Chapter 16
F!ltlml llesearch Trends
In this brief concluding chapter some attempt is
made to assess the present state of knowledge of the
geology of fluvial deposits, and to predict the kinds
of reSearch developments that might be expected in
the next decade.
Facies Analysis. Although some workers still prefer to
establish new fades classifications with each new
field study, the classification and coding system
described in Chaps. 4 and 5 are by now virtually
standard methodologies. Room remains for the recognition and better description of facies that are
rarely fo rmed or preserved in the sedimentary
record, such as those formed under very high shear
stresses. There continues to be a need for additional
case studies of ancient units to serve as a basis for a
wide variety of interpretive studies.
In-channel Depositional Processes. Observations of natural
sand-bed and gravel-bed rivers and flume observations and models have provided a thorough understanding of the processes of formation of most
bedforms and macroforms. Work in this area continues, with the use of flume experiments, flow visualization techniques, and numerical models.
The Architecture of Ch annel-and-Bar Deposits. The development of the architectural-element method of description has fa cilitated the documentation of the
complex three-dimensional nature of the channeland-bar deposits that characterize many modern
and ancient fluvial systems. Classifications of architectural elements and bounding surfaces have been
developed, but there is scope for considerable development and refinement. This is a case where work on
large outcrops of ancient deposits has forced a reexamination of many concepts derived from studies of
modern rivers that were restricted to data derived
from shallow trenches dug above the water table. For
example, it is only relatively recently that the accretionary geometry of most bar complexes in braided
systems has been recognized. The application of
high-resolution seismic reflection techniques and
ground-penetrating radar promises to provide
much valuable information on the three-dimensional structure of both modern and ancient fluvial
systems in the near future, to further improve our
data base of architectural information.
The Architecture of Overbank Regions. There is room for
considerable additional work on the regional mapping of floodplain units, using catena and pedofacies
concepts. Such work is needed in order to understand the long-term dynamics of channel avulsion
and flooding mechanisms, as well as floodplain construction.
Flu vial Styles. Most sedimentological studies of modern river systems have been carried out in temperate,
arctic, and hot arid regions. There is a need for
comparable research in tropical humid regions, such
as the rivers of the African and South American rain
forests. Very few detailed studies of the ancient
record have been completed, and a 'Wide variety of
architectural case studies is needed to complement
our knowledge of modern rivers.
Stratigraphic Architecture. One of the most interesting
areas of research in recent years has been the
application of high-resolution chronostratigraphic
techniques, particularly magnetostratigraphy, to the
study of alluvial stratigraphies. The availability of
correlation frameworks of this type permits much
more detailed reconstructions of regional sedimentary controls) particularly tectonism, and allows for
the quantitative examination of the rates of such
processes as basin accumulation rates and channel
avulsion fr equency. Such data are essential for the
modeling of the autogenic and tectonic control of
alluvial stratigraphy, many studies of which are now
appearing, particularly as an aid to the reconstruction and interpretation of fluvial petroleum reservoirs.
Sequence Stratigraphy. Basic sequence models for fluvial systems are now available and are being applied
F!ltlml llesearch Trends
In this brief concluding chapter some attempt is
made to assess the present state of knowledge of the
geology of fluvial deposits, and to predict the kinds
of reSearch developments that might be expected in
the next decade.
Facies Analysis. Although some workers still prefer to
establish new fades classifications with each new
field study, the classification and coding system
described in Chaps. 4 and 5 are by now virtually
standard methodologies. Room remains for the recognition and better description of facies that are
rarely fo rmed or preserved in the sedimentary
record, such as those formed under very high shear
stresses. There continues to be a need for additional
case studies of ancient units to serve as a basis for a
wide variety of interpretive studies.
In-channel Depositional Processes. Observations of natural
sand-bed and gravel-bed rivers and flume observations and models have provided a thorough understanding of the processes of formation of most
bedforms and macroforms. Work in this area continues, with the use of flume experiments, flow visualization techniques, and numerical models.
The Architecture of Ch annel-and-Bar Deposits. The development of the architectural-element method of description has fa cilitated the documentation of the
complex three-dimensional nature of the channeland-bar deposits that characterize many modern
and ancient fluvial systems. Classifications of architectural elements and bounding surfaces have been
developed, but there is scope for considerable development and refinement. This is a case where work on
large outcrops of ancient deposits has forced a reexamination of many concepts derived from studies of
modern rivers that were restricted to data derived
from shallow trenches dug above the water table. For
example, it is only relatively recently that the accretionary geometry of most bar complexes in braided
systems has been recognized. The application of
high-resolution seismic reflection techniques and
ground-penetrating radar promises to provide
much valuable information on the three-dimensional structure of both modern and ancient fluvial
systems in the near future, to further improve our
data base of architectural information.
The Architecture of Overbank Regions. There is room for
considerable additional work on the regional mapping of floodplain units, using catena and pedofacies
concepts. Such work is needed in order to understand the long-term dynamics of channel avulsion
and flooding mechanisms, as well as floodplain construction.
Flu vial Styles. Most sedimentological studies of modern river systems have been carried out in temperate,
arctic, and hot arid regions. There is a need for
comparable research in tropical humid regions, such
as the rivers of the African and South American rain
forests. Very few detailed studies of the ancient
record have been completed, and a 'Wide variety of
architectural case studies is needed to complement
our knowledge of modern rivers.
Stratigraphic Architecture. One of the most interesting
areas of research in recent years has been the
application of high-resolution chronostratigraphic
techniques, particularly magnetostratigraphy, to the
study of alluvial stratigraphies. The availability of
correlation frameworks of this type permits much
more detailed reconstructions of regional sedimentary controls) particularly tectonism, and allows for
the quantitative examination of the rates of such
processes as basin accumulation rates and channel
avulsion fr equency. Such data are essential for the
modeling of the autogenic and tectonic control of
alluvial stratigraphy, many studies of which are now
appearing, particularly as an aid to the reconstruction and interpretation of fluvial petroleum reservoirs.
Sequence Stratigraphy. Basic sequence models for fluvial systems are now available and are being applied