Chemical weathering in a humid temperate environment

Chemical weathering in Maryland (USA) takes place in an open system flushed by through flowing meteoric waters. Weathering of a felsic schist results in thick saprolite composed of quartz and clay minerals ; where leaching is enhanced, gibbsite occurs. Weathering of serpentinite produces no saprolite due to lack of resistant minerals, and lack of alumina, but SiO is precipitated. Isovolumetric chemical weathering of mafic rocks results in loss of 30-60% of mass, bulk density decrease, and porosity increase. In well drained profiles plagioclase alters before hornblende, and large amounts of x-ray amorphous matter are produced. In poorly drained sites, hornblende and plagioclase alter simultaneously.Cleaves E.T. Chemical weathering in a humid temperate environment. In: Pétrologie des altérations et des sols. Vol. II : Pétrologie des séquences naturelles. Colloque international du CNRS, Paris 4-7 juillet 1983. Strasbourg : Institut de Géologie – Université Louis-Pasteur, 1983. pp. 47-55. (Sciences Géologiques. Mémoire, 72