Packstone (carbonate)
A grain-supported carbonate rock that retains depositional carbonate mud.
Language and route: English pack + stone; formal carbonate texture sense in Dunham (1962). English pack + stone; formal carbonate texture sense in Dunham (1962)
Literal gloss: packed-grain carbonate stone
The name and its history
Robert J. Dunham · 1962 original abstract checked
- What does the word literally mean?
- Immediate source or formation: English pack + stone; formal carbonate texture sense in Dunham (1962). Literal gloss ‘packed-grain carbonate stone’. This linguistic evidence is distinct from claims about the namer’s intentions.
- What did the original author mean?
- Dunham 1962 rejected a simple opposition between mud-rich and grain-rich rocks and used physical support relationships.
- Why was the name needed?
- Without packstone, grain-supported muddy deposits might be forced into either grainstone or wackestone, obscuring porosity and transport history.
- What evidence supported the original concept?
- Microscopic grain contacts plus carbonate mud; Dunham’s 1962 original abstract contrasts packstone explicitly with wackestone.
- How has geology changed the concept?
- Packstone indicates texture, not one sediment-energy category, and recrystallisation may obscure original mud.
Further historical context
Dunham 1962 rejected a simple opposition between mud-rich and grain-rich rocks and used physical support relationships.
Without packstone, grain-supported muddy deposits might be forced into either grainstone or wackestone, obscuring porosity and transport history.
Microscopic grain contacts plus carbonate mud; Dunham’s 1962 original abstract contrasts packstone explicitly with wackestone.
Packstone indicates texture, not one sediment-energy category, and recrystallisation may obscure original mud.
Editorial qualification
Priority and exact original naming language not independently authenticated; distinguish documented later use from first coinage.
Related names
Grainstone (carbonate) · Wackestone (carbonate) · Boundstone · Micrite
Sources
- Dunham 1962, Classification of Carbonate Rocks According to Depositional Texture, AAPG Memoir 1:108–121 — identified original; author abstract directly inspected
- SEPM Strata, carbonate classification comparing Folk, Dunham and extensions — professional retrospective of distinct schemes and Embry–Klovan 1971 extension
- Folk 1959, Practical Petrographic Classification of Limestones, AAPG Bulletin 43:1–38 — identified original publication; abstract directly inspected, not every page