Weathering rates of buried machine-polished rock disks, Kärkevagge, Swedish lapland

Some 48 dolomite, 37 granite, and 19 limestone machine-polished disks were buried at soil horizon boundaries in 16 soil pits to maximum depths of 0.5-0.6 m within Kärkevagge, a presently periglacial, glaciated trough in Arctic Sweden. The objective of the ongoing study is to determine near-surface 'potential' weathering rates beneath birch forest, Dryas heath, heath, meadow, solifluction meadow, and willow vegetation cover types. Selected disks were excavated after 1 year, and all disks were excavated after 4 or 5 years. The limestone disks weathered fastest, followed closely by the dolomite disks, but the granite disks weathered at much slower rates. Mean annual percentage mass loss over 4 or 5 years was 0.473 ± 0.145% (two standard errors) for dolomite disks, 0.032 ± 0.005% (two standard errors) for granite disks, and 1.104 ± 0.446% (two standard errors) for limestone disks. For dolomite disks the Dryas heath and heath environments weathered the most slowly, a trend that was generally followed by the granite disks. Poor drainage (i.e. increasing wetness) and decreasing pH were found to promote dolomite weathering rates in a statistically significant manner. Surficial and subsurface weathering rates at individual sites were generally found to be correlated for dolomite, but not granite.