The sub-Cambrian peneplain is well-known in Scandinavia, outcropping in Finland, Sweden and Norway. This peneplain is thought to have formed within the Baltic Sea region in Cryogenian and Ediacaran/early Cambrian time, when Baltica, a part of Rodinia for most of that time, experienced tectonic stability, strong sheet-wash weathering and glaciations. While the peneplain outcrops in the Baltic Shield region, it continues beneath Phanerozoic strata of the Baltic Basin. This buried part of the sub-Cambrian peneplain is known to have several isolated inselbergs. We interpret newly acquired 2D and 3D seismic data and show that the sub-Cambrian peneplain extends at least to Western Lithuania where the palaeotopography of the Precambrian basement changes its character from peneplain-like flat to hilly terrain with a large array of inselbergs. Even though some of the largest features of this palaeotopography have been known before, they are here demonstrated for the first time within the regional context of the sub-Cambrian peneplain.

亚寒武纪准平原在斯堪的纳维亚半岛闻名，在芬兰、瑞典和挪威露头。这个准平原被认为是在低温纪和埃迪卡拉纪/寒武纪早期的波罗的海地区形成的，当时波罗的海作为罗迪尼亚的一部分，大部分时间都经历了构造稳定性、强烈的海床风化和冰川作用。虽然波罗的海地盾地区的准平原露头，但它继续在波罗的海盆地显生宙地层之下。众所周知，这个亚寒武纪准平原的埋藏部分有几个孤立的岛。我们解释了新获得的 2D 和 3D 地震数据，并表明亚寒武纪准平原至少延伸到立陶宛西部，前寒武纪基底的古地形将其特征从类似准平原的平原变为丘陵地形，并带有大量的海岛。