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ISSN 0869-5938, Stratigraphy and Geological Correlation, 2008, Vol. 16, No. 6, pp. 683–685. © Pleiades Publishing, Ltd., 2008.Original Russian Text © M.A. Semikhatov, E.E. Milanovslii, Yu.B. Gladenkov, A.S. Alekseev, D.P. Naidin, V.T. Frolov, D.I. Panov, 2008, published in Stratigrafiya. Geolog-icheskaya Korrelyatsiya, 2008, Vol. 16, No. 6, pp. 110–112.

On October 18, 2008, Georgii Pavlovich Leonov, aneminent Soviet geologist, Honored Scientist and Engi-neer of the RSFSR, Professor of the Moscow State Uni-versity (MGU), a distinguished specialists in stratigra-phy, regional geology, methodology of historical-geo-logical investigations, and an outstanding teacher whoeducated many generations of Soviet geologists, wouldbe 100 years old.

Since young years G.P. Leonov’s life has been asso-ciated with geology and Moscow State University,which he entered in 1926 as a student of GeologicalFaculty. In 1930, he reentered the Moscow GeologicalExploration Institute, which he graduated from in 1931.In 1932, he returned to the MGU as a lecturer at theChair of Geology founded by A.N. Mazarovich. At thechair reorganized later into the Chair of Historical andRegional Geology and turned into the core of the recon-structed Geological Faculty at the MGU, Leonovworked all his life and went the way from a junior col-league of teaching staff to a professor.

Leonov was first to start teaching the course of geo-logical mapping at the MGU; he was one of first orga-nizers and supervisors of the geological training prac-tice in the Crimea. At the MGU, he lectured the maincourse “Historical Geology.” Although the course istraditional one at universities, Leonov reworked it overagain believing that it is of vital importance for habitu-ating students to geological consideration of the Earth.Unlike other lecturers, he regarded the course “Histori-cal Geology” not as a purely educational descriptivediscipline but as the most important part of geologicalscience, the aim of which is understanding of trends inthe Earth’s geological evolution based on the wholecomplex of geological data studied and analyzed. Thisapproach was expounded in abridged textbook “Histor-ical Geology” (1956) and two volumes of the full text-book (1980, 1985), which Leonov did not manage tocomplete.

Leonov paid much attention to general theoreticaland methodical problems of geology during all histeaching activity. For many years he lectured specialcourses “Methods of Stratigraphy” and “Methods ofHistorical-Geological Investigations,” published aseries of papers on principal problems of methodologyof geological investigations: on cyclicity in the Earth’shistory, historical methods versus actualism in geology,chronological and historical–geological ways of inves-tigations, etc.

The interest to principal theoretical and methodicalproblems is evident in full measure from scientificactivity of Leonov’s, which was devoted almost com-pletely to stratigraphy. In the pre-war years, he studiedthe Paleogene deposits in the Volga region andextended the study area to the Northern Caucasus in thepost-war years. It is likely that Leonov was on his own,individual way since the very beginning of researchbecause of peculiar features inherent of Paleogenedeposits. While the concern When geologists who stud-ied Jurassic and Cretaceous deposits were drowned intochronostratigraphic subdivision of sections and world-wide recognition of the general scale units (stages, sub-stages, chronological zones), Leonov focused hisefforts on elaborating the regional stratigraphicschemes, distinguishing regional stratigraphic unitscorresponding to stadia of geological evolution in theregions he studied. His research of the Paleogeneresulted in publication of respective papers and the

On the 100th Anniversary of G.P. Leonov (1908–1983)

DOI:

10.1134/S0869593808060087

PERSONALIA

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monograph

Basic Problems of Regional Stratigraphyof Paleogene Deposits in the Russian Plate

(1961),which is so far the basic work for our understanding thePaleogene stratigraphy of the plate. In this work, hepresented for the first time the reliably substantiatedregional and interregional schemes of the Paleogenestratigraphy for the whole Russian plate, which werecorrelated with the North Caucasian scheme. Using thehistorical-geological methods, he distinguished strati-graphic units (formations, complexes) in the schemesas equivalents of stadia in geological evolution of majorregions and the whole Russian plate, and this is themain methodical significance of his work.

Later on, Leonov published another series of impor-tant works, where he considered correlation of Paleo-gene deposits in the Russian Plate and Mediterraneanbelt, implication and potential of micropaleontologicalanalysis for subdivision and correlation of Paleogenedeposits (along with his wife V.P. Alimarina), and theproblem of distinguishing stages in the Paleogene Sys-tem.

