Geology Reference
In-Depth Information
1 New Perspectives in Microfacies
as 1927 by the use of microscopic features of lime-
stones for oil exploration in Texas.
Hovelaque and Kilian (1900) published the first il-
lustrated volume of thin-section photographs of car-
bonates. This approach was continued by the 'Interna-
tional Sedimentary Petrographical Series' initiated by
Cuvillier at the Third International World Petroleum
Conference in Paris in 1951. The volumes published
within this series as well as other comprehensive mono-
graphs containing numerous plates with thin-section
photographs (see Sect. 10.4) contributed substantially
to the rapid adoption of the microfacies approach.
A rapid evolution in our understanding of carbonate
rocks was triggered in the mid- to late 50's by the dis-
covery of carbonate reservoirs in various parts of the
world, followed by intensive research of recent car-
bonates. Modern and ancient carbonate environments,
diagenetic processes and facies models were studied
between about 1955 and 1965. During the late 60's and
the 70's microfacies became an essential part of facies
analysis and paleoenvironmental interpretation of lime-
stones. The increasing importance of limestones and
dolomites as reservoir rocks and the use of thin-sec-
tion fossils in subdividing carbonate platforms gave
substantial impetus to the progress of microfacies re-
search. The 1980's were characterized by an increased
application of geochemical techniques with the object
of developing predictive models for carbonate diagen-
esis and porosity. The subsequent period of time has
seen the rapid development of sequence stratigraphy
which now plays a major role in the characterization
of the geometry and reservoir potential of carbonate
rocks.
During the past decades microfacies has become an
established part of the study of carbonate rocks. How-
ever, many authors use microfacies criteria in describ-
ing and classifying limestones but fail to explore the
significance of these criteria for the interpretation of
depositional and diagenetic histories of carbonate rocks.
Part 2 and 3 of this topic demonstrate the great poten-
tial of microfacies studies in basin analysis and applied
carbonate geology.
1.1 The Microfacies Concept
1.2 New Perspectives
As originally defined by Brown (1943) and again
independently by Cuvillier (1952) the term 'micro-
facies' referred only to petrographic and paleontologi-
cal criteria studied in thin-sections. Today, however,
microfacies is regarded as
the total of all sedimento-
logical and paleontological data which can be de-
scribed and classified from thin sections, peels, pol-
ished slabs or rock samples.
New perspectives in the study and application of
microfacies have resulted from the application of new
techniques, from the availability of new comparative
data on modern and ancient carbonates, from new data
concerning the origin and distribution patterns of car-
bonate grains and the dominant biological control on
carbonate sedimentation, from new concepts on defin-
ing facies models, and from new ideas concerning the
course of carbonate sedimentation through geological
time.
Field geology, including mapping and profiling, is a
prerequisite for successful microfacies analysis. The
importance of combined field work and thin-section
studies was already emphasized in the earliest thin-sec-
tion based investigations of carbonate rocks directed
towards genetic interpretations of limestones (Peters
1863; Gümbel 1873; Sorby 1879; Hantken 1884). The
practical application of thin-section criteria of lime-
stones was demonstrated by Udden and Waite as early
New techniques.
Whilst microscopy is essential in
the study of carbonate rocks there are many additional
techniques which should also be utilized to maximize
the information offered by microfacies analysis (Tucker
1988). Cathodoluminescence microscopy, fluid inclu-
sion microscopy, scanning electron microscopy as well