Transgressive Systems Tract(TST) which bottom is a first flooding surface and top is marked by the emergence of condensed section formed during the period from the lowest point(L) to the ascent inflexion point(R) of lacustrine level change.

• 水进体系域以初始湖泛面为底界，以凝缩段出现为顶界，形成于湖平面最低点L至上升拐点R之间；