Properties of Conglomerates from the Middle Ordovician Dongchong Formation and Its Response to the Yunan Orogeny in the Yunkai Area, South China

The strata in the Shita Mountain, Yunkai region, are predominantly composed of clastic rocks with intercalated limestones. However, precise stratigraphic age remains uncertain due to scarcity fossils. Previously, conglomerate layers this region were considered indicative Yunan Orogeny during Cambrian–Ordovician transition. through identification 12 lithofacies types and 5 combinations Mountain section, it has been confirmed that these represent a fan delta depositional environment characterized by debris flow, traction torrent, rock flow. Based on presence brachiopod fossils dating Early–Middle Ordovician, we propose novel two-episode model for Orogeny. first episode corresponds submarine deposition, while second involves tectonic uplift short-term sedimentary hiatus. Further analysis detrital zircon provenance reveals strong affinity among area, India, Antarctica, Lhasa, Himalayas, Southern Qiangtang, Western Australia Ordovician transition under Gondwana assemblage background.