System Tracts and their deposition

System Tract

A system tract is  part of a sequence, identified on the basis of stratal stacking pattern, position in a sequence and in the sea level curve and type of its bounding surfaces..

Generally there are four system tracts in a sequence  i.e. 

High Stand System Tract (HST),

Falling Stage System Tract (FSST),

Lowstand Stand System Tract (LST),

Trangressive System Tract (TST),

This figure shows deposition of different system tracts with reference to sea level changes and hierarchy of straigraphic sequences.

Order of Sequences (Sequence Stratigraphy)

Cycle Order

Attenuation of cycles produces maximum sea level high and lowstands

Sequence Straigraphic orders

Sequence Straigraphic orders:

Duration of different orders of sequence is different according to different authors. (See Table Below)

Duration of sequence cycles according to different authors.