2 Continental Sediments
2.5 Lake Sediments
2.5.1 Introduction
2.5.2 General Processes in Various Lake Systems
(Overview)
2.5.3 Sediments ofOpen Lake Systems
Lakes Dominated by Detrital Clastics
Lakes with Significant Proportions of
Biogenic Sediments
Post-Glacial Lake Evolution
2.5.4 Sediments ofClosed Lake Systems
Overview
Carbonate Lakes
Sulfate Lakes, Soda Lakes, Chloride Lakes
Playa Lakes (Inland Sabkhas)
Examples of Closed Lake Basins and their
Sediments
2.5.5 Black Shale Deposits in Lakes
2.5.6 Succcssions ofLake Sediments
2.5.7 Specific Features ofLake Sediments
Sedimentation Rates and Lifetime ofLakes
Isotopes and Fluid Inclusions Indicating
Paleoclimate
Subsurface Brines and Diagenesis
2.5.8 Economic Aspects ofLake Sediments
Residual Brines and Mineral Deposits
Oil Shales and Hydrocarbons
2.5.9 Summary (Lake Sediments)
2.5.1 Introduction
The origin of weH exposed ancient lake sediments is
often evident at first glance. Many lake deposits are
particularly weH horizontaHy bedded or laminated
and, in addition, show frequent vertical changes in
lithology and color. The principal reasons for these
phenomena are that lakes and their sediments are (1)
little affected by waves and currents and (2) very
sensitive to changes in climate and other environmental factors.
Fresh-water carbonates, thin doJomitic beds, iron
oxides or siderite concretions, oil shales, and
evaporites (commonly differing from those of the
marine realm) characterize certain stages and types of
lacustrine environments. One or several of these rock
types are found in many lake deposits. Furthermore,
lake deposits are frequently associated with fluvial
sediments and fossil soils (paleosols).
Faunal remains usuaHy comprise only a limited
number of species and are often restricted to certain
beds. Important microfossils are diatoms,
dinoflagellates, and ostracods. Particularly ostracods
can tolerate a varying chemical environment from
fresh to brackish and hypersaline water. Bioturbation
is less common than in normal marine environments.
Fresh-water lakes usually contain less than 1 g/l
dissolved constituents, brackish water lakes 1-5 g/l,
and saIt lakes more than 5 g/l. Righly concentrated
brines reach ion concentrations of 200 to 300 g/l and
more. The pR of lake waters may vary from about 4
to 10.
From these criteria one can conclude that lake deposits displaya great variety of facies types. Modem
lake systems including their drainage areas have been
often quoted as natural laboratories which are better
suited than larger systems for the study of various
processes controlling their biota and sediments. All
this cannot be described and explained here in detail.
A more thorough treatment of this topic is given, for exampIe, by Dean and Fouch (1983), Anadon et al. (1991),
Gierlowski-Kordesch and Kelts (1994), Talbot and Allen
(1996), Noe-Nygaard (1998) and a number of special articles mentioned below. The origin of lakes and their classitkation are discussed, e.g., by Horie (1978) and Meybeck
(1995). For hydrological and physical processes in lakes
see, e.g., Sturm and Matter (1978), Lerman et al. (1995).
Lakes originate from different exogenetic and
endogenetic geologie al processes. They occur in areas of crustal subsidence such as rift zones, continental sag basins, fore land and backarc basins (cf. Chap.
1) which cannot be inundated by sea water or rapidly
filled with sediment. Most of the oldest, presently
persisting lakes are associated with continental rift
zones, such as Lake Baikai in Asia and the lakes of
the East African Rift. VoIcanic craters and chalderas
are often filled with water and collect voIcaniclastic,
chemical and biogenic sediments, but they usually
are of limited areal extent. Today, glacier-shaped
lakes within and close to mountain ranges or former
large ice sheets are very common (cf. Sect. 2.1). Another type of lake is known from some arid to semiarid lowlands where wind-induced deflation has created shallow morphological depressions which later
have been filled with water.
