Of the American Quantitative Igneous Rock Classification: Part 5

2012 ◽  
Vol 31 (1) ◽  
pp. 1-41 ◽  
Author(s):  
Davis Young
Keyword(s):  
Igneous Rock ◽  
Essential Elements ◽  
Igneous Rocks ◽  
Single Individual ◽  
Chemical Analyses ◽  
Rock Classification ◽  
Natural Classification ◽  
Quantitative Classification ◽  
The Creation

The preference of the authors of the quantitative igneous rock classification for an artificial rather than a natural system, coupled with their invention of a new nomenclature to accompany the classification, indicates that some essential elements of scientific work are not empirically ascertained but are proposed and accepted (or rejected) by the relevant scientific community as a matter of free choice. The use of igneous rocks as exemplars in the education of novice geology students is discussed. It is claimed that the CIPW classification could not have been produced by a single individual geologist. The factors that allowed for the collective success in the creation of the quantitative classification are examined.Upon publication of their monumental quantitative chemico-mineralogical classification (CIPW 1902, 1903), C. W. Cross, J. P. Iddings, L. V. Pirsson, and H. S. Washington immediately received numerous letters of congratulation. Initial published reviews ranged from highly supportive to suspicious. To help buttress their classification, Washington (1903) published a compilation of igneous rock chemical analyses and Iddings (1903) published several diagrams to drive home the point that a natural classification of igneous rocks was not feasible. Led by Washington, Pirsson, and Cross, several geologists began using the CIPW classification in their petrological studies and some contributed new sub-rang names. In the meantime, Iddings worked on the first volume of a projected two-volume work on igneous rocks based on the quantitative CIPW scheme. Unsympathetic to artificial, overly precise classifications, Harker in particular rejected the CIPW system and its norm calculations and European geologists generally were unenthusiastic. Cross (1910b) offered a major rebuttal to the criticisms, particularly those of Harker, in which he challenged the likelihood of producing a valid natural classification of igneous rocks. Iddings (1913) published the second volume on igneous rocks in which he developed an elaborate correlation between the old qualitative system and the new quantitative CIPW scheme. Washington and Pirsson produced many more petrological studies of Mediterranean volcanic rocks, New Hampshire, and Hawaii that incorporated the quantitative system. Washington (1917) produced a vastly expanded compilation of chemical analyses arranged in accord with the CIPW system. Criticisms, however, continued to mount from Fermor, Daly, Shand, and others, while Tyrrell and Johannsen were lukewarm toward the new classification. The criticism that the CIPW system was of little value in fieldwork repeatedly surfaced. Dissatisfaction with the quantitative scheme led to the publication of many new classifications by geologists, such as Hatch, Winchell, Lincoln, Shand, Holmes, Johannsen, and Niggli. With the creation of satisfactory quantitative mineralogical classifications, the increasing ability to determine the proportions of minerals quantitatively, and the death of Iddings and Pirsson, enthusiasm for the CIPW system gradually began to wane. By the 1960s the classification had become a thing of the past. The value of the norm calculation, however, gained recognition and has survived to the present, assisted no doubt by the capability for doing the necessary calculations by computer.

Origin of the American quantitative igneous rock classification: Part 3

2010 ◽  
Vol 29 (2) ◽  
pp. 264-290 ◽  
Author(s):  
Davis Young
Keyword(s):  
Igneous Rock ◽  
Igneous Rocks ◽  
Rock Classification ◽  
Quantitative Classification ◽  
Two Factors ◽  
Rough Draft

