The Shingai Unit in the Kurosegawa Belt is subdivided into sedimentary zone and mélange zone. Sandstones of the sedimentary zone vary from lithic wackes to feldspathic arenites in ascending stratigraphic order. However, the timing of this change and the depositional ages are not constrained. U-Pb age spectra for detrital zircons from sandstone samples have main clusters of late Paleozoic-earliest Mesozoic ages and minor Proterozoic-early Paleozoic age components. Detrital zircon ages show that the depositional age of the Shingai Unit is Early Triassic and that these grains were derived mainly from igneous rocks and hornfels of the Paleo-Ryoke Belt and from rocks of the Kurosegawa Belt. These age data combined with sandstone compositions and stratigraphic relationship suggest that basement rocks in the Kurosegawa Belt constituted the provenance area for the lower Shingai Unit before uplift of the volcanic arc, the provenance subsequently changed to a volcanic arc either because these rocks had been completely eroded or the supply of sediment derived from the volcanic arc increased. This provenance change supports progressive denudation of the volcanic arc. By comparison with the detrital age spectra, upper Permian-Lower Triassic strata in the Kurosegawa and South Kitakami belts are considered to have the same provenance. In addition, the sedimentary environment of these strata is inferred to have been a trench and shelf adjacent to an island arc that was isolated from the Sino-Korean and South China blocks by a back-arc basin.

黑濑川地带的Shingai单元又分为沉积带和混杂带。沉积带的砂岩从岩性瓦砾到长石地层均以递增的地层顺序变化。但是，这种变化的时间和沉积年龄不受限制。砂岩样品中碎屑锆石的U-Pb年龄谱具有晚古生代-中生代的主要簇和元古生代-早古生代的次要组分。碎屑锆石年龄表明，Shingai单元的沉积年龄为早三叠世，这些晶粒主要来自古洛克山脉的火成岩和角rocks以及黑濑川地带的岩石。这些年龄数据加上砂岩成分和地层关系表明，在火山弧抬升之前，黑濑川带的基底岩石就构成了新加河下部的物源区，随后物源变成了火山弧，原因是这些岩石已被完全侵蚀了。或来自火山弧的沉积物供应增加。这种物源变化支持火山弧的逐渐剥蚀。通过与碎屑年龄谱的比较，认为在黑濑川和南北上带中的上二叠统-下三叠统地层具有相同的物源。此外，推断这些地层的沉积环境是邻近岛弧的海沟和陆架，岛弧是通过后弧盆地与中韩和华南块体隔离的。