NOGAFLUIS · Noble gases in fluid inclusions of stalagmites as a new palaeoclimate proxy

The project being delineated in this proposal intends to study fluid inclusions in speleothems. It is assumed that atmospheric noble gases dissolve in the seepage water according to the cave temperature, when speleothems, namely stalactites and stalagmites, are being formed. Since the cave temperature not too close to the entrance corresponds with the annual mean air temperature, except in case of too deep caves and/or the ones affected by thermal effects, the NGT of the seepage water reflects to the mean temperature of the air. During the formation of speleothems, tiny amounts of dripping seepage water can be enclosed between the precipitating carbonate layers. This water constitutes the fluid inclusions. The whole research project is based on mass spectrometric measurements of the noble gas content of fluid inclusions of speleothems. All of the five noble gases, namely helium, neon, argon, krypton and xenon are expected to be examined. During the performance of the research project, a preparation line for treatment of stalagmite samples will be built. Additionally, an appropriate measurement process will be developed. Although, the first results in the previous Marie Curie Fellowship have shown that many stalagmite samples include a significant fraction of air-filled inclusions that makes the sample preparation and the evaluation more complicated, it has been found that appropriate stalagmite samples that contain very little air inclusions do exist. In this latter case, about 1 ºC error for noble gas temperature determination can be achieved, which provides the possibility to apply this method as a palaeoclimate proxy. The present project in this proposal intends to go on in this new field.