Effect of Environmental Factors on the Chemical Weathering of Plagioclase in Hawaiian Basalt

Abstract

Much of the literature that analyzes the effect of various factors on basaltic weathering rates does not assess the synergistic effects of several factors at once. Those studies that do address such synergies generally report their results in formats that are difficult to integrate into geographic analysis. The research outlined in this paper employs multivariate statistics to assess the effect of several environmental variables on the weathering rate of basalts on the Island of Hawaii. The presence of lichens on the surface of the basalt increases weathering rate by an order of magnitude. Weathering that occurs in the absence of lichen cover is regulated by high elevation/low temperature conditions, moisture availability, and the age of the flow. Weathering that occurs in the presence of lichen cover is regulated primarily by moisture availability only. The statistical results reported here are consistent with the results of a geochemical-style analysis of the same dataset reported elsewhere, suggesting that a multivariate approach is appropriate for assessing the simultaneous effects of multiple weathering factors on the weathering rate. A multivariate statistical approach allows for the construction of quantitative weathering rate models that build on previously published qualitative models for describing geographic variation in weathering rates.