Precambrian Geology of the USSR

522 Pages·1993·10.178 MB·ii-vi, 1-528\522

by  D.V. Rundqvist and F.P. Mitrofanov (Eds.)

DEVELOPMENTS IN PRECAMBRIAN GEOLOGY
Advisory Editor B.F. Windley
Further titles in this series
1. B.F. WINDLEY and S.M. NAQVl (Editors)
Archaean Geochemistry
2. D.R. HUNTER (Editor)
Precambrian of the Southern Hemisphere
3. K.C. CONDIE
Archean Greenstone Belts
4. A. KRONER (Editor)
Precambrian Plate Tectonics
5. Y.P. MEL'NIK
Precambrian Banded Iron-formations. Physicochemical Conditions of Formation
6. A.F. TRENDALL and R.C. MORRIS (Editors)
Iron-Formation: Facts and Problems
7. B. NAGY, R. WEBER, J.C. GUERRERO and M. SCHIDLOWSKI (Editors)
Developments and Interactions of the Precambrian Atmosphere, Lithosphere and
Biosphere
8. S.M. NAQVI (Editor)
Precambrian Continental Crust and its Economic Resources
DEVELOPMENTS IN PRECAMBRIAN GEOLOGY 9
PRECAMBRIAN GEOLOGY
OF THE USSR
Edited by
D.V. RUNDQVIST
Institute of Ph ysics of the Earth, Russian Academy of Sciences, B. Gruzinskaya 10,
723810 Moscow, Russia
and
F.P. MITROFANOV
Institute of Precambrian Geology and Geochronology, Academy of Sciences of Russia,
nab. Makarova 2, Leningrad 199164, Russia
Translated by C. Gillen
The University of Edinburgh
ELSEVIER, Amsterdam - London - New York - Tokyo 1993
ELSEVIER SCIENCE PUBLISHERS B.V.
Sara Burgerhartstraat 25
P.O. Box 211,1000 AE Amsterdam, The Netherlands
Library of Congress Cataloging-ln-Publlcatlon Data
Dokembriiskah geologlh SSSR. English.
Precambrian geology of the USSR / edited by D.V. Rundqvist and
F.P. Mitrofanov.
--
p. cm. (Developments in Precambrian geology ; 9)
Translation of. Dokembr i iskah geo logi SSSR.
Includes blbliographical references and index.
ISBN 0-444-89380-6
1. Geology, Stratigraphic--Precambrian. 2. Geology--Soviet Union.
I. Rundkvist. D. V. (Dmitril Vasil’evich) 11. Mitrofanov. F. P.
111. Title. IV. Series.
PE653.D643513 1992
551.7’1’0947--dC20 92-8594
CIP
Precambrian Geology of the USSR was first published in Russian in 1988 as “Dokembriyskaya
geologiya SSSR” by Nauka Publishers, Leningrad. ISBN 5-02-024367-1,440 pp.
Q 1988 Nauka, Leningrad
ISBN: 0-444-893806
0 1993 Elsevier Science Publishers B.V. All rights reserved.
No part of this publication may be reproduced, stored in a retrieval system or transmitted in any
form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the
prior written permission of the publisher, Elsevier Science Publishers B.V., Copyright and Permis-
sions Department, P.O. Box 521,1000 AM Amsterdam, The Netherlands.
Special regulations for readers in the U.S.A. - This publication has been registered with the Copy-
right Clearance Center Inc. (CCC), Salem, Massachusetts. Information can be obtained from the
CCC about conditions under which photocopies of parts of this publication may be made in the
U.S.A. All other copyright questions, including photocopying outside of the U.S.A., should be
referred to the publisher.
No responsibility is assumed by the publisher for any injury and/or damage to persons or property
as a matter of products liability, negligence or otherwise, or from any use or operation of any
methods, products, instructions or ideas contained in the material herein.
This book is printed on acid-free paper.
Printed in The Netherlands
V
FOREWORD
Precambrian Geology of the USSR is an attempt to draw together and
generalise new geological, geochronological, petrological and geophysical
material for the two fundamental continental geostructures within the
Soviet Union - ancient cratons and Phanerozoic fold belts. This material
reflects the results of research by a large team of geologists in the
Institute of Precambrian Geology and Geochronlogy of the USSR Academy
of Sciences (in Leningrad) who have been studying Precambrian regions for
over 30 years. The book also takes account of the achievements of other
scientific and industrial organisations in this area. It has been written
by a team of authors who are the leading specialists in problems of the
Precambrian and in the geology of individual Precambrian regions.
