01883nas a2200133 4500008004100000245008900041210006900130300001100199490000800210520140200218100002301620700001901643856008701662 2019 eng d00aWatershed-scale chemical weathering in a merokarst terrain, northeastern Kansas, USA0 aWatershedscale chemical weathering in a merokarst terrain northe a1189880 v5273 a
Carbonate weathering in the merokarst landscape at the Konza Prairie (near Manhattan, KS) is governed by kinetically rapid reaction rates, similar to other carbonate settings. The geology of the site consists of repeating couplets of shale and limestone mantled by Pleistocene loess, on which most soils are built. The headwater stream that is the subject of this study is intermittent and well connected to the secondary porosity in the limestone aquifers, such that the water chemistry is groundwater-dominated. Despite increasing in situ weathering rates shown by increasing solute concentrations, long-term (~21 of 24 years) decline in stream-water discharge has reduced chemical denudation. The current chemical denudation rate is 0.02 mm yr−1. Limestone bedrock thickness (~26.6 m) is 38% of total bedrock thickness (~70 m); the present landscape would have taken 1–4 million years to dissolve at current weathering rates. Despite paleogeographic reconstructions suggesting exposure for the past 260 Ma, estimates of the time to erode younger strata using current physical and chemical denudation rates are 80–159 Ma, still much less than the age of the rocks. An alternate source of material, dust, is proposed that may slow limestone weathering, which in turn protects shales from physical erosion, thereby slowing landscape evolution.
1 aMacpherson, G., L.1 aSullivan, P.L. uhttps://www.sciencedirect.com/science/article/abs/pii/S0009254118305874?via%3Dihub