2.5 Lake Sediments
a · OPEN" LAKE SYSTEMS
OUTFLOW
INFLOW
DENSITY
OVERTURN
UNDERFLOW ( THIN TURBIDITES)
WATER FRESH OR SLiGHTLY BRACKISH.
RIVER ·DOMINATED CLASTIC SEDIMENTS.
TENDENCY TO:
OLIGOTROPH
LlTTLE NUTRIENTS
~
~ ----r- Of\-b · CLOSED" LAKE SYSTEMS
WIDE SAND AND
MUD FLATS
(SHIFTING FACIES BELT , REPEATED
REWORKING AND DISSOLUTION OF SALTS)
EUTROPH
EPILIMN ION
(WELL OXYGENATED~
77
= STABLE
I
.
_ _
1
.....
NO PERMANENT •• _ _ __
BOTTOM LlFE
STRATIFICATION
HYPOLIMNION.
STRATIFICATION ~:"l;:~ ~LL OXYGENATED
ANNUAL VARVES OR POOR LAMINATION .
BOTTOM Ll FE
3L\*",OXYGEN MINIMUM
SPARSE OR ABSENT
\
ZONE
LlTTLE ORG MATTER. PARTLY IRON
HYDROXIDES. TURBIDITES
" "
MATTER. = SIDERITE CONCRETIONS
~
DISTINCT LAMINATION. RICH IN ORG,
b 3
EPHEMER AL LAKES
b 2 PERENNIAl L AKES
(PLAYA, INLAND SABKHA)
MUD CRACKS . CRUSTS OF MG · CALCITE .
FRESHWATER
FLUCTUATING LAKE LEVEL
DOLOMITE. GYPSUM. OR HAllTE
CARBONATE
-...
h
/'
"5(--- ---j
PERMANENT
WATER BODY .
BUT CHANGING
SALINITY
a 2 LAKE CHAIN
/
BEDDED C ARBONATES AND I OR
THICK EVAPORITES ALTERNATING
WITH FI NE·GRAINED CLASTICS
OR BLACK SHALES
(SPRING)
~· : ' : - · · . l> .?r; . }~" .. ·:·/t ,'".·k -
EVAPORATIVE PUMPING
CENTRAL THIN SALT
FROM HIGH WATER TABLE
DEPOSITION. ALTERNAT ING
WITH CLASTICS
b 4 WATER TABlE BElOW LAKE FlOOR
DEFLATION AND
LEACHING OF SALTS
CLAY DUNES ( WIND ,BLOWN
CLAY PELLETS)
IIN SEMIARID TO ARID REGION)
INCREASING SALINITY
',':.'"
~ ~, ~o:-:"":~-:,,:, • ..;.;..~ ;..' .: .-::.~;.':," .:~~:~~:::::;:;.
~:. ~' ~.: -7.~,~ 7': ~R;~~~~~-!: :E~'~ ~:. ~.~: ~ ~:~~
-E- -- ------- ---- -
CHLOR IDE
SU LF AT E
k"
CARBONATE
PRECIPITATION
SEA
Fig. 2.28. Overview of different lake systems. a
Open system with inflow and outflow; the lake water
ehemistry is river-dominated. al Weil oxygenated,
oligotrophie lake (poor in nutrients). a2 Chain of
eonneeted lakes, at the downstream end open or
c1osed. b Closed systems without outflow; eoneentration of dissolved speeies eommonly inereasing
withlowering lake water level and time. bl Stable
stratifieation of lake water and eutrophie eonditions
with oxygen-defieient bottom water (also feasible for
C SEA-LAGOON-LAKE SYSTEM
CHANGING WATER CHEMISTRY
..,, -------:--- - -:-. .
. .
:
r': ...... :
....
/1 ' . ~
.
'I'"
~ ... :.
_____ : .. :71
' - ~ -
-7 -~OUNDWATER
DIFFERENT CA R80N~TES \INCL DOLOMITE )
a). b2 Perennial lake, suffieiently deep with enough
inflow to maintain a permanent water fil\. b3 Ephemeral lake, usually dry or redueed to small shallow
pond(s), seasonally or irregularly flooded.
b4 Ephemeral or permanently dry lake with groundwater table below lake floor, and downward leaehing
of salts, c Open sea-lagoon-lake system, eontrolled
mainly by subsurfaee sea water and groundwater
flow (Coorong model, Australia). For further explanation see text
a · OPEN" LAKE SYSTEMS
OUTFLOW
INFLOW
DENSITY
OVERTURN
UNDERFLOW ( THIN TURBIDITES)
WATER FRESH OR SLiGHTLY BRACKISH.
