The Scandinavian Caledonides comprise nappe stacks of far-travelled allochthons that record closure of the Iapetus Ocean and subsequent continental collision of Baltica and Laurentia. The Seve Nappe Complex (SNC) of the Scandinavian Caledonides includes relics of the outermost Baltoscandian passive margin that were subducted to mantle depths. The earliest of the deep subduction events has been dated to ca. 500–480 Ma. Evidence of this event has been reported from the northern exposures of the SNC. Farther south in the central and southern segments of the SNC, (ultra)high-pressure rocks have yielded younger ages in the range of ca. 470–440 Ma.

This study provides the first record of the early Caledonian event in the southern SNC. The evidence has been obtained by depth profiling of zircon grains that were extracted from the Tväråklumparna microdiamond-bearing gneiss. These zircon grains preserve eclogite facies overgrowths that crystallized at 482.6 ± 3.8 Ma. A second, chemically-distinct zircon overgrowth records granulite facies metamorphism at 439.3 ± 3.6 Ma, which corroborates previous geochronological evidence for granulite facies metamorphism at this time. Based on these results, we propose that the entire outer margin of Baltica was subducted in the late Cambrian to early Ordovician, but the record of this event may be almost entirely eradicated in the vast majority of lithologies by pervasive late Ordovician to early Silurian metamorphism.

斯堪的纳维亚喀里多尼德群岛由轻推的异物推覆而成，记录了伊帕特斯海域的封闭以及随后的波罗的海和劳伦西亚大陆碰撞。斯堪的纳维亚喀里多尼德群岛的塞夫纳普综合体（SNC）包括俯冲至地幔深度的最外巴尔托斯卡纳被动缘遗迹。最早的深俯冲事件可追溯到大约 500–480马。据报道，该事件的证据来自北卡罗来纳州北部。在SNC的中部和南部部分的更南端，（超）高压岩石产生的年轻年龄范围大约为。470–440马。

这项研究提供了南部SNC早期喀里多尼亚事件的第一条记录。通过对从含Tväråklumparna微金刚石的片麻岩中提取的锆石进行深度剖析获得了证据。这些锆石颗粒保留了榴辉岩相的过度生长，其结晶度为482.6±3.8 Ma。第二次化学上不同寻常的锆石过度生长记录了粒状岩相变质作用为439.3±3.6 Ma，这证实了之前的时间学证据表明粒状岩相变质作用。根据这些结果，我们认为波罗的海的整个外缘在寒武纪晚期至奥陶纪晚期就被俯冲了，但是这一事件的记录在绝大多数岩性中几乎可以通过从晚奥陶纪到志留纪早期的变质作用而被根除。