| Theoretical & Applied Karstology TAK-Online |
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| Theoretical and Applied Karstology, vol. 17/2004 Contents and Abstracts |
| TAK Articles Luetscher, M. & Jeannin, P.-Y. — A process-based classification of alpine ice caves, pp. 5-10. A short historical outlook provides a general overview of the processes at the origin of ice caves. A classification based on two criteria is proposed: (1) the cave air dynamics enables differentiation between cases where thermal trapping is at the origin of the ice (static ice cave) from those where a cold thermal anomaly is induced by a chimney effect (dynamic ice cave) and, (2) the type of ice enables one to distinguish endogenic ice caves (congelation ice) from exogenic ice caves (accumulation and transformation of snow). The intermediate types being frequent, the suggested classification consists of nine classes covering most ice caves of temperate regions. Rachlewicz, G. & Szczucinski, W. — Seasonal, annual and decadal ice mass balance changes in the ice cave Jaskinia Lodowa w Ciemniaku, the Tatra Mountains, Poland. pp. 11-18. Jaskinia Lodowa w Ciemniaku (Ice Cave in Ciemniak) is located in the Western Tatra Mountains (Tatry Zachodnie) and it hosts the largest known subterranean block of perennial ice in Poland. Its entrance is situated at 1715 m a.s.l and the cave climate is classified as dynamic type with seasonal and diurnal variations of air temperature. The mass balance of ice body was investigated on monthly, annual and decadal scale through a set of detailed measurements of ice geometry performed during 2000–2004 years and in comparison with existing older data. The nature of recent perennial ice changes was determined through temperature measurements and seasonal ice surface observations. In general the ice mass reveals negative mass balance, however melting is not continuous throughout the year. The largest lowering of ice surface was observed in summer, due to melting, and in winter (when temperatures were well below zero) on account of sublimation. The increase in ice volume was observed in springtime when percolating water was available and the temperature was slightly below zero. In the balance year 2000–2001, 37.8 m3 of ice was lost and in 2001–2002 as much as 53.2 m3. During the subsequent period, 2002–2004, the average negative mass balance was even of about 66.8 m3. Comparison between the detail geodetic survey in 2002 and published data from 1986 reveals that the averaged annual ice volume lost was 36.6 m3 y–1, slightly less than recently. The confrontation of reported ice mass geometries in 1922, 1950 and 1986 allows to estimate averaged annual ice mass loss in the period 1922–1950 as 23.0 m3 y-1 and, during the time-period 1950–1986 as 24.8 m3 y-1. It clearly shows that ice mass losses were significantly higher in the last decade. Luetscher, M. & Jeannin, P.-Y. — The role of winter air circulations for the presence of subsurface ice accumulations: an example from Monlési ice cave (Switzerland). pp. 19-25. Investigations carried out in Monlési ice cave document the presence of significant air circulation between the two main cave entrances during the winter season. Air velocities measured in a known cross-section enable assessment of a maximal air flow of more than 10 m3/s. The resulting annual heat exchange is expressed by the temperature difference between the air inflow and outflow. The quantification of evapo-condensation processes sets the contribution of winter cooling to the final energy balance of the system. Citterio, M., Turri, S., Bini, A., Maggi, V., Pelfini, M., Pini, R., Ravazzi, C., Santilli, M., Stenni, B., & Udisti, R. — Multidisciplinary approach to the study of the Lo Lc 1650 “Abisso sul Margine dell’Alto Bregai” ice cave (Lecco, Italy). pp. 27-44 In 1999 we selected the LoLc 1650 “Abisso sul Margine dell’Alto Bregai” ice cave to be a test site for a large number of different studies dealing with both ice caves climatology and cave ice glaciology. To investigate the dynamics of the vegetation cover outside the cave we constructed a local 850 years long Larix decidua Miller growth curve. We recorded air temperatures both inside and outside the cave, and described the surface morphology and internal structure of the fossil, stratified, clear ice deposit found at a depth of -80 m below the cave entrance. On 5 cm-thick ice samples cut from a 1.20 m-long ice core we determined chemical composition, d18O and pollen content, and performed atmospheric dust counting. We also cut thick sections for the morphological description of fluid inclusion and thin sections for ice fabric observations and measurements of c-axis orientations. Most of the investigation is still ongoing and comparisons with