Pyroclastic deposits are important reservoirs and can be divided into fallout tephradeposits

pyroclastic flow deposits

lahar deposits and base surge deposits by their genesis.The four kinds of pyroclastic deposits have different reservoir characteristics and potential.The identification and interpretation of the pyroclastic deposits can significantly influence the exploration methods of volcaniclastic sequences and the prediction of reservoir geometry and quality.The Lower Jurassic Wrightson Formation in Arizona is a multi-crater complex.Its pyroclastic deposits and lavas with various genesis can be divided into crater

proximal

middle and distal facies.The influences of these facies on reservoir quality are discussed.Volcanic clasts are mostly composed of chemically active and unstable minerals that can change rapidly and extensively during burial diagenesis.The occurrence of volcanic clasts may contribute to the development of dissolution porosity which can enhance reservoir quality.