After evaluating two contrasting proposals, four American petrographers, Cross, Iddings, Pirsson, and Washington, meeting in late March 1901, formulated a preliminary quantitative classification of igneous rocks on a chemico-mineralogical basis. The team agreed that five different mineral groups should serve as factors for subdivision of the rocks into different orders. They also defined several further categories of subdivisions and established chemical and/or mineralogical criteria for those taxonomic levels. Washington began work on appropriate nomenclature for the various subdivisions.During the ensuing month, Iddings and Washington suggested several modifications to the group proposal. After intense discussion by way of letter, the quartet struggled to work out further details of their scheme logically even as they encountered a host of difficulties in applying the scheme. Washington recognized that their preliminary scheme was too complex and impractical for use by working petrographers.To meet the challenges, Washington and Pirsson met in late April 1901 and proposed that the team abandon its scheme and substitute one based on two factors only: ‘light minerals’ rich in Si, Al, K, and Na and ‘dark minerals’ rich in Si, Ca, Mg, Fe, and Al. All four agreed in principle to the new scheme and worked feverishly on the identity of and criteria for the subdivisions. Meeting in July 1901, Iddings, Pirsson, and Washington decided that the time had come to move toward publication of a statement of principles of the new two-factor scheme. Iddings was commissioned to write a rough draft describing the scheme and Washington was charged with working on nomenclature.

Origin of the American Qantitative Igneous Rock Classification: Part 2

2009 ◽  
Vol 28 (2) ◽  
pp. 175-203 ◽  
Author(s):  
Davis Young
Keyword(s):  
Igneous Rock ◽  
Premature Death ◽  
International Committee ◽  
Washington Dc ◽  
Rock Classification ◽  
Quantitative Classification ◽  
International Geological ◽  
International Geological Congress ◽  
Major Factors

After the tragic premature death of George Huntington Williams in 1894, the attempt by four young American petrographers to collaborate on construction of a quantitative classification of igneous rocks fell apart. The three survivors of the original quartet, C. Whitman Cross, Joseph P. Iddings, and Louis V. Pirsson, kept up their close friendship but produced their important petrological papers, including some contributions relating to classification, independently. In time, Henry Stephens Washington befriended the three.Discussions about igneous rock classification at the VII International Geological Congress (St Petersburg, 1897); establishment of the International Committee on Rock Nomenclature; efforts to develop an international classification; and renewed discussion at the VIII International Geological Congress (Paris, 1900) re-ignited Iddings' passion to develop a cooperative American scheme. Beginning with preliminary conferences at Iddings' instigation at annual meetings of the Geological Society of America in Washington, DC (1899), and Albany, NY (1900), Cross, Iddings, Pirsson, and Washington renewed the effort to produce a new classification to be based on chemico-mineralogical principles.In the first three months of 1901, Iddings and Washington offered proposals on the number and identity of major factors, namely chemically-based mineral groups, on which to base initial subdivision into major rock groups. They also generated ideas for diagrams on which to represent major rock groups in terms of the major factors, and they took tentative steps toward a new rock nomenclature. Remaining somewhat in the background, Cross and Pirsson cheered on their friends and offered an occasional response to the proposals.

Origin of the American Quantitative Igneous Rock Classification: Part 4

2011 ◽  
Vol 30 (1) ◽  
pp. 1-38 ◽  
Author(s):  
Davis Young
Keyword(s):  
Igneous Rock ◽  
Igneous Rocks ◽  
Primary Group ◽  
Chemical Compositions ◽  
Calculation Algorithm ◽  
Rock Classification ◽  
Team Members ◽  
Quantitative Classification ◽  
Two Factors ◽  
Primary Groups