In the 1950s and latest 1960s, Leonov studied Juras-sic deposits of the Northern Caucasus, where the onlypurpose of previous stratigraphic study was, like inother regions, the age determination and recognitionstages and substages in sections. Leonov, who studiedthe Jurassic of the Northern Caucasus from the samehistorical-geological viewpoint, like the Paleogenebefore, managed to suggest first regional stratigraphicschemes of the study region. With respect to the UpperJurassic, he revised therewith the misleading conceptsof forerunners (for instance, of K. Rents), used to becited in geological literature for many decades. Theother fact was more important: a group of geologistsfrom MGU and VNIIGaz headed by Leonov proposedin 1958 the truly regional stratigraphic scheme ofLower–Middle Jurassic deposits of the Northern Cau-casus, which had the historical-geological basis andwas adopted at the Conference on Elaborating the Uni-fied Stratigraphic Schemes for the Alpine Zone of theSoviet Union European Part. Along with chronostrati-graphic units of the General Scale, the scheme includedfor the first time the local and regional subdivisions(complexes, formations, faunal ammonite zones)exemplifying stages of geological history andammonoid evolution in the Northern Caucasus. Atpresent, this is a common practice legalized in theStratigraphic Code, but that was a revolution in 1958.At any rate, nothing of this kind could be found in theUnified Scheme of Mesozoic Stratigraphy for the Rus-sian Platform, which was accepted three years before,in 1955.

Theoretical concepts of Leonov’s concerningstratigraphy are most completely expounded in two-volume monograph

Fundamentals of Stratigraphy

(1973, 1974) which had no analogs in the world andwon the First Prize of the Moscow Society of Natural-ists (MOIP) in 1975. Close consideration is given in

this monumental work to key theoretical problems ofstratigraphy that is a basic division of historical geol-ogy: to its principal notions and problems, to historicalroots and principles of creating the InternationalGeochronological Scale, to methods of stratigraphicstudies, to significance of paleontological data andfacies analysis in solving problems of stratigraphicsubdivision and correlation, etc. In understanding ofLeonov, the main objective of stratigraphy is “classifi-cation” of layered supracrustal rocks from the historicalstandpoint. As the objective is attainable in the courseof regional studies, the regional stratigraphic researchis basic in opinion of Leonov, whereas geochronologi-cal investigations aimed at the age determinationscould be of secondary, probably transient significance.

According to Leonov, the main objective of regionalstratigraphy is natural periodization of formation his-tory of supracrustal rock in major geological regionsand subdivision of rock sequences into natural com-plexes corresponding to successive stages in evolutionof the study regions. He considered these rock com-plexes as basic stratigraphic units, the key objects ofstratigraphic and historical–geological investigations.He termed them first the “natural stratigraphic com-plexes” and used later on the terms “formation” and“group” customary for Russian geologists. He pro-posed an apt term “geostratigraphic units” for this cat-egory of stratigraphic subdivisions distinguishedbased on historical-geological principles. The succes-sion of geostratigraphic units in the regional strati-graphic scheme is a basis for objective analysis of thegeological history of a region, first of all, of stages inits evolution. Correlation of regional schemes is away to recognition of evolutionary stages of a higherorder (interregional or even global). Exactly this isessence of historical-geological (not chronological,lithological, paleontological, etc.) approach to strati-graphic investigation that was basic one in works byLeonov.

According to Leonov, the General (International)Scale, which is originally of the regional nature, can beused beyond the stratotype areas as a chronostrati-graphic scale, and its subdivisions distinguished on thechronological principle only have no physical bound-aries, being inappropriate for regional geological inves-tigations. They perform an auxiliary geochronologicalfunction necessary for correlation of separate sectionsand determination of relative geological age of regionalunits.

The same historical-geological approach is inherentof other works by Leonov devoted to general problemsof historical geology and tectonics. He was decisiveadvocate of the geosynclinal theory and argued againstmisrepresentation of the notion geological content. Heproposed and substantiated new notions to designatesome important types of tectonic areas, e.g., aulacogeo-synclines and paraplatforms. Of prime methodicalimportance was his work

The Problem of Cyclicity in

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the Earth’s History

(1962), in which he analyzed thedifferent-order cycles and stages in the Earth’s evolu-tion.

Leonov was not a “public” scientist. He succes-sively expounded his standpoints in papers, mono-graphs, and textbooks, in lectures for students, butnever imposed them to other people, never was bent onexposing at conferences, committees, and commis-sions. It is encouraging to note that main his conceptsare embodied and successfully developed in currentstratigraphic studies, although without references to hisworks in many cases.

First, in all modern Russian handbooks on stratigra-phy, geostratigraphic (in terminology of Leonov) units,i.e., formations, groups, horizons, are regarded alongwith chronostratigraphic units as key stratigraphic sub-divisions of historical-geological nature. Second, allresearchers understand the necessity of elaboratingregional stratigraphic schemes of major geologicalregions as a basis for reconstructing their geological

history. This is certainly realization of ideas by Leonov,which often struck during his life against a “blank wallof misunderstanding”. Finally, a rapid development of“sequence stratigraphy” in this country and abroad istrue manifestation of the historical-geological approachin stratigraphic studies of nowadays.

Leonov will be forever in our memory as a brightand eminent scientist, a researcher of deep principlewho always followed his own original path in science,was perceptible to new ideas, but made no compro-mises to please situation of the moment. He is remem-bered with gratitude by friends, colleagues, and numer-ous disciples who could always rely on his sincerekindness, harsh but fair constructive criticism, and all-round support and help.

M.A. Semikhatov, E.E. Milanovskii,Yu.B. Gladenkov, A.S. Alekseev,

D.P. Naidin, V.T. Frolov, D.I. Panov