PLATE TECTONICS AND SEA-FLOOR SPREADING: A CITATION ANALYSIS STUDY FOR IDENTIFYING PERIODICAL LITERATURE

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1 Annals of Library 98,9(4},7t'-8'- Science and Documentation PLATE TECTONICS AND SEA-FLOOR SPREADING: A CITATION ANALYSIS STUDY FOR IDENTIFYING PERIODICAL LITERATURE DAVENDRA k. GUPTA Department of Library Studies University of Ibadan IBADAN {Nigeria] A paper by LePichon on sea-floor spreading published in 968 in the Journal of Geophysical Research was cited 64 times during the years 968 to journals originating from 9 countries throughout the world cited this work. The work was not only cited by the journals of geophysics and geology but by several in general science, chemistry, physics, botany, zoology etc. Wide scattering and seepage of information was observed as the citations were made in a large number of journals of various subject areas and specialities, published from so many countries, This supports the hypothesis of epidemic nature of this work of X LePichon. A list of the citing journals is presented and a group of core journals is suggested for the documentalists who are to serve the scientists in the research areas of Earth Tectonic or Geotectonics. INTRODUCTION Citation analysis is becoming an important research tool for the understanding of science, scientists, scientific contributions and publications. Citation studies and other bibliometric techniques are being applied for the management of science, analysing the structure and direction of science, measuring the utility of journals and relationships between journals and fields and measuring the performance of scientists. A vast amount of literature is getting published on such kind of evaluative studies. The literature on bibliometrics and citation indexing and analysis is well documented in a recent bibliography [6]. A comprehensive review of the whole area is available in a report [8]. Narin 78 in his report [8] has made a thorough review of several papers in which bibliometric measures, publication and citation counts have been correlated with other measures of eminence such as awards, listings and academic rank or affiliation. In almost all cases the bibliometric measures for groups of scientists are correlating reasonably well from 0.5 to 0.8 with the other measures. As a communication system, the network of journals play a paramount role in the exchange of scientific and technical information. Garfield has said that citation analysis could be used as a tool in evaluating and ranking the journals []. In his Essays [4] Garfield has reported several studies on journal citations in specific subject areas. In his Current Comments [] there -is reference to most cited journals in geology and geophysics; and also on one of the most cited journal in geophysics []. SCOPE OF THE STUDY In this paper, an attempt is made to present data about the periodical literature which cited the most cited article of LePichon on sea-floor spreading published in the most cited journal in geophysics []. The data of citation analysis of LePichon's works and detailed analysis of this specific paper are reported in an earlier study [5]. The scope, definition etc. of sea-floor spreading and plate tectonics are also given in the same paper. It was found that LePichon's paper published in 968 received 59 citations out of 5 citations received for all his contributions. Moreover, this was not only cited heavily, but was also cited for a considerably Ann Lib Sci Doc

2 PLATE TECTONICS AND SEA-FLOOR SPREADING longer period of time. To illustrate how widely LePichon's ideas, contained in this paper, have spread it was necessary to analyse the range of journal titles in which this work was cited. Therefore, the scope of the previous study was extended to examine the followings: the range of the journal titles which have cited this paper to prove the hypothesis that the greater the number of titles the more widely the ideas are spread; etc. was supplemented by consulting the latest edition of Ulrich's International Periodicals Directory (0th edition, 98). 4 ANALYSIS AND DISCUSSION The data about the forms of publications citing this work, year to year for the period are given in Table. 4. Annotations: the countries in which the citing journals are published, to prove that fur a set of journals, the greater the number of countries the more widely the ideas have spread; the disciplines to which the citing journals belong to prove that larger the number of disciplines (wide scattering) of the journals, wider the spread of ideas and better the interrelationship of the disciplines; (greater interaction with other fields is the measure of multidisciplinary activity of a specific field). The main purpose of this investiga-. tion was to build a model of journal communication network that should provide more functional definition of discipline (Marine geology in this case) and speciality (sea-floor spreading in this case) that will make it possible to define in detail how different fields of knowledge interact; Further, it also aimed to make a rank list of citing journals which may be useful to scientists and documentalists who are concerned with this area of specialization. METHODOLOGY The data base which was created for a previous study to examine the epidemic nature of Le- Pichon's paper [5] was used in this study. The analysis is extended upto 979 in the present study. Citations were counted for the years 968 to 979 for LePichon's most cited paper [7] and data were collected for the titles of citing journals, kind of publications citing the paper, the year of citation etc. The information regarding the full titles, country of publication. During the period, , 64 citations were received by this paper. " the paper was very heavily cited during 970, 97 and q7 receiving almost 00 citations per year on the average.. There is a declining trend of citations over the rest of the years but the number of citations even during the year 979, after years of its publication, is quite high, being. 4. Journal articles have cited it for 56 times, ie, 87.4% of all the citations; 5. Review articles are next in number, and still continuing to cite this item. Other characteristics of citations for this paper have been already discussed in the earlier paper[5]. The data of citing journals for different periods are given in Table. l. Annotations: Citing journals:. In all, 79 journals have cited it for 69 times. This number is quite large for a speciality like "sea-floor spreading" which is a minor aspect of marine geology and tectonics. This clearly indicates that the ideas contained in this work of LePichon were. very widely cited and that confirms the hypothesis made in this study; Vol 9 No 4 Dee 98 79

