Stratified ice accumulations as a source of climate proxy data
Abstract (Summary)This thesis describes and interprets layered ice from caves in New Mexico and from islands of the Bolivian Altiplano. The potential for these layered ice deposits as paleoclimate indicators is evaluated. Photographs of Candelaria Ice Cave (CIC) are used to understand the natural history of cave ice. A 72-year photographic record of CIC and radiocarbon dates indicate that (1) the existing ice body is at least 2,000 to 3,000 yrs. old; (2) an ice body filled most of the cave, becoming unstable in the late 19th century due to extraction of ice by locals;(3) more than half the ice body was lost through ablation of the vertical ice cliff by 1924; (4) since 1924, 2 m of ice accumulated in the resulting ice "pond" while the ice cliff ablated vertically by 1 m. The calculated accumulation history for CIC generally agrees with local climate data suggesting a paleoclimate history may be obtained from cave ice accumulations having less complicated histories.Isotopes, microparticles and anion concentrations in ice cores from Candelaria and La Marchantia ice caves are used to describe the ice deposits. These analysis indicate that (1) ice in visible layers forms from a number of precipitation events occurring in one or more years; (2) ice formed in climatic conditions similar to those of today and the "Little Ice Age;" (3) the structure of the catchment basin of an individual cave may greatly affect isotopes within ice from similar caves; (4) most ions are greatly affected during transport to the cave and by humans. X-ray mineralogy, isotopes, microparticles, radiocarbon dates and conductivity in ice-sediment islands in Laguna Colorada indicate (1) the sediments were deposited between 12,000 yrs. BP, when the lake dried out, and 8,000 yrs. BP; (2) most of the sediment is aragonite precipitated from high-magnesium brines; the remainder is composed of diatoms and fluvial and eolian deposits; (3) ice-sediment islands may form by processes similar to that of palsas. A lack of sufficient information on the developmental history of ice-sediment islands complicate determination of the exact age of ice emplacement.
School:The Ohio State University
School Location:USA - Ohio
Source Type:Master's Thesis
Date of Publication:01/01/1996