Pseudoconglomerate and a re-examination of some paleoenvironmental controversies

Pseudoconglomerate, an unusual fragmental rock that contains pebblelike clasts, is described from the Barberton greenstone belt, South Africa. It occurs in concordant and discordant bodies that are closely associated with silicification, carbonation, and in situ brecciation and veining. Pseudoconglomerate is interpreted as a product of submarine exhalative activity in a hemipelagic environment. It is thought to develop in subsurface breccia bodies that form by hydraulic disaggregation of the host rock. Breccia clasts are jostled during continued fluid flow and become rounded as the result of attrition between adjacent fragments. The previous interpretation of this rock as a normal marine sediment at Barberton, and possibly in other Archean and Paleozoic sequences, may have resulted in paleoenvironmental misinterpretation.