Resumo

MIRANDA-AVILES, Raúl; PUY-ALQUIZA, María Jesús; RAMOS-ARROYO, Yann Rene  e  NAVARRO-BARRERA, Ricardo. Distribution and historic evolution of the fluvial terraces from Santa Teresa valley Guanajuato. Invest. Geog [online]. 2007, n.63, pp.93-104. ISSN 2448-7279.

The present work reports the fluvial terraces originated during historical floods throughout the fluvial plain of the Guanajuato river. Six different terraces levels were identified and mapped that correspond to T1 (1,8 m), T2 (3,0 m), T3 (4,2 m), T4 (5,2 m), T5 (6,0 m), T6 (+6,8 m). A sequence analysis of terraces was supported by 2 isotopic C¹⁴ dating. The T1 corresponds to the present floodplain, the T2, T3, T4 was formed during periods of extreme floods, between 10 to 100 years in relation to the present. The T5 morphology corresponds to 1905 historical flood. The T6 deposit was followed by a degradation process that was interrupted by a period of increasing sediment budget between 1660 +/-40 to 1905 (T5), during the great mining activity of the Guanajuato Mining District. After 1905 the sediments budget to the Guanajuato River, diminishes substantially, generating a gradual degradation by pulses conforming the T4 to T1 terraces.

Palavras-chave : Fluvial terraces; Guanajuato; anthropogenic sediments; fluvial terraces evolution; Mesa Central Mexico.

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