19_1

Volume 19, 1, 2000

Petrology and Minerageny

A.A.Marakushev, Sang Longkang, A.V.Bobrov, N.A.Paneyakh, N.N.Pertsev, I.A.Zotov. Asian eclogite diamondiferous belt 3
A.A. Sidorov, I.N. Tomson.Conditions of origin for black shale complexes and their metallogenic implication 37
S.S. Zimin, V.G. Moiseenko, R.A. Oktyabrsky, S.G. Baturin, B.M. Tishkin, V.P. Molchanov. On the first finding of metamorphosed bauxites in Middle Priamurie with the reference to their potential 50
L.B. Sushkin. Geology of Sologu-Chaydakh gold ore field ( the Amur Region) 56

Geochemistry

A.Yu.Antonov. Geochemistry of REE in Late Mezozoic volcanic complexes of the Stanovoy Range 66
F.I.Rostovsky.Some aspects of tungsten geochemistry in the process of igneous rock formation in Primorye 79
L.F. Syritso, M.D. Ryazantseva, E.V. Volkova, V.N.Toporsky. New data on geochemical peculiarities of intrusive formations of the Voznesenka ore district (Primorye) and some problems of their petrogenesis 89

Stratigraphy
A.G. Klets, S.G. Kislyakov, V.B. Grigoriev. Regional Permian stratigraphic units of southeastern Verkhoyanie and Northern Priokhotie 98

Tectonophysics and Volcanism
V.G. Bykov. Waves of activation in crustal faults 104
Zhang Hong, Zhao Chunjing, Yao Yizheng, Quan Heng. The dynamic background of Mesozoic volcanic activity in northern part of Daxing'anling Mts. (China) 109

Discussions
V.A. Buryak. On the genesis of black shale formations and related gold, gold and platinoid and other mineralization 118

Notes for Contributors 130

A.A.Marakushev, Sang Longkang, A.V.Bobrov, N.A.Paneyakh, N.N.Pertsev, I.A.Zotov
Asian eclogite diamondiferous belt

Results of the joint Russian–Chinese study of eclogites of the southern and western Proterozoic folded framing of the Asian continent are summarized. Detailed correlation of the Dabie Shan Complex (Central China), the Kokchetav Massif in Kazakhstan (the Zerenda Series), and the Maxyutov Complex (the Southern Urals) together with literary data on other complexes permitted a conclusion about the existence of a global folded structure in the Proterozoic, called the Asian fold belt. In the Phanerizoic, this structure became disintegrated into blocks, and its Proterozoic age was essentially masked by imposed processes. Petrological studies provide an evidence for the initially magmatic nature of eclogites of the whole foldbelt, in spite of the imposed folded deformations and allochemical metamorphism. A polyfacial nature of eclogites, crystallization of which began deep in mantle and terminated in the crust, is determined from mineralogical features. Zonation of eclogite garnet with the increase of Mg- content to the edge of its grains is the most typical feature. Processes of alkalization of magmatic chambers, which feeded eclogite magmatism, gave grounds to establish close structural and genetic relations between the eclogite magmatism and alkali (blueschist) metamorphism. As a result, eclogite–blueschist complexes, which have a complex character, were formed. Correlation of these formations with mantle magmatic chambers determines their diamond potential; mantle nature of the latter is masked by superposed metamorphic processes. Metamorphic recrystallization of diamond results in desintegration of its grains, degassing, and loss of helium, especially its light isotope. Eclogite and garnet pyroxenites of the fold belts have a similar nature with the analogous rocks of kimberlite pipes. However, the latters differ by the lesser development of superposed metamorphism restricted to fluid influence of kimberlite and lamproite magmatism on them. In contrast to sodic eclogite–blueschist formations, this influence has a potassic geochemical profile. Similarly to metamorphic complexes, the influence of the kimberlite magmatism on diamond in pipes leads to desintegration and recrystallization of its grains, degassing, and loss of helium, especially its light isotope. Complex correlations of mantle and crustal processes during the formation of the eclogite–blueschist suites are discussed.

