Packstone

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title: "Packstone" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["limestone"] topic_path: "general/limestone" source: "https://en.wikipedia.org/wiki/Packstone" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::figure[src="https://upload.wikimedia.org/wikipedia/commons/2/27/DunhamPackstone.jpg" caption="A Packstone: grain supported by small grains (width of picture is 7mm)"] ::

Under the Dunham classification (Dunham, 1962) 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 (2016) as a carbonate-dominated lithology containing carbonate mud (2 mm.

The identification of packstone

::figure[src="https://upload.wikimedia.org/wikipedia/commons/b/b6/4_x2_PPL.jpg" caption="Thin section photomicrograph of peloid packstone with fragmented bioclasts."] ::

A study of the adoption and use of carbonate classification systems by Lokier and Al Junaibi (2016) 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.

References

References

  1. Dunham, R.J. (1962) Classification of carbonate rocks according to depositional texture. In: Classification of Carbonate Rocks (Ed. W.E. Ham), Am. Assoc. Pet. Geol. Mem., 1, 108–121.
  2. Lokier, Stephen W.. (2016-12-01). "The petrographic description of carbonate facies: are we all speaking the same language?". Sedimentology.

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limestone