The Use of a Modified Camera for the Classification of Sedimentary Rocks

2016 ◽  
Vol 2016 (4) ◽  
pp. 191-210
Author(s):  
Cezary Toś
Keyword(s):  
Sedimentary Rocks

Petrophysical Rocks: Electrofacies and Lithofacies

2014 ◽  
Author(s):  
John H. Doveton
Keyword(s):  
Particle Size ◽  
Physical Properties ◽  
Sedimentary Rocks ◽  
Well Control ◽  
The Core ◽  
Lateral Extent ◽  
Petrophysical Logs ◽  
Definition Of

Many years ago, the classification of sedimentary rocks was largely descriptive and relied primarily on petrographic methods for composition and granulometry for particle size. The compositional aspect broadly matches the goals of the previous chapter in estimating mineral content from petrophysical logs. With the development of sedimentology, sedimentary rocks were now considered in terms of the depositional environment in which they originated. Uniformitarianism, the doctrine that the present is the key to the past, linked the formation of sediments in the modern day to their ancient lithified equivalents. Classification was now structured in terms of genesis and formalized in the concept of “facies.” A widely quoted definition of facies was given by Reading (1978) who stated, “A facies should ideally be a distinctive rock that forms under certain conditions of sedimentation reflecting a particular process or environment.” This concept identifies facies as process products which, when lithified in the subsurface, form genetic units that can be correlated with well control to establish the geological architecture of a field. The matching of facies with modern depositional analogs means that dimensional measures, such as shape and lateral extent, can be used to condition reasonable geomodels, particularly when well control is sparse or nonuniform. Most wells are logged rather than cored, so that the identification of facies in cores usually provides only a modicum of information to characterize the architecture of an entire field. Consequently, many studies have been made to predict lithofacies from log measurements in order to augment core observations in the development of a satisfactory geomodel that describes the structure of genetic layers across a field. The term “electrofacies” was introduced by Serra and Abbott (1980) as a way to characterize collective associations of log responses that are linked with geological attributes. They defined electrofacies to be “the set of log responses which characterizes a bed and permits it to be distinguished from the others.” Electrofacies are clearly determined by geology, because physical properties of rocks. The intent of electrofacies identification is generally to match them with lithofacies identified in the core or an outcrop.

VII.—On the Base of the Sedimentary Series in England and Wales

1890 ◽  
Vol 7 (7) ◽  
pp. 308-315 ◽  
Author(s):  
J. F. Blake
Keyword(s):  
Present State ◽  
Volcanic Rocks ◽  
Sedimentary Rocks ◽  
Present Stage ◽  
England And Wales ◽  
Accurate Knowledge ◽  
Geological Magazine

As Dr. Callaway has asked in a recent Number of the Geological Magazine for the grounds on which I suggest that some of the volcanic rocks of Shropshire may perhaps be classed as Cambrian, I take this opportunity for bringing before your readers the present state of the inquiry into the nature and classification of the earliest sedimentary rocks in this country. This inquiry has been spoken of by Dr. Callaway as the “Archæan controversy”; but we must not necessarily call everything that is earlier than the Cambrian “Archasan,” any more than in old days it was right to call everything Precarboniferous “unfossiliferous greywacké”; nor should the inquiry be considered a controversy in its present stage, but rather a search for more accurate knowledge.

The Megascopic Study and Field Classification of Sedimentary Rocks

1948 ◽  
Vol 56 (2) ◽  
pp. 130-165 ◽  
Author(s):  
Paul D. Krynine
Keyword(s):  
Sedimentary Rocks
Sign in / Sign up

Export Citation Format

Share Document