On the problem of the horizontal heterogeneity of the earth's crust and uppermost mantle in southern Eurasia

Tectonophysics - Elsevier Publishing Company, Amsterdam Printed in The Netherlands

29

ON THE PROBLEM OF THE HORIZONTAL HETEROGENEITY OF THE EARTH’S CRUST AND UPPERMOST MANTLE IN SOUTHERN EURASIA

B.A. PETRUSHEVSKY Institute of the Physics of the Earth, .XS.S.R. Academy of Sciences, Moscow (U.S.S.R.)

(Received April 24, 1970) ABSTRACT Petrushevsky, B.A., 1971. On the problem of the horizontal heterogeneity of the earth’s crust and uppermost mantle in southern Eurasia. Tectonophysics, 11: 29-60. An analysis of the geological structure and history of development of the Himalayas points to the conclusion that prior to the Neogene most of that territory was part of the epi-Proterozoic Indian Platform; it was reworked only in the epoch of Neogene-Quaternary activation of tectonic movements. It was precisely during this period that the mountain ridge of the Himalayas formed. Only the narrow northern zone - the Himalayas of Tibet - which is composed of marine deposits of all systems of the Paleozoic and Mesozoic groups possibly did not develop on the platform with the Precambrian basement. Most likely, it is a near-fault folded zone that arose on the site of a near-fault trough, which already in the Cambrian Period had formed along the northern boundary of the Indian Platform. The Cenozoic geosynclinal structures located to the west and east of the Himalayas are fundamentally different in structure and history of development. This is clearly evident from an analysis of geological and geophysical data. These differences may be traced far back into geological history and are related to processes which took place and are now taking place at considerable depths, some of which are far below the bottom of the earth’s crust. The western Cenozoids are part of the Laurasian segment, the eastern Cenozoids, part of the Pacific Ocean segment of the earth. Obviously, one must speak of a large horizontal heterogeneity of the earth’s crust and the uppermost mantle within the limits of the territory described above. The Himalayas - this northern boundary zone of the Indian Platform which was elevated only in very recent times - represents a natural border between the Mediterranean and Pacific Ocean folded zones. INTRODUCTORY REMARKS

Many geologists have investigated the problems of the geological structure and history of development of the young folded zones of Southern Eurasia. This is particularly true of the Mediterranean. During recent years, extensive geophysical data on this territory have come to light, though not all findings for various sections are of equal value as to detail and reliability. However, so far no attempt has been made to correlate the geological and geo physical data on this region as a whole (such attempts have been made relative to separate areas within the region). The present paper represents a brief exposition of such a preliminary comparison which the author has just recently completed. Because of its brevity, only a portion of the source materials have been cited and only a few illustrations given. The work has come out in full (in the form of two articles) in the oldest Russian geological journal, the geological section of the Bulletin of the Moscow Society of Naturalists (F’etrushevski, 1970 a, b). The paper is based on an analysis of the literature. However, field studies carried out by the author over the years in the Tien-Shan, Middle Asia, the Kopet-Dag and in the Far Tectonophysics,

11 (1971) 29-6Q

30

B.A. PETRUSHEWKY

East have had a substantial influence on working out the theoretical views concerning the regularities of tectonic development of the territory under question. Some role was also played by visits to other areas (Caucasus, Carpathians, Balkans, Dinarids, Himalayas), though, being brief, they contributed solely to a build-up of personal impressions.Jncidentally, these impressions proved useful in that they supported the results of the analysis of the literature. If we view the matter as to topic and territory, this paper will be seen to deal with two different problems: that of the tectonic nature of the Himalayas; and the geological-geophysical phenomena in Cenozoic folded areas lying to the west and east of the Himalayas.

ON THE TECTONIC NATURE OF THE HIMALAYAS

The picture of a geotectonic unity of the folded geosynclinal alpine belt of Southern Eurasia, ordinarily known as the Mediterranean, has become firmly established in the minds of many generations of geologists. This belt is considered to be continuous from the Atlantic to the Pacific Ocean and to include Burma and Indonesia. Among the proponents of such views are such prominent representatives of Western European and Russian geological science as L. Kober, E. Argand, H. Stille, A.P. Pavlov, A.D. Arkhangelsky, A.N. Mazarovich, V.V. Beloussov, M.V. Mouratov and others. However, in recent years this point of view has come under criticism with increasing frequency. In the analysis of the problem as a whole, a central place is occupied by the definition of the tectonic nature of the Himalayas. As far as I know, the first one to cast doubt on the Himalayas belonging to an Alpine geosynclinal structure was Sinitsyn (1955). Somewhat later Rezvoi (1961, 1964) made a very clear and substantiated stand. His views were not welcomed by most Soviet geologists, but the situation changed somewhat after the publication, in Russian, of the works of Gansser (1965, 1967) on the geology of the Himalayas. Gansser is known to be one of the best specialists in the geology of this area. He has stated that it may be considered as outstanding that a small part of the Himalayas was formed from a geosyncline, whereas in the main the mountain ridge arose out of an activated area of the Indian Shield (1965, p. 67), or that if one disregards the Kashmir, it may be said that the Sub-Himalayas, and the Low and High Himalayas are composed of elements which once belonged to the boundary part of the Hindustan Shield (1967, p. 306), or that it is quite dbvious that the main Himalayan Range did not originate from a geosyncline and for this reason the classical theory of alpine orogenesis cannot be applied to it (ibid). Very interesting and symptomatic in this respect is the stand of such a noted geologist as D.N. Wadia. In his latest paper on the Himalayas (1966), Wadia points out, on the one hand, that a substantial part of the area they cover is a recently elevated part of the Indian Platform. On the other hand, he considers the zone of the Himalayas of Tibet and also certain other sections of the Himalayas as belonging to geosynclinal postPrecambrian structures. But then Wadia perspicaciously remarks &at the Himalayan geosyncline does not conform to the modern conceptions concerning either eugeosynclines or miogeosynclines. However, all these findings (and many others as well) proved insufficient for a radical

THE CRUST AND UPPER MANTLE IN SOUTHERN EURASIA

31

change in views concerning the tectonic nature of the Himalayas’. The view still persists that the Himalayas are an Alpine folded structure, That is precisely the way they are indicated on the Tectonic Map of Eurasia (Yanshin et al., 1966a). In the very latest works of a number of prominent Soviet geologists “allowances” are made only for the southern zone of the Himalayas, which is classed as a portion of the reworked epi-Proterozoic platform (Milanovsky and Khain, 1968; Mouratov and Khain, 1968). Similar views are held by geologists of other countries as well. Some geologists of India (Pande, 1966; Pande and Saxena, 1968) indicate, in the zone of the Himalayas of Tibet, a eugeosyncline from the Cambrian to the Paleocene; in the zone of the lower Himalayas, a miogeosyncline from the Carboniferous-Permian to the Tertiary Period. In his earlier works, Ray (1966, 1967) wrote about differing ages of eugeosynclines and miogeosynclines of different parts of the Himalayas and about the presence here of Caledonian and Hercynian folding. In 1968, Fuchs expressed the opinion that in the Late Precambrian-Early Paleozoic the northwestern Himalayas exhibited a geosyncline which ceased to exist after the Caledonian folding. Yet, if one is to believe the actual material given in the literature, such views are unacceptable. Note first of all that on the territory of the Himalayas, outside the extremely northern zone and the region of Kashmir, definitely post-Precambrian-pre-Gondwana deposits are known to exist only at a very few sites. This has been emphatically pointed out by Gansser. They are characterized by moderate thicknesses and a platform type of sediments (Fig.1). The remaining territory of the Himalayas is made up of metamorphic strata. In part they are definitely Precambrian with analogues on the Indian Platform. For the rest, a Precambrian age is most probable, whereas assumptions concerning a Paleozoic or Mesozoic age are proved untenable on closer examination of the problem. In certain cases, these assumptions were justified by the lithological “similarity” of the metamorphic strata of the Himalayas and developed strata hundreds and thousands of kilometres away in Burma and even in the Alps. Gansser has already spoken of the inadmissibility of such comparisons which were made, in particular, by Bordet (1961) and Hagen (1960). A complete sequence of Paleozoic and Mesozoic deposits is known to exist only in the extreme northern zone of the Himalayas (the zone of the Himalayas of Tibet) along the boundary line of structures of the Karakorum and Tibet. Conformably bedded sediments of all systems of the Paleozoic and Mesozoic groups have been established in this narrow (100 to 150 km) and long (1,500 to 2,000 km) zone. The overall thickness is extremely small (about 6,000 m). The striking thing about it is the generally uniform distribution among all members of the sequence. This is clearly evident from the table (Table I) which has been compiled mainly from the findings of Gansser. Of particular interest is the uniformity of strata of Upper Paleozoic-Mesozoic deposits, which on the Tectonic Map of Eurasia are classed in the “geosynclinal” complex. Over this enormous distance, the thickness varies within an extremely narrow range, from 3,600 to 3,900 m. This of course in no way

