A.M. Petrishchevskiy
Gravitational autocorrelation indicators of deep-seated geological structures

The features of description of typical deep structural elements of the crust (discontinuities of structure-and-substance complexes, blocks and plates, faults and nappes) in the spatial-statistic distributions of gravity sources studied by an uninterrupted sliding autocorrelation procedure in a wide spatial range are examined. The results of statistic interpretation of gravity anomalies in areas with wide development of collision structures (East Sikhote-Alin, southeastern framing of the North Asian craton) are discussed. The opportunities of gravity autocorrelation sounding of the Pacific lithosphere, marginal seas and the Australian continent are shown. The features of statistical indication of vertical and horizontal deep tectonic discontinuities are investigated on simulation models.

 G.V. Kotlyar, O.L. Kossovaya, A.V. Zhuravlev
Interregional correlation of the main event boundaries in the Permian system

The paper considers the main event boundaries in the development of biota: Middle Artinskian, Middle Kungurian, Kazanian, Middle Tatarian and Midian/Dzhulfinian regarded as the first phase of global extinction at the Permian-Triassic boundary. The revealed boundaries are traced in the most complete sections of different paleoclimatic areas. Based on data of the sections of the Urals, Northeast Russia and the Russian Far East, an analysis was made of the dynamics of taxonomic diversity, and the levels of dying out and renewal of brachiopods, Rugosa, bivalves, ammonoides, conodonts and foraminifera. The Middle Kungurian, Kazanian, and Middle Tatarian events have been established for the first time in Northeast Russia and in the Pacific region. The appearance of ecotone faunas in South Primorye in Middle Tatarian (Wodian/Capitanian or Middle Midian) time is regarded as a result of extensive transgression and warming. Changes in the direction of interprovincial migrations of species in some faunal groups have been established. Focal reconstructions of biota were due to abrupt transgressions or regressions and climatic changes ascertained from Ca/Mg thermometry evidence and oxygen isotope ratios.

A.N. Filippov, I.V. Kemkin
Kultukhinskaya “suite” as a tectono-stratigraphic complex of the Jurassic-Berriassian accretionary prism of the Western Sikhote-Alin

The results of lithological-stratigraphic study of volcanogenic-sedimentary formations of a Jurassic–Berriassian accretionary prism on the right bank of the Ulitka River middle reaches, right tributary of the Bikin River (western Sikhote-Alin), which earlier were referred to the Kultukhinskaya suite, are given. It is recognized that the Kultukhinskaya “suite” is a package of tectonic slabs composed of different-age and different-origin deposits. Among them are Triassic-Jurassic cherts and Late Triassic limestones, Late Jurassic siliceous mudstones, Berriassian mudstones, siltstones and sandstones associated with different-thickness bodies of basic volcanic rocks. This structural unit is proposed to be called as the Kultukhinskaya tectono-stratigraphic complex. It reflects the Berriassian stage of formation of the accretionary prism.

Yu.D. Zakharov, Ye.A. Sokolova, O.P. Smyshlyaeva, Y. Shigeta, K. Tanabe, H. Maeda, T.G. Velivetskaya, A.M. Popov, A.V. Ignatyev, T.B. Afanasyeva
New oxygen and carbon isotopic record, and the problem of low isotopic paleotemperatures in tropics during Maastrichtian

In the Late Cretaceous, high and middle latitude temperatures declined most sharply in the Maastrichtian; at the same time we have contradictory information on climatic conditions at low latitudes during the Maastrichtian. On the basis of new data on Maastrichtian mollusks from the Western Interior Seaway of North America and latest publications it has been proposed that tropical sea surface temperatures of the Pacific calculated from the oxygen isotopic composition of the majority of investigated Maastrichtian planktonic foraminifera are, obviously, underestimated. Unusually low isotopic temperatures obtained from tropical planktonic foraminifera, probably, reflect both local conditions provoked, first of all, by the influence of tropical upwelling zones, and the ability of Maastrichtian planktonic foraminifera of migration within a large vertical interval in the tropical zone. The average tropical surface ocean paleotemperatures estimated for the Maastrichtian seem to be not less than 23.7-26.6°С, but apparently, did not reach the level established, for example, for the Late Albian (32-33°С). Negative carbon-isotopic shifts at the end of the Early Maastrichtian and at the Cretaceous-Tertiary boundary seem to be connected with the fall of temperature and eventual reduction of oxygen content in the atmosphere and hydrosphere.

 B.I. Pavlyutkin, V.S. Pushkar, M.V. Cherepanova, T.I. Petrenko
The Miocene stratigraphy problems of the Khanka depression of Primorye, Russian Far East

The paper discusses the problems of Miocene stratigraphy of the Khanka depression, exemplified by the Fagus chankaica-bearing strata found in the geologic sections of the northwestern part of Lake Khanka shoreline. The straton corresponding to the indicated strata should be rated as a higher rank unit and may be equivalent in rank to a formation. The following name is proposed for this straton: the Novokachalinsky Formation. The type section of the stratotype of the new formation, lithologic and paleofacies characteristics of the rocks composing the stratotype, and a description of biota (macro- and microflora) are presented. Sedimentation occurred in warm-temperate climatic conditions and was characterized by alternating lacustrine and alluvial environments. The new formation was formed in Middle Miocene time. The lower age limit for the Novokachalinsky Formation may be considered to be late Early Miocene. On the basis of the Novokachalinsky Formation stratotype, a horizon under the same name is proposed to be distinguished.

A.M. Ivanova, A.S. Smirnov, Ye.A. Pashkovskaya
Geological and commercial types of placers in shelf areas of the World Ocean

The main geological and commercial types of placers of the petrogenic group (gold, cassiterite, platinoids, chromite, minerals of titanium, iron, circonium and rare earths) and biomineral raw materials (amber, amber-like pitches, fossil ivory) are briefly considered.
Apart from the mineral composition, the distinguished types of placers are characterized by a particular set of placer-forming formations, the availability or absence of intermediate collectors (including crusts of weathering): the types differ in their geographic position (latitude), spatial distribution (local or regional), genesis of the producing horizons, and the scale of resources.
A considerable proportion of the placers accounts for the Pleistocene-Holocene period. The largest deposits of “black sands” with ilmenite, titanomagnetite, zircon, monozite in the regional and transregional zones and belts along the coasts of Africa, Australia, India, America, the islands of Madagascar, Shri Lanka and New Zealand as well as magnetite-ilmenite placers connected with the volcanic systems of the Pacific Ocean belong to this stage of formation.
Placers of diamonds along the Atlantic coasts of Africa are predominantly associated with Pleistocene-Holocene formations. Local placers of plationoids and chromite, the known auriferous deposits of Nomsk as well as commercial accumulations of fossil ivory at the Russian East Arctic continental margin have a young age.
Placers of tin (cassiterite) and gold with a long formation period (Eocene-Holocene) and the polygenetic producing horizons occurring in the Cenozoic cover of seaside lowlands, at the bottom of water areas and islands of the East Arctic are of high resource potential. Tin placers of the largest Malaysian-Indonesian province also formed in a close age range. Unique placers of amber in Kaliningrad region of the Russian Federation are of Eocene–Oligocene age; at the same time, the young amber-bearing formations on the coasts of many regions of the Euro-Asian province are much less producing.
The distribution of placers of definite mineral compositions, period of formation and scale are closely connected with the geostructural features of continental margins and their paleogeography in the Cenozoic, which is governed by the global processes of the formation and development of ceanic basins in the general geodynamic system “the World Ocean – continents”.