Lichenometric dating using Rhizocarpon subgenus Rhizocarpon in the Patagonian Andes, Argentina

GARIBOTTI, I.; VILLALBA, R.

QUATERNARY RESEARCH

Elsevier

Lugar: Whasington; Año: 2009 vol. 71 p. 271 - 283

0033-5894

This study represents the first attempt to develop and apply lichenometric dating curves of Rhizocarponsubgenus Rhizocarpon for dating glacier fluctuations in the Patagonian Andes. Six glaciers were studied alongthe Patagonian Andes. Surfaces of known ages (historical evidences and tree-ring analyses) were used ascontrol sites to develop indirect lichenometric dating curves. Dating curves developed for the studied glaciersshow the same general logarithmic form, indicating that growth rate of subgenus Rhizocarpon decreases overtime. The strong west–east precipitation gradient across the Andean Cordillera introduces statisticallysignificant differences in the growth curves, with faster growth rates in the moist west sites than the driereastern sites. Latitudinal difference among the studied glaciers does not appear to be amajor factor regulatinglichen growth rates. Therefore, we developed two lichenometric curves for dating glacier fluctuations in wetterand drier sites in the Patagonian Andes during the past 450 yrs. Application of the developed curves to morainedating allowed us to complement glacial chronologies previously obtained by tree-ring analyses. A firstchronosequence formoraine formation in the Torrecillas Glacier (42°S) is presented. Our findings confirm theutility of lichenometry to date deglaciated surfaces in the Patagonian Andes.