RIVER ·DOMINATED CLASTIC SEDIMENTS.
TENDENCY TO:
OLIGOTROPH
LlTTLE NUTRIENTS
~
~ ----r- Of\-b · CLOSED" LAKE SYSTEMS
WIDE SAND AND
MUD FLATS
(SHIFTING FACIES BELT , REPEATED
REWORKING AND DISSOLUTION OF SALTS)
EUTROPH
EPILIMN ION
(WELL OXYGENATED~
77
= STABLE
I
.
_ _
1
.....
NO PERMANENT •• _ _ __
BOTTOM LlFE
STRATIFICATION
HYPOLIMNION.
STRATIFICATION ~:"l;:~ ~LL OXYGENATED
ANNUAL VARVES OR POOR LAMINATION .
BOTTOM Ll FE
3L\*",OXYGEN MINIMUM
SPARSE OR ABSENT
\
ZONE
LlTTLE ORG MATTER. PARTLY IRON
HYDROXIDES. TURBIDITES
" "
MATTER. = SIDERITE CONCRETIONS
~
DISTINCT LAMINATION. RICH IN ORG,
b 3
EPHEMER AL LAKES
b 2 PERENNIAl L AKES
(PLAYA, INLAND SABKHA)
MUD CRACKS . CRUSTS OF MG · CALCITE .
FRESHWATER
FLUCTUATING LAKE LEVEL
DOLOMITE. GYPSUM. OR HAllTE
CARBONATE
-...
h
/'
"5(--- ---j
PERMANENT
WATER BODY .
BUT CHANGING
SALINITY
a 2 LAKE CHAIN
/
BEDDED C ARBONATES AND I OR
THICK EVAPORITES ALTERNATING
WITH FI NE·GRAINED CLASTICS
OR BLACK SHALES
(SPRING)
~· : ' : - · · . l> .?r; . }~" .. ·:·/t ,'".·k -
EVAPORATIVE PUMPING
CENTRAL THIN SALT
FROM HIGH WATER TABLE
DEPOSITION. ALTERNAT ING
WITH CLASTICS
b 4 WATER TABlE BElOW LAKE FlOOR
DEFLATION AND
LEACHING OF SALTS
CLAY DUNES ( WIND ,BLOWN
CLAY PELLETS)
IIN SEMIARID TO ARID REGION)
INCREASING SALINITY
',':.'"
~ ~, ~o:-:"":~-:,,:, • ..;.;..~ ;..' .: .-::.~;.':," .:~~:~~:::::;:;.
~:. ~' ~.: -7.~,~ 7': ~R;~~~~~-!: :E~'~ ~:. ~.~: ~ ~:~~
-E- -- ------- ---- -
CHLOR IDE
SU LF AT E
k"
CARBONATE
PRECIPITATION
SEA
Fig. 2.28. Overview of different lake systems. a
Open system with inflow and outflow; the lake water
ehemistry is river-dominated. al Weil oxygenated,
oligotrophie lake (poor in nutrients). a2 Chain of
eonneeted lakes, at the downstream end open or
c1osed. b Closed systems without outflow; eoneentration of dissolved speeies eommonly inereasing
withlowering lake water level and time. bl Stable
stratifieation of lake water and eutrophie eonditions
with oxygen-defieient bottom water (also feasible for
C SEA-LAGOON-LAKE SYSTEM
CHANGING WATER CHEMISTRY
..,, -------:--- - -:-. .
. .
:
r': ...... :
....
/1 ' . ~
.
'I'"
~ ... :.
_____ : .. :71
' - ~ -
-7 -~OUNDWATER
DIFFERENT CA R80N~TES \INCL DOLOMITE )
a). b2 Perennial lake, suffieiently deep with enough
inflow to maintain a permanent water fil\. b3 Ephemeral lake, usually dry or redueed to small shallow
pond(s), seasonally or irregularly flooded.
b4 Ephemeral or permanently dry lake with groundwater table below lake floor, and downward leaehing
of salts, c Open sea-lagoon-lake system, eontrolled
mainly by subsurfaee sea water and groundwater
flow (Coorong model, Australia). For further explanation see text