3 GUPTA Tabl,e : Chronological, distribution of citations according to the forms of citing publications: Year of citation: A R N L D E Total percentage of total ) 9 6 Total 56 Percentage of tota I: Only a few journals, say only five of them or 6% of all have cited 4 times (5.6% of all the citations);. Only journals (5% of all) have given upto 75% of all the citations; 4. All other journals, 67 of them carry the remaining citations in which the contributions on the topic of sea-floor spreading is scattered. 5. Nature in first five, Science in first eight, and American Journal of Scien- ce in first twelve titles have emerged as important journals of this speciality also. In Garfield's list [] of most cited journals in geology and geophysics, they were listed at 5th, rd and th rank respectively while in this case Nature has improved its rank. Although these journals are not devoted to geology/geophysics journals, they are "general science" journals, yet they are ranked as important journals in geosciences as well as in this speciality. 80 Ann Lib Sci Doc

4 PLATE TECTONICS AND SEA-FLOOR SPREADING Tabl.e : RANK LIST OF CITING JOURNALS: S. Abbreviated title of Period of Citation Total No. cumul at ive percentage cumulat. No. Journals citations c itat ions of total % I Jou r Geophys Res Geol Soc Amer Bull ~ Na ture iectonophys ics Earth Planet sci lett Am Assoc Pet.Geol.Bull Geophys J Roy Astro Soc Science Bull Seismol Soc.Amer Phil T Roy A ].8 0 Amer J se t, J. Geology Cr Acad Sci Can J Earth Sci Marine Geology Tr ans Amer Geophys (EOS) Nz J Geology Rev Geophys space Phys. 0 " Rev (,eog Ph 0 ; Deep Sea Research Annals Acad Brasil Geology Pure App. Geophys J Geomagn Geoelect Anatarctica J U.S Annual Rev Earth PI.net Contrib Mln.Petrol Naturwi ssen J Geophysics Annals de Geophysique Geop.hysics Ann Ny Acad Sci ScJ.J Botan Rev Papers Meteoro I Geophys Geological Magazine Earth Science Review J.Fluid Mechanics Economic Geology J Geol Soc India Pa Iaeogeog P J Petrology Table (Contd.) Vol 9 No 4 Dee 98 8

