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在大别造山带双河地区中温超高压榴辉岩中,石榴石含有不同类型的多相固体包裹体,从纯石英到纯钾长石,以及钾长石+石英±其他硅酸盐(钠长石、斜长石、绿帘石、褐帘石或重晶石).这些多相固体包裹体以钾长石+石英为主,呈细晶交互生长结构,为自形至半自形且具有放射状爆裂纹,与石榴石或绿辉石中柯石英假象或柯石英包裹体类似.研究指示,在深俯冲陆壳折返早期,超高压岩石发生降压脱水乃至部分熔融,形成了这些富Si-K-Al的长英质熔体.采用原位LA-ICPMS分析技术,对长英质多相固体包裹体进行微量元素分析,分别采用外剥法和内剥法这两种方法,定量计算熔体微量元素组成.结果显示,两种方法给出了相似的微量元素组成,具有相对富集LILE,Sr和Pb,相对亏损HFSE的微量元素分布型式,与弧型岩浆岩的分布型式相近.熔体具有变化的K,Rb和Sr含量,说明可能是多硅白云母脱水引发部分熔融,继而形成具有长英质成分的多相固体包裹体.
In the mid-temperature ultrahigh-pressure eclogites from the Shuanghe area of the Dabie orogen, garnets contain heterogeneous solid inclusions ranging from pure quartz to pure potassium feldspar, and potassium feldspar + quartz ± other silicates (sodium Feldspar, plagioclase, epidote, brown curtain stone or barite.) These heterogeneous solid inclusions are mainly composed of potash feldspar and quartz, with fine-grained intergrowth structure and self-shaped to semi-self-shaped With radial burst cracks similar to those of garnet or omphacite in coesite or coesite inclusions.Studies indicate that in the early stage of the deep subduction of the continental crust, the ultrahigh-pressure rocks are depressurized and dehydrated and partially melted to form these Si-rich -K-Al. The in-situ LA-ICPMS technique was used to analyze the trace elements in the feldspathic multiphase solid inclusions by using the methods of ablation and stripping respectively The results show that the two methods have similar trace element composition, and have relatively enriched LILE, Sr and Pb, relatively depleted HFSE trace element distribution patterns, which are similar to those of argular magmatic rocks. The melt has varying K, Rb and Sr contents, indicating that it may be polysilicone Water initiator partial melting, followed by formation of a multiphase solid inclusions having felsic component.