Abstract <p>Original data illustrating the phenomenon of reverse zoning in picritic gabbro-dolerites of the Talnakh intrusion are presented. A sharp geochemical boundary and differently directed trends in the evolution of the magmatic system for picritic gabbro-dolerite and the overlying rocks of the main layered series are shown on the basis of the distribution of petrogenic and rare earth elements. For the first time, a new subtype of interrupted reverse zoning is revealed for layered intrusives. Reverse zoning is manifested in the most primitive composition in the upper part of the picritic gabbro-dolerites and a more fractionated composition in the lower part of the main layered series. It is shown that picritic gabbro-dolerites cannot be the lower part of the main layered series during fractionation in situ and be formed within the framework of a single mechanism.</p>