After several failed attempts to construct a new chemico-mineralogical igneous rock classification on the basis of three or more factors, C. Whitman Cross, Joseph P. Iddings, Louis V. Pirsson, and Henry S. Washington decided to establish a practical and logically consistent scheme on the basis of only two factors, namely, two primary groups consisting of hypothetical minerals with ideal chemical compositions, the amounts of which were to be calculated from the chemical compositions of igneous rocks. One primary group consisted mainly of alkali alumina silicates and quartz (salic minerals), whereas the other consisted mainly of calcic ferromagnesian minerals (femic). A list of the amounts of these calculated standard minerals within an igneous rock was termed the norm, and the list of the proportions of actual minerals in a rock was termed its mode.In the Fall of 1901 the quartet decided to publish a preliminary paper that presented the major themes of their two-factor classification scheme. Iddings was charged with writing a draft of the scheme, and Washington was assigned the task of producing an essay on nomenclature to be published later. The team continually refined the definitions of specific subdivisions of the scheme proposed by Iddings as well as the corresponding nomenclature proposed by Washington. They also refined the norm calculation algorithm and developed methods for calculating the norm from the mode of rocks containing aluminous ferromagnesian minerals such as hornblende and biotite.After a few months of evaluating and revising a succession of drafts, the team eventually determined to publish their work of classification and nomenclature all at once by combining the refined drafts into one large comprehensive manuscript in three parts: Part I on classification, Part II on nomenclature, and Part III on methods of calculation. Iddings coordinated and edited the various criticisms and drafts contributed by team members into one large manuscript and shepherded the project to final publication in late October 1902 in Journal of Geology. The massive 139-page article entitled ‘A quantitative chemico-mineralogical classification and nomenclature of igneous rocks’ was preceded in earlier issues of the same journal by a two-part series authored by Cross on the historical development of systematic petrography. In early 1903, both of Cross's papers and the CIPW article were combined and published as a book, Quantitative Classification of Igneous Rocks.

Origin of the American Quantitative Igneous Rock Classification: Part 1

2008 ◽  
Vol 27 (2) ◽  
pp. 188-219 ◽  
Author(s):  
Davis Young
Keyword(s):  
Chemical Composition ◽  
Igneous Rock ◽  
Conceptual Development ◽  
Igneous Rocks ◽  
Magmatic Differentiation ◽  
Rock Classification ◽  
Quantitative Classification ◽  
Geological Age ◽  
The Press ◽  
Simple Question

In 1902, four American petrologists, C. Whitman Cross, Joseph P. Iddings, Louis V. Pirsson, and Henry S. Washington co-authored a lengthy paper in which they proposed an extremely complex, quantitative classification of igneous rocks. Taking advantage of developments in microscopic petrography, the theory of magmatic differentiation, and knowledge of the chemical composition of igneous rocks, the ‘CIPW’ classification marked a radical break with all previous igneous rock classification schemes such as those of Rosenbusch and Zirkel.The present paper is the first in a series that explores the genesis and conceptual development of the American quantitative classification. In 1893 Iddings posed a simple question to three young American petrologist friends, Cross, Pirsson, and George H. Williams, about the legitimacy of the use of the terms ‘porphyry’ and ‘porphyrite’. Henry Washington was to join the group later, but Williams was one of the original four. From this question there emerged an expanded discussion, conducted primarily via correspondence and mutual criticism of lengthy essays written by each of the four, dealing with larger questions of principles of classification and nomenclature. Any future classification, they agreed, should be based on igneous rock chemical composition and must reject geological age and geological occurrence as factors. Despite calls within the group for construction of a totally new igneous rock classification, the process evolved cautiously to a decision to publish a statement of general principles of igneous rock classification together with suggestions for changes in nomenclature for the benefit of petrologists. Eventually the project foundered because of health problems for Williams and the press of other obligations and interests on all four. In 1894, the project ground to a halt with the untimely death of Williams from typhoid fever.