Material for the major regions - tectonic provinces or “geoblocks”
- is basically presented according to a unified pattern. Since the book
was written by a large team, individual chapters are to a certain extent
independent essays in which the understanding of scientific questions is
given from the author’s point of view,
The book gives the complete Precambrian history of each region, al-
though the early Precambrian is treated more fully than the late Precam-
brian, which for many regions is presented in outline only. It is not possible
in a single book to describe all aspects of early Precambrian geology for each
region equally comprehensively. Therefore, certain individual aspects are
treated as fully as possible for one or two regions and in a more condensed
form for the others. For example, the lithological composition and petro-
chemistry of lower Archaean rocks in high grade metamorphic complexes
is given in detail for the Aldan Shield; deformation sequences and their
relation to migmatites and granites are given in detail for the Belomorides
and Svecofennides. The exhaustive reference lists for each region will allow
the interested reader to obtain further information.
Problems in the regional geology of the Precambrian of such major
regions as ancient cratons require many questions to be resolved in
relation to the establishment of the time and space correlation of tectonic
structures at various stages in crustal evolution; the construction of vertical
and horizontal crustal sections; and an explanation of the commonest
patterns in the development of the Precambrian lithosphere and in the
evolution of processes taking place in the lithosphere. These questions
are far from being finally resolved, and their discussion in the book
VI Foreword
reveals only the trends and directions of research in the Institute of
Precambrian Geology and Geochronology. Attempts are being made in this
research to combine the results of analysing recent data on Precambrian
regions into a unified system. Some problems in Precambrian geology are:
the evolution of sedimentation, defining the conditions existing in upper
sections of the Precambrian crust in different geological periods; features of
metamorphic processes of different ages at various crustal depths, reflecting
the thermodynamic conditions in the Precambrian crust at various stages
in its growth; the conditions pertaining to the appearance of igneous melts
and the origin of magmatic bodies, which characterise P-T parameters in
the crust and mantle; the definition of metallogenic cycles and ore-bearing
structures - these relate to a number of topical problems which are
reflected in several sections in the book and in the conclusions.
The work was designed by G.P Pleskach and A.A. Mikhaylova. Enormous
help was given in the preparation of the manuscript by G.A. Buyko and E.N.
Turunova. All the tables on features of mineral deposits and ore shows were
prepared by Dr. RA. Gorelov. The authors express their sincere gratitude to
them. Dr. A.N. Kazakov and Dr. G.M. Belyayev are thanked for their helpful
and constructive suggestions on the manuscript.
D.V RUNDQVIST and El? MITROFANOV
Authors:
RYa. Khiltova, A.B. Vrevsky, S.B. Lobach-Zhuchenko, K.A. Shurkin, VA.
Glebovitsky, A.K. Zapolnov, A.N. Berkovsky, VB. Dagelaysky, D.V: Rund-
qvist, Yu.M. Sokolov, RL. Dook, G.M. Drugova, R.I. Milkevich, S.I. Turchen-
ko, N.I. Moskovchenko, L.Ye. Shustova, F.E Mitrofanov, I.K. Kozakov, R.Z.
Levkovsky, A.R Sochava, RA. Gorelov.
Referees:
G.M. Belyayev, A.N. Kazakov
Introduction
The Precambrian developed in the USSR presents an ideal opportunity
to study it in all its structural forms. Different vertical levels of the early
Precambrian crust are exposed in the continental basement. The upper
Precambrian plays an important role in the structures of the sedimentary
cover. Precambrian rocks of various ages are exposed in Late Proterozoic
and Phanerozoic fold belts.
Ancient cratons, in which the Precambrian is the main constituent, and
Phanerozoic fold belts, in which the Precambrian is of minor importance,
occupy approximately equal areas within the Soviet Union (Fig. 1-1).
