First investigations of fine-grained cryogenic cave carbonates from a High-Arctic permafrost karst system in Greenland
<p>In recent years, cryogenic cave carbonates (CCC) have become the focus of studies tracking past climate change in periglacial environments. Two types of these speleothems occur, fine-grained CCC (CCC<sub>fine</sub>), which form due to the rapid freezing of a thin water film on ice, and coarse-grained CCC whose origin is related to the slow freezing of water pockets inside cave ice. Here, we report for the first time the occurrence of CCC<sub>fine</sub> from a cave in northeast Greenland, presently situated in continuous permafrost.</p><p>Eqik Qaarusussuaq (Cove Cave), located at 80.2&#176; N, is a 103 m long, gently-dipping phreatic passage that was discovered during the 2019 Greenland Caves Project Expedition (www.greenlandcavesproject.org). CCC<sub>fine</sub> were found in a dry chamber 65 m behind the entrance. The cave air temperature at the CCC site of -14.7 &#176;C contrasts with outside air temperatures of up to +18.0 &#176;C in July 2019. This, together with current dry conditions at the sampling site, indicates that water infiltration, necessary for CCC formation, is not possible under present-day climate conditions. This is further supported by a lack of ice found within the cave.</p><p>Stable isotope analyses of CCC show &#948;<sup>18</sup>O values ranging from -21.9 to -16.0 &#8240; and &#948;<sup>13</sup>C values between 8.4 and 11.7 &#8240; VPDB. While the &#948;<sup>13</sup>C values are consistent with published data of CCC<sub>fine</sub> from caves at lower latitudes, the &#948;<sup>18</sup>O values are significantly lower and plot in the field of CCC<sub>coarse</sub> (cf. &#381;&#225;k et al., 2018). This shift reflects the much lower &#948;<sup>18</sup>O values of meteoric precipitation in northeast Greenland compared to lower latitude sites.</p><p>Exploratory radiocarbon dating suggests that CCC<sub>fine</sub> formed in this High Arctic cave as recent as during the end of the Little Ice Age.</p><p>&#160;</p><p>Reference</p><p>&#381;&#225;k, K., Onac, B.P., Kadebskaya, O.I., Filippi, M., Dublyansky, Y., Luetscher, M., 2018. Cryogenic mineral formation in caves. In: Per&#351;oiu, A., Lauritzen, S.-E. (Eds.), Ice caves. Elsevier, Amsterdam, Netherlands, pp.&#160;123&#8211;162.</p>