The Grain-size Factor in Classification of Igneous Rocks

1938 ◽  
Vol 75 (9) ◽  
pp. 417-422 ◽  
Author(s):  
A. Kingsley Wells
Keyword(s):  
Grain Size ◽  
Mineral Content ◽  
Igneous Rocks ◽  
British Association ◽  
Size Factor ◽  
Rock Classification ◽  
Size Classification ◽  
Mode Of Occurrence

Although two years have passed since the British Association Committee on Rock Nomenclature and Classification reported in favour of using grain-size as an important factor inclassification, very few petrologists have accepted the Committee's invitation to discussand criticize the suggested scheme. This silence may be taken to mean consent; but in some quarters the older scheme, based on mode of occurrence of the rocks, still finds favour. It is instructive to inquire how far it is correct to speak of the scheme as new. Actually one does not have to dig deeply into petrological literature to realize that the principle of grain-size classification has been advocated for many years; indeed, it was the guidmg principle in some of the earliest scientific attempts at rock classification, notably in the well-known scheme elaborated in his Lehrbuch der Petrographie by Ferdinand Zirkel in 1866 and 1893–4. The reactionagainst the complete subordination of mode of occurrence found expression in the second edition of Rosenbusch's Mikro-skopische Physiographie (1887), in which the igneous rocks were divided into (1) deep-seated rocks, (2) dyke rocks, and (3) effusive rocks, each of these main categories being subdivided in terms of mineral content. In quite recent times A. Johannsen (1931)

scholarly journals Development of an igneous rock database with geologic functions: Application to Neogene bimodal igneous rocks and mineral resources in the Great Basin

Geosphere ◽  
2010 ◽  
Vol 6 (5) ◽  
pp. 691-730 ◽  
Author(s):  
Douglas B. Yager ◽  
Albert H. Hofstra ◽  
Katheryn Fifarek ◽  
Ank Webbers
Keyword(s):  
Information System ◽  
Great Basin ◽  
Relational Database ◽  
Igneous Rock ◽  
Igneous Rocks ◽  
Geographical Information ◽  
Rock Classification ◽  
Volcanic System ◽  
Relative Age ◽  
Sample Data

Abstract Geologists routinely use sample data (descriptive, qualitative, quantitative) to characterize a hierarchy of larger geologic features that each have their own independent attributes, use physical relationships between geologic features to establish their relative ages, combine this information with dated features to understand evolutionary histories of study areas at various scales, and produce maps to display such information in space and time relative to other features of interest. This paper demonstrates how we integrated such routine geologic functions into an existing igneous rock relational database designed to store, organize, update, query, and retrieve sample data that have well-defined locations. The resulting igneous rock database is utilized to capture information on Neogene bimodal igneous rocks in northern Nevada and the eastern Great Basin Province. The database is a useful tool that facilitates queries to generate geographical information system displays and petrologic plots that elucidate the time-space-composition relationships of volcanic centers to one another and to geophysical anomalies, structural features, and mineral deposits. Database information is parsed into the following data tables: physical hierarchy of scale, absolute and relative age, chemistry, paleomagnetic, rock mode, image, cross section, X-ray diffraction, and igneous-related structure. Information is organized in a telescoping geologic hierarchy schema: igneous province, volcanic field, volcanic system or caldera, extrusive flow or intrusion, sample, and various subsamples. Absolute radiometric age determinations on samples from geologic features and expert interpretations of relative age relationships between different features may be captured and used together to constrain the ages of undated features. Such age information is linked to features of various scales in the hierarchy. Common attributes that are shared between the relational database and geographic information system (GIS) features include feature-identification or sample-identification, and they permit linking of geographic entities and tabular data for query, analysis, and display in GIS or derivative tables. Relational database keys merge analytical, map, and image data across this geologic hierarchy-age-location schema to facilitate queries that address geologic problems. Data acquired at the sample scale of observation is linked to increasingly larger features that have their own independent attributes using GIS. This schema enables users to retrieve information on one or more hierarchical features for input into external software for various GIS, statistical, petrologic, and other display, analysis, or comparison purposes. Fundamental interpretations resulting from such analyses or displays, e.g., rock classification, may be used to populate additional fields in the database. The database is designed for flexibility and can accommodate information resulting from both detailed and reconnaissance studies. The geologic functions that were developed and that we added to an existing igneous rock database (Lehnert et al., 2000) for this study have wide applicability and could readily be integrated into other geoscience databases.

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