Principles of Paleocurrent Analysis
79
Table 4.1. Facies classification. (Modified from Miall l978c)
Facies code
Facies
Sedimentary structures
Interpretation
Gmm
Matrix-supported,
Weak grading
Plastic debris flow
massive gravel
(high-strength, viscous)
Gmg
Matrix-supported
Inverse to
Pseudoplastic debris flow
gravel
normal grading
(low strength, viscous)
Gci
Clast-supported
Inverse
Clast-rich debris flow (high strength),
gravel
grading
or pseudoplastic debris flow (low
strength)
Gem
Clast-supported
Pseudoplastic debris flow
massive gravel
(inertial bedload, turbulent flow)
Gh
Clast-supported,
Horizontal bedding,
Longitudinal bedforms,
crudely bedded
imbrication
lag deposits,
gravel
sieve deposits
Gt
Gravel,
Trough cross-beds
Minor channel fills
stratified
Gp
Gravel,
Planar cross-beds
Transverse bedforms,
stratified
deltaic growths from older
bar remnants
St
Sand, fine
Solitary or grouped
Sinuous-crested and linguoid
to very coarse,
trough cross-beds
(3-D) dunes
may be pebbly
Sp
Sand, fine
Solitary or grouped
Transverse and linguoid
to very coarse,
planar cross-beds
bedforms (2-D dunes)
may be pebbly
Sr
Sand, very
Ripple
Ripples (lower flow regime)
fine to coarse
cross-lamination
Sh
Sand, very fine
Horizontal lamination
Plane-bed flow
to coarse,
parting or streaming
(critical flow)
may be pebbly
lineation
Sl
Sand, very fine
Low-angle ( < 15°)
Scour fllls, humpback or
to coarse,
cross-beds
washed-out dunes,
may be pebbly
antidunes
Ss
Sand, fine to
Broad, shallow scours
Scour fill
very coarse, may
be pebbly
Sm
Sand, fine
Massive, or faint
Sediment-gravity
to coarse
lamination
flow deposits
Fl
Sand, silt,
Fine lamination,
Overbank, abandoned channel, or
mud
very small ripples
waning flood deposits
Fsm
Silt, mud
Massive
Backswamp or abandoned channel
deposits
Fm
Mud, silt
Massive, desiccation
Overbank, abandoned channel, or
cracks
drape deposits
Fr
Mud, silt
Massive, roots,
Root bed, incipient soil
bioturbation
c
Coal, carbon�
Plant, mud films
Vegetated swamp deposits
aceous mud
p
Paleosol carbonate
Pedogenic fe atures:
Soil with
(calcite, siderite)
nodules, filaments
chemical precipitation
79
Table 4.1. Facies classification. (Modified from Miall l978c)
Facies code
Facies
Sedimentary structures
Interpretation
Gmm
Matrix-supported,
Weak grading
Plastic debris flow
massive gravel
(high-strength, viscous)
Gmg
Matrix-supported
Inverse to
Pseudoplastic debris flow
gravel
normal grading
(low strength, viscous)
Gci
Clast-supported
Inverse
Clast-rich debris flow (high strength),
gravel
grading
or pseudoplastic debris flow (low
strength)
Gem
Clast-supported
Pseudoplastic debris flow
massive gravel
(inertial bedload, turbulent flow)
Gh
Clast-supported,
Horizontal bedding,
Longitudinal bedforms,
crudely bedded
imbrication
lag deposits,
gravel
sieve deposits
Gt
Gravel,
Trough cross-beds
Minor channel fills
stratified
Gp
Gravel,
Planar cross-beds
Transverse bedforms,
stratified
deltaic growths from older
bar remnants
St
Sand, fine
Solitary or grouped
Sinuous-crested and linguoid
to very coarse,
trough cross-beds
(3-D) dunes
may be pebbly
Sp
Sand, fine
Solitary or grouped
Transverse and linguoid
to very coarse,
planar cross-beds
bedforms (2-D dunes)
may be pebbly
Sr
Sand, very
Ripple
Ripples (lower flow regime)
fine to coarse
cross-lamination
Sh
Sand, very fine
Horizontal lamination
Plane-bed flow
to coarse,
parting or streaming
(critical flow)
may be pebbly
lineation
Sl
Sand, very fine
Low-angle ( < 15°)
Scour fllls, humpback or
to coarse,
cross-beds
washed-out dunes,
may be pebbly
antidunes
Ss
Sand, fine to
Broad, shallow scours
Scour fill
very coarse, may
be pebbly
Sm
Sand, fine
Massive, or faint
Sediment-gravity
to coarse
lamination
flow deposits
Fl
Sand, silt,
Fine lamination,
Overbank, abandoned channel, or
mud
very small ripples
waning flood deposits
Fsm
Silt, mud
Massive
Backswamp or abandoned channel
deposits
Fm
Mud, silt
Massive, desiccation
Overbank, abandoned channel, or
cracks
drape deposits
Fr
Mud, silt
Massive, roots,
Root bed, incipient soil
bioturbation
c
Coal, carbon�
Plant, mud films
Vegetated swamp deposits
aceous mud
p
Paleosol carbonate
Pedogenic fe atures:
Soil with
(calcite, siderite)
nodules, filaments
chemical precipitation