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The distribution, structure, and composition of freshwater ice deposits in Bolivian salt lakes

Hydrobiologia

By:
and
DOI: 10.1007/BF00026285

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Abstract

Freshwater ice deposits are described from seven, high elevation (4117-4730 m), shallow (mean depth <30 cm), saline (10-103 g l-1) lakes in the southwestern corner of Bolivia. The ice deposits range to several hundred meters in length and to 7 m in height above the lake or playa surface. They are located near the lake or salar margins; some are completely surrounded by water, others by playa deposits or salt crusts. Upper surfaces and sides of the ice deposits usually are covered by 20-40 cm of white to light brown, dry sedimentary materials. Calcite is the dominant crystalline mineral in these, and amorphous materials such as diatom frustules and volcanic glass are also often abundant. Beneath the dry overburden the ice occurs primarily as horizontal lenses 1-1000 mm thick, irregularly alternating with strata of frozen sedimentary materials. Ice represents from 10 to 87% of the volume of the deposits and yields freshwater (TFR <3 g l-1) when melted. Oxygen isotope ratios for ice are similar to those for regional precipitation and shoreline seeps but much lower than those for the lakewaters. Geothermal flux is high in the region as evidenced by numerous hot springs and deep (3.0-3.5 m) sediment temperatures of 5-10??C. This flux is one cause of the present gradual wasting away of these deposits. Mean annual air temperatures for the different lakes probably are all in the range of -2 to 4??C, and mean midwinter temperatures about 5??C lower. These deposits apparently formed during colder climatic conditions by the freezing of low salinity porewaters and the building up of segregation ice lenses. ?? 1988 Dr W. Junk Publishers.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
The distribution, structure, and composition of freshwater ice deposits in Bolivian salt lakes
Series title:
Hydrobiologia
DOI:
10.1007/BF00026285
Volume
158
Issue:
1
Year Published:
1988
Language:
English
Publisher location:
Kluwer Academic Publishers
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Hydrobiologia
First page:
271
Last page:
299