5 GUPTA The following 7 journals have contributed one citation each comprising total percentage 5. f} of the total: at the rank of 4: SI.No. Name of the Journal ; f Scientific American Dann)SSR Sf Riv ltal Geo Geof is /'Ie t. IBIS J Zoology Search Ann Geof i5 Current sc ience B Mar ine Sci Astro Aeron Q Rev lew Bioi Stud Geophys Geoch Cos A Annual Rev Fluid Copeia Annual Rev Entom Act Cicntifica Venezuela Bioscience Syst Zool. Vie e t Milieu Engineering geology American Scientist BioI J Linn Lthos Okeaneologia Report of Progress Phys. Rer.herche Annee Bioi CC/Phys Chern Rev Geol Dy Phys_E 'Plan B CSAR 'Belgium 8 Astr I Cz Rev.I.F.Pet. J Voldcanology J. Sed. Pet. The data of citations by the publications other than the journal articles and journals in which they have been cited are presented m Table. 4. Annotations. Out of 64 citations, 56 citations are made by the journal articles and the remaining 80 by other forms like reviews, letters to editors, notes, discussions and editorials. This also confirms the hypothesis that the item has been covered by all kinds of publications. Coverage by review publications accounting for 5 citations is of considerable importrnce.. Out of 79 journals, journals have cited the item only through review and notes. Out if, nine journals have cited the item only once in a place other than a journal article.. One can easily observe that the first six journals listed in Table, are listed in Table also; and that the Nature is the only journal which has cited the item in its editorials. The wide scattering of information on seafloor spreading could be seen from the data and analysis presented above and they support the hypothesis on the epidemic nature of the ideas contained in the work of LePichon. The data on the publications from the various countries! regions are presented in Table 4. Index to the publications is given in Appendix I. 8 Ann Lib Sci Doc

6 PLATE TECTONICS AND SEA-FLOOR SPREADING Table J: Distribution of citations made Ly the publications at her than the journal articles: Journal/publ ication: Review letters Notes Discussion Editorial Rev. Geophys Ann. Rev. Earth Botan Rev Earth Science Rev Tectonophysics(4) AAPG Bulletin (6) J Geophys Res () Amer J. Sci. () IBIS ' Canad J Earth set (4) Antarct ica Astro aeron 9 + Q~Rev. B io I. 4 J Fluid Mech. + 5 Ann. Rev. Flu id +6 Li thos 7 Palaegeog P + 8 J Volcanol + 9. Rep.prog.phys. I' + 9. Ann. Rev. Entomol 0 Books Earth Sc.Planet lett. (5) Nature () Nz.J.Geol. Geol S Am B () Deep sea Res. Current science 5 7 Geophysics 8 Phil.T Roy Soc A other 5 journals 8 Total: T* Total including journal articles; + published only in one form, i.e., Review, Notes Note: Within the parentheses is given the rank number of the journals. Vol 9 No 4 Dee 98 8

7 GUPTA Table 4: ~ of pubuoation ~f tlw ";'tinq journals C""nl:y of N"",ber of percentage cumulative publlc.otlon Journals of total percentage. ij.!:.a. 5 ~~.) ~~.. U.K T~ Nether ands 9 n." 68.~ ~. Fr.nce West Ger.nany ). ~ Italy U.S.S;R Belgium razll Canada Czecko,s 'avak I II India.~ 9.. Japan. ~.5 4. NewZeland Norway Swt t zer land Venzuel..~ 00.0 Total Annotations. In all, 7 countries published the 79 journals which have cited LePichon's work. TIle scatter of the countries of publication indicate that the ideas contained in LePichon's paper have in fluenced many. The nature of the seepage of information can be estimated by considering the subject spread of the citing journals. This is shown in Table Annotations Table s: LiaV-'ibution."bj.,t of tlul citing jourrtale =rding to subject.rea nl.lftber of percentage cumulative Journals of tot.' percentage General ScIence Ceophys ; cs : theoret Ica, exp l0- ration. astronortl'f; 5 Geoiogy 9 Ceo logy + Geop""s! es ~ (G.neral) 80SCIEHCE~: Biology ZooJo'JY Bot.any Entomolog'' Horine geolojiy Phys I cs Fluid mechanics Pet ro leum 'Geology Engineering geology Geochem is t rv Petrology Sedimentology Oceanography Geomagnet ism. VolcatJology* Tectonophys j cs * ~eismoiogy* Heteorology* Economic 9eolng~ Pa aeogeography Geography Mineralogy Total 79 Conmon "";th (;eophy8i.,. azao '.0 J.8 7~ ~ H. 8i ~ I.l ioo.o The seepage of information can be observed from a large number of journals in the specialities of geology and geophysics, physics and other related disciplines,. The group of journals in general science is the largest, and many of them occupy higher ranks. This a group which serves a general population of researchers, specially to the people who are working in the areas of multidisciplinary nature. This group of journals is also a faster media of communication of recent developments in a specific field, controversial areas and issues on a specific topic. The large number of citing journals in this group indicates that idea of seafloor spreading must have attracted the attention of scientists in many disciplines.. '.The seepage of information through the journals in the subject areas in Biosciences and Chemistry, Geography etc, affirms the wider scope and influence of the ideas contained in LePichon's paper. 4. The analysis of this data establishes the theory of infectious and epidemic nature of the idea and also establishes the new theory of global tectonics. The subject has become now a target of research of several specialities" forming an important and Integral part of Ocean Sciences - Tectonics. 84 Ann Lib Sci Doc

