Resumo

SOSA-NAJERA, Susana; LOZANO-GARCIA, Socorro; ROY, Priyadarsi D.  e  CABALLERO, Margarita. Historical drought record in western Mexico based on the elemental analysis of lacustrine sediments: the case of the Santa María del Oro lake. Bol. Soc. Geol. Mex [online]. 2010, vol.62, n.3, pp.437-451. ISSN 1405-3322.

This paper presents high-resolution data of titanium (Ti) and calcium (Ca) concentrations and magnetic susceptibility of lacustrine sediments from Lake Santa Maria de Oro, located in western central Mexico. Major element measurements were carried out with an ITRAX XRF core scanner. The Ti record for the last 700 years (1300-2000 AD) was validated as a marker for wash and runoff events (and therefore precipitation) by comparison with historical information and tree ring chronologies related to major droughts events from several areas in Mexico. The register of Ti identifies 21 drought events, six of which are of major intensity and/or duration (i.e. 1365-1384, 1526, 1655-1670, 1818, 1900 and 1930-2000 AD). Spectral analysis of Ti suggests periodicities of 25, 39, 50, 70 and 117 years for the drought events. These periodicities could be related to solar activity and/or climatic factors such as El Niño Southern Oscillation (ENSO). The drought events documented at Lake Santa Maria del Oro were compared with records of latitudinal displacement of the Intertropical Convergence Zone (the Ti record from Cariaco Basin in the Atlantic Ocean) and the ENSO index. Some of the main drought events (1448-1435, 1485-1474, 1605-1601, 1673-1655 and 1770-1773 AD) correlate with summer southern migration of the Intertropical Convergence Zone (ITCZ), while others, i.e.1818, 1832, 1866, 1900, 1939-1929 and 1958-2000 AD, show a correlation with the ENSO index. The events of 1386-1354, 1536-1510, 1579-1585 and 1780-1808 AD correlate positively both with the ENSO index and southern ITCZ migration.

Palavras-chave : droughts; titanium; late Holocene; ITRAX; ITCZ; Mexican Monsoon.

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