Evidências sedimentares de antigo ambiente marinho, Montanhas Ellworth, Antártica Ocidental
DOI:
https://doi.org/10.20396/sbgfa.v1i2017.1851Palavras-chave:
Antártica. Paleoclimatologia. Geomorfologia Glacial SedimentologiaResumo
O vale Elephant Head (79°.298’S / 83°20.426’W) é um vale deglaciarizado no qual amostras sedimentares foram coletadas em depósitos morâinicos. Análise do tamanho e morfometria das partículas, composição química e mineralógica foram efetuadas. O predomínio de carbonato de cálcio foi observado na maioria das amostras. Marcas onduladas (ripple marks) sugerem a existência de ambiente marinho raso. Um processo de sedimentação marinha preencheu possivelmente esse mar interior, associado com soerguimento tectônico local, posterior cobertura e ação glacial. Sedimentação calcária e clástica domina o vale, refletindo a natureza e composição das principais fontes de sedimentos. Os depósitos e sedimentos no vale Elephant Head corroboram com outros estudos que caracterizam a área como uma zona de rift em um ambiente sedimentar marinho raso. A principal lacuna é o timing desses eventos.
Referências
BASU, A. Reading provenance from detrital quartz. In: Zuffa, G.G. (Ed), Provenance of Arenites. Reideo Publishing, Dordrecht, p. 231-247, 1985.
BENN D.I., BALLANTYNE C.K. Reconstructing the transport history of glaciogenic sediments – a new approach based on the covariance of clast form indices. Sedimentary Geology, 91 (1–4), p. 215-227, 1994.
BENNETT, M.R., HAMBREY, M.J., HUDDART, D. Modification of clast shape in high Arctic environments. Journal of Sedimentary Research, 67 (3), p. 550-59, 1997.
BUGGISH W., WEBERS, G.F. Facies of Cambrian carbonate rocks, Ellsworth Mountains, West Antarctica. Geological Society of America. Memoir 170, p. 81-100, 1992.
CURTIS, M.L., LOMAS, S.A. Late Cambrian stratigraphy of the Heritage Range, Ellsworth Mountains: implications for basin evolution. Antarctic Science, 11(1), p. 63-77, 1999.
CURTIS, M.L., LEAT, P.T., RILEY, T.R., STOREYA, B.C., MILLAR, I.L., RANDALL, D.E. Middle Cambrian rift-related volcanism in the Ellsworth Mountains, Antarctica: tectonic implications for the palaeo-Pacific margin of Gondwana. Tectonophysics, 304, p. 275-299, 1999.
DENTON, G.H., BOCKHEIM, J.G., RUTFORD, R.H., ANDERSEN, B.G. Glacial history of the Ellsworth Mountains, West Antarctic, in Webers, G.F., Craddock, C. e Splettstoesser, J.F. (Eds), Geology and Paleontology of the Ellsworth Mountains, West Antarctic: Boulder, Colorado, Geological Society of America, Memoir 170, 403-432,1992.
DUEBENDORFER, E.M., REES, M.N. Evidence for Cambrian deformation in the Ellsworth-Whitmore Mountains terrene, Antarctica: stratigraphic and tectonic implications. Geology, 26, p. 55-58, 1998.
EVANS, D.J.A., BENN, D.I. Facies description and the logging of sedimentary exposures. In: Evans, D.J.A. and Benn, D.I. (Eds). A Practical Guide to the Study of Glacial Sediments. Arnold, p. 11-51, 2004.
FITZGERALD, P.G., STUMP, E. Early Cretaceous Uplift of the Southern Sentinel Range, Ellsworth Mountains, West Antarctica. Recent Progress in Antarctic Earth Science: edited by Y.Yoshida et al., p. 331-340, 1992.
FOLK, R.L., WARD, W.C. Petrol Brazos River bar: a study in the significance of grain size parameters. Journal of Sedimentology, 3 (27), p. 3-26, 1957.