8 PLATE TECTONICS AND SEA-FLOOR SPREADING 5. CONCLUSION The seepage and scattering of information through several forms of publications and in a large number of journals, journals of several disciplines and specialities, journals originating from 7 countries throughout the world, support the hypothesis that LePichon's paper contained ideas of edidemic and infectious nature.. A core of five most important journals can be identified out of 79 journals which have cited this work, as carrying and conveying most of the information on this speciality. The journals which have larger citing frequency are likely to contain greater amount of data and information in that specific speciality.. A documentation or information centre serving the needs of scientists who are working in the areas of sea-floor spreading and plate tectonics, should have at least the first fifteen journals listed in Table, and should also scan journals from other disciplines and specialities or make use of secondary services to supplement information needs of their users. 4. The concept of sea-floor spreading and plate tectonics appears' now to have been accepted and recognised very widely among the scientists. 5. Further analysis of this data to identify the most active workers, their affiliations.jnetwork of scientists and schools of thought within this speciality would be interesting. Another area of investigation suggested is to test the applicability of Bradford's law on the citation data of this single work of epidemic nature. The data seems to be adequate enough having 64 citations to analyse. REFERENCES. Garfield, Eugene. Citation analysis as a tool in journal evaluation. Science, 97, 78(4060), jcurrent Comments: J oumal Citation Studies x. Geology and Geophysics. Current Contents, 0j 5-9j (July 4,974) jcurrent Comments: Journal Citation Studies. xi. Journal of Geophysical Research. Current Contents. j 5-8? (August 4, 974) jessays of an Information Scientist. Volume -. lnstitute for Information Science, Philadelphia, Pa., Gupta, D.K. Plate Tectonics: A Study of Transmission of Ideas: Ann Lib Sci Doc, 978,5,86-9. Hjerppe, Roland. A bibliography of bibliometrics and citation indexing and analysis. Report TRITA-LIB-0, RIT, Stockholm, LePichon, Xavier. Sea-floor spreading and continental drift. J Geophysics Res, 968, 8. 7(), Narin, F. Evaluative bibliometric: the use of publication and citation analysis in the evaluation of scientific activity. Computer Horizon project, 976. Vo9 No 4 Dee 98 85

9 GUPTA Appendix-I Index to the journals and country of publication (item numbers) l. U.S.A.,,7,8,9,,,6,8,.5.6,7,,,.4, 9,4,47,5,5,5,54, 55,57,58,59,6,6,65, 66,7,77. U.K.,6,0,0,5,6,8, 4,48,69. The Netherlands 4,5,5,7,4,64,74, 78,79, 4. France,9,0,6,70,7,7, 5. Italy 45,46,50 6. West Germany 8,9,68 7. U.S.S.R. 44,56 8. Belgium Brazil 0. Canada 4. India 40. Japan 4. Newzealand 7 4. Norway Switzerland 6. Venezuela Czekoslavakia 76 Appendix-II Index to the subjects covered (item numbers) l. General Science,8,0,,,,5, 8,,,4,44,47, 4~~5,60,65,70,75.. Geophysics,7,6,8,,4,9, 0,,46,50,5,55, 74,76.. Geology,,4,7,9,,6, 40,45,67 4. Geology + 5,6,7,7 geophysics 5~ Botany 4 6. Biology 54,6,6,66, 7 7. Entomology Zoology 48,58,6 9. Physics 69,7 0. Fluid Mechanics 8,57. Economic 9 geology. Engineering 64 geology. Geochemistry Marine Geology 5,0,5 5. Petroleum 6,77 Geology 6. PE'!"Croogy 4 7. Palaeogeography 4 8. Mineralogy 7 9. Sedimentology Geomagnet ism 4 l. Meteorology 5. Oceanography 68. Seismology 9 4. Tectonophysics 4 5. Volcanology Ann Lib Sci Doc