|
Fan Deltas
Fan deltas form where high mountains stand abruptly next to deep depositional basins, such as in rift valleys (see Wilson Cycle Stage B), or next to subduction-created volcanic arcs (see Wilson Cycle Stage E).The original conception of a fan delta was an alluvial fan that has prograded from an adjacent highland into a standing body of water, either a lake or a sea." Hear fan delta refers to alluvial fans and their adjacent submarine deposits (the "delta"), implied to be submarine fan type (including proximal slumps and debris flows and/or more distal turbidite deposits). A typical sequence of depositional environments in a fan delta is alluvial fan and/or braided-river transitioning to a gravel beach, and then into a submarine fan and finally a basin. The basin center is frequently deep and anoxic, and thinly laminated black shales and silts are deposited. |