Five year measurements of rock tablet weathering on a forested hillslope in a humid temperature region

摘要

In order to elucidate the effect of rock type andgeomorphic setting on weathering rates, field experiments usingmicroweight-loss techniques were carried out. Rock tablets foreight kinds of rock types: granite; granodiorite; gabbro; limestone;andesite; rhyolite; crystalline schist; and tuff, with a diameter of3.5 cm and a thickness of about 1 cm, were enclosed in a nylonmesh bag and placed in the four corners of a soil-bedrock interfaceon a granodiorite hillslope of central Japan for over 5 years. Theresults show that: (1) the saturated grus layer is the main locus ofsolutional denudation; (2) the 18 and 11% weight losses oflimestone and tuff under a saturated soil layer were clearly thelargest of all the rock types examined; and (3) the weight loss issmaller for granite, gabbro, crystalline schist, and andesite, while itis larger for tuff and rhyolite at every location. These resultssuggest that weathering rates are influenced by both lithology andenvironmental conditions.