmintopsis-Planolites, Cylindrichnus-Thalassinoides, Helminthopsis, Macaronichnus, Ophiomorpha, Palaeophycus, Planolites, Thalassinoides, and Thalassinoides-Palaeophycus occur in the marginal marine settings, while the Thalassinoides-Palaeophycus-Helminthopsis ichnofabric is present in the shallow marine deposits. The marginal-marine ichnofabrics are characterized by the low bioturbation index, the reduced size of burrows, and the low ichnodiversity, whereas the marine ones show a moderate to high degree of bioturbation and ichnodiversity. The ichnofabric pattern, its stratigraphic distribution, and its sedimentological relationships allow recognizing four ichnological signatures, three suggesting stress caused by changes in the salinity gradient, and one substratecontrolled. Ichnofabrics of Helmithopsis, Palapeophycus, and Planolites in lithofacies SiltArg suggest the dominance of oligohaline to freshwater conditions. Ichnofabrics of Thalassinoides-Palaeophycus and Cylindrichnus-Thalassinoides reflect the dominance of mesohaline conditions, each one representing, respectively, more calm and stable environments (impoverished Cruziana Ichnofacies suite), and moderate to high energy settings (mixed Skolithos-Cruziana Ichnofacies suite). The Thalassinoides-Palaeophycus-Helminthopsis ichnofabric represents an arquetypical Cruziana Ichnofacies suite, indicating shallow marine settings. The reduced size of the burrows, however, suggests dominance of polyhaline rather than stenohaline conditions and its local distribution allow infer deposition in embayments, which mimic the environmental conditions found in the lower shoreface/offshore transition zones. The Thalassinoides ichnofabric is substrate controlled, representing Glossifungites Ichnofacies suítes. It demarcates autocyclic stratigraphic surfaces in sequences C and D, and an allocyclic stratigraphic surface (sequence boundary) that separates the basal sequences from the sequence E. The integrated analysis of the ichnology and sedimentology of the studied deposits, in high resolution scale, allowed refine the pre-existent paleoenvironmental and stratigraphic interpretations of the Rio Bonito sedimentary succession in the study area.