The boundaries between them separate late Precambrian (< 1650 Ma)
sediments, formed on ancient continental platforms in a stable regime,
from the geosynclinal sediments in younger fold belts. The basement to
cratons is exposed in regions amounting to a little over 12% of the area
of each craton. The East European and Siberian cratons are almost mirror
images of each other in terms of the distribution of areas of exposure. In
the East European craton, the northern part of the basement, the Baltic
Shield, is best exposed, while the southern part, the Ukrainian Shield, is
much less so. In the Siberian craton, on the other hand, areas of exposure
are situated mainly in the south - in the Aldan Shield, the Stanovoy region
and the marginal uplifts in the south-west of the craton, while in the north
the Anabar Shield accounts for only a small area.
There are many points of view concerning the nature of the boundaries
between exposed shields and cratonic areas. We take them to be historical-
geological boundaries which had already been initiated in the Precambrian.
Huge areas of Precambrian rocks of the cratons are hidden beneath
a sedimentary cover. Investigating them by geological and geophysical
methods is of great significance in defining the space-time boundaries of
the major categories of early Precambrian tectonic structures.
The basement to ancient cratons is subdivided by persistent lineaments
into a system of blocks. Major crustal segments, or provinces (geoblocks),
correspond to tectonic regions which developed independently and are
2

I
n
tr
Fig. 1-1. Tectonic regions of the USSR. 1 = younger fold belts: a = exposed, b = beneath platform cover; 2 = Upper Precambrian in younger od
fold belts; 3 = Lower (Upper in part) Precambrian in younger fold belts; 4 = Precambrian of cratons: a = exposed (shields), b = buried uc
basement; 5 = geological boundaries; 6 = craton margins. tio
n
Introduction 3
thereby distinguished from one another. The main difference is in the
timing of the final processes: Archaean for example in the Kola and
Karelian provinces of the Baltic Shield; Early Proterozoic in the West
Ukrainian province of the Ukrainian Shield, etc.
The block structure of the crust, identified during the analysis of geo-
logical and geophysical data, probably reflects the earliest subdivision of
the lithosphere. This is indicated by important statistical relations discov-
ered between the composition of Archaean igneous rocks and a number of
geophysical characteristics of the modern lithosphere, including the gravity
potential and some parameters of the geomagnetic field (Abramovich and
Klushin, 1978). Although the exposed Precambrian, especially the earlier,
in younger fold belts amounts to a tiny percentage, it is nevertheless
documented in belts which completed folding at different times. The Pre-
cambrian is exposed in two types of tectonic structure: median massifs and
anticlinal elevations.
The study of the Precambrian in the territory of the USSR began
over 100 years ago. From the 1880s to the 1940s, research was mainly
carried out in crystalline shield areas. Investigations in this period by N.I.
Inostrantsev, VM. Timofeyev, A.A. Polkanov, VA. Obruchev, M.A. Usov and
others were mainly directed at solving problems in practical geology and
basic methods were evolved for the successful scientific study of various
aspects of Precambrian geology. The idea emerged in this period that
Precambrian geology possessed certain well-expressed specific features. The
reason for this was a lack of study of the late Precambrian, while the
early “crystalline” Precambrian could confidently be contrasted with the
Phanerozoic.
Since the 1950s, the techniques of isotope geochronology began to be
applied widely by A.F? Vinogradov, E.K. Gerling, A.I. Tugarinov and N.l?
Semenenko. This resulted in a qualitatively new understanding of geological
processes in the Precambrian. One of the most important outcomes was
the radiometric dating of major magmatic episodes, mainly granitic, and
metamorphic episodes, which in reality were relatively brief intervals of
intense activity, often defined as tectononietamorphic or tectonomagmatic
cycles or epochs. Data from all Precambrian regions showed that they
subdivided Precambrian geological history into major segnients-stages of
continental crustal development lasting for 800-1000 Ma (Neyelov, 1965;
Kratz et al., 1981). Internal processes affected all crustal levels. Up to
the present, the application of tectono-metamorphic cycles or epochs is the
only useful basis for the general subdivision and interregional correlation
of Precambrian rocks. They form the basis of the general geological-
geochronological scale for the early Precambrian (Keller et al., 1977).
Each stage in the development of the early Precambrian crust - Early
Archaean, Archaean and Early Proterozoic - is reflected in structural-
lithological terrains. The geological and geochronological boundaries of
4 Introduction
these terrains are defined by periods of intense internal processes, which
are dated by radiometric methods. Structural-lithological terrains include
volcanogenic-sedimentary rocks and intrusive rocks, formed in the time
interval between these boundaries. Since these terrains evolved over very
long periods, their supracrustal components could contain formations
which accumulated under varied tectonic and palaeogeographic conditions
- either relatively quiet or active.
