1954-1961, Junior Research Fellow, USSR Academy of Sciences, V.G. Khlopin Radium Institute, Leningrad
1961-1967, Junior Research Fellow, USSR Academy of Sciences, Laboratory of Precambrian Geology, Leningrad
1967-2016, Junior Research Fellow to Head of Laboratory, Russian Academy of Sciences, Institute of Precambrian Geology and Geochronology, St.Petersburg
2017 – Principal Scientist, Russian Academy of Sciences, Institute of Precambrian Geology and Geochronology, St.Petersburg
Born on 6 April 1932 in Leningrad, Russia, Igor M. Gorokhov entered the Leningrad State University in 1949. After five years of study there, he graduated in radiochemistry (with honours). Later he obtained a PhD degree in Chemistry (Dissertation: “The Rb-Sr isochron method for the age determination of rocks, its appreciation and application”) from the Leningrad Technological Institute (1965) and then Dr Science degree in Geological and Mineralogical Sciences (Dissertation: “The Rb-Sr method and its application for dating geological processes”, 04.00.02 - geochemistry) from the Institute of Geochemistry and Mineral Physics, Kiev (1981). In 1979 he qualified as Senior Research Officer in Geochemistry by the Higher Education Board of the USSR.
Igor M. Gorokhov is an expert in isotope geoscience, who contributed significantly to the progress of the rubidium-strontium method of dating geological processes and strontium isotope geochemistry. His scientific activity started in 1961 at the Laboratory of Precambrian Geology (the USSR Academy of Sciences, Leningrad), where he began to work under supervision of Professor Erich K. Gerling (1904-1985).
Igor M. Gorokhov is an author of more than 300 scientific publications (including two books) covered a wide range of problems. Among these are the following: (i) the technical and analytical problems of geochronometry, (ii) the application of currently available methods of the mathematical statistics to geochronological studies, (iii) the methodology of the age determination of minerals and rocks, (iv) the mineralogical and geochemical criteria of sedimentary geochronometers reliability, (v) the regional geochronology and calibration of the Precambrian chronostratigraphic scale, (vi) the isotope chemostratigraphy of the Proterozoic, and (vii) the geodynamical problems.
The scientific career of Igor M. Gorokhov was accompanied by his participation in the Commission on the Absolute Age Determination of Geological Formations (1973-85), in the East European Commission on the Earth Crust Investigation (1978-89) and in Council on Isotope Geology and Geochronology (1985-91). He was a member of the Editorial Board of Chemical Geology (Isotope Geoscience Section), Elsevier, Amsterdam (1987-99) and a supervisor of the Leningrad Isotope Seminar (1978-92). From 1988 he is a member of the Commission on the Upper Precambrian of Russian Stratigraphic Committee.
In recognition of his dedication to his career, Professor Gorokhov has received two medals for scientific service from the Geological Surveys of Czechia and of Slovakia (1986). He has been recipient of the awards from INTERPERIODICA Publishing House (1996, 2003, 2014) and of the A.P. Karpinsky prize (2007).
The scientific biography of Igor M. Gorokhov can be chronologically subdivided into two stages which are roughly equal in duration. In the first stage, at a period of 1960-1985 years, his methodical and regional studies made him a well-known expert in the rubidium-strontium isotope geochronology. Over these years he investigated the possibilities of the mass spectrometric isotopic dilution method for determination of the rubidium and strontium microconcentrations in geological materials. Among other factors he studied instrumental and chemical reasons for the mass discrimination effects involved in thermal ionization mass spectrometric (TIMS) isotope analyses, and together with his collaborators Drs. Eduard P. Kutyavin and Nikolai N. Melnikov proposed some procedures which improved the accuracy and precision of the isotopic composition measurement of solid samples. In addition, Igor M. Gorokhov assisted to promote the new methods of statistical analysis in the practice of the geochronological laboratories of the USSR.
At this first stage Igor M. Gorokhov also contributed to the methodology of rubidium-strontium age determination for the rocks of different genesis. Of particular value are his investigations in dating metamorphic processes. He studied the impact of regional metamorphism on the rubidium-strontium systems in the rocks of different genesis and chemical composition and evaluated some prerequisites which are necessary to determine the age of metamorphic event. As a consequence, the technique was suggested for isotope dating of the individual evolution stages of polymetamorphic complexes which included preliminary structural and petrological studies and regulated the scale and mode of geochronological sampling.
By using the rubidium-strontium method, Igor M. Gorokhov together with his colleagues Drs. Elvina S. Varshavskaya, Eduard P. Kutyavin and Nicolai N. Melnikov obtained many geochronological dates in the time range from the Archean to the Early Paleozoic for crystalline rocks of Russia, Ukraine, Kazakhstan, Tadjikistan and Georgia, and for those of Spitsbergen, Czechia, Germany, Nepal and North Korea as well. These dates contributed to improvements of regional geochronological scales.
Theoretical prerequisites and practical results of the rubidium-strontium method application to dating geological processes were generalized by Igor M. Gorokhov in books: “Graphical Methods of Isotope Geology” (co-authored with Professor Yuri A. Shukolyukov and Dr. Oleg A. Levchenkov), Nedra, Moscow, 1974 and “Rubidium-Strontium Method of Isotope Geochronology”, Energoatomizdat, Moscow, 1985.
