Contents
Volume 17, ¹ 5, 1998
ContentsVolume 17, ¹ 5, 1998 |
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Geodynamics and Geophysics
A.V. Prokopiev. The Verkhoyansk-Chersky collisional orogenic belt 3
M.D.Ryazantseva, V.V.Golosubov, V.V.Ratkin, A.N.Sokarev. Geodynamical typification of Primorye granitoids 11
V.E.Kononov, K.F.Sergeev, V.V.Argentov, S.K.Bikkenina, V.V.Zhigulev, E.G.Zhiltsov. Possibilities of refraction method for oil-gas search investigations in the Northeastern shelf of the Sakhalin Island 27
S.V.Solovjov. Heat transfer by convection in subduction zone 39
Stratigraphy
V.S.Pushkar, N.G.Razjigaeva, A.M.Korotky, T.A.Grebennikova, V.V.Shapovalov, L.A.Ganzey, L.M.Mokhova. Pliocene-Pleistocene deposits and events in the Izmena bay coast (South Kunashir, the Kuril Islands) 50
Magmatism and Ore Genesis
V.F. Belyi. Chukotsk alkaline-ultrabasic volcanoes of the Bering volcanic province 65
A.K.Rub, M.G.Rub, N.I.Chistyakova, N.N.Krivoshchekov. Mineralogical and geochemical peculiarities of tin-tungsten ores of the Tigrinoye deposit, central Sikhote-Alin (Primorye) 78
V.A.Stepanov, Yu.P. Shergina, G.S.Shcorbatova, L.N. Shishakova, A.G.Rublev. Age of the Kabaka gold deposit (Omolon massif) 89
V.A.Guriyanov, M.V.Goroshko, L.P.Karsakov, A.L.Osipov. Gold mineralization of the Precambrian complexes of the Uchur-Uyansky region, and its prospects (southeastern part of the Siberian Platform) 98
L.F. Mishin, Yu.P.Pototsky, V.G. Nevstruyev. Zonation of hydrothermally altered rocks and gold-silver mineralization of Krasivy dome (Ul’insky depression) 106
Cronicles
N.A.Shilo, I.N. Kigay, E.N. Kamshilina . On a joint meeting of the Scientific council and Russian group of MAGRM on ore mineralization and mettalogeny 117
G.L.Kirillova. Geology, mineral and energy resources of Southeastern Asia 119
Obitnaries
Borukaev Ch.B. (1936-1998) 121
A.V. Prokopiev
The Verkhoyansk-Chersky collisional orogenic belt
The Verkhoyansk-Chersky orogenic belt embraces the western part of the Verkhoyansk-Kolyma Mesozoides from the Priverkhoyansk foreland basin in the west to the Zyryanka basin in the east. It was formed as a result of the collision of the North Asian craton and the Kolyma-Omolon superterrane in the late Late Jurassic-Neocomian and the closing of their separating Oymyakon lesser ocean basin. The belt reveals almost all major elements of the idealized orogen. The outer zone includes the Priverkhoyansk foreland basin and the Verkhoyansk fold-and-thrust belt. The inner zone, or the core of the orogen (the Chersky-Selennyakh belt) extends along the western periphery of the Kolyma-Omolon superterrane and is made of terrigeneous-carbonate deposits of Ordovician-Upper Devonian age. They were formed on the margin of the North Asian craton in Early-Middle Paleozoic time, then were detached from it in the course of Late Paleozoic rifting and displaced over a distance of 1500-2000 km from the craton in the Carboniferous, Permian and Triassic. This led to the formation of the Oymyakon lesser ocean basin. Separate ophiolite fragments of presumed Early Paleozoic age which make up tectonic nappes were obducted during the amalgamation of the terranes and formation of the Kolyma-Omolon superterrane in the late Middle Jurassic. The orogen core includes the Kular-Nera slate belt, too. The orogen core is an allochthon overlying the outer zone deposits over a distance of 150 km. It includes the Upper Jurrasic calc-alkaline volcanics of the Uyandina-Yasachnaya magmatic arc formed over the zone of subduction of the oceanic crust of the Oymyakon basin beneath the Kolyma-Omolon superterrane on its convergence to the North Asian craton. The Polousny and Inyali-Debin synclinoria with complexly deformed flysch series of Middle-Late Jurassic age are referred to as formations of the fore-arc basins of the Uyandina-Yasachnaya arc. The rear zone of the collisional belt includes the Ilin-Tass fold-and-thrust belt, which appeared in the site of the back-arc basin under the same name, and the Zyryanka basin. The accretionary wedge complex includes deposits of the Kular-Nera slate belt, turbidites of fore-arc basins and deep-water cherty-clayey rocks on the slope and rise of the superterrane. The suture zone separating the accretionary wedge deposits from those of the fore-arc basins is represented by the Yana-Indigirka fault. The fold structures of the collisional belt resulted from the two-staged deformations in Late Jurassic - Cretaceous time.