The early Precambrian terrains formed under varying P-T condi-
tions. This book places great significance on sillimanite-andalusite and
sillimanite-kyanite facies series when characterising metamorphic condi-
tions. It is assumed that these series formed in response to different
thermal gradients: high or low. High gradient metamorphism usually cor-
responds to processes that occurred at low P (5-6 kbar for T = 700-
8OO0C), while low gradient metamorphism occurred at high P (7-13 kbar
for T = 700-800°C).
The study of the composition of Precambrian complexes - the division
into primary sedimentary and primary volcanic, and the determination of
which magmatic series volcanic rocks belong to - is based on the use of
various petrochemical diagrams. For sedinientary-volcanogenicr ocks, the
Neyelov et al. (1979), Predovsky (1979) and Golovenok (1977) diagrams
were used; for igneous rock determinations, diagrams developed by the
USSR Petrographic Committee were used (Andreyeva et al., 1980); and
for distinguishing magmatic series, Na20 +KzO-A1203-MgO and others,
triangular diagrams were used. The Neyelov petrochemical diagram is used
throughout for analysing metamorphic rocks of the Aldan Shield; being a
classification diagram for sedimentary and volcanic rocks, it provides an
opportunity to compare simultaneously the compositions of the same rocks
with different parageneses and to define the petrochemical features of the
parageneses as a whole.
In Precambrian regions which have evolved in a cyclical fashion, the
structural development of individual complexes was reflected in numer-
ous phases of folding, designated 8’1, 8’2, ...n,d uring deformational cycles
... n.
Figure 1-2 illustrates the early Precambrian structural-lithological ter-
rains in the main regions of the USSR which are described in this book.
Periods of intense internal processes are shown in Fig. 1-2 as fold episodes,
some of which - those that appeared over a whole region and at all crustal
levels - correspond to major boundaries (solid lines), while others that
appeared locally correspond to local boundaries (broken lines).
Geological-geochronological boundaries are defined using the 1978 Pre-
cambrian geochronological scale of the USSR (Keller et al., 1977; Mitro-
fanov, 19791, in which the Precambrian is divided into the Archaean, lower
Proterozoic and upper Proterozoic (Riphean+Vendian), the main bound-
aries being 2600 f 100 Ma, 1650 f 50 Ma and 650 f 25 Ma, and the internal
Introduction 5
Fig. 1-2. Correlation of structural-compositional complexes and tectonic epochs in the early
Precambrian of the USSR.
boundaries 2300 Ma, 1350 f 50 Ma and 1000 f 50 Ma. This scale differs
in certain respects from the geochronological scales of other continents.
In particular, the two-fold instead of three-fold division of the Proterozoic,
and the lesser signficance compared to elsewhere of the 1000 f 100 Ma
boundary. These differences relate significantly to the fact that the 1978
geochronological scale of the USSR was established on the basis of material
from the Precambrian of ancient cratons, in the geological history of which
the 1700 f 100 Ma date represents the boundary between the latest events
in the mobile development of these regions and their aulacogen-pericratonic
stage, which in Vendian to Palaeozoic times merged with the stage of
formation of the platform cover succession. Geological and geochronological
material for the early Precambrian, so far accumulated, has assisted the
authors in a number of cases to subdivide major geochronological units
into smaller ones. For example, three subdivisions are recognised, as in
the Archaean of the Siberian craton: AR; > 3400 Ma, AR: > 3000 Ma and
AR; > 2600 f 100 Ma.
In determining the age of structural-lithological terrains, the timing of
metamorphism and the age of igneous rocks, account has been taken of
all dates using different radiometric methods: U-Pb and Rb-Sr isochrons,
Pb-Pb zircon ages, K-Ar and Sm-Nd, the latter at present used only to
a very small extent. Preference was given to U-Pb, Rb-Sr and Sm-Nd
methods. Results from the Pb-Pb thernio-emission method (Zr evaporation
technique) were regarded as reflecting the minimum age of an event,
although in many cases the figures obtained by this technique were close
to or even coincided with U-Pb zircon isochron dates. Dates obtained from
the K-Ar method were taken into consideration when evaluating the time