microbreccia

microbreccia

[¦mī·krō′brech·ə]
(geology)
A poorly sorted sandstone containing large, angular sand particles in a fine silty or clayey matrix.
References in periodicals archive ?
A bulk gold model hosted in highly siliceous breccia and microbreccia derived from a rhyolite dome and its extrusive equivalent is considered appropriate for Blackwater mineralization (NR Sept 24 2009).
Also anomalous on Isle Madame are three long narrow belts of "basement" rocks, together with voluminous chloritic microbreccia and minor semi-ductile mylonite, which are separated from the conglomerate-dominated successions by faults.
The metamorphic basement and/or Glenkeen Formation are everywhere separated from the Carboniferous conglomerate-dominated sedimentary successions by faults, marked by chloritic breccia and microbreccia developed within both metamorphic basement and Glenkeen Formation.