‘Extremely interesting in this respect is an article by Qureshy (1969) published

so recently

that its

findings are not yet generally known (it was my luck to read it in manuscript form). Proceeding from gravimetric and, in part, geological material,iqureshy sets out to prove the non-geosynclinal origin of the Himalayas; he rightly compares the genesis of this mountain ridge with the genesis of the very latest elevations of High Asia - Tien-Shan, Kun-Lun, etc. Zctonophysics, 11 (1971) 29-60

32

B.A. PETKUSHEVSKY

loo

0

400

km

Fig,l. Geological scheme of the Himalayas (after Gansser, 1967, simplified). 1 = Precambrian rocks and intrusions of all ages (except ophiolites); 2 = Paleozoic deposits; 3 = Upper Paleozoic-Lower Mesozoic deposits (Crol Belt); 4 = Mesozoic deposits; 5 = Cenozoic deposits; 6 = Quaternary deposits; 7 = traps of Kashmir and Abor of Upper Paleozoic-Lower Mesozoic age; 8 = Upper Cretaceous ophiolites; 9 = main Himalayan fault; and 10 = main Boundary fault.

resembles what is known about geosynclinal regions. On the adjacent Indian Platform, the rock thicknesses of some systems exceed, by a factor of two to three, those of similar aged strata in the zone of the Himalayas of Tibet (Krishnan, 1954). Add to this the fact that the Himalayas of Tibet exhibit an almost total lack of volcanic and magmatic manifestations. Exceptions are the flysch zone of the Indus and regions of development of ophiolites associated with themain Himalayan fault. Finally, note the relative simplicity of dislocations of deposits forming the zone of the Himalayas of Tibet. The foregoing is convincing evidence that what we are confronted with is an extremely peculiar structure. A structure that is not in the least like what we find in geosynclines or on platforms. Consequently, one is forced to look for a different solution to the problem of its genesis. Most likely, the persistently (and slowly) developing trough under consideration was intimately associated with the large and deep fault of considerable extension that existed here. This fault still exists and is called the main Himalayan fault. In the Cenozoic, the Paleozoic-Mesozoic near-fault trough was converted into a near-fault folded zone. It is in many respects similar to the Talaso-Ferghana, Zaalaisky and other fault zones situated to the north in the Tien-Shan and Pamir-Alai. Like these more northern structures, the Himalayan-Tibet near-fault trough (we can now call it by that name) developed on the boundary line between sharply different geotectonic elements (in this case, between the ancient Indian Platform and the younger structures adjoining on the north). This development was, as it were, “independent” of what occurred in the immediate vicinity, which is a peculiarity that is exceedingly characteristic of structures of this sort.

THE CRUST AND UPPER MANTLE IN SOUTHERN EURASIA

TABLE I Table of thicknesses of non-metamorphosed of Tibet and in Kashmir Site of section

conformable deposits in the zone of the Himalayas

Kashmir (m)

Himalayas of Tibet Spiti (m)

Kumaon (m)

Tkhakkola (m) (northern part of central Nepal)

Everest (m)

Tertiary Upper Cretaceous Lower Cretaceous Jurassic Triassic Permian Carboniferous Devonian Silurian Ordovician Cambrian

-

-

SO-70 350 1,000 1,300 350 850 100 450 550 600

1,500 500-700 850 700 100 800 1,200 500 1,200

Total thickness

5,600

7,350

9,350

4,450

9,250

Thickness of so-called “geosynclinal complex” (Carboniferous-Tertiary)

3,900

3,650

3,600

3,750

7,000 (3,500)’

Thickness of deposits below “geosynclinal” complex

1,700

3,700

5,750

750

500 250 750 1,500 600 500 1

1,250

850 1,100 200 600 500

1

750

4,500

_ 400 1,500 900 3,200 .400

1

500

1,350

2,250

‘The thickness of the Panjal traps of Kashmir (which are absent in all other sequences) reaches 3,500 m. With this subtracted, the thickness of the “geosynclinal complex” of Kashmir should be estimated at 3,500 m.

In only one region (in the Kashmir, on the southern slopes of the mountains where deposits of facies of the Himalayan-Tibet zone are known to exist) do we observe appreciable departure from the typical sequence of this zone. We see here a thick stratum of so-called “Panjal traps”. In age, it corresponds to a period of time from the Upper Carboniferous to the Upper Triassic Epochs inclusive, reaching a thickness of about 3,500 m. The boundary of erosion in the upper part of the Carboniferous is sharper here. Finally, effusive and intrusive rocks (Krishnan, 1954) are indicated in the Cretaceous deposits of the Kashmir (not substantially developed). All these differences are quite clear-cut. However, they cannot be of any significance in determining the character of the structure of the zone of the Himalayas of Tibet. There can be no doubt that the small Kashmir depression located on the other side of the Himalayan ridge belongs to a different tectonic unit than that within which the Himalayan-Tibet near-fault folded zone was formed. The assumption can be made that the genesis of the Kashmir depression is associated with movements that occurred Tectonophysics,

11 (1971) 29-69

34

B.A. PETRUSHEVSKY

in the region of the articulation of the Indian Platform and the young geosynclinal structures located to the west. This interesting and still very obscure problem is, unfortunately, beyond the scope of the present article. Thus, taken generally, the Himalayas must be considered as part of the Indian Platform which during the Neogene-Quaternaryperiod experienced rapid and sharp elevations (Fig.2). In the process, the platform structure was reworked. However, in pIaces strikes have persisted that are characteristic of Precambrian strata of platform territory that was untouched by the intensive movements of the latest period. The nature of this uplift is very close to that of the latest uplifts of High Asia. But if that is the situation, then we must exclude from the Alpine geosynclinal region of Southern Eurasia the Himalayan sector, which reaches 2,500 km in length. The site of this sector is occupied by the northern projection of the Indian Platform reworked during the Neogene-Quaternary period. The Alpine geosyncIin~ regions (Mediterranean and the Burma-Indonesian) approaching from the west and the south-

Fig.2. Structuralscheme of Himalayas and adjacent regions (compiled by B.A. Petrushevsky). I = outcrop of Precambrian foun&tion of Indian PIatform (with Paleozoic mantle in places); 2 = foundation in zones of subsidence (in places, with outcropp~g of Mesozoic mantle); 3= platform uplift of Salt Range; 4 = Deccan Traps on platcorm; 5 = Himalayan mountain ridge rocks of Precambrian foundation of northern fringe area of Indian Platform (including intrusions of various ages) raised high in the Neogene-Quaternary period; 6 = Himalayan-Tibet near-fault folded zone composed of sedimentary deposits of the Paleozoic and Mesozoic; 7 = large-scale projections of the Precambrian foundation in this zone; 8 = regions of development of the Upper PaleozoicLower Mesozoic traps of Kashmir and Abor in the Himalayas; in the Kashmir, also full sequence of Paleozoic and Mesozoic in facies of the Himalayan-Tibet near-fault folded zone; 9 = zones of devef; opment of Cenozoic deposits along southern slopes of the Himalayas; 10 = pre-Him~ayan NeogeneQuatemary troughs; II = Mesozoic folded region of the Karakorum; 12 = pm-Mesozoic folded region of Hindu Kush; 13 = Paleozoic folded region of Kun-Lun; 14 = zones of Tibet mass and the Mesozoic of Burma; 1.5 = Alpine folded regions of Baluchistan and Burma; 16 = foredeeps of Alpine folded regions; I7 = some large faults; and 18 = lines of strike.