the results from a new 4.6 m long ice core are being carried out. In the present paper we summarize the results obtained thus far, and show that the integration of data coming from different disciplines is the fundamental step in the study of ice caves and cave ice. We also briefly discuss some terminological issues about various classifications commonly found in literature. Citterio, M., Turri, S., Bini, A., & Maggi, V. — Observed trends in the chemical composition, d18O and crystal sizes vs. depth in the first ice core from the LoLc 1650 “Abisso sul Margine dell’Alto Bregai” ice cave (Lecco, Italy). pp. 45-50. A stratified clear ice deposit was drilled in an ice cave located at 2030 m a.s.l. in the Moncodeno area (Grigna Settentrionale, Lecco, Italy), and a 1.20 m-long ice core was recovered. Due to the topography of this cave the snowfalls cannot reach the ice deposit which is located at a depth of 80 metres below the cave entrance. Thin sections cut along the whole length of the core show significant textural evolution from equidimensional pluricentimetric at the top to columnar pluridecimetric crystals near the bottom of the thickest stratum. The samples from the ice core follow a well-defined general trend with depth both in the d18O values and ionic concentration (Na+, K+, NH4+, Ca2+, Mg2+, Cl-, SO42-, NO3–). We argue that the observed features are compatible with a “repeated freezing of shallow lakes” genetic model. The origin of the local deviations from the main trends observed at certain depths is discussed. Kern, Z., Fórizs, I., Nagy, B., Kázmér, M., Gál, A., Szánto, Z., Palcsu, L., & Molnár, M. — Late Holocene environmental changes recorded at Gheţarul de la Focul Viu, Bihor Mountains, Romania. pp. 51-60. This paper synthesizes the isotope and tree-ring data gathered at Focul Viu Ice Cave (Romania). The 850 ±50 year BP radiocarbon age (1160–1260 cal. AD) from 6.67 m depth of ice indicate, that the stable isotope data of the 7 m long ice core approximately represent the past 800–900 years. However, melting events introduce obvious hiatuses in the sequence. The response function analysis revealed that main growth influencing climate factors for Abies alba are June mean temperature and early summer water supply. The sufficiently represented part of the 420 year long tree-ring index curve suggests particular periods unfavourable for annual increment of firs: 2000–1980, 1940–1920, 1890–1870 and 1860–1820, while the favourable periods are 1980–1940, 1920–1890 and 1870–1860. The fit between the growth-favorable decades and the mud layer concentrations seems to be a promising dating method of ancient melting events and partially preserved remained ice bands. Previously negative intervals of Easton coefficient time-series were fitted to ice accumulating periods. These independent dating methods – Easton coefficient and fir index – show similarity back to 1730 for ice accumulation and melting periods. Fórizs, I., Kern, Z., Szántó, Z., Nagy, B., Palcsu, L., & Molnár, M. — Environmental isotopes study on perennial ice in the Focul Viu Ice Cave, Bihor Mountains, Romania. pp. 61-69. The Focul Viu Ice Cave situated at the elevation of c.1100 m a.s.l. in the karstic area of the Bihor Montains, Romania, has a perennial ice block with a thickness of about 14 m. Radiocarbon datings of the wood remnants captured by the ice gave a 0.84 cm/year long term rate for ice growth (based on a 1200-year period), while tritium measurements on the ice samples resulted in a 2 cm/year short term growth rate. The difference can be explained by the fact that the long term growth rate includes time-periods when the balance of ice accumulation/melting was negative. A 7-meter long ice-core has been taken from the ice block. The average stable oxygen isotope composition (d18O) of the uppermost 136 cm of the ice block is –9.5 ‰ VSMOW, which is considerably more positive than the estimated annual mean d18O value of the local precipitation. The process, which causes this 18O enrichment, is most probably the partial melting of the ice. Short Notes Persoiu, A. — Ice speleothems in Scărisoara Cave: dynamics and controllers. pp. 71-76. The presence of perennial ice in static caves is generally a consequence of the accumulation of cold air and the freezing of seepage water. When dealing with the dynamics of the ice in these caves, a distinction must be made between the ice block, a typical glacial presence, and the ice stalagmites, developed in periglacial conditions. While the dynamics of the stalagmites is rather a simple one, governed by meteorological controllers, the dynamics of the ice block is more complex, involving geothermal heat flux and an important positive feedback process. |
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