A.A. Sidorov, I.N. Tomson
Conditions of origin for black shale complexes and their metallogenic implication

The paper develops the concept of endo- diogenic ore content nature of dlack shales which were considered as the most important protometallogenic reerve for future metal concentrations when ore deposits were forming. Regional sulfidization zones in the black shales produce future complex deposits. At preent, the fragments of these zones represent unique noble metal deposits.

S.S. Zimin, V.G. Moiseenko, R.A. Oktyabrsky, S.G. Baturin, B.M. Tishkin, V.P. Molchanov
On the first finding of metamorphosed bauxites in Middle Priamurie with the reference to their potential

Mineral and chemical composition of metamorphosed bauxites, a fragment of which was found in the Bolshaya Kalakhta river valley north of the Oktyabrsky mine, is described. These units are composed of corundum and spinel with the admixture of diaspore, magnetite, ilmenite, prochlorite, baddeleyite, and goethite. The chemical composition of these minerals is given. The perspectives for searching bauxites in the Amur Region are discussed.

L.B.Sushkin
Geology of the Sologu-Chaydakh gold ore field (the Amur Region)

The Sologu-Chaydakh gold ore field is located in the Mesozoic structure of tectono-magmatic activation in the Lower Archean gneiss strata, crystalline shales and basite-metaultrabasites with marble and calciphyre lenses. The Colchedanniy Utyos gold ore deposit of this field consists of gold-quartz-sulphide ores of commercial grade. The ores are assumed tto be connected with propylite-beresite- type metasomatic rocks and skarnoides. Potential resources of the deposit and gold ore field are considerable. In addition, some shows of platinoid mineralization have been revealed in the ore field and region on the whole.

A.Yu. Antonov
Geochemistry of REE in Late Mezozoic volcanic complexes of the Stanovoy Range

REE spectrum in most of varieties (38 samples) of Late Mesozoic Stanovoy Range volcanites of basalt-rhyolite series was studied for the first time. This investigation revealed:
- The Stanovoy Range Mesozoic volcanites of the rhyodacite-rhyolite series could not be the result of fractional differentiation of any mafic magmas. In most cases mafic and salic magmas were formed separately. A large portion of andesite volcanites there are evidently the products of mixing of salic and basaltic magmas.
- Similar to the SiO2-saturating volcanic and plutonic formations of the corresponding parts of the Stanovoy Range have in general the same REE composition that suggests their genetic relationship. In addition, REE-compositions of the magmatic formations are often different indicating that they were formed in different conditions even in the limits of one large part of the region.
- By high REE-concentrations, the Late Mesozoic volcanic (and plutonic) rocks of the Stanovoy Range in the most degree correspond to magmatic formations of rift intracontinental zones,similar in age, alkalinity and SiO2-saturation. To the lesser degree they correspond to the magmatic formations of active continental margins, and to the least degree - to the corresponding island arc volcanic rocks.

F.I. Rostovsky
Some aspects of tungsten geochemistry in the process of igneous rock formation in Primorye

Behaviour of tungsten in magmatic process depends on its variable valency and the pattern of redox-potential change in crystallized systems. When tholeiitic melts are crystallized, crystallochemical dispersion of tungsten predominates, because W 4+ ions come into the lattice of rock-forming ferromagnesian silicates, plagioclase, and titaniferous minerals. Considerable growth of redox-potential in the process of magmatic differentiaton of calc-alkaline rock series increases the valence of tungsten ions in melts. Transition of W 4+ into W 6+ is a dynamic geochemical barrier controlling the change of crystallochemical dispersion of tungsten for its emanation concentration in fluidal (fluid-hydrothermal) phase of melts together with alkalis. Scales of the tungsten emanation concentration in granitoids depend on geodynamic situation in certain massifs during crystallization. The criterion of the potential tungsten content in granitoids may be the ratio of tungsten content in the rock to that in the total rock-forming quartz, the crystalline lattice of which excludes tungsten isomorphic coming into it. At relatively low values of this ratio (4), granitoids of Sikhote-Alin are in potential promissing for molybdenite-scheelite mineralization. With this ratio increasing, granitoids become in potential promissing for apatite-scheelite-pyrite mineralization, and then for wolframite-cassiterite mineralization with pronounced tendency of tin presence in magmatogene-ore systems.