Fig.3. Location of epict Pacific Ocean folded be The epicentres are base1 (1961), Savarensky et a the tectonic zones are t Eurasia” (Yanshin et al 1 = regions of Precambl 4 = regions of Cenozoic oceans belonging to reg “granite” layer; 9-12 = of class “a” (magnitude (magnitude 7.0-7.7, in 6.0-6.9, intensity 8-9 6-7-8); 13-15 = grou earthquakes (foci dowr and 15 = same for deer

pp.35-36

:ntres of strong earthquakes of Mediterranean and the southwestern part of the Its. 1 on the findings of Gutenberg and Richter (1954), Gorshkov (1961), Tandon l. (1962), Richter (1963), Beloussov et al. (1968) and others. The boundaries of aken from the scheme of the tectonics of Eurasia in the book “Tectonics of (Editors), 1966b). &n folding; 2 = regions of Paleozoic folding; 3 = regions of Mesozoic folding; folding; 5 = foredeeps of regions of Cenozoic folding; 6 = regions of seas and ions of Cenozoic folding; 7 = deepsea trenches; 8 = deep-sea basins without : class of earthquakes with respect to magnitude: 9 = epicentres of earthquakes : 7.75-8.5, intensity 10-11-12); 10 = epicentres of earthquakes of class “b” ten&y 9--10-11); II = epicentres of earthquakes of class “c” (magnitude -10): 12 = enicentres of earthauakes of class “d” (magnitude 5.3-5.9, intensity ps ofearthquakes ranked acco&ing to depth of foci: I3 = epicentres of surface I to 70 km); 14 = same for intermediate earthquakes (foci down to 70-300 km); earthquakes (foci deeper than 300 km).

pp.37-38

Fig.4. Scheme of isostatic anomalies of lndo~e~ after Artemyev (1966) (spied). ~ntemation~ normal form&a of 1930. Intensity of anomalies (in rn~~): I = from 0 to +SO; 2 = from +50 to +lOO; 3 = from +lOO to +150; 4 = over + 150; 5 = from 0 to -SO,6 f from -50 to -100; 7= from -100 to -150; 8 = below -150; and 9 = areas not investigate&

pp.3940

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Fig.% Scheme of isostatic ~a~rn~i~~ af ~~~i~~~~~e~. ~S~p~ied after A~~~m~ev,1966). ~~t~r~t~~~~ normat formula of 1930. I~tensj~ of ~orn~~~s (in palsy: I = from 0 to GO; 2 = from +30 to +lOO; 3 = fram +I00 to +tSO; 4 = over +t50; 5 = from 0 to -50; 5 If from -SO to -100; 7 = from -100 to -150; and 8 = areas not investigated.

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THE CRUST AND UPPER MANTLE IN SOUTHERN EURASIA

43

east come to a dead end. Neither of them is connected with the Himalayan-Tibet near-fault folded zone lying to the north and separated from them by a Precambrian barrier of the Himalayan Mountains. However, does this mean that the indicated geosynclinal regions belong to two different folded belts? Might it not be that the folded belt is unitary after all, but with a kind of squeeze at the site of the Himalayas? To decide this question, let us see what an analysis of the geophysical and geological data on Alpine folded structures located to the west and east of the Himalayas yields. In other words, we have to make an attempt to determine the geotectonic relationship between the Mediterranean and Pacific Ocean folded belts. ON THE GEOTECTONIC RELATIONSHIP OF THE MEDITERRANEAN AND PACIFIC OCEAN FOLDED BELTS

Geophysical data Let us first of all investigate earthquakes, the most objective of indicators of the activity of modern movements. Strong earthquakes are considered (beginning with magnitude 5.3, which corresponds (Fig.3) roughly to intensity 6 or 7’). We see that seismicity manifests itself differently in various regions of the territory under discussion. In the west (in the Mediterranean belt proper) seismicity generated by movements of the earth’s crust is relatively uniform. In subcrustal layers it diminishes eastwards, which permits one to speak of a reduction, in this direction, of mobility at considerable (100 to 200 km) depths. The relative uniformity of seismic manifestations in the earth’s crust (which are not particularly intensive on the whole) indicates that the causes of seismicity on this level are the same over the whole area. On the contrary, earthquakes occurring in the subcrustal layers down to depths 200 or 300 km are generated by local causes, which is evident from the isolated nature and the small sizes of the groups of their foci. The sole exception, apparently, is the region of the Gellen Trench. With respect to seismicity, Pacific Ocean Cenozoic structures, which are for the most part associated with deep-sea trenches, differ radically from regions lying to the west of the Himalayas. The seismicity here is very high and is ordinarily greatest near trenches. But at some distance from trenches it is extremely weak, even in what would appear to be the most “suitable” structural situation in which earthquakes frequently occur in the west. I refer to the weak seismicity over most of the territory of the Cenozoic folded structures of Sumatra, Borneo, and New Guinea. The sufficient similarity in character of the seismicity of all such Pacific Ocean structures compels one to take the view that very deep movements (down to 600-700 km) are of prime importance. Apparently, they are the ones which produce

‘In order to maintain uniformity in the approach to seismic data, I used primarily summary seismological studies in the plotting of epicentres, and seismogeological studies only in part (Gutenberg and Richter, 1954; Tandon, 1961; Gorshkov, 1961; Savarensky et al., 1962; Richter, 1963; Beloussov et al., 1968, and others). Most of these works are not of recent publication and so, unfortunately, some recent strong earthquakes have not been included here. Tectonophysics, 11 (1971) 29-60

44

B.A.PETRUSHEVSKY

surface earthquakes, since these are absent (or are rare) outside of regions in which subcrustal earthquakes occur. Being regional, these deep movements are peculiar in the extreme, since they are associated with narrow zones extending over thousands of kilometres. Thus, proceeding from seismotectonic data, it is impossible to separate Indonesia from the definitely Pacific Ocean structures of the Philippines or New Guinea. These circumstances compel us to take a negative view of conceptions that include Indonesia with the Mediterranean belt. On the contrary, there are very good grounds for including it in the Pacific Ocean structures. The foregoing is evidence of undoubted differences in the character and intensity of modern movements within the range of Cenozoids located to the west and east of the Himalayas. In this connection, the quantitative data concerning seismicity warrant particular attention. Calculations of seismic power over intervals of different depth (Shebalin, 1968; see Table II) point obviously to a sharp increase (at times by a factor of 6 to 8) in the seismic power in the surface level of the fringe area of the Pacific Ocean as compared with the Mediterranean. No less obvious is its steep increase for subcrustal movements as well accompanied by a general tremendous eastwards deepening of the process. There is also an appreciable increase in the density of epicentres (Table III) in the fringe area of the Pacific Ocean. Distinct differences between Indonesia and the Mediterranean also arise from a comparison of the distribution and nature of gravity anomalies over those areas. This is clearly seen with respect to isostatic anomalies (Artemyev, 1966; Fig.4, 5). In all the examined regions of the south-western fringe of the Pacific Ocean the peculiarities of their anomalous field (or, in other words, the deep tectonic structure) are brought about by regional causes. These causes are manifested in extremely peculiar fashion (but more or less of the same type) in the form of extended narrow zones of very large isostatic minima on the southwestern Pacific Ocean ring. Here, they are also associated with deep-sea trenches. Most likely, these zones of isostatic minima correspond to very peculiar, regionally uniform and extremely deep-seated geotectonic elements which were formed in the boundary strip between the Pacific Ocean proper and the Asiatic continent. Most of the numerous earthquakes (including very strong ones) are associated precisely with these deep-seated elements. Now, in the Mediterranean we have greater uniformity. There are far fewer examples here of a pronounced gravimetric individuality of a regional nature. This would seem to suggest a shallower depth to the processes involving the formation of the surface structure of the Mediterranean. Seismic findings would appear to be in agreement with this view. Consequently, one feels compelled to doubt very seriously the truth of any unity or considerable similarity in deep-seated processes over the area of the Mediterranean and the southwestern fringe of the Pacific Ocean. Within the Mediterranean possible analogues of such highly characteristic Pacific Ocean structures as deep-sea trenches and islands arcs are rare and atypical. One has to bear in mind that in the Mediterranean more or less identical isostatic anomalies characterize definitely distinct structural zones: for instance, negative anomalies of close-lying values are observed both in the folded system of the Betic Cordillera and in the deep Lombardian depression. We also see that earthquakes here are associated with anomaly fields of essentially