M.D.Ryazantseva, V.V.Golosubov, V.V.Ratkin, A.N.Sokarev
Geodynamical typification of Primorye granitoids
New tectonic map of Primorye based on the terrane concept and paleogeodynamical analysis allowed to classify granitoids according to geodynamical conditions of their formation. The following types of granitoids were distinguished: 1) collision-related ones, 2) subduction-related ones, 3) intra-plate «mixed» series ones. Each geodynamical type of granitoids (independently of age) is characterized by typical mineralogical, petrological, geochemical, petrophysical features, and is accompanied by quite certain ore mineralization.
V.E.Kononov, K.F.Sergeev, V.V.Argentov, S.K.Bikkenina, V.V.Zhigulev, E.G.Zhiltsov
Possibilities of refraction method for oil-gas search investigations in the Northeastern shelf of the Sakhalin Island
Results of the investigations by refraction method in the north-eastern shelf of the Sakhalin Island were set forth. As a result of the analysis of P-waves, two-dimensional velocity models were constructed from two profiles. The geological-geophysical cross-section was constructed from the refraction profiles. The thickness of the sedimentary deposits within the region under consideration is 7-10 km. the velocity models permitted to determine structure and thickness of different katagenetic zones. The refraction method good informativity appears to be useful for solving oil geological problems.
S.V.Solovjov
Heat transfer by convection in subduction zone
The results of numerical simulation in the Earth's mantle are given. The paper considers the subduction zone in which a moving lithosphere plate runs into moving on continental plate, then along the trough, axis of which is located under the angle to the day surface, ocean plate submerges in the mantle. Four schemes of lithosphere immersion: initial, small, middle and full (concerning immersion depth ) are investigated.In result of thenumerical solution of the task, which is solved in natural variables by control volume method , the distributions of temperature, stream function, pressure, vector velocity field, friction stress and Nusselt numbers were obtained.
V.S.Pushkar, N.G.Razjigaeva, A.M.Korotky, T.A.Grebennikova, V.V.Shapovalov, L.A.Ganzey, L.M.Mokhova
Pliocene-Pleistocene deposits and events the Izmena bay coast (South Kunashiri, Kurile Islands)
The paper deals with lithological features of the Plio-Pleistocene sedimentary and volcancclastic shelf deposits embracing the Golovnin Formation, and Late Pleistocene terrestrial facies. The diatom, pollen and spores and paleomagnetic analysis were made. It is suggested to divide the Golovnin Formation into three subformations reflecting different transgressive-regressive cycles and volcanic activity (Lower Unit - the Late Pliocene, Middle one - the Early Pleistocene, and the Upper unit - the Middle Pleistocene). The terrestrial deposits are referred to as Belozersky Layers of Late Pleistocene second interstadial age. Two Late Pliocene transgressions were established: Kunashir I (2.12-2.0 Ma) and Kunashiri II (0.43-0.28 Ma). The Late Golovnin Transgression (0.43-0.28 Ma) with two phases is correlated to the Middle Pleistocene. The tephrochronologic markers were recognized for diatom zones and Reunion and Olduvai paleomagnetic events. Correlation of the paleogeographical events was made between South Kuril, Japan, Kamchatka, Chukotka and Alaska.