L.F. Syritso, M.D. Ryazantseva, E.V. Volkova, V.N.Toporsky
New data on geochemical peculiarities of intrusive formations of the Voznesenka ore district (Primorye) and some problems of their petrogenesis

Analysis of distribution of rare and trace elements and their isotopic ratio (for strontium, neodymium, and oxygen) in the intrusive formations of the Voznesenka ore district (VOD) allowed to distinguish a vertical petrogenetic series. Before, we have used the rare-metal provinces of Zabaykalye as the example to work out a petrogenesis model of such series. The model represents an integrated effect of processes of mantle and crustal matter mixing. In the VOD this petrogenetic series is presented by the following means. Formation of rare-metal Voznesenka granite complex was preceded by a development of a section of gabbro-monzonite-syenite complex being distinguished from the general body of rocks of this series by high alkalinity and high concentrations of infusible elements, such as Ti, Zr, Nb, Y, F, P, and Rb and Sr. The Voznesenka granite complex is composed of a number of differentiates from a single magmatic chamber. Two magma intrusions have been identified by geochemical data in the granite complex composition: (1) biotite and biotite leucocratic granites, (2) protolithioniite leucogranites with an associated series of inter-chamber differentiates and «apogranites». These notions are based on the regularities of distribution of petrogenic, rare and trace elements corresponding to the standard differentiates of leucogranite formation of rare-metal provinces. The Voznesenka granite complex is well correlated to a rare-metal leucogranite formation of the Kukulbey complex of Zabaykalye. The position of the intrusive complexes of the VOD on the Y.Pearce diagram bears witnesses to a geodynamic evolution of the region, as well as to a presence here of two different geodynamic settings - an early within-plate one for the Voznesenka granitoids and the active continental margin setting for the gabbro-monzonite-syenite complex.

A.G. Klets, S.G. Kislyakov, V.B. Grigoriev
Regional Permian stratigraphic units of southeastern Verkhoyanie and Northern Priokhotie

A successive change of the faunal assemblages was established in the Permian sections of the Verkhoyano-Kolyma fold area and in the Okhotsk massif. Lower Permian beds containing fauna were distinguished. Type sections of the structural-formational zones were correlated to each other and the sections of the adjacent regions. Biostratigraphic characteristics of the regional and provincial stratigraphic units is presented.

V.G. Bykov
Waves of activation in crustal faults

It has been shown that the local deformation effects may cause the solitary waves of activation in crustal faults. The analysis has been made to study the influence of geometry inhomogeneities and friction in the crust on evolution of velocity of waves of activation. The possibility is illustrated as for using the “perturbed” sine-Gordon equation for modeling seismic process starting from fault activation with further generation of waves of deformation due to seismic slip, which are considered to be the trigger of earthquakes.

Zhang Hong, Zhao Chunjing, Yao Yizheng, Quan Heng
The Dynamic Background of Mesozoic Volcanic Activity in Northern Part of Daxing’anling Mts. (China)

The Mesozoic volcanic activity in northern Daxing’anling Mts. was very violent, in which a lot of geologists are interested. The volcanic rocks were formed mainly in the Late Jurassic to Early Cretaceous (150 ~ 100Ma) in the compressional background apparently according to the analyses in petrochemistry, trace elements and tectonics. The study of the regional tectonics and magmatic activity, palaeomagnetism as well as stable isotope shows that the Mesozoic volcanic rocks derived from the mantle source were formed in the compressional background with a “reduced pressure” and “shearing” process. That is why there are so many materials of the crust- source added in the Mesozoic volcanic rocks.

V.A. Buryak
On the genesis of black shale formations and related gold, gold and platinoid and other mineralization

As a discussion to the paper “conditions of origin for black shale complexes and their metallogenic implications ” by A.A.Sidorov and I.N.Tomson, the conditions of the origin of the black shale formations and genesis of gold and associated mineralization in them are examined. It is concluded that carbonaceous rocks have quite a definite chemical composition resulting from their accumulation in the redox conditions with the supply of consedimentation fluids and solutions containing Au, S, As and other elements. Successive processes of diagenesis, epigenesis metamorphism and often intrusive magmartism lead to essential re-distribution of these syngenetic concentrations forming gold-quartz reefs. Gold, uranium and especially tin mineralization are not closely connected with each other.