1.3 APPLIED SEDIMENTOLOGY
5
phy (Payton, 1977). While it had long been recognized that sediments tended to be deposited in organized, and often cyclic, packages, modern high-quality seismic data enabled these to be mapped over large areas. Sequence boundaries could be identified
and calibrated with well and outcrop data.
Referring again to Fig. 1.1 we come to the chemical aspects of sediments. It has already been shown how both environmental and facies analyses utilize knowledge of
the chemistry of sediments. Petrology and petrography are terms that are now more or
less synonymously applied to the microscopic study of rocks (Tucker, 1991; Blatt, 1992;
Boggs, 1992; Raymond, 1995). These studies include petrophysics, which is concerned
with such physical properties as porosity and permeability. More generally, however,
they are taken to mean the study of the mineralogy of rocks. Sedimentary petrology is
useful for a number of reasons. As already pointed out, it can be used to discover the
provenance of terrigenous rocks and the environment of many carbonates. Petrography also throws light on diagenesis: the postdepositional changes in a sediment. Diagenetic studies elucidate the chemical reactions that took place between a rock and the
fluids which flowed through it. Diagenesis is of great interest because of the way in
which it can destroy or increase the porosity and permeability of a rock. This is relevant
in the study of aquifers and hydrocarbon reservoirs. Chemical studies are also useful in
understanding the diagenetic processes that form the epigenetic mineral deposits, such
as the lead-zinc sulfide and carnotite ores. Lastly, at the end of the spectrum the pure
application of chemistry to sedimentary rocks is termed sedimentary geochemistry. This
is a vast field in itself (Krauskopf and Bird, 1995; Faure, 1998). It is of particular use in
the study of the chemical sediments, naturally, and of microcrystalline sediments that
are hard to study by microscopic techniques. Thus the main contributions of sedimentary geochemistry lie in the study of clay minerals, phosphates, and the evaporite rocks.
Organic geochemistry is primarily concerned with the generation and maturation of
coal, crude oil, and natural gas. Organic geochemistry, combining biology and chemistry, brings this discussion back to its point of origin. The preceding analysis has attempted to show how sedimentology is integrated with the other geological disciplines.
The succeeding chapters will demonstrate continuously how much sedimentology is
based on the fundamental sciences of biology, physics, and chemistry.
1.3 APPLIED SEDIMENTOLOGY
Sedimentology may be studied as a subject in its own right, arcane and academic; an end
in itself. On the other hand, sedimentology has a contribution to make to the exploitation of natural resources and to the way in which man manipulates the environment.
This book has been written primarily for the reader who is, or intends to be, an industrial geologist. It is not designed for the aspiring academic. It is relevant, therefore, to
consider the applications of sedimentology. Table 1.1 documents some of the applications of sedimentology. Specific instances and applications will be discussed throughout the book. Most of the intellectual and financial stimulus to sedimentology has come
from the oil industry and, to a lesser extent, the mining industry. The applications of
sedimentology in these fields will be examined in some detail to indicate the reasons for
this fact.
5
phy (Payton, 1977). While it had long been recognized that sediments tended to be deposited in organized, and often cyclic, packages, modern high-quality seismic data enabled these to be mapped over large areas. Sequence boundaries could be identified
and calibrated with well and outcrop data.
Referring again to Fig. 1.1 we come to the chemical aspects of sediments. It has already been shown how both environmental and facies analyses utilize knowledge of
the chemistry of sediments. Petrology and petrography are terms that are now more or
less synonymously applied to the microscopic study of rocks (Tucker, 1991; Blatt, 1992;
Boggs, 1992; Raymond, 1995). These studies include petrophysics, which is concerned
with such physical properties as porosity and permeability. More generally, however,
they are taken to mean the study of the mineralogy of rocks. Sedimentary petrology is
useful for a number of reasons. As already pointed out, it can be used to discover the
provenance of terrigenous rocks and the environment of many carbonates. Petrography also throws light on diagenesis: the postdepositional changes in a sediment. Diagenetic studies elucidate the chemical reactions that took place between a rock and the
fluids which flowed through it. Diagenesis is of great interest because of the way in
which it can destroy or increase the porosity and permeability of a rock. This is relevant
in the study of aquifers and hydrocarbon reservoirs. Chemical studies are also useful in
understanding the diagenetic processes that form the epigenetic mineral deposits, such
as the lead-zinc sulfide and carnotite ores. Lastly, at the end of the spectrum the pure
application of chemistry to sedimentary rocks is termed sedimentary geochemistry. This
is a vast field in itself (Krauskopf and Bird, 1995; Faure, 1998). It is of particular use in
the study of the chemical sediments, naturally, and of microcrystalline sediments that
are hard to study by microscopic techniques. Thus the main contributions of sedimentary geochemistry lie in the study of clay minerals, phosphates, and the evaporite rocks.
Organic geochemistry is primarily concerned with the generation and maturation of
coal, crude oil, and natural gas. Organic geochemistry, combining biology and chemistry, brings this discussion back to its point of origin. The preceding analysis has attempted to show how sedimentology is integrated with the other geological disciplines.
The succeeding chapters will demonstrate continuously how much sedimentology is
based on the fundamental sciences of biology, physics, and chemistry.
1.3 APPLIED SEDIMENTOLOGY
Sedimentology may be studied as a subject in its own right, arcane and academic; an end
in itself. On the other hand, sedimentology has a contribution to make to the exploitation of natural resources and to the way in which man manipulates the environment.
This book has been written primarily for the reader who is, or intends to be, an industrial geologist. It is not designed for the aspiring academic. It is relevant, therefore, to
consider the applications of sedimentology. Table 1.1 documents some of the applications of sedimentology. Specific instances and applications will be discussed throughout the book. Most of the intellectual and financial stimulus to sedimentology has come
from the oil industry and, to a lesser extent, the mining industry. The applications of
sedimentology in these fields will be examined in some detail to indicate the reasons for
this fact.