Composition and origin of the clay cover on North Brazilian laterites

摘要: The Belterra Clay in Northern Brazil is a uniform, yellowish, unstratified kaolinitic clay with variable contents of gibbsite. It generally 5–10 m thick and covers lateritic weathering crust on remnants dissected table-land. Complete profiles Clay, the underlying bauxite/laterite saprolite/bed rock were sampled three areas Amazon region. chemical mineralogical data show distinct affinity between layers above all saprolite. Variations composition underlaying are reflected by Clay. Among structural textural features important for discussion origin sharp contact cover laterite as well conglomeritic/brecciate textures occasional bedding structure upper part crust.