Volume 21, 2, 2002
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Volume 21, 2, 2002 |
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L.I. Krasny. Geological and structural features of the Okhotsk Sea region 3
A.N. Bulgatov, V.S. Klimuk. Facial formation conditions and basalts composition of the Riphean Kulinda and Onon suites of the interfluve of the Onon and Aga Rivers (Eastern Transbaikalia) 9
Lee, Byung-Su. Revision on Conodont Zones of the Hwajeol Formation(Upper Cambrian-Lower Ordovician), Kangweon-do, South Korea 18
V.I. Beryozkin. The Subgan complex (the Aldan Shield) in the petrotypical locality: geochemistry, geochronology, and geodynamic nature 31
V.M. Shevchenko. Geologic structure of the Zakoronny nose of the Precambrian Omolon massif. 40
Y.D. Zakharov, O.P. Smyshlyaeva, A.M. Popov, V.V. Golozubov, A.V. Ignatiev, T.A. Velivetskaya, K. Tanabe, Y. Shigeta, H. Maeda, T.B. Afanasyeva, A.K. Cherbadji, Yu.L. Bolotsky, and K. Moriya. Oxygen and carbon isotope composition of the Cretaceous organogenic carbonates, the Koryak Upland. Paper 1 The Penzhin Bay 55
S.T. Tassos. The role of micro-fractures in the excess mass stress tectonics model 74
Yu.P. Yushmanov. Structure and zonality of Au-Cu mineralization, the Lazurny deposit, Central Sikhote-Alin 85
L.F. Simanenko, V.G. Khomich, A.A. Lotina. Composition and morphological specific features of placer gold, the Sinegorsk ore region, with special reference to the problem of native source 91
G.S. Mirzekhanov. Evaluation of precious metal loss when developing precious metal placers 99
Reviews
P.V. Ivashov. Ecological geochemistry - a new geologic science? 110
L.I. Krasny
Geological and structural features of the Okhotsk Sea region
The history of the geological and geophysical investigation of the Okhotsk Sea region and principal features of its geochemical composition are discussed. A specific location of the region and its autonomous evolution are given a special attention. The scheme of the geological and structural zonation of the Okhotsk Sea is correlated with the locations of dredging sites and known outcrops of different types of rocks.
A.N. Bulgatov, V.S. Klimuk
Facial formation conditions and basalts composition of the Riphean Kulinda and Onon suites of the interfluve of the Onon and Aga Rivers (Eastern Transbaikalia)
Structure and composition of the Riphean Kulinda and Onon suites of the interfluve of the Onon and Aga Rivers (the left tributary of the Onon River) are characterized. The chemical composition of the basalts was made for the first time, and facial conditions of their formation were reconstructed. It was concluded that sedimentary rocks of the Kulinda and Onon suites were formed in a hemipelagic basin, evidently of the marginal sea basin. Subsidence of the basin and spreading of its bottom were accompanied by the outflow of low-siliceous, high-titanic and high-phosphatic enriched basalts. Facial and geodynamic conditions of sedimentation and basalt composition show that they are similar to the Tsusima basin, the Sea of Japan, and the Daito basin, the Philippine Sea, as well as to the Sebuchar suite (D3-P1) of the Daubikhin-Ariaden marginal basin of the Sikhote-Alin. The non-depleted mantle was the initial substratum of the basalt melts.
Lee, Byung-Su
Revision of Conodont Zones of the Hwajeol Formation (Upper Cambrian - Lower Ordovician), Kangweon-do, South Korea
Through recent intensive conodont biostratigraphic study, five conodont zones were proposed in the Hwajeol Formation (Upper Cambrian-Lower Ordovician), easten Yeongweol and Samcheog areas, Kangweon-do, Korea, namely Proconodontus Zone, Eoconodontus notchpeakensis Zone, Cambrooistodus minutus Zone, Cordylodus proavus Zone and Fryxellodontus inornatus-Monocostodus sivierensis-Semiacontiodus lavadamensis Zone in ascending order. The zones are redefined, and partly emended herein. The possibility of subdivision of Proconodontus Zone is discussed. Korean conodont zones are correlatable with those of northern China, Iran, Australia, Europe and North America, respectively. The potential Cambrian-Ordovician boundary in this area appears to be the base of Fryxellodontus inornatus-Monocostodus sivierensis- Semiacontiodus lavadamensis Zone which lie within the uppermost part of the formation. Six species are newly described : Hirsutodontus hwajeolensis, Hirsutodontus n. sp. A, Hirsutodontus n. sp. B, Proscandodus dissimilaris n. sp., Rotundoconus bulbousus and Fryxellodontus fengshanensis.
V.I. Beryozkin
The Subgan complex (the Aldan Shield) in the petrotypical locality: geochemistry, geochronology, and geodynamic nature
Distinctive discriminations in geochemistry of the metamorphosed basic volcanites and sedimentary rocks from the Subgan greenstone belt (GSB) in comparison with the same rocks of other greenstone belts of the Aldan Shield and other cratons have been established. Basic volcanites are enriched in aluminium but differ in low LREE content and positive or negative europium anomalies. Pelitic schists are characterized by their maturity, predominance of the granitic source area, and the absence of the geochemical relations with volcanites. On the basis of geochemistry and geochronology of these rocks and surrounding granites, geodynamic evolution of the Subgan GSB is discussed. Sedimentation and volcanism have taken place on the mature continental crust, and granitic magmatism and culminating metamorphism have occurred in the collision setting.
