PMC

Types of hybrid rocks of hybrid clastic shelf in the Devonian Yangmaba Formation, Ganxi section the northwestern of Sichuan Basin. (a) Intermediate yellow-gray quartz sandstone intercalated with gray claystone, with HCS, proximal-source sandy storm, layer 20. (b) Gray-yellow calcareous quartz sandstone, with large hummocky and swaley cross-stratification, proximal-source sandy storm, layer 27. (c) Gray-yellow calcareous quartz sandstone, composed of the bottom scour surface, HCS and parallel bedding storm sequence, proximal-source sandy storm, layer 37. (d) Developmental trace fossil Zoophycos and Thalassinoides, layer 27. (e) Calcareous quartz sandstone, proximal-source sandy storm, layer 36; (f) Bioclastic quartz sandstone, proximal-source sandy storm, layer 37. ES: Erosion surface; GC: Gutter cast; HCS: Hummocky cross-stratification; SCS: Swaley cross-stratification; Z: Zoophycos; T: Thalassinoides.

Geological map of the study area (Qft1 = High level piedmont fan and valley terrace deposits; Qft2= Low level piedment fan and valley terrace deposits; PlQc = Fluvial conglomerate, Piedmont conglomerate and sandstone; Qs = Sand dunes and sand sheet; Qm = Swamp and marsh; PlQabv = Andesite, andesitic basalt and olivine basalt (Bazman Volcanism); Qs = Sand dunes and sand sheet; om2 = Tectonized association of pelagic limestone, radiolarian chert, radiolarian shale with basic volcanic and intrusive rocks of ophiolitic rocks; EOf = Rytmically bedded sandstone and shale with volcanoclastic sandstone, minor limestone and tuff; Plms = Marl, shale, sandstone and conglomerate; E2-3f = sandstone, calcareous sandstone and limestone; TRn4 = Black limestone, shale and sandstone; I = Massive, recrystalized limestone with minor phyllite and schist) (References: Iran geology organization) (created with ArcGIS version 10.5, https://www.arcgis.com/index.html).

A, B, C, D) Calcareous corroded sandstone E, F) Subeuheudral calcite grains created elongated pore; G, H) Cathodoluminescence view of calcareous sandstone with 2 generation of cementation C1 and C2.