Ancient lacustrine systems of a green- or hothouse
world (cf. Sect. 7.8) were prcdominantly controlled
2.5 Lake Sediments
2.5.1 Introduction
2.5.2 General Processes in Various Lake Systems
(Overview)
2.5.3 Sediments ofOpen Lake Systems
Lakes Dominated by Detrital Clastics
Lakes with Significant Proportions of
Biogenic Sediments
Post-Glacial Lake Evolution
2.5.4 Sediments ofClosed Lake Systems
Overview
Carbonate Lakes
Sulfate Lakes, Soda Lakes, Chloride Lakes
Playa Lakes (Inland Sabkhas)
Examples of Closed Lake Basins and their
Sediments
2.5.5 Black Shale Deposits in Lakes
2.5.6 Succcssions ofLake Sediments
2.5.7 Specific Features ofLake Sediments
Sedimentation Rates and Lifetime ofLakes
Isotopes and Fluid Inclusions Indicating
Paleoclimate
Subsurface Brines and Diagenesis
2.5.8 Economic Aspects ofLake Sediments
Residual Brines and Mineral Deposits
Oil Shales and Hydrocarbons
2.5.9 Summary (Lake Sediments)
2.5.1 Introduction
The origin of weH exposed ancient lake sediments is
often evident at first glance. Many lake deposits are
particularly weH horizontaHy bedded or laminated
and, in addition, show frequent vertical changes in
lithology and color. The principal reasons for these
phenomena are that lakes and their sediments are (1)
little affected by waves and currents and (2) very
sensitive to changes in climate and other environmental factors.
Fresh-water carbonates, thin doJomitic beds, iron
oxides or siderite concretions, oil shales, and
evaporites (commonly differing from those of the
marine realm) characterize certain stages and types of
lacustrine environments. One or several of these rock
types are found in many lake deposits. Furthermore,
lake deposits are frequently associated with fluvial
sediments and fossil soils (paleosols).
Faunal remains usuaHy comprise only a limited
number of species and are often restricted to certain
beds. Important microfossils are diatoms,
dinoflagellates, and ostracods. Particularly ostracods
can tolerate a varying chemical environment from
fresh to brackish and hypersaline water. Bioturbation
is less common than in normal marine environments.
Fresh-water lakes usually contain less than 1 g/l
dissolved constituents, brackish water lakes 1-5 g/l,
and saIt lakes more than 5 g/l. Righly concentrated
brines reach ion concentrations of 200 to 300 g/l and
more. The pR of lake waters may vary from about 4
to 10.
From these criteria one can conclude that lake deposits displaya great variety of facies types. Modem
lake systems including their drainage areas have been
often quoted as natural laboratories which are better
suited than larger systems for the study of various
processes controlling their biota and sediments. All
this cannot be described and explained here in detail.
A more thorough treatment of this topic is given, for exampIe, by Dean and Fouch (1983), Anadon et al. (1991),
Gierlowski-Kordesch and Kelts (1994), Talbot and Allen
(1996), Noe-Nygaard (1998) and a number of special articles mentioned below. The origin of lakes and their classitkation are discussed, e.g., by Horie (1978) and Meybeck
(1995). For hydrological and physical processes in lakes
see, e.g., Sturm and Matter (1978), Lerman et al. (1995).
Lakes originate from different exogenetic and
endogenetic geologie al processes. They occur in areas of crustal subsidence such as rift zones, continental sag basins, fore land and backarc basins (cf. Chap.
1) which cannot be inundated by sea water or rapidly
filled with sediment. Most of the oldest, presently
persisting lakes are associated with continental rift
zones, such as Lake Baikai in Asia and the lakes of
the East African Rift. VoIcanic craters and chalderas
are often filled with water and collect voIcaniclastic,
chemical and biogenic sediments, but they usually
are of limited areal extent. Today, glacier-shaped
lakes within and close to mountain ranges or former
large ice sheets are very common (cf. Sect. 2.1). Another type of lake is known from some arid to semiarid lowlands where wind-induced deflation has created shallow morphological depressions which later
have been filled with water.
Ancient lacustrine systems of a green- or hothouse
world (cf. Sect. 7.8) were prcdominantly controlled