V.M. Shevchenko
Geologic structure of the Zakoronny nose of the Precambrian Omolon massif.
Two metaformations of the Zakoronny metamorphic series of the Precambrian Zakoronny nose, southeastern Omolon massif, are described: a schist-enderbite meta-assemblage of high-temperature and high-bar garnulites, and gneiss-calciphyre meta-assemblage of supracrustal granulites. By using U-Pb method, the granulite metamorphism was dated as 1901-2058 Ma, and intense garnite formation as 1952 Ma.
Y.D. Zakharov, O.P. Smyshlyaeva, A.M. Popov, V.V. Golozubov, A.V. Ignatiev, T.A. Velivetskaya, K. Tanabe, Y. Shigeta, H. Maeda, T.B. Afanasyeva, A.K. Cherbadji, Yu.L. Bolotsky, and K. Moriya
Oxygen and carbon isotope composition of the Cretaceous organogenic carbonates, the Koryak Upland. Paper 1. The Penzhin Bay
Available data on the Cretaceous isotope paleotemperatures for high paleolatitudes of the Northern Hemisphere are scare. The information published refers only to the Valanginian of Spitsbergen (7,7°C), Turonian of the Pakhacha River basin, eastern Koryak Upland (14,1-16,3°C), and Coniacian-Santonian of Greenland (about 17,3°C). Stable oxygen isotope data on well preserved Lower and Upper Cretaceous brachiopod, bivalve, including inoceramid, scaphopod and ammonite shells from the Penzhin Bay area and Talovka River basin, western Koryak Upland (95 samples) and also Southern Alaska (3 lower Albian ammonoid shells), are compared with some Callovian invertebrate shells from the Russian Platform and Late Cretaceous molluscs from Alaska and Hokkaido. Warming maxima have been recognized in the early Barremian (24,5°C), early Aptian-early Albian (18,4-25,9°C), late Cenomanian (20,8-23,3°C), and late Campanian (22,4°C). The early Maastrichtian shallow-water cooling (10,2-16,9°C) was also established there. The greatest biological productivity of high latitude seas falls on the early Aptian (d13C =3,6-6,8‰) and Turonian (d13C =3,2-4,3‰). It was suggested that extremely low d18O values found in aragonite elements of the Turonian Inoceramus, western Koryakia, and well preserved lower Turonian bivalves of the planktonic foraminifers from high latitudes of Atlantics seem to be connected with freshenning of the surface waters, which might be a result of the final stage of the Turonian humid climate in circum-Pacific areas. The data newly obtained agree well with the isotope data for the Southern Hemisphere, and the paleobotanical evidences from the Koryak Upland and adjacent territories. High temperatures of the surface waters in high latitudes of both hemispheres and atmosphere warming in circum-Pacific areas during the Cretaceous are most likely explained by active poleward heat transport and particularly due to the existence of a series of meridional seas and straits at that time.
S.T. Tassos
The Role of Micro-Fractures in the Excess Mass Stress Tectonics Model*
In an anisotropic medium micro-fractures caused by Excess Mass (EM) solid 'wedges', increase in size and concentrate in time and space when the EM 'wedges' meet structural discontinuities-'obstacles', and serve as 'resonant cavities' wherein 'old' free electrons from the metallic bond of Fe2,3+ and 'new' electrons from Fe2- accumulate, resonate through ERSEME (Electron Resonance Stimulated by Excess Mass Electrons) and produce the high stress and strain rates, of the order of 1015 Pa?s-1 and 10-5 s-1 respectively, compatible with adiabatic change and earthquake generation. Secular weak stress rates of the order of 10-2 Pa?s-1 can only cause aseismic creep, i.e., 10-14 s-1. A model is proposed in which a plastic material responds elastically for a band of frequencies between 105 and 1015 Hz. The type of fault, normal, reverse, or oblique is determined by the direction of the maximum compressive stress, which depends on the orientation of micro-fractures. In an isotropic medium, due to the lack of structural discontinuities, the accumulation of 'old' and 'new' electrons is not facilitated and resonance does not frequently occurr. Low seismic activity, oceanization-basification of the granitic continental crust, low velocity zones, volcanic activity, ophiolites, and finally juvenile oceanic crust basalts are the products of the symmetrical spatial and temporal distribution of micro-fractures.
Yu.P. Yushmanov
Structure and zonality of Au-Cu mineralization, the Lazurny deposit, Central Sikhote-Alin
The paper presents data on geology of the Lazurny deposit which correspond to a prospecting and forecasting model of the gold-copper-porphyre system. Ore and metasomatic zonality and structural control of ore stockwork are described. An area prospective for commercial gold and copper mineralization has been identified.
L.F. Simanenko, V.G. Khomich, A.A. Lotina
Composition and morphological specific features of placer gold, the Sinegorsk ore region, with special reference to the problem of native source
The paper deals with the results of study of native gold from heavy concentrations collected in the Uralsky Creek basin (the right tributary of the Baranovsky River), the Sinegorsk ore district. The chemical and morphological features of placer gold and evaluation of probable types of gold primary sources enable us to propose gold occurrences in the Sandugan granitic massif and among the effusive deposits of the Suputin suite.
G.S. Mirzekhanov
Evaluation of precious metal loss when developing precious metal placers
Some factors have been recognized, and it was attempted to show their quantitative effect on precious metal losses when developing gold placers. On this basis, the computer program has been set up. It enables to estimate automatically total losses determined by joint effect of various factors, to evaluate the resource potential of technogenic products at different stages of the object development, and to predict average precious metal content in piles.