THE CRUST AND UPPER MANTLE IN SOUTHERN EURASIA

45

TABLE II Specific seismic power of seismic zones at various depths after Shebalin (1968) Region

Western Mediterranean Eastern Mediterranean Carpathians Iran Baluchistan Hindu Kush Burma Sunda Arc Celebes Philippines New Guinea Marianas

Period of observation, years

Normal earthquakes (O-60 km)

Shallow depth earthquakes (70-270 km)

V,

43

0.040

1.9

44 40 39 31 39 38 45 40 45 44 43

0.045 0.092 0.010 0.033 0.050 0.018 0.026 0.031 0.027

1.3

E

VS 0.006

0.032 0.0008 0.85 0.0025 1.4 0.0065 -1.9 2.7 0.084 6.6 0.051 10.1 0.037 4.6 0.025 1.3 0.054

f 0.3

Medium-depth earthquakes (280-470 km) VS

E

VS

E

-

-

-

-

0.7 1.1 1.1

0.029 0.021 -

_ _ -

2.116.0 2.6 24.0 - 2.3 3.3 1.2 1.8 3.4

Deep earthquakes (480-720 km)

I 0.007 0.0022 0.032

0.6 0.7 _ -

V, = active volume of seismic zone in cm3 (10z4cm3); and E= specific seismic power ifl erg. Cme3. Yeti-‘.

TABLE III Data on density of epicentres and shape of seismic zones Region

Density of epicentres (number of epicentres per 100,000 km2; earthquakesofall depths are taken into account)

Coefficient of isometricity (ratio of length of seismic zone to its width)

Mediterranean

4

1.7-2

Turkey, Caucasus, Iran, Afghanistan, West Pakistan

3.8

3.2

West and Central Himalayas

6

4

East Himalayas, Burma

11.8

2.1-3

Andaman and Nicobar islands, Sumatra, Java

5.4

7

Celebes and eastern part of Sunda archipelago

7.3

1.3 (as a whole) 3-4 (in separate elements)

Philippines New Guinea (western part) Tectonophysics, 11 (1971) 29-60

10 5.8

3.7 3

46

B.A. PETRUSHEVSKY

different values, for example, with a strip of negative anomalies in the zone of the Gellen Trench and with a substantial maximum to the immediate north of Crete. Such deviations are perceptibly more feeble in the southwestern part of the Pacific Ocean. A few words are in order concerning the Himalayas. The field of gravity of this region is quite distinct, differing from what we find in the western and eastern regions. We find an exceedingly interesting variation of isostatic anomalies in the three adjacent high-mountain ridges corresponding to folded structures of different ages: Himalayan, Karakorum and Kun-Lun (Desio and Marussi, 1960; Fig.6). From the ancient structure of the Himalayas to the definitely young Karakorum, there is a fall-off in anomaly values reaching 150 milligals (from +90 in the Himalayas to -60 in the Karakorum), and from the young Karakorum to the most definitely ancient Kun-Lun there is an increase of 120 milligals (from -60 to t60). This is also an excellent (though indirect) confirmation of the ancient age of the folding of the Himalayas and of their structural isolation from the Karakorum. Likewise, the findings concerning the structure and thickness of the earth’s crust unquestionably point to the individuality of the Himalayas (together with the regions contiguous on the north of the latest uplifts, though these are of a different tectonic build). Here, the “basalt” layer is radically thickened (up to 50 km). As a result, the overall thickness of the crust reaches 80 km (Qureshy, 1969). This is incomparably greater than in any other regions of the territory in question. In particular, in the Cenozoic folded structures directly adjacent to the Himalayas, the thickness of the crust is less by a factor of almost two. In a recent analysis of this problem in its general aspect, Belyaevsky pointed out that the enchanged thicknesses of the earth’scrust of lnner Asia, including the Himalayas, form “. . .the Inner Asian maximum of crustal thicknesses, which is the largest on the globe and, accordingly, the largest Asiatic depression in the relief of the Mohorovic’id surface (covering an area of over 4 million square kilometres)” (1969, pp.39,40). This region is in contrast with all the remaining regions of continental Eurasia. The presence, both along the southwestern fringe of the Pacific-Ocean and in the Mediterranean, of indisputably young marine depressions, the crust of which is devoid of a “granite” layer, makes most probable the recent process of oceanization of the crust in these areas. The scale is noticeably more modest in the zone of the Mediterranean than in the fringe areas of the Pacific Ocean. Summarizing the examination of geophysical data, we can say with assurance that these findings permit establishing essential differences between different regions of our territory. Schematically, these differences permit isolating three sectors: (1) western, embracing the area from the western Mediterranean to Baluchistan, inclusive; (2) eastern, from Burma southeastwards and eastwards; and (3) the much smaller central area - the Himalayan. The differences between the sectors are much greater than those that can be found within any one of them. This is an indication of appreciable differences both in the modern deep-seated processes and in the modern deep-seated build of the structures that interest us. On the whole, geophysical data (in conjunction with geological data when speaking of the Himalayas) also speak eloquently against the conceptions of a unity of the Mediterranean belt from Spain to Indonesia and against conceptions that the Himalayas are to be considered only a peculiar squeeze in the Alpine geosynclinal belt. It is much more likely that we have two independent mobile Cenozoic belts which come to a dead end at the

THE CRUST AND UPPER MANTLE IN SOUTHERN EURASIA

-80

*qe d Precam folding brian

47

-60

Alpine

Here _nian Precambrian

Fig.6. Scheme of geological structure and isostatic anomalies of High Asia. (After Desio and Marussi, 1960). A. I = granites; 2 = granodiorites; and 3 = basic rocks. B. 1 = granites; 2 = granodiorites; 3 = basic rocks; 4 = folds; and 5 = isostatic anomalies.

Himalayas. In that case, we must speak of a large horizontal heterogeneity not only of the earth’s crust but, apparently, of the uppermost mantle as well. The boundaries between all three sectors obtained on the basis of geophysical observations (the same goes for boundaries of less significance within the western and eastern sectors) are transversal. Up to this point we have considered the picture solely in the literal sense of today. In order to make the foregoing arguments convincing and also to put them in their proper historical geological perspective, let us investigate the geological findings historically. First, however, a few remarks concerning modern volcanism are in order. Tecfonophysics, 11 (1971) 29-60

