Chapter 12
What Does Fluvual l.ithofades Reveal About Climate?
12.1 Introduction
Integrated analyses of past climates are now becom�
ing commonplace, as attempts are being made to
produce complete reconstructions of ancient environments incorporating numerical global climate
models linked to the details of local plate-tectonic
position and paleogeography. Evidence from the
stratigraphic record, including the distribution of
certain types of lithology, plus fossil evidence and
isotopic data are combined in such analyses. This
chapter is concerned with the nonmarine lithostratigraphic record and the information it can yield
regarding climate.
Several climatic indicators of chemical or biochemical origin are present in the nonmarine sedimentary record, such as coal, evaporite, bauxite,
laterite, and paleosols, all of which yield limited information on some of the main attributes of climate,
particularly rainfall and temperature (F rakes 1979;
Parrish and Barron 1986). Some of the clearest climatic signals available in nonmarine sediments are
the wind patterns that can be deduced from giant
fossil ergs (e.g., Parrish and Peterson 1988), the
chemical rhythms in lacustrine sediments and the
climatically driven changes in lake levels recorded in
lacustrine- fluvial interbedding (Katz 1990), redox
and water-table information from paleosols (Wright
1986; Retallack 1981, 1988), and the various indicators of continental glaciation, such as tills, glaciolacustrine dropstones, and striated pavements
(Hambrey and Harland 1981). It was once thought
that continental redbeds were a clear indicator of
oxidizing and probably arid depositional environments (see Pettijohn 1957; Van Houten 1973), but
Walker (1967) clearly demonstrated that the red
color may be produced by diagenesis, requiring that
color be interpreted with caution.
Eolian, lacustrine, and continental glacial sediments, and the chemical sediments in fluvial floodplain deposits may therefore yield some evidence of
climate. What about clastic fluvial deposits - the
coarse fluvial channel and bar deposits and the detrital overbank deposits? Are there any characteristics
of the assemblage, vertical succession, and associated sedimentary structures of fluvial gravels, sands,
and muds that can be interpreted in terms of local
climate? Many studies of ancient fluvial deposits
include an interpretation of the contemporary climate, but in most cases the interpretation is based on
the stratigraphic context, on paleosols, or on associated faunas and floras. Other studies infer climate
from regional paleogeography and make predictions
of temperature, rainfall and seasonality from knowledge of comparable geographic configurations on
the modern earth [e.g., the discussion of monsoonal
conditions in Pangea by Dubiel et al. (1991) and
Parrish (1993 )]. The purpose of this chapter is to
focus on the lithofacies of clastic deposits in fluvial
systems to determine whether they contain any useful independent information regarding .climate. This
chapter specifically does not focus on paleosols or
the paleoecology of nonmarine systems, which have
received ample coverage elsewhere.
Although the history of global climates during the
Phanerozoic is in general fairly well known (e.g.,
Frakes 1979; Parrish and Barron 1986; Parrish 1993 ),
many local details remain to be resolved, and the
kinds of field criteria described in this chapter may
therefore be useful, especially where the more obvious evidence from lacustrine, eolian, glacial, or other
related facies is absent. In addition, there is increasing interest in climate change) particularly changes
driven by orbital forcing. The recognition of
Milankovitch rhythms in the nonmarine sedimentary record is a subject barely in its infancy, and
again the kinds of observational approach reviewed
here may provide useful tools for this type of study
(Sect. 12.12).
The main body of this chapter (Sects. 12.5-12.7 )
provides a systematic discussion of the lithofacies
evidence that can be obtained from detailed local
studies of conglomerates, sandstones, and finegrained facies, focusing on the major climatically
sensitive attributes for each sediment type. The evi-
What Does Fluvual l.ithofades Reveal About Climate?
12.1 Introduction
Integrated analyses of past climates are now becom�
ing commonplace, as attempts are being made to
produce complete reconstructions of ancient environments incorporating numerical global climate
models linked to the details of local plate-tectonic
position and paleogeography. Evidence from the
stratigraphic record, including the distribution of
certain types of lithology, plus fossil evidence and
isotopic data are combined in such analyses. This
chapter is concerned with the nonmarine lithostratigraphic record and the information it can yield
regarding climate.
Several climatic indicators of chemical or biochemical origin are present in the nonmarine sedimentary record, such as coal, evaporite, bauxite,
laterite, and paleosols, all of which yield limited information on some of the main attributes of climate,
particularly rainfall and temperature (F rakes 1979;
Parrish and Barron 1986). Some of the clearest climatic signals available in nonmarine sediments are
the wind patterns that can be deduced from giant
fossil ergs (e.g., Parrish and Peterson 1988), the
chemical rhythms in lacustrine sediments and the
climatically driven changes in lake levels recorded in
lacustrine- fluvial interbedding (Katz 1990), redox
and water-table information from paleosols (Wright
1986; Retallack 1981, 1988), and the various indicators of continental glaciation, such as tills, glaciolacustrine dropstones, and striated pavements
(Hambrey and Harland 1981). It was once thought
that continental redbeds were a clear indicator of
oxidizing and probably arid depositional environments (see Pettijohn 1957; Van Houten 1973), but
Walker (1967) clearly demonstrated that the red
color may be produced by diagenesis, requiring that
color be interpreted with caution.
Eolian, lacustrine, and continental glacial sediments, and the chemical sediments in fluvial floodplain deposits may therefore yield some evidence of
climate. What about clastic fluvial deposits - the
coarse fluvial channel and bar deposits and the detrital overbank deposits? Are there any characteristics
of the assemblage, vertical succession, and associated sedimentary structures of fluvial gravels, sands,
and muds that can be interpreted in terms of local
climate? Many studies of ancient fluvial deposits
include an interpretation of the contemporary climate, but in most cases the interpretation is based on
the stratigraphic context, on paleosols, or on associated faunas and floras. Other studies infer climate
from regional paleogeography and make predictions
of temperature, rainfall and seasonality from knowledge of comparable geographic configurations on
the modern earth [e.g., the discussion of monsoonal
conditions in Pangea by Dubiel et al. (1991) and
Parrish (1993 )]. The purpose of this chapter is to
focus on the lithofacies of clastic deposits in fluvial
systems to determine whether they contain any useful independent information regarding .climate. This
chapter specifically does not focus on paleosols or
the paleoecology of nonmarine systems, which have
received ample coverage elsewhere.
Although the history of global climates during the
Phanerozoic is in general fairly well known (e.g.,
Frakes 1979; Parrish and Barron 1986; Parrish 1993 ),
many local details remain to be resolved, and the
kinds of field criteria described in this chapter may
therefore be useful, especially where the more obvious evidence from lacustrine, eolian, glacial, or other
related facies is absent. In addition, there is increasing interest in climate change) particularly changes
driven by orbital forcing. The recognition of
Milankovitch rhythms in the nonmarine sedimentary record is a subject barely in its infancy, and
again the kinds of observational approach reviewed
here may provide useful tools for this type of study
(Sect. 12.12).
The main body of this chapter (Sects. 12.5-12.7 )
provides a systematic discussion of the lithofacies
evidence that can be obtained from detailed local
studies of conglomerates, sandstones, and finegrained facies, focusing on the major climatically
sensitive attributes for each sediment type. The evi-