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Abstract: Three Types of Pressure Solution in Limestones

Previous HitHaroldTop R. Wanless

Limestones that have been subjected to overburden or tectonic stress can be expected to have changed by some combination of deformation (plastic or brittle), neomorphism (as micrite conversion to microspar or aggrading pseudospar), and solution. Specific limestone units (beds, structures, or grains) preferentially may be resistant or responsive to change and with or without impurities (especially magnesium ions and clay particles) that will influence the character of change.

Three types of pressure solution response are recognized. (1) Sutured seam solution (common stylolites and grain contact sutures) occurs in limestones that have structural resistance to stress and very little clay or platy silt content. (2) Nonsutured seam solution (microstylolites, microstylolite swarms, and clay seams) occurs in limestones having significant clay or platy silt content, whether the limestone is structurally resistant or responsive. Stress is accommodated both by solution and lateral movement, along microstylolite surfaces. Dolomite rhomb growth may or may not occur along microstylolite surfaces. (3) Nonseam solution (pervasive solution thinning of a unit) occurs in clean limestones that have little or no structural resistance to stress. Dolomite growth always is asso iated with nonseam solution.

Nodular limestones are a characteristic product of nonsutured seam solution in silty-clayey limestones. Fitted nodule form and scale may or may not have a primary structure influence.

The three forms of limestone pressure solution produce finely crystalline stratigraphic dolomite, provide ample local sources of magnesium for dolomitization and calcite for porosity filling cement, and severely distort primary sedimentary structures or create secondary structures.

AAPG Search and Discovery Article #90961©1978 AAPG Annual Convention and Exhibition, Oklahoma City, Oklahoma