The Plinsbachian- Early Toarcian in Kermanshah radiolarite basin was recognized by pelagic limestone with intercalations of pyroclastic, siliceous and internalite deposits. Pyroclastic deposits, vitric tuffs, are extensively altered to clay (i.e. monthmorionolite) and calcite minerals. The siliceous deposits are dark to dark Green and gray in color identified as radiolarian bearing mudstone in thinsection. skeletone as mudstone. Pyroclastic and siliceous deposits are characterised by relatively high Nb, Hf, Th, and Zr and relatively high Th/Sc and (La/Yb)N ratios which is in favor of felsic rocks for this deposits. Also, the chondrite-normalized rare earth element (REE) patterns of the thesepyroclastic and silicious rocks are characterized by LREE enrichment, negative Eu anomaly and flat HREE similar to an upper continental crust source with dominant felsic rock component. Early Toarcian Oceanic Anoxic Event has been recognized as one of the most important environmental upheavals in Mesozoic during which the flare-up of volcanic activities (Karoo-Ferrar Large Igneous Province) released copious amounts of CO2 into the atmosphere. In the Kermanshah basin, this event couple with volcanic eruptions influenceed sea-surface fertility by providing nutrients and stimulation of diazotrophic, N-fixing bacteria and radiolarian productivity (Abdi et al., 2016). Therefore, due to the local role of these activities in the Early Toarcian Event, the study of origin of the pyroclastic deposits would be important.

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