Non-perennial to ephemeral fluvial systems dominated by seasonal discharge fluctuations and episodic rapid flood-flow events are typical of arid to semi-arid climatic conditions. Dryland fluvial systems have been described from many ancient and modern, predominantly tectonically-controlled sedimentary basins across the globe. This study provides detailed sedimentological analysis and palaeoenvironmental interpretation of the lowermost part of the early Permian (?Asselian) Krajanów Formation exposed within the continental, fault-bounded Intra-Sudetic Basin (ISB), located on the NE periphery of Bohemian Massif. High-resolution sedimentological logging and facies analysis indicate that the early Permian fluvial system in this area was dominated by ephemeral fluvial processes influenced strongly by a semi-arid to arid climate. Rapid (?catastrophic) flood events led to episodic sedimentation of vertically and laterally amalgamated fluvial channel infills, with abundant upper flow regime structures as well as poorly channelized, laterally extensive sheet-like bodies of sandstone. The overbank deposits are poorly preserved due to frequent lateral shifting of the channels. Soft-sediment deformation structures formed due to events of river bank collapse as well as debris flow facies point to high-energy, waning flows. It is concluded that deposition occurred on broad, terminal-type alluvial fans, probably in their proximal- to medial segments within a distributive fluvial system of the Permian Intra-Sudetic Basin. Petrographic composition and measured palaeocurrent directions show that the sediment was sourced from the neighbouring massifs – the Sowie Mts. Massif to the east, the Bardo Structure and a hypothetical Southern Massif to the south/south-east.

以季节性流量波动和偶发性快速洪水事件为主的非常年至短暂河流系统是典型的干旱至半干旱气候条件。全球许多古代和现代的、主要受构造控制的沉积盆地都描述了旱地河流系统。这项研究对暴露在位于波希米亚地块东北边缘、以断层为界的大陆性苏台德盆地 (ISB) 内的早二叠世 (?阿塞利安) Krajanów 地层的最下部进行了详细的沉积学分析和古环境解释。高分辨率沉积测井和相分析表明，该地区早二叠世河流系统以短暂的河流过程为主，受半干旱至干旱气候的强烈影响。快速（灾难性）洪水事件导致垂直和横向合并的河道填充物发生间歇性沉积，具有丰富的上部流态结构以及渠道化不良、横向广泛的片状砂岩体。由于渠道频繁横向移动，超岸存款保存不良。由于河岸崩塌事件和泥石流相而形成的软沉积物变形结构表明存在高能量、减弱的水流。结论是，沉积发生在宽阔的终端型冲积扇上，可能发生在二叠纪苏台德盆地分布河流系统内的近内侧段。岩相成分和测量的古水流方向表明，沉积物来自邻近的地块——索伊山。东部地块，巴尔多结构和南部/东南部假设的南部地块。