~ectonophysics,

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B.A.PETRUSHEVSKY

Findings of modern volcanism I will not risk entering into a discussion of such an enormous and complicated problem as the relationship of modern volcanism of the Pacific Ocean belt and the Mediterranean. My task here is limited in the extreme: I aim to stress the incomparably greater intensity of Quaternary volcanism of the Pacific Ocean belt over that of the Mediterranean. This is clearly seen in the scheme of locations of Quaternary volcanoes (Fig.7). A distribution of this nature indicates a greater contemporary mobility of the Pacific Ocean region and is in complete agreement with the earlier stated geophysical findings. The percentage of extinct Quaternary volcanoes relative to active volcanoes is much smaller in the southwestern Pacific than in the Mediterranean belt. This is an indication of greater stability, in time, of fractures feeding the volcanoes of the Pacific Ocean fringe, thus again suggesting its greater tectonic mobility. It is also extremely interesting to note that many volcanoes of the southwestern Pacific ring (like numerous earthquakes) are associated with zones of negative isostatic anomalies. This once again emphasizes the great geotectonic significance of the deep-seated structures which give rise to these zones. Finally, there is the conspicuous absence of Quaternary volcanoes throughout the Himalayas. Historical geological findings In approaching the geological data just as briefly and generally as was done in the case of geophysical materials, we must concentrate our attention on those findings which deal with the degree of tectonic mobility of the regions under discussion. The author’s task was simplified by the extensive literature dealing with this territory. Firstly, we have a number of fundamental studies of earlier years which have not lost their significance to this day. I should first of all like to mention the survey study of Van Bemmelen (1957) on Indonesia. Secondly, recent years have seen the appearance of a large number of new studies dealing with large parts of the above mentioned territory or even the whole (or nearly the whole) of that area (Belov, 1957; Schneider, 1957; Hunting Survey, 1960; Arkhipov, 1964; Gansa, 1964; Ketin, 1966; St&klin, 1966; Khain, 1967, 1968, 1969, a, b; Sikijsek et al., 1967; Wolfart, 1967; Gatinsky et al., 1968; Milanovsky and Khain, 1968; Mirzod et al., 1968; Mouratov and Khain, 1968; Sokolov and Movshovich, 1968; Mouratov, 1969, Stepanov, 1969; and many others). The interest of Soviet scientists in this region (which is quite evident from the incomplete list of works given above) was spurred by work on the tectonic maps of Europe and Eurasia (Bogdanov et al., 1964; Yanshin et al., 1966 a, b). A particularly important roIe was played by the work on the map of Europe, in which many Soviet geologists and geologists from other countries participated. Let us begin our examination from the west. During recent years it has been established with sufficient assurance that the Mediterranean belt developed largely on the Baikal folded foundation (Mouratov, 1969). The reworking of this foundation began first in the west where there are rather large numbers of Paleozoic geosynclines of different types (Fig.8). Judging by the relationship of area occupied by geosynclines on dry land and free of them, the process of reworking took place with comparative intensity in the

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49

Mediterranean. To the east (in Turkey, Iran, Afghanistan) this process set in at a later date; there are few Hercynian geosynclines, the dominant role being played by Alpine geosynclines. The initial stage of geosynclinal subsidences in the northern half of this part of the belt refers to the middle Mesozoic, in the southern half it refers to the end of the Mesozoic or the beginning of the Cenozoic. The geosynclinal reworking of extensive areas between the northern and southern linear troughs was not so noticeable. Yet it was not so weak as to compel one to regard these areas as median masses. Most likely, only small regions like the Lut or South-Afgan masses are in the class of median masses here. Thus, the genera1 tectonic mobility was greater in the western part of the Mediterranean belt and less in the eastern part. At the same time, the geosynclinai troughs in the northern branch of the belt were initiated earlier; in the Paleozoic and the beginning or middle of the Mesozoic as against the end of the Mesozoic or the beginning of the Cenozoic in the south. Also, the development of the troughs, particularly in the east, was completed earlier. The general weakening of tectonic mobility towards the east in the northern branch led to a degeneration in its eastern regions of geosynclines, the whole area was covered by small and at times relatively shallow troughs of extremely short duratio,l, like the Triassic-Liassic troughs to the north of the Hindu Kush. However, it is difficult to give a general comparative evaluation of the mobility of the northern and southern branches, which developed at different times, particularly if we recall that the northern branch embraces all the geosynclines with longer lifetimes (Italy, Dinarids, Pointids, south Caucasian). Eugeosynclines of very prolonged development within a given region (Paleozoic and Mesozoic to Cenozoic, though there may have been certain interruptions in time) are an extreme rarity in the Mediterranean belt. There appears to be only one example of this kind, the south Caucasian trough, the closest to which is the Dinarid region. The boundaries between large areas of different structure and different history of development are associated with narrow transverse zones of meridional or submeridional directions. For some of them, we can consider as proved their correspondence to zones of large-scale deep-seated faults, which at times are apparently of Precambrian subsidence (the Indo-Pamir zone) (Petrushevsky, 1969). For other zones, such assumptions are possible mainly by analogy with the former. A number of these transverse systems are of the type of disiocations which are common both to geosynclines and to platforms, which were first distin~ished by Schatsky (1948). The most important of them is the Indo-Pamir zone. It is a dislocation which is common not only to geosynclinal and platform structures, but also to continental and oceanic structures as well. It is precisely this transverse zone that serves as the eastern boundary of the Mediterranean Alpine folded belt. In regions of the mobile Cenozoic zone of the southwestern part of the Pacific Ocean, where the age of deposits may be confidently dated far into geological history (this applied to Sumatra and Borneo), geosynclinal development embraces (even though not strictly continuously) the Cenozoic and Mesozoic eras and one or two periods of the Paleozoic. Earlier than that we do not know anything definite about rock ages. Apparently, the development was eugeosynclinal. This is suggested by the abundance of volcanic rocks in all or most parts of a sequence, the multiplicity and diversity of intrusions, great (sometimes enormous) thickness: for example, up to 15 km of Cenozoic in Burma or 10-l 1 km of Paleogene and 15 km of Neogene on Borneo. This is also suggested by the formational composition of the Tecronophysics,11 (1971)29-60

50

B.A. PETRUSHEVSKY

deposits and by other indications of an enhanced degree of tectonic mobility. For the Cenozoic (and Mesozoic as well in places where the appropriate deposits exist), the above-mentioned peculiarities of development are on the whole similar throughout the southwestern part of the Pacific Ocean, whether we find the Upper Paleozoic here or not. For this reason, we are justified in assuming a long-term eugeosynclinal regime over the entire area, though of course certain exceptions are possible (miogeosynclinal conditions in the Paleozoic on New Guinea). Another thing to bear in mind is that unlike the Mediterranean belt where the geosynclinal regime ordinarily terminated in the middle of the Cenozoic, in the fringe area of the Pacific the stage of most intensive geosynclinal development comes in the Neogene. Finally, let us take into account the facies diversity of deposits and the multiplicity of angular unconformities, which ordinarily occur in the absence of unified region phases of folding, all of which is an indication of differentiated movements. One must also bear in mind the difference (from the Mediterranean) in the structural set-up, with less uniform linear forms, an abundance of sharp bends in strike, butt junctions etc. Taken together, these geological findings lead to the conclusion of an appreciably greater tectonic mobility of Cenozoids in the southwestern fringe area of the Pacific as compared with the Mediterranean belt, including the most mobile regions of the latter. One can hardly be convinced by such objections as the suggestion that it is simply the stage of development that we are now observing on the outskirts of the Pacific occurred in the Mediterranean a long time ago. Those, in fact, are essentially the views of Scheinmann (1968) and, in part, StilIe (1964). First of all, it appears highly improbable that such a definitely ancient geotectonic element as the Pacific Ocean belt should suddenly today, appear at an earlier stage of development than the Mediterranean, which is roughly of the same age. That, however, is not the most important thing. If the Mediterranean had indeed passed through the stage at which the fringe area of the Pacific now stands, then the Mediterranean sequences would definitely have recorded the peculiarities which at present characterize the southwestern part of the Pacific Ocean ring. The Mediterranean sequences would have had to reflect clearly such phenomena as a sharpincrease in thicknesses, intensity of volcanic and magmatic activity, multiplicity of angular unconformities, and so on and so forth, all of which point to a long-term and intensive geosynclinal process. But if the Mediterranean does not manifest all these peculiarities, one can assert that the characteristic features of development so typical of the southwestern fringe area of the Pacific today were never very well developed in the western part of Eurasia. Let it be stressed that the comparison can be carried out only on correlatable scales, that is to say, over broad areas and for long periods of time. Separate areas, on the contrary, can and even must be very similar in both regions, for the simple reason that in both places we have Alpine geosynclines which develop largely in accord with general laws. Indeed, in the west we have structures that are rare relative to the Mediterranean type of development but are common in the Pacific Ocean zone; for example, a single small deep-sea trench (Gellen) or only two troughs of very long-term eugeosynclinal development (south Caucasian and, in part, Dinaridian), or only two (!!) strong earthquakes with foci deeper than 400 km etc. These exceptions only prove the rule that processes of the Pacific type are alien to the Mediterranean and other western regions. We thus arrive at the conclusion that the western and eastern parts of the young sub-

