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岩石学显微结构证据表明,苏鲁造山带西南部超高压变质岩石经历了不同程度的深熔作用.在花岗片麻岩和石英岩中识别出结晶自深熔熔体的锆石,其U-Pb年龄集中在220±2 Ma.少量深熔锆石含有柯石英包裹体,U-Pb年龄主要集中在224±2 Ma,部分与含较低压矿物包裹体的锆石域类似.因此,深熔作用开始于早期折返阶段,部分仍处于超高压变质域.折返过程中多硅白云母脱水熔融是这些岩石发生深熔的主要机制.黝帘石榴辉岩的石榴石和绿辉石中发现了由石英+斜长石±钾长石±重晶石组成的多相固体包裹体.它们具有高钠和变化的钾含量,可能是榴辉岩中黝帘石和多硅白云母脱水分解诱发部分熔融形成,同时深熔过程中有大量绿辉石的参与.超高压变质岩石在地幔深度的部分熔融,可能促进了深俯冲陆壳在俯冲隧道内部的快速折返.
The petrological and microstructural evidence shows that ultrahigh-pressure metamorphic rocks in the southwestern Sulu orogenic belt experienced different degrees of deep-melting, and zircons from the crystalline gneiss and quartzite were identified from the granitic gneiss and quartzite, U-Pb ages are 220 ± 2 Ma. A small amount of deep-melt zircons contain coesite inclusions, and the U-Pb ages are mainly concentrated at 224 ± 2 Ma, partly similar to zircons with lower-pressure mineral inclusions. , The deep melting begins at the early reenforcement stage and the part is still in the ultrahigh pressure metamorphic zone.The dehydration and melting of polysilicic mica during reentry are the main mechanisms of deep melting of these rocks.It is found in the garnet and omphacite of the zoisite eclogite The heterogeneous solid inclusions consisted of quartz + plagioclase ± potassium feldspar ± barite with high sodium and varying potassium content, possibly induced by dehydration and decomposition of zoisite and polysilicone in the eclogites Melting and forming a large amount of omphacite during the deep-melting process.The partial melting of ultrahigh-pressure metamorphic rocks in the mantle depth may promote the rapid reversion of deep-subducted continental crust in the subducted tunnel.