Petrogenesis of Garnet Periodotites and Eclogites in the Bohemian Massif, Czechoslovakia

波西米亚地块捷克部分的石榴石橄榄岩和榴辉岩的野外和实验室综合调查计划进行，该地块是瓦里斯坎造山带在欧洲的最东端。这些高压岩石赋存于莫尔达努比亚带中的陆壳岩石序列中，该带是瓦里斯坎造山带内部最内部、变质程度最高的构造地层单位。前人的研究表明：1)存在两种不同成因模式、不同温压历史和不同冷却速率的石榴石橄榄岩；2)橄榄岩中A类榴辉岩透镜体为地幔成因，由高压结晶堆积形成，并被华力西造山期构造侵位的橄榄岩包裹带入地壳。将对已进行岩石学特征的精选橄榄岩和生态岩样品进行进一步的同位素研究，并将对更多的橄榄岩岩体和片麻岩中的B类榴辉岩透镜体进行综合野外、岩石学、地球化学和同位素研究。这一结果将为确定华力西带这一段高压变质作用的时间和性质提供依据，并加深我们对造山过程中地幔与地壳相互作用的复杂性的理解。

An integrated field and laboratory investigation is planned of garnet peridotites and eclogites in the Czech portion of the Bohemian Massif, which is the easternmost extent of the Variscan Orogen in Europe. These high-pressure rocks occur in sequence of continental crustal rocks in the Moldanubian Zone, which is the most internal and highly metamorphosed tectonostratigraphic unit of the Variscan Orogen. Previous studies have demonstrated: 1) the occurrence of two types of garnet peridotites, which exhibit different modes of origin, T-p histories, and cooling rates, and 2) a mantle origin for Group A eclogite lenses in peridotites, which formed by high-pressure crystal accumulation and were carried into the crust by enclosing peridotites that were tectonically emplaced during the Variscan Orogeny. Further isotopic investigations will be performed on selected peridotite and ecologite samples that have already been characterized petrologically, and integrated field, petrologic, geochemical, and isotopic studies will be made of additional peridotite bodies and Group B eclogite lenses in gneisses. The results should provide a basis for establishing the timing and nature of high-pressure metamorphism in this portion of the Variscan belt, an improve our understanding of the complexities involved in the interaction of mantle and crust during orogenesis.