HR: 08:45h
AN: T51D-04    [Abstracts]
TI: Interactions Between Tectonics, Sedimentation and Climate in the Intramontane B\'{o}lson de Fiambal\'{a} Basin: Southern Puna Plateau (NW Argentina)
AU: * Carrapa, B
EM: carrapa@geo.uni-potsdam.de
AF: Institut fuer Geowissenschaften, Universit„t Potsdam, Karl-Liebknecht-Str. 24,Golm, Potsdam, D-14476 Germany
AU: Barbieri, C
EM: chiara.barbieri@manhattan.unipv.it
AF: Dipartimento di Scienze della Terra, Universita di Pavia, Via Ferrata, 1, Pavia, 27100 Italy
AU: Hauer, J
EM: jchauer@rz.uni-potsdam.de
AF: Institut fuer Geowissenschaften, Universit„t Potsdam, Karl-Liebknecht-Str. 24,Golm, Potsdam, D-14476 Germany
AU: Sosa Gomez, J
AF: Laboratorio de Sedimentolog¡a de la Facultad de Ciencias Naturales e Instituto Miguel Lillo Universidad Nacional de Tucuman, Miguel Lillo 205, San Miguel de Tucuman, Tucuman, 4000 Argentina
AU: Strecker, M
EM: strecker@rz.uni-potsdam.de
AF: Institut fuer Geowissenschaften, Universit„t Potsdam, Karl-Liebknecht-Str. 24,Golm, Potsdam, D-14476 Germany
AU: Schoenbohm, L
EM: lindsays@geo.uni-potsdam.de
AF: Institut fuer Geowissenschaften, Universit„t Potsdam, Karl-Liebknecht-Str. 24,Golm, Potsdam, D-14476 Germany
AB: The Puna Plateau is part of the larger Puna-Altiplano region which is the second largest Plateau on Earth. The Puna is characterized by high mean elevation at ~3700m with peaks above 6000m, internal drainage and hyper-aridity. The uplift of this important region must have influenced climate patterns, erosion, sediment- dispersal patterns and the evolution of the tectonic stress field in adjacent regions. In order to better understand the interactions between these important processes we have investigated the intramontane Bols\'{o}n de Fiambal\'{a} Basin (BF) at about 27 \deg45'S, 67 \deg45'W. The BF is located in the structural transition between the high-angle reverse fault bounded Sierra Pampeanas structural province and the southern margin of the intra-Andean Puna. The investigation of clastic sediments deposited in intramontane basins straddling the eastern and southern margin of the Puna provides fundamental information on timing and spatial patterns of plateau evolution in the orogen interior. Our sedimentologic and structural data show that sedimentation in the BF started under E-W contraction in late Miocene time in an climate characterized by an ephemeral fluvial system sourced in the west. Subsidence analysis suggests that accommodation space was provided by tectonic loading due to the eastward advance of thrust sheets. Sedimentation with more humid intervals continued during the late Miocene-Pliocene associated with further thrust-front advance and the influence of proximal western sediment sources and the formation of an established fluvial system. Probably by late Pliocene time the BF became overfilled and thick, coarse alluvial fan conglomerates sourced in the W and NE were deposited. Our analysis suggests that subsidence in this last period was mainly due to sediment loading, while tectonic loading by western thrusts apparently played a minor role. This interpretation is in line with provenance data which suggest an enlargement of the drainage system with the contribution of Puna-related rocks to the basin fill, suggesting an uplift pulse in the plateau realm. These events appear to have been roughly coeval with a change in the shortening direction from E-W to WNW-ESE to a neotectonic ENE-WSW orientation, also observed in other parts of the Argentine Andes farther north. Our new observations in the BF thus provide important information on the last phase of plateau uplift at the transition between the late Pliocene and early Pleistocene.
DE: 8102 Continental contractional orogenic belts
DE: 1815 Erosion and sedimentation
DE: 1625 Geomorphology and weathering (1824, 1886)
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting