Packstone
Under the Dunham classification system of limestones, a packstone is defined as a grain-supported carbonate rock that contains 1% or more mud-grade fraction. This definition has been clarified by Lokier and Al Junaibi as a carbonate-dominated lithology containing carbonate mud in a fabric supported by a sand grade grain-size fraction and where less than 10% of the volume consists of grains >2 mm.A study of the adoption and use of carbonate classification systems by Lokier and Al Junaibi identified three common problems encountered when describing a packstone:
- Failure to identify the fabric as supported by the sand grade grain-size fraction - resulting in misidentification as wackestone.
- Packstones with very small volumes of carbonate mud may be misclassified as grainstone.
- Incorrectly estimating the volume of the component grains >2 mm.
