Lithofacies paleogeography and exploration significance of Sinian Doushantuo depositional stage in the middle-upper Yangtze region, Sichuan Basin, SW China

Zecheng WANG,Jingjiang LIU,Hua JIANG,Shipeng HUANG,Kun WANG,Zhengyu XU,Qingchun JIANG,Shuyuan SHI,Mengyi REN,Tianyu WANG

Table 1 Sedimentary system of Doushantuo Formation in mid-upper Yangtze.

Sedimentary system Sedimentary facies Sedimentary subfacies Sedimentary microfacies and lithology Strata Carbonate platform Restricted, semi-restricted platform Algae mound, inter-mound depression, granular shoal, algal dolomitic flat, evaporative lagoon Algal laminar dolomite, micritic condensate dolomite, phosphorous stromatolite dolomite; Oxidized sandy mudstone, argillaceous dolomite, siliceous stripe dolomite, arenaceous dolomite Z2d3 Platform- margin slope Upper slope, lower slope Microlite tuff lime-mud mound, zebra micrite carbonate, nodular carbonate, slump brecciform carbonate, turbidite, dark mudstone, siliceous rock Z2d3 Onshore and lagoon Lagoon Mudstone lagoon, gypsum-salt lacustrine Celadon mudstone, dolomite containing anhydrite, gypsum layer, cross-bedding sandy mudstone Z2d2 Z2d3 Z2d4 Tidal flat Supralittoral zone, intertidal zone and subtidal zone Mud flat, sand flat, mixed flat, argillaceous gypsiferous dolomite Z2d2 Z2d4 Onshore Offshore, foreshore, backshore Sand shoal, sand dam Continental shelf and marine basin Continental shelf Marine basin Shallow and deep continental shelf, marine basin Zebra dolomite, thin dolomitic mudstone, siliceous mudstone, argillaceous dolomite, dolomitic sandstone with phosphorous, black shale Z2d1- Z2d4