Global Volcanism Program | Image GVP-07966
The Acatlán Ignimbrite is a compositionally zoned ignimbrite that grades from a white-or-pink colored basal rhyolitic tuff to a black upper andesitic tuff. The upper andesitic tuff is welded in the western part of the ignimbrite, with the degree of welding increasing to the top of the deposit. The ignimbrite erupted continuously from the same magma chamber and covers an area of 150 sq km.
Photo by Jim Luhr, 1983 (Smithsonian Institution).