Sedimentological Controls on the Reservoir Characteristics of the Mid-Triassic Tredian Formation in the Salt and Trans-Indus Surghar Ranges, Pakistan: Integration of Outcrop, Petrographic, and SEM Analyses

The current study uses an integrated lithofacies, optical microscopy, and scanning electron microscopy (SEM) analysis to investigate the sedimentary processes, depositional architecture, reservoir rock potential of Tredian Formation’s (Mid-Triassic) mixed siliciclastic carbonate succession in Salt Trans-Indus Ranges. formation has been divided litho-stratigraphically into two components: lower Landa Member, which consists fine-grained sandstone shale, upper Khatkiara coarse-grained sandstone. Based on structures lithology, four distinct types lithofacies are identified. Two representing sandstones interbedded with shale (LF1) thick-bedded (LF2) suggestive fluvio-deltaic settings among them. Another thin-bedded (LF3) dolomite (LF4) suggest a tidal flat environment, correspondingly. petrographic examination indicates lithology ranging from sub-feldspathic arenite feldspathic moderate packing. presence primary calcite cement, silica iron oxide/hydroxide cements were shown by diagenetic investigation, was supported SEM studies. In addition, secondary include ferroan-dolomite, chlorite, illite, is linked chemical alteration unstable grains. paragenetic sequence depicts evolution early late phases. quality LF1 LF4 destroyed early-stage cementation, but LF2 LF3 have strong owing scarcity dissolution feldspar grains, grain fracture.