1. n. [Reservoir Characterization]

A systems tract overlying a sequence boundary and overlain by a transgressive surface. Characterized by a progradational to aggradational parasequence set, this systems tract commonly includes a basin-floor fan, a slope fan and a lowstand wedge. It is often abbreviated as LST.

See related terms: highstand systems tract,  maximum flooding surface,  parasequence,  sequence boundary,  sequence stratigraphy