Geological, pedological and paleomagnetic study of the late Cenozoic sedimentary sequence in southwestern Uruguay, South America

The results of interdisciplinary studies carried out on the coastal cliffs of southern Uruguay are presented here. The Raigón Formation (late Pliocene-middle Pleistocene) has a cratonic provenance and comprises two sections limited by a regional discontinuity. Each section is composed of an associat...

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Detalles Bibliográficos
Autores principales: Tofalo, O.R., Orgeira, M.J., Morrás, H., Vásquez, C., Sánchez, L., Pecoits, E., Aubet, N., Sánchez, G., Zech, W., Moretti, L.
Formato: JOUR
Materias:
Cenozoic
cliff
climate variation
craton
discontinuity
floodplain
geochronology
interdisciplinary approach
lithofacies
magnetostratigraphy
paleoclimate
paleogeography
paleomagnetism
paleosol
pedogenesis
pedology
Pliocene-Pleistocene boundary
provenance
rhizolith
sedimentary sequence
sedimentation
stratification
South America
Uruguay
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_10406182_v210_n1-2_p6_Tofalo
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
Descripción
Sumario:The results of interdisciplinary studies carried out on the coastal cliffs of southern Uruguay are presented here. The Raigón Formation (late Pliocene-middle Pleistocene) has a cratonic provenance and comprises two sections limited by a regional discontinuity. Each section is composed of an association of lithofacies Ss, Sp, Sr, rare St, and Fm. The last one represents floodplain deposits and the others are interpreted as channel-filled deposits. In the upper part, a well-structured paleosol with clay coatings and abundant rhizoliths is observed in a sharp contact with silty deposits of the Libertad Fm. (early-middle Pleistocene); these sediments have a mixed provenance (magmatic arc and cratonic), sheet-like geometry, thick stratification and vertical walls, and are composed of lithofacies Fr. These characteristics suggest a loessic origin. A paleosol with illuvial B horizons and silty loam texture is recognized at the bottom of this unit. The recent soil (Argiudoll) is developed at the top of the Libertad Fm. The characteristics of the sequence indicate climatic fluctuations and several cycles of erosion, sedimentation and pedogenesis. According to magnetostratigraphy, the chronology is roughly compatible with that one based on the fossil contents and is in agreement with magnetic ages determined in Argentine fossiliferous sequences. © 2009 Elsevier Ltd and INQUA.

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