At the second stage of his scientific activity, starting in the early 1980s, Igor M. Gorokhov together with Professor Mikhail A. Semikhatov (of the Russian Academy of Science, Geological Institute, Moscow) addressed one of the most complicated fields in Earth sciences – isotope geochemistry and geochronology of non-metamorphosed sedimentary rocks of the Proterozoic. Their studies take two paths: (i) isotope geochronology and (ii) chemostratigraphy. In these fields stratigraphic and isotopic investigations combine with exhaustive mineralogical and chrystallochemical studies of lithogenetic evolution of sedimentary material.
Being a member of several projects of the International Geological Correlation Program (IGCP) and the projects supported by the Russian Foundation for Basic Research (RFBR), the International Science Foundation (ISF), and the International Association for the promotion of co-operation with scientists from the New Independent States of the former Soviet Union (INTAS), Igor M. Gorokhov have made a significant contribution to methodology of isotope dating of the non-metamorphosed Upper Precambrian sedimentary rocks. His basic achievements in this field are as follows:
- The approach to isotope age determination of shales is suggested that elaborates the ideas of French geochronologists, especially of Dr. Norbert Clauer (CNRS-ULP, Centre de Gйochimie de la Surface, Strasbourg, France). This approach is based on a study of mixing systematics of the non-cogenetic components of shale and includes separation and analysis of a set of the submicron clay fractions varied in size, together with the employment of the leaching technique and the XRD and TEM controls of illite evolution. In many cases the approach makes it possible to determine the timing of the diagenesis and catagenesis of clayey sediments by the analysis of a single shale sample. In addition, this study gives an information about the nature of interstitial solutions which contribute to crystallization of different illite generations and allows one to form an opinion about the closeness or openness of geochemical systems in the shale at the different stages of lithogenesis.
- The reasons for the loss of radiogenic argon and strontium from Precambrian globular phyllosilicates were founded, and the geological situations responsible for a ’rejuvenation’ of these minerals were determined. With the aid of Mössbauer and infrared spectroscopy, Igor M. Gorokhov in collaboration with Dr. Tatyana S. Zaitseva and Oxana V. Yakovleva demonstrated that the ’rejuvenation’ of glauconite took place during retrogressive diagenesis of sedimentary rocks and resulted from the low-temperature globular phyllosilicates alteration followed by the cations ordering in octahedral layer of the minerals. Thus the crystallochemical criteria for disturbance of the K-Ar and Rb-Sr systems in glauconite have been gained, and now geochronologists have a possibility to control the stratigraphic validity of glauconite isotope dates.
- In collaboration with Dr. Galina V. Ovchinnikova the new technique has been developed for the uranium-lead and lead-lead dating of the Upper Precambrian carbonate rocks. The basis for this technique is a selective dissolution of the carbonate constituent of limestones and dolostones. Coupled with above-mentioned approaches, the technique resulted in a notable advance in calibration of the Late Proterozoic chronostratigraphic scale, especially in determination of the isotope age of the Middle-Late Riphean boundary.
- In cooperation with Professor Mikhail A. Semikhatov and Dr. Anton B. Kuznetsov the impressive success has been achieved in studying the secular variations of strontium isotope composition in Proterozoic seawater. This scientific team introduced an obligatory selection of the samples on basis of hard geochemical criteria in the practice of chemostratigraphic investigations of Proterozoic carbonate rocks. In addition, Igor M. Gorokhov proposed a procedure of preliminary leaching of carbonate samples which allows the elimination of secondary carbonate phases and evaluation of the extent of postsedimentary alteration of the rocks. These improvements resulted in marked widening of the potentialities of strontium isotope stratigraphy in the Proterozoic. Among other things this scientific team managed to show that the published 87Sr/86Sr ratios in the paleoocean for some time intervals (especially for the Middle and Late Riphean) may be invalid. The improved curve of the 87Sr/86Sr variations in seawater during the Proterozoic based on many new results revises conventional notions about relationship of continental and mantle fluxes of strontium to the paleoocean. These data are of prime importance for global geodynamics.
- In collaboration with Professors Victor A. Melezhik (Geological Survey of Norway, Trondheim) and Antony E. Fallick (Scottish Universities Environmental Research Centre, Glasgow, Scotland) it was found that even metamorphosed Proterozoic and Paleozoic carbonate rocks can under certain circumstances maintain their original isotope features. Relying on these facts, these authors were able to solve several controversial questions of stratigraphy of the Norwegian Caledonides.
- Using the aforementioned advancements in sedimentary isotope geochronology and geochemistry, Igor M. Gorokhov together with his colleagues Drs. Galina V. Ovchinnikova, Anton B. Kuznetsov, Nikolai N. Melnikov, Galina V. Konstantinova, Eduard P. Kutyavin, Tatyana S. Zaytseva and also Tatyana L. Turchenko and Olga K. Kaurova obtained a great body of geochronological and chemostratigraphical data for Proterozoic and Paleozoic sedimentary rocks of Russia, Ukraine, Estonia and Norway which help to solve many problems of regional stratigraphy and incorporate some modifications in the Precambrian geochronological scale.