Abstract—Accessory REE- and Ti-bearing minerals have been investigated in rocks of the northern part of the West Ny Friesland anticlinorium, Svalbard Archipelago. The anticlinorium is formed by Paleoproterozoic and Early Riphean metamorphic complexes overlain with an angular unconformity by Late Riphean–Early Paleozoic metasedimentary sequences of the ancient platform cover. Representative samples of metapelites with the assemblage Ms–Bt–Grt–Qz–Pl and calcic pelitic schists with additional calcite and clinozoisite were studied. Special attention was paid to the microstructure of accessory minerals aggregates and its rock-forming interpretation. Several accessory assemblages were delineated, corresponding to distinct “time slices” of the metamorphic history. The earlier assemblage consists of REE-bearing minerals: monazite-(Ce) and REE-rich clinozoisite and epidote overgrown on detrital (?) allanite-(Ce). These minerals appeared before garnet porphyroblast nucleation (<530–540°C, <5.5–7.5 kbar) and at the initial stages of its growth. Clinozoisite rims on allanite-(Ce) grains were formed during the same time as evidenced by zoned crystals of clinozoisite with allanite cores, which is preserved as inclusions within garnet. In the late stages of porphyroblast growth, rutile stabilized and the Fe–Ti oxide assemblage with rutile and metastable ilmenite originated due to attainment of maximum temperature and pressure (670–690°С, 10–11 kbar). During the retrograde metamorphic stage at 450–470°C and 3–5 kbar, rutile and ilmenite were replaced by titanite associated with late chlorite. The conditions and mechanisms of phase reactions controlling accessory mineral formation are discussed.

摘要— 已在斯瓦尔巴群岛西新弗里斯兰背斜岩北部的岩石中研究了含 REE 和 Ti 的辅助矿物。背斜层由古元古代和早Riphean变质杂岩组成，由古台盖的晚Riphean-早古生代变沉积层序覆盖有角度不整合。研究了具有组合 Ms–Bt–Grt–Qz–Pl 的变泥质岩和具有额外方解石和斜闪石的钙质泥质片岩的代表性样品。特别关注副矿物聚集体的微观结构及其成岩解释。描绘了几个附属组合，对应于变质历史的不同“时间片”。早期的组合由含 REE 的矿物组成：独居石-(Ce) 和富含 REE 的斜斜长石和绿帘石在碎屑 (?) 紫蓝石-(Ce) 上长满。这些矿物出现在石榴石成核前 (<530–540°C, <5.5–7.5 kbar) 及其生长的初始阶段。在同一时期形成了在所有的斜闪石-(Ce) 晶粒上的边缘，这可以从具有红绿石核心的斜斜长石的带状晶体中得到证实，该晶体作为石榴石中的夹杂物而被保存下来。在 porphyroblast 生长的后期阶段，由于达到最高温度和压力（670-690°С，10-11 kbar），金红石稳定，Fe-Ti 氧化物与金红石和亚稳定钛铁矿的组合起源。在 450-470°C 和 3-5 kbar 的逆行变质阶段，金红石和钛铁矿被与晚期绿泥石伴生的钛铁矿所取代。