Fig.7. Scheme of local Ocean folded belts. VI (1957), Tectonic Map I = regions of Cenozo volcanoes.

pp. 51-52

ions of Quaternary volcanoes of Mediterranean and southwestern part of Pacific kanoes are plotted on the basis of the data of Van Bemmelen (1957), Gansser of Eurasia (Yanshin et al., 1966), and others. K folding; z = active volcanoes (or active in historical time); and 3 = extinct

x

pp.53-54

THECRUSTANDUPPERMANTLEINSOUTHERNEURASIA

55

latitudinal folded belt of Southern Eurasia differ in essential respects. These differences characterize a lengthy geological history and are so significant that one cannot regard them as not being fundamental. The question naturally arises: How justified is the conception of these differences and if sufficiently justified, then wherein lie the causes that generated them? To find an answer to this important question let us examine certain correlations based on a joint analysis of geological and geophysical data. Some conclusions based on a comparison of geological and geophysical data We have seen that on the territory of the Mediterranean belt, tectonic processes during the post-Precambrian were in the main characterized by a relatively slight intensity. During many geological periods the development of a number of extensive areas occurred under conditions of a shallow foundation of the fringe areas of the two ancient platforms: the Arabian and the Indian. The foundation underwent an earlier and more fundamental reworking in a geosynclinal situation in the west, in the Mediterranean. To the east, the reworking began only in the Mesozoic or even in the Cenozoic, and in places was extremely peculiar. This was first demonstrated (in the case of Iran) by Stiicklin (1966). The totality of geological findings permit the assumption that the tectonic processes were not particularly deep-seated on the territory of the Mediterranean zone. Geophysical findings corroborate this supposition as of today. Tectonic processes in the southwestern fringe area of the Pacific Ocean were very intensive over a long period of time: apparently, at least from the Carboniferous Period to the Neogene inclusive. They are the same today. The data of geological history indicates that during the whole of this period the structural-tectonic, lithological-formational and volcanic-magmatic peculiarities that existed were such as characterized these regions in recent epochs and still do today. We can thus assume that the tectonic processes here were, in the past, of the same great depth as (judging by geophysical findings) at the present time. Similar peculiarities are also observed in most of the other regions of the Pacific Ocean ring. There can be no doubt that we must also include the Sumatra-Java and Burma geosynclines where all these peculiarities are found. They represent an apophysis of the Pacific Ocean belt. Between the Mediterranean belt and the Cenozoids of the Pacific lies the Indian Platform with its highly elevated (this occurred during the Neogene-Quaternary period) northern boundary, which corresponds to the Himalayas. The isolated nature of the Himalayas (both from the western and the eastern Alpine geosynclines) is supported by all geological and geophysical findings. There is sufficient evidence of a weakening of tectonic mobility eastwards within the Mediterranean belt. The question arises as to whether we might not be able to account for this by the general increase in the tectonic process closer to the surface as we approach the border of the Indo-Pamir transverse depth zone. The point is that the western Cenozoids do not pass through it to the east, and the eastern Mesozoids do not pass through it to the west. Such an assumption appears probable. Also note that in that case we have a general explanation for the reduction of geosynclines of the Mediterranean belt in the easterly direction. At the same time, east of the Himalayas where geosynclines of the Pacific region begin the tectonic process almost at once drops to considerable depths (which increase in the southeasterly direction) without any of the gradual transitions which we sometimes read about.

B.A. PETRUSHEVSKY

56

Such is the overall picture of the structure and history of development of this territory as established for past epochs on the basis of geological findings, and for the present time on the basis of geophysical data. But if this is so, then the unavoidable conclusion is that the views concerning extremely significant differences between the Mediterranean and Pacific sectors are sufficiently justified. What can the causes of these differences be? I believe that the total sum of geological findings compel us to suggest a long-standing essential difference in deep-seated processes in the west and in the east. This brought about the differences in the near-surface and in the surface layers. Geophysical materials support this assumption for the present period. In this connection, we must point out that 45 years ago a suggestion was made concerning the individuality of the Pacific segment of the earth. The idea was advanced by Vernadsky (1934) who introduced into geological science the concept of “dissymmetry of structure of the earth’s crust”. Eight years later (1942) he examined the problem more fully and, as Kheraskov puts it, he delineated “the problem of the Pacific Ocean in its modern form”. Later still, more or less similar views, substantiated in various degrees, were expressed by many different geologists: Scheinmann (1958); Schatsky (1960); Kheraskov (1963); Petrushevsky (1964); Pushcharovsky (1967, 1968); Bogdanov (1968) and N.A. Belyaevsky (Belyaevsky and Petrushevsky, 1968). Such, in part, are the views of Stille (1964) and Mouratov (1965). There are also some who oppose these views, for example, Beloussov (1968). In the light of conceptions concerning the dissymmetry of the earth’s crust, an understanding can be gained of the existence of fundamental differences between young and simultaneously developing folded belts which geographically form a kind of unified zone embracing over a third of the earth’s circumference. Whereas the Mediterranean belt is part of the Atlantic segment (which it would seem better to define more broadly as Laurasian), Burma, Indinesia, the Philippines and other eastern regions belong to the Pacific segment of the earth. SOME GENERAL

REMARKS

Geological and geophysical data are in agreement in supporting the horizontal heterogeneity of the earth’s crust and the uppermost mantle of southern Eurasia. The heterogeneity finds expression both in the large and in the small scale. The western and eastern parts of the territory at hand are included in the two segments of the earth: the Laurasian and the Pacific segment, the differences between which may be traced to considerable depths and have existed for a long time. That is heterogeneity in the large scale. A consequence is the independence of the Pacific and Mediterranean Alpine belts. In the small scale, heterogeneity is seen in the presence of a number of large blocks (within the limits of the indicated zones) whose roots go below the earth’s crust. They go to smaller depths in the Mediterranean belt than along the fringe area of the Pacific Ocean. The ancient Indian Platform serves as a border line and, to some extent, a “neutral” region between the Laurasian and Pacific segments. An active part is played by enormous transverse deep faults, particularly the western one (Indo-Pamirian zone) which bounds it on the east and the west. As far as we can judge from available fragmentary materials, similar differences

THE CRUST AND UPPER MANTLE IN SOUTHERN EURASIA

57

between the west and east of Asia come to light to the north as well’. This permits one to assume horizontal heterogeneity of the earth’s crust and the uppermost mantle over the whole southern half of the Eurasian continent. The foregoing phenomena obey a large meridional tectonic zoning due to deep faults which persist over thousands of kilometres. This conclusion is of great theoretical interest, although we are still in the dark concerning the essential nature of the differences of the deep-seated processes and deep structure which underlie this heterogeneity. Here is another interesting theoretical consequence. It is obvious that in the literature, geosynclines are defined so as to include radically different structures which are also exceedingly different as to depth of the processes occurring within them. Here we have large island arcs with deep-sea trenches, island arcs consisting of chains of minute islets along the edges of such trenches, and continental zones with depths of movements 5- 10 times less than in the two preceding types. Quite naturally, by using the term geosyncline for such divergent structures, one confuses concepts that should not be confused. Examples from the Laurasian segment are usually taken as the standard. In other words, only the less deep phenomena are taken into account. It would therefore seem appropriate to reconsider the concept and term “geosyncline”. The differences between the two segments of the earth likewise call for a revision of certain other established concepts and terms. It might very well be that a new approach is in order with respect to the problem of regularities in location of useful minerals in the Pacific segment (primarily ore minerals). The point is that the conceptions concerning these regularities were for the most part elaborated on the basis of examples taken from the Laurasian segment. Finally, there are two more interesting theoretical consequences that follow from the foregoing analysis. Firstly, the geological history of the Mediterranean belt is an excellent instance of the possibility of restoring a geosynclinal regime on areas occupied by platform structures. Actually, almost the entire Mediterranean belt arose on the site of a platform which had existed for a very long time - from one to one and a half or even two geological eras (Paleozoic and Mesozoic). This instance enables one to return, at a higher level, to the old debate concerning the possibility or impossibility of inversion of platforms. Secondly, the time-stable meridional zoning of the Mediterranean belt serves as a reliable indication of the absence here of large horizontal translations. Quite naturally, a variety of shifts could occur along zones of transversal faults. However, the existence of these faults (which are sometimes common not only to geosynclines and platforms but to continental and oceanic structures as well - the Indo-Pamirian deep transverse zone) in one place for a very long time, occasionally since the Precambrian, can only be interpreted in one way. Such constancy is an excellent argument against recent overthrust sheets moving many hundreds of kilometres from the south, or against hypotheses according to which the Hindustan peninsula floated over here from a distance of thousands of kilometres in the Mesozoic. The author realizes that there are many debatable points in the picture he has drawn. ‘The suggestion of a large meridional (of long extension) tectonic division in Asia was first substantiated most clearly by Rezvoi (1964b). On this question, our points of view differ in many respects. Tectonophysics,

