Ce anomaly in minerals of eclogite and garnet pyroxenite from Dabie-Sulu ultrahigh pressure metamorphic belt: Tacking subducted sediment formed under oxidizing conditions

Abstract

In-situ excimer laser ICP-MS analysis of minerals of eclogites and garnet pyroxenites from type localities (Shuanghe, Maowu, Bixiling, and Yangkou) in the Dabie-Sulu ultrahigh-pressure metamorphic belt reveals highly variable Ce anomalies from negative to positive in garnet. Similar Ce anomalies are also present in omphacite or clinopyroxene but to a much lesser extent. Such mixed negative and positive Ce anomalies mimic those found in severe weathering profiles developed under oxidizing conditions. They suggest the presence of subducted sediment components in the eclogites and garnet pyroxenites, which in turn points to the potential importance of the recycled sediments in modification of the mantle composition during the deep subduction of the continental crust. Copyright by Science in China Press 2004.