Downward Intrusive Breccias in the Huronian Espanola Formation, Ontario, Canada
Some breccias in the early Aphebian Espanola Formation of the north shore of Lake Huron apparently formed by downward injection caused by sudden release of high pore pressures in water saturated sediments. Pressure release was effected by movement of sediment-water mixtures into fissures formed in the Espanola Formation by early (probably pre-Gowganda) tectonic movements.