Geoscience Reference
In-Depth Information
limestone type
principal
grain type
cemented by sparite
micritic matrix
bioclasts
biosparite
biomicrite
ooids
oosparite
oomicrite
peloids
pelsparite
pelmicrite
intraclasts
intrasparite
intramicrite
limestone formed
in situ
(e.g. reef or stromatolite)= biolithite
Figure A6.11
Folk scheme for
the classifi cation of limestones.
(Modifi ed after Folk 1962.)
fenestral limestone (micrite with cavities)
= dismicrite
Boundstones:
original components
organically bound
during deposition
original components not organically
bound together during deposition
contains lime mud
>10% grains >2 mm
organisms
build a
rigid 3-D
framework
mud-supported
organisms
encrust
and bind
grain-
supported
with muddy
matrix
lacks mud
and is
grain-
supported
supported
by >2 mm
component
organisms
act as
baffles
matrix-
supported
<10%
grains
>10%
grains
baffle-
stone
frame-
stone
mudstone
wackestone packstone grainstone
floatstone rudstone
bindstones
Figure A6.12
Dunham scheme for the classifi cation of limestones. (Modifi ed after Dunham 1962 with
additions from Embry and Klovan 1971.)
