Packstone

thumb|A Packstone: grain supported by small grains (width of picture is 7mm) Under the Dunham classification (Dunham, 1962<ref>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.</ref>) 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)<ref name=":0">{{Cite journal|last=Lokier|first=Stephen W.|last2=Al Junaibi|first2=Mariam|date=2016-12-01|title=The petrographic description of carbonate facies: are we all speaking the same language?|journal=Sedimentology|language=en|volume=63|issue=7|pages=1843–1885|doi=10.1111/sed.12293|issn=1365-3091|doi-access=free}}</ref> as ''a carbonate-dominated lithology containing carbonate mud (<63 μm) in a fabric supported by a sand grade (63 μm to 2 mm) grain-size fraction and where less than 10% of the volume consists of grains >2 mm''.

== The identification of packstone == thumb|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)<ref name=":0" /> 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.

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Category:Limestone