LUKAS, S., BENN, D.I., BOSTON, C.M., BROOK, M., CORAY, S., EVANS, D.J.A, GRAF, A., KELLERER- PIRKLBAUER, A.,
KIRKBRID, M.P., KRABBENDAM, M., LOVELL, H., MACHIEDO, M., MILLS, S.C., NYE, K., REINARDY, B.T.I., ROSS, F.H.,
SIGNER, M. Clast shape analysis and clast transport paths in glacial environments: A critical review of methods and the role of lithology. Earth-Science Reviews, 121, p. 96-116, 2013.
POWERS, M.C. A new roundness scale for sedimentary particles. Journal of Sedimentary Research, 23 (2), p.117-119, 1953.
RIVERA, A., ZAMORA, R., RADA, C., WALTON, J., PROCTOR, S. Ice dynamics of Union Glacier in the Ellsworth Mountains, West Antarctica. Annals of Glaciology, 51 (55), p. 1-6, 2010.
RIVERA, A., ZAMORA, R., URIBE, J.A., JÁÑA, R., OBERREUTER, J. Recent ice dynamic and surface mass balance of Union Glacier in the West Antarctic Ice Sheet. The Cryosphere, 8, p.1445-1456, 2014.
SOUZA, C.D. Gênese, propriedades e mineralogia de solos de deserto polar da porção sul das Montanhas Ellsworth, Antártica Continental. Viçosa: UFV. Cap. 1 (Tese - Doutorado em Solos e Nutrição de Plantas), p. 3-38.
SPORLI, K.B. Stratigraphy of the Crashsite Group, Ellsworth Mountains, West Antarctic. In: Webers, G.F., Craddock, C., Splettstoesser, J.F. (Eds). Geology and Paleontology of the Ellsworth Mountains, West Antarctic. Geological Society of America, Memoir 170, Boulder, Colorado, p. 21-35, 1992.
STEIG, E.J., SCHNEIDER, D.P., RUTHERFORD, S.D., MANN, M.E., COMISO, J.C., SHINDELL, D.T. Warming of the Antarctic ice-sheet surface since the 1957 International Geophysical Year. Nature, 457 (7228), p. 459-462, 2009.
STOREY, B.C. Antarctic. In Selley, R.C., Cocks, R.M., Plimer, I.R. (Eds). Encyclopedia of Geology. Elsevier. 731 p., 2005.
STUMP, E. Ross Orogeny of the Transantarctic Mountains. Cambridge University Press, New York, 284 p. 1995.
VIALOV, O.S. Problematica of the Beacon Sandstone at Beacon Height West Antarctica. New Zealand Journal of Geology and Geophysics, 5, p. 718-732, 1962.
WEBERS, G.F., CRADDOCK, C., SPLETTSTOESSER, J.F. Geological history of the Ellsworth Mountains, West Antarctica, in: Webers, G.F., Craddock, C., Splettstoesser, J.F. (Eds). Geology and Palaeontology of the Ellsworth Mountains, West Antarctica. Geological Society of America, Memoir 170: p. 1-8, 1992a.
WEBERS, G.F., POJETA, J., YOCHELSONE, L. Cambrian Mollusca from the Minaret Formation, Ellsworth Mountains, West Antarctica. In Webers, G.F., Craddock, C., Splettstoesser, J.F. (Eds) Geology und paleontology of the Ellsworth Mountains, West Antarctica. Geological Society of America, Memoir 170, p. 181-248, 1992b.
WEBERS, G.F., SPLETTSTOESSER, J.F. Review of the geology and paleontology of the Ellsworth Mountains, Antarctica. In Antarctica: A Keystone in a Changing World. Online Proceedings of the 10th ISAES, edited by A.K. Cooper and C.R.
Raymond et al., USGS Open- File Report 2007-1047, Short Research Paper 107, 5 p. 2007.
WELTJE, G.J., EYNATTEN, H. Quantitative provenance analysis of sediments: review and outlook. Sedimentary Geology, 171, p. 1-11, 2004.