V.F. Belyi
Chukotsk alkaline-ultrabasic volcanoes of the Bering volcanic province
The Nunyamuveem and Enmelen areals of Late Cenozoic alkaline-urabasic volcanism in the south of theChukotsk Peninsula are characterized. In the first areal olivine melanephelites are spread, and in the second - leicite-olivine melanephelites are distributed (relatively «natrium» and «potassium» volcanic associations). In both areals, tephrites (3% of the volcanite volume) are present. Lavas of olivine melanephelites and tephrites are homogeneous, predominantly massive, and they fill river valleys. In contrast ,volcanoes of leicite-olivine melanephelites occurred in the mountain throughs and their slopes; their eruptions were o explosive-effusive in nature. Structural and textural lava types are various; there are slaggy lavas; and pyroclastic deposits are also found. Various deep inclusions are associated only with these volcanoes. «Natrium»association developed under the influence of chloride-fluoride fluid, and «potassium» association was influenced by fluoride fluid. The high activity of fluoride fluid has determined a major peculiarity of chemical evolution of «potassium» series : double increase of K2O contents with the sharp decrease in SiO2 and MgO contents. The combination of crystallized differentiation and liquation that developed in the intermediate and peripheral magmatic chambers is observed in the evolution of lava chemical features. Lavas and deep inclusions of the Enmelen areal are considered to be the unified complementary series.
A.K.Rub, M.G.Rub, N.I.Chistyakova, N.N.Krivoshchekov
Mineralogical and geochemical peculiarities of tin-tungsten ores of the Tigrinoye deposit, central Sikhote-Alin (Primorye)
The tin-tungsten ores of the Tigrinoye deposit are classified as those of the cassiterite-quartz formation. But they differ much from similar deposits of other regions by the extensive development of stannite, oxidation zone and a small amount of sulfides in the course of the extensive development of topaz and lithium-iron micas. Sc-W-Nb minerals were first found in these ores. Scandian ixiolite and scandian-tungsten ixiolite occur in the form of wolframite and cassiterite inclusions. Tin mineralization of the greisen association in the Tigrinoye deposit is genetically related with rare-metal granites. Extensive veinlet ore zones in metasedimentary rocks and granites are related paragenetically with them.
V.A.Stepanov, Yu.P. Shergina, G.S.Shcorbatova, L.N. Shishakova, A.G.Rublev
Age of the Kabaka gold deposit (Omolon massif)
Results of isotopic-geochronological studies of ore minerals and near-ore metasomatites of the Kubaka gold-silver deposit by Rb-Sr isochronous method are given. To interpretate the results, geological materials on structure of the Kubaka deposit, Omolon province and contiguous territories are taken. Conclusion on the Early Carboniferous (335-330 Ma) formation of ores of the deposit, their partial regeneration and redeposition in the Mesozoic (160-128 Ma) has been made.
V.A.Guriyanov, M.V.Goroshko, L.P.Karsakov, A.L.Osipov
Gold mineralization of the Precambrian complexes of the Uchur-Uyansky region and its prospects (southeastern part of the Siberian Platform)
Gold mineralization of Precambrian complexes of the Uchur-Uyansky region, southeastern part of the Siberian Platform, is characterized, and gold potential is considered. Gold mineralization in the region, whose prospects until recently were related to the Mesozoic stage of development, was identified in the crystalline rocks of the Aldan-Stanovoi shield, in the Lower Proterozoic sedimentary-volcanogenic complex of the Ulkansky trough, in the Lower Proterozoic deposits of the platform mantle. The ore-bearing Uyanskaya zone was distinguished in the crystalline rocks of the Tyrkansky uplift. Quartz gravel with gold from this zone is present in Riphean conglomerates. Gold mineralization in the conglomerates is confined to basal strata of the Birindinskaya, Konkulinskaya, and partly, of the Gonamskaya suite of the Lower Riphean. They are characterized by large parameters with gold content up to 1.7 g/ton; more rare, up to 5.6 g/ton. These ancient placers are of complex nature, and like elsewhere in the world, they include uranium shows. The Lower Riphean assemblages also reveal gold mineralized zones confined to thrusts, probably, of Riphean age. On the whole, the Uchur-Uyansky region is very similar to the areas of gold deposits in Tarkva and Witwatersrand conglomerates.
L.F. Mishin, Yu.P.Pototsky, V.G. Nevstruyev
Zonation of hydrothermally altered rocks and gold-silver mineralization in the Krasivy dome (Ul’insky depression)
Presented are the results of detailed structural mapping and bulk studying of hydrothermalites and gold-silver mineralization of the Krasivy creek ore showing which can be regarded as a standard stockwork Au-Ag deposit of quartz-adularia type. The deposit is confined to tectono-subintrusive dome. The dome structure with its axial symmetry determines the shape and sizes of trachydacitic subintrusions and distribution and occurrence of facies of metasomatites and Au-Ag mineralization. Zonation of hydrothermally altered rocks has been shown. Above-ore facies of hydrothermalites significant for exploration and assessment of weakly eroded deposits have been studied in detail.