256
Chapter 6 Special Depositional Environments
a PRIMARY ALLOCHTHONOUS RED BEDS
WET -DRY TROPICS
DESERT
HUMID
~
RED-STAINED WINDBLOWN
~~~
DUST
SW~MP PEAT
/ ,
RED LATERITlC SOlL
l ~»",,,m
---\----1=;-/
I
PLAYA LAKE
;,
; : ' RED MUD
EVAPORITES
GREEN MUD
(PRIMARILY RED,
HEMATITE REDUCED
BY ORGANIC MATTER)
GREEN
b RED BEDS FORMED IN SITU
VARIOUS SEDIMENT SOURCES
(GENERALLY BROWN, OXIDIZED MATERIAL)
~
VARIOUS, WELL OXYGENATED
FLUVIAL
~A DEPOSITIONAL ENVIRONMENTS
(E_G., ARID, SEMIARID WITH LlTTLE
VEGETATION)
SEDIMENT SURFACE
DELTAIC, SUPRATIDAL (WITH
LlTTLE ORG. C )
(DESTRUCTION OF
ORGANIC MATTER
BY REWORKING)
DEEP SEA, OCEANIC
RISE , DEEP PLATEAUS
(V ERY SLOW SEDIMENTATION, OXIDATION
OF ORG. MATTER
e
'"
/ /
' / / /
ZONE OF RAPID OXIDATION
(FAST EXCHANGE OF GAS
AND WATER) .
':S ~"p':''' ~~:.c(_!_ ~!/..t.
DRAB GRAY
C-ORG CONTENT}TO REDUCE
DEPTH
- - SUFFICIENT
FERRIC
7nr,7j7rnTnrnT/'7T/n
COMPOUNDS
~ BROWN (LIMONITE;/ ~~~~ INSUFFICIENT
/'/I')//'/"GOETH'TE)~'///
/ / /
/~~~':~~~;~~ .. / / / / /
C
BURIAL DEPTH,
d
AGE, AND
TEMPERATURE
PRIMARY BEDDING
RED
DRAB
ALTERATION OF IRONBEARING MINERAL
OXIDIZING
INTERSTITIAL
WATERS
IN SITU WEA -
THERING, NEOFORMATION OF
CLAY MINERALS
AND HEMATITE
Fig.6.3. Various ongms of red beds.
increasing burial depth, temperature, and age.
a Allochthonous primary red beds formed by eroded,
redeposited lateritic soils. b Secondary red beds resulting from buried brown, well oxygenated sediments too poor in organic matter to allow complete
reduction of ferric iron present in primary limonite
and goethite. c Slow transformation of brown limonite and goethite into hematite (red pigment) with
d In situ alteration of iron-bearing minerals (e.g.
pyroxene, biotite) by interstitial water with high redox potential; release of ferric iron and neo-formation of hernatite within sediment. (After Walker
1967, 1976). e Secondary discoloring of red beds by
circulation of waters with low redox potential along
faults . (After Franke and Paul 1980)
Chapter 6 Special Depositional Environments
a PRIMARY ALLOCHTHONOUS RED BEDS
WET -DRY TROPICS
DESERT
HUMID
~
RED-STAINED WINDBLOWN
~~~
DUST
SW~MP PEAT
/ ,
RED LATERITlC SOlL
l ~»",,,m
---\----1=;-/
I
PLAYA LAKE
;,
; : ' RED MUD
EVAPORITES
GREEN MUD
(PRIMARILY RED,
HEMATITE REDUCED
BY ORGANIC MATTER)
GREEN
b RED BEDS FORMED IN SITU
VARIOUS SEDIMENT SOURCES
(GENERALLY BROWN, OXIDIZED MATERIAL)
~
VARIOUS, WELL OXYGENATED
FLUVIAL
~A DEPOSITIONAL ENVIRONMENTS
(E_G., ARID, SEMIARID WITH LlTTLE
VEGETATION)
SEDIMENT SURFACE
DELTAIC, SUPRATIDAL (WITH
LlTTLE ORG. C )
(DESTRUCTION OF
ORGANIC MATTER
BY REWORKING)
DEEP SEA, OCEANIC
RISE , DEEP PLATEAUS
(V ERY SLOW SEDIMENTATION, OXIDATION
OF ORG. MATTER
e
'"
/ /
' / / /
ZONE OF RAPID OXIDATION
(FAST EXCHANGE OF GAS
AND WATER) .
':S ~"p':''' ~~:.c(_!_ ~!/..t.
DRAB GRAY
C-ORG CONTENT}TO REDUCE
DEPTH
- - SUFFICIENT
FERRIC
7nr,7j7rnTnrnT/'7T/n
COMPOUNDS
~ BROWN (LIMONITE;/ ~~~~ INSUFFICIENT
/'/I')//'/"GOETH'TE)~'///
/ / /
/~~~':~~~;~~ .. / / / / /
C
BURIAL DEPTH,
d
AGE, AND
TEMPERATURE
PRIMARY BEDDING
RED
DRAB
ALTERATION OF IRONBEARING MINERAL
OXIDIZING
INTERSTITIAL
WATERS
IN SITU WEA -
THERING, NEOFORMATION OF
CLAY MINERALS
AND HEMATITE
Fig.6.3. Various ongms of red beds.
increasing burial depth, temperature, and age.
a Allochthonous primary red beds formed by eroded,
redeposited lateritic soils. b Secondary red beds resulting from buried brown, well oxygenated sediments too poor in organic matter to allow complete
reduction of ferric iron present in primary limonite
and goethite. c Slow transformation of brown limonite and goethite into hematite (red pigment) with
d In situ alteration of iron-bearing minerals (e.g.
pyroxene, biotite) by interstitial water with high redox potential; release of ferric iron and neo-formation of hernatite within sediment. (After Walker
1967, 1976). e Secondary discoloring of red beds by
circulation of waters with low redox potential along
faults . (After Franke and Paul 1980)