Monday, April 6, 2015

Salt Structure chapter 2

Regardless of the mechanism responsible for salt movement, flow of salt into a growing structure creates a withdrawal basin that is a structural low and an isopach thick.

Three main growth stages of salt diapirs observed in the East Texas basin, this model can be used as a basis to interpret seismic-reflector configurations. Diagnostic configurations for the various stages are:

  1. Pillow stage : Syndepositional thnning of sediments over the pillow crests and flanks , developed in response to pillow growth, is the most diagnostic feature of this stage. Only minor thickening usually develops into the primary rim syncline.
  2. Diapir stage : Withdrawal of the salt into the growing diapir leads to a collapse of the flanking sequence that thinned toward the original pillow. A secondary rim syncline, its axis immediately adjacent to the diapirs's edge, develops above the collapsed area. The secondary rim syncline is usually more extensive than primary rim syncline and also accumulates a thicker sequence. 
  3. Postdiapir stage: During this stage, diapirs stay at or near the sediment surface (assuming there is sufficient salt for continued movement) despite continued subsidence. A small, often subtle , tertiary rim syncline flanks the diapir.

Reference : Practical Seismic Interpretation , Michael E. Badley

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