11 (1971) 29-60

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B.A. PETRUSHEVSKY

However, it would appear that there can hardly be any doubt about the principal conclns~o~ of this work as based upon the joint utilization of geophysics and geological findings: the Mediterranean and Pacific Ocean geosynclinal behs belong to different eIements of the earth’s crust and upper mantle. The much greater depth, activity and stability of the tectonic process on the outskirts of the Pacific Ocean makes the individuality of this region particularly conspicuous.

At various stages of this investigation, a brief survey of which has been presented in this paper, and after its completion the author has had the advantage of the suggestions and remarks of a number of scientists. Some of the remarks have been extremely valuable. The author wishes particularly to thank Prof. V.V. Beloussov, Prof. A.A. Bogdauov, Dr. 1-V. Kirilfova, Prof. D.P. Rezvoi, Dr. E.M. Ruditch and Prof. Yu.M. Scheinmann for the interest they took in this study.

LITERATURE Arkhipov, I.V., 1964. Tectonic sketch of Sunda Islands. Tr. Geol. Inst., Akad Nauk S.S.S.R., 113: 88-136 (in Russian). Artemyev, ME., 1966. Isostatic Anomalies of Gmvity and Some Problems of their Geological Interpretation. Nauka, Moscow, 138 pp. (in Russian). Barkhatov, B.P., 1968. On the Paleozoic history and the northern boundary of the Alpine folded beIt in the south of the U.S.S.R. Orogenic Belts- Intern, Geol. Congr., 23rd Prague, 1968, Session, Rept. Soviet Geo~o~sts,Problem 3: 148-153. (in Russian). Beloussov, V.V., 1968. The Earth’s tist und Upper Mantle of theOceans Nauka, 255 pp. (in Russian). Beloussov, V.V., Sorsky, A.A. and Bune, V.I., (Editors), 1968. Seismotectonic Map of Europe (Explanatory Note). Nauka, Moscow, 39 pp. (in Russian and in English). Belov, A.A., 1967. The tectonic development of the Alpine folded belt during the Paleozoic (the Balkan Peninsula - the Iran Highland - the Pam&). Geotectonics,1967 (3): 19-31. (in Russian). Belyaevsky, N.A., 1969. Geological structures and earth’s crust depth structure relation (by seismic data). By& Jfosk: ObshchestvaZs~ytuteZei~rody~ Otd Geof, 1969 (2): 24-43. (in Russian). Belyaevsky, N.A. and Petrushevsky, B.A., 1968. Principles of the problem of the geology of the conjugation zone of the Asiatic continent and the Pacific Ocean. In: Tectonics of Soviet Fur East and Adjacent Sea Areas Nauka, Moscow, pp. 15-29. (in Russian). Bogdanov, A.A., 1968. Tectonic history of the U.S.S.R. and neighbouring regions. I’estn. Mask. Univ. Ser. IV, Geol., 1968 (1): 5-24. (in Russian). Bogdanov, A.A., Mouratov, M.V. and Schatsky, N.S., (Editors), 1964. Tectonics of Europe (Explanatory Note to International Tectonic Map of Europe; scale: 1:2,500,000). NaukaNedra, Moscow, 364 pp. (in Russian). Bordet, P., 1961. Recherches geologiques dans SHimalayadu Nepal, region du Makalu. Edit. Cent. Natl. Rech. Sci., Paris, 275 pp. &riE, B.M., 1967. Evolution of the Dinarids during the Alpine Orogeny. Geotectonics, 1967 (6): 3-24. (in Russian). De&o, A. and Mart&, A., 1960. On the geotectonics of the granites in the Karakorum and Hindu Kush ranges (Central Asia). Intern Geoi. Congr., 2Ist, Copenhagen, 1960, Rept. Se&on Norden, 2: 156-167. Falcon, N.L., 1967. The geology of the north-east margin of the Arabian Basement Shield. Advan. Sci, 30(2): 31-42.

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Fuchs, G., 1968. The geological history of the Himalayas. Orogenic Belts. - Intern. Geol. Congr., 23rd, Prague, 1968, Proc. Sect., 3, pp. 161-174. Ganss, O., 1964. Zur geologischen Geschichte der Belutschistan-Indus-Geosynklinale. Geol. Jahrb., 82: 203-242.

Gansser, A., 1965. Geological and tectonic history of the Himalayas. Soviet Geol.. 1965 (10): 67-79. (in Russian). Gansser, A., 1967. Geology of the Himalqvas. Mir, Moscow, 320 pp. (Russian translation from the English). Gervasio, F.C., 1967. Age and nature of orogenesis of the Philippines. Tectonophysics, 4 (4-6): 379-402.

Gorshkov, G.P., 1961. Problems of seismotectonics and seismic zonation of territory of the Burma Union. Bull. Council Seismol., L!S.S.R. Acad Sci, 1961 (12): I- 127. (in Russian). Gutenberg, B. and Richter C.F., 1954. Seismicity of the Earth and Associated Phenomena. Princeton University Press, Princeton, N.J., 310 pp. Hagen, T., 1960. Nepal. Kimmezly and Fzey, Bern, 119 pp. Hunting Survey Corporation, 1960. Reconnaissance Geology of Part of West Pakistan - Colombo Plan. - Cooperative Project. Hunting Survey Corporation, Toronto, Ont., 550 pp. Ketin, I., 1966. Tectonic structures of Anatolia (Asia Minor). Geotectonics, 1966 (3): 61-71. (in Russian). Khain, V.E., 1967. Most important peculiarities of structure and development of the Alpine belt of Eurasia. Carpatho-Balkan Geol. Assoc., Congr., 8th. Belgrade, 1967, 1: 109-l 14. (in Russian). Khain, V.E., 1968. Principal features of the structure of the Alpine pelt of Eurasia within the Near and Middle East, 1. Vestn. Mosk. Univ., Ser. IV: Geol., 1968 (6): 3- 18. (in Russian). Khain, V.E., 1969a. Principal features of the structure of the Alpine belt of Eurasia within the Near and Middle East, 2. Vestn. Mosk. Lmiv., Ser. IV: Geol., 1969 (1): 3-25. (in Russian). Khain, V.E., 1969b. Principal features of the structure of the Alpine belt of Eurasia within the Near and Middle East, 3. Vestn. Mosk. Univ., Ser. IL? Geol., 1969 (2): 3-20. (in Russian). Kheraskov, N.P., 1963. Certain general laws in the structure and development of the Earth’s crust. Tr. Geol. Inst.. Akad. Nauk. S.S.S.R., 91: 119 vv. (in Russian). Krause, D.C., 1966. Tectonics, marine geology and baihymetry of the Celebes Sea - Sulu Sea region. Geol. Sot. Am, Bulk, 77(8): 813-832. Krishnan, MS. 1957. Geology of India and Burma. Publishing House of Foreign Literature, Moscow, 424 pp. (Russian translation from English). Kudryavtsev, G.A., Gatinsky, Yu.G., Mishina, A.V. and Stroganov, A.N., 1968. Some tectonic features of Burma and the Malacca Peninsula. Geotectonics, 1968 (4): 99-113. (in Russian). Milanovsky, E.E. and Khain, V.E., 1968. Main features of tectonic development of the Alpine Mediterranean-Indonesian belt. In: Orogenic Belts- Intern. Geol. Congr., 23rd, Prague 1968, Rept. Soviet Geologists, Problem 3: 176-182. (in Russian). Mirzod, S.Kh., Kolchanov, V.P. and Manucharyanz, O.A., 1968. Afghanistan (brief information of geological structure and essential minerals). Byul. Mosk. Obshchestva Ispytatelei Prirody, Otd. Geol., 1968(l): 31-52. (in Russian). Mouratov, M.V., 1965. Folded geosynclinal belts of Eurasia, Geotectonics, 1965(6): 3-l 8. (in Russian). Mouratov, M.V., 1969. The structure of the folded basement of the Mediterranean belt of Europe and Western Asia and stages of evolution of the belt. Geotectonics, 1969(2): 3-21. (in Russian). Mouratov, M.V. and Khain, V.E., 1968. Geosynclinal belts, erogenic belts, folded belts and their relations in time and space. In: Orogenic Belts - Intern. Geol. Congr., 23rd, Prague, 1968, Rept. Soviet Geologists, Problem 3: 48-54. (in Russian). Pande, I.C., 1966. Palaeo-tectonic evolution of the Himalaya. Publ CentreAdvancedStudy Geol. Panjab, 3: 107-116.

Pande, I.C. and Saxena, M.N., 1968. Birth and development of the Himalaya. Publ. Centre Advanced Study Geol., Panjab, 4: l--19.

Petrushevsky, B.A., 1964. Problems of the Geological History and Tectonics of Eastern Asia. Nauka, Moscow, 300 pp. (in Russian).. Petrushevsky, B.A., 1969. The Indo-Pamirian deep-seated zone and the West Deccan Earthquake. Geotectonics, 1969(2): 22-37. (in Russian). Petrushevsky, B.A., 1970a. On the tectonic nature of the Himalaya. Byul. Mosk. Obshchestva Ispytatelei prirody, Otd Geol., 1970(l): 5-30. (in Russian).

Tectonophysics,

11 (1971) 29-60

60

B.A. PETRUSHEVSKY

Petrushevsky, B.A., 1970b. On the geotectonic relationship of the Mediterranean and Pacific Ocean folded belts. B_yull. Mosk. Obshchestva Ispytatelei Prirody, Otd GeoL, 1970(2): 33-82. (in Russian). Pushcharovsky, Yu.M., 1967. The Pacific segment of the Earth’s crust. Geotectonics, 1967(5): 90-102. (in Russian). Pushcharovsky, Yu.M., 1968. The Pacific tectonic belt of the Earth’s crust. In: Tectonics of Soviet Far East and Neighbouring Sea Areas. Nauka, Moscow, pp. 7-14. (in Russian). Qureshy, M.N., 1969. Thickening of basalt layer as a possible cause for the uplift of the Himalayas - a suggestion based on gravity data. Tectonophysics, 7(2): 137-157. Ray, D.K., 1966. Some aspects of the Mezo-Cenozoic mobile belt of India. Geotectonics, 1966(2): 3-14. (in Russian). Ray, D.K., 1967. Tectonic Map of India. In: Tectonic Maps of Continents at 22nd Session of the International Geological Congress. Nauka, Moscow, pp. 63-74. (in Russian). Rezvoi, D.P., 1961. Some suppositions of the geological development of the Himalayan part of the Tethys. Call. Geol. Papers, Lvov Geol. Sot., 1961 (7-8): 282-288. (in Russian). Rezvoi, D.R., 1964a. Tectonics of the Himalayas (development of conceptions and the present state of the problem). In: Folded Regions of Eurasia Nauka, Moscow, pp. 348-365. (in Russian). Rezvoi, D.P., 1964b. On the Great Boundary Belt (Geological Divide) of Asia. In: Himalayan and Alpine Orogenesis

- Intern. Geol. Congr., 22nd, New Delhi, 1962, Rept. Soviet Geologists,

Problem II: 171-186. (in Russian). Richter, Ch.F., 1963. Elementary Seismology. Publishing House of Foreign Literature, Moscow, 670 pp. (Russian translation from the English). Savarensky, E.F.. Solloviev. S.L.. Kharin. D.A. (Editors). 1962. Atlas ofEarthauakes in the U.S.S.R. U.S.S.R. Academy of Sciences Publishers, Mosc&. Schatsky, N.S., 1948. On deep dislocations embracing both platforms and folded regions (Volga Region, Caucasus). Izv. Akad. Nauk. S.S.S.R., Ser. Geol. 1948(S): 39-66. (in Russian). Schatsky, N.S., 1960. Geotectonic regularity in distribution of endogenous ore deposits. Izv. Vysshykh Uchebn, Zavedenii, Geol. i Razvedka, 3(11): 9-18. (in Russian). Scheinmann, Yu.M., 1958. Some features in the development of folded structures of Asia. Izv. Vysshykh. Uchebn. Zavedenii, GeoL i Razvedka, 2(8): 3-14. (in Russian). Scheinmann, Yu.M., 1968. Outline of Deep Geology. Nedra, Moscow, 231 pp. (in Russian). Schneider, HI., 1957. Tektonik und Magmatismus in NW-Karakorum. Geol. Rundschau, 46: 426-476. Shebalin, N.V., 1968. On the nature of deep earthquakes. Dokl. Akad Nauk,S.S.S.R., 181(5): 1119-1122. (in Russian). Sikol[ek, B., GrubiE, A., CiriE, B. et al. (Editors), 1967. The geological problems of the Dinarids. CarpathoBalkan Geol. Assoc., Congr.,8th, Belgrade, 65 pp. Sinitsyn, V.M., 1955. General scheme of tectonics of High Asia. Byul. Mosk Obshchestva Ispytatelei Prirody, Otd. Geol., 1955(2): 51-66. (in Russian). Sokolov, B.A. and Movshovich, E.B., 1968. Geological history of Sulaiman-Kirthar Mountain folded structure (West Pakistan). Zzv. Akad Nauk, S.S.S.R., Geol. Ser., 1968(5): 75-94. (in Russian). Stepanov, D.L., 1969. Palaeozoic stratigraphy of Iran. ByuL Mosk Obshchestva IspytateleiPrirody. Otd Geol., 1969(l): 5-16. (in Russian). StilIe, H., 1964. “Atlantische”und “pazifische” Tektonik. Mir, Moscow, pp. 856-863. (Russian translation of original German book published in 1957). Stiicklin, J., 1966. Tectonics of Iran. Geotectonics, 1966(l): 3-21. (in Russian). Tandon, A.N., 1961. Seismology in India - Report of the UNESCO Seminar. India Meteorol. Dept., New Delhi, 1961.

Van Bemmelen, R.W., 1957. The Geology of Indonesia Publishing House of Foreign Literature, Moscow, 394 pp. (Abridged Russian translation from the English) Vernadsky, W.I., 1934. Outline of Geochemistry. Gorgeonefteizdat, Moscow, 2nd edition, 380 pp. (In Russian, originally published in French, 1924, as La Geochimie and then in Germany, 1930, under the title Geochemie in ausgewahlten Kapiteln) Vernadsky, W.I., 1948. On the geological shells of the Earth as a planet. Izv. Akad. Nauk, S.S.S.R., Ser. Geogr. Geophys., 1942(6): 251-262. (in Russian). Wadia, D.N., 1966. The Himalayan geosyncline. Proc. Natl Inst. Sci India, Pt.A, 32 (5-6): 523-531. Wolfart, R., 1967. Zur EntwlckIung der pallozoischen Tethys in Forderasien. Erdiil Kohle-Erdgaz-Petrochemie,

20(3):

168-180.

Yanshin, A.L. et al. (Editors), 1966a. U.S.S.R. Academy of Sciences, Yanshin, A.L. et al. (Editors), 1966b. Scale: I to S,OOO,OOO).Nauka,

Tectonic Map of Eurasia, scale: I to .5,000,000.

Geological Institute Moscow and Chief Management of Geodesy and Cartography.

Tectonics of Eurasia (Explanatory

Moscow, 487 pp. (in Russian).

Note to Tectonic Map of Eurasia,