A.M. Petrishchevsky
Gravitational heterogeneity of the Earth’s crust and upper mantle of Priamurye (spatial and statistical models)

Under study are structural, metallogenic and geodynamic features of spatial distributions of "compact-type" density heterogeneities in the Earth’s crust and upper mantle of Priamurye. The investigations resulted in correlation of low-crust gravity disturbances with Moho relief and near-surface tectonic structures: the approach of deep density heterogeneities to the earth’s surface under Cenozoic-Mesozoic successor basins, Bureya Mesozoic trough; and a plunge under Paleozoic accretionary-fold complexes are observed. The spatial relationships of statistical gravity discontinuities in the middle part of the Earth’s crust and upper mantle allow an assumption of a wedge-formed plate characterized by features of intrusion beneath the fold framing of the eastern part of the Amur superterrane from the West Pacific lithosphere plate. Based on concurrence of near-surface ore deposits with the deep density anomalies of the Earth’s crust and upper mantle, features of regional vertical metallogenic zoning of the Priamurye lithosphere have been determined; the zoning is expressed by a regular increase in the vertical extent of ore-magmatic systems from mainly tin-bearing up to mainly gold-bearing systems: Sn (5–15 km )  W, Mo (30–60 km )  Au (80–100 km). The spatial relationship of low-crust density heterogeneities (depth of occurrence 30 km) and seismic foci can be used for long-term seismicity predictions in the region.

 A.N. Derkachev, N.A. Nikolaeva, S.A. Gorbarenko
The peculiarities of supply and distribution of clastogenic material in the Sea of Okhotsk during Late Quaternary

The mineralogical composition of sediments from cores taken on three latitudinal profiles in the Sea of Okhotsk has been studied. Based on the integration of the data obtained by multivariate statistic methods, the main associations of heavy minerals have been distinguished, and the peculiarities of variations in the conditions of supply and distribution of clastogenic material during the period up to 350 thousand years ago have been established. Considerable influence of the Amur River solid discharge on the processes of sedimentation has been traced. The periods of intensification of discharge and increase in the distance at which material is carried are in agreement with stages of Late Pleistocene warming. Correlation schemes of clastogenic material in sediments related to its arrival from the Amur-Sakhalin and Kurile-Kamchatka supplying provinces for four temporary sections of the Late Pleistocene-Holocene are listed. The volcanic ash interlayers being good age markers have been studied and identified.

S.V. Zyabrev, A.N. Perestoronin, A.E. Zharov
Сommencement of siliсiclastic sedimentation in the West Sakhalin forearc: an aspect of the early history of the Sakhalin-Hokkaido accretionary system

Siliciclastic sedimentation in the West Sakhalin forearc started prior to the end of early Aptian as constrained by radiolarian ages obtained for the lower portion of the forearc deposits. The west-directed subduction beneath the forearc to the east and subduction-related volcanism to the west are inferred to have begun by that time. The earlier siliciclastic sedimentation in the southern continuance of the forearc in Hokkaido corresponds to the earlier development of the volcanic arc to the west and associated accretionary complex to the east. This is explicable by earlier subduction in the accretionary system in Hokkaido. More sophisticated models for the Late Mesozoic tectonic zonation and evolution of the Circum-Japan-Sea regions are required to explain the dissimilarity in the early histories of the accretionary systems in Sakhalin and Hokkaido that later co-evolved.

P. N. Kolosov
The Trimembral Yudomian in the Yudoma-Maya basin

The Yudoma-Maya basin contains the most complete stratotype section of the Yudomian (carbonate type of the Vendian or the Proterozoic terminal system). It is subdivided into Yudomian I, Yudomian II, and Yudomian III. The deposits of these subdivisions within the Siberian platform differ from one another in their areal distribution.

 S.P. Yermakova
The problem of a global stratotype at the Induan-Olenekian boundary

Results of the study of the Early Olenekian ammonoids and the sequence of their occurrence in the revised sections in the eastern Boreal realm are offered. The description of the Lower Triassic section along Burgundzha Creek is given. The Induan-Olenekian boundary drawn at the base of the Hedenstroemia hedenstroemi zone is substantiated.

V.V. Baranov, Т.S. Alkhovik
Devonian Cyrtinoidea (Brachiopoda) of Northeast Russia

Cyrtinoid nanospiriferids have been described from the Lower to Middle Devonian deposits of Northeast Russia, including the Pygmaspiriferidae Avdeeva et Baranov family, the genera Calceolospirifer Avdeeva et Baranov with the type species C. frequens Avdeeva et Baranov, Pygmaspirifer Avdeeva et Baranov with the type species P. bicostatus Avdeeva et Baranov, and Valentinispirifer Avdeeva et Baranov with the type species V. pennatus Avdeeva et Baranov.

E.L. Shkolnik, Ye.A. Zhegallo, I.N. Ponomareva, M.Ye. Melnikov, E.A. Yeganov, T.M. Khulapova, T.Ye. Sedysheva, I.K. Basov
Results of the study of substratum of cobalt-manganese crusts based on the cores from the holes drilled on IOAN and Dalmorgeologiya Guyots, Magellan Seamounts, Pacific Ocean

The substratum of cobalt-manganese crusts penetrated by numerous deep-sea holes drilled on IOAN and Dalmorgeologia Guyots of Magellan seamounts in the Pacific Ocean has been studied. The complex of rocks has been characterized, and ferromanganese formations (including Si, Al, and frequently Ti) developed in the substratum in different forms have been studied in detail. They are considered to be the products of deposition of water fluids arising in the volcanic pedestal and unloading on the guyot’s periphery when penetrating into the top parts of rocks to a different degree phosphatized mainly by replacement, which is demonstrated by numerous relicts of the substratum and the remains of organisms in them.

A.I. Kiselev, K.N. Yegorov, R.A. Chernyshov, A.V. Chashchukhin, Yu.T.Yanygin
The nature of basic explosive breccias within the Nakyn kimberlitic field (Yakutian diamondiferous province

The Nakyn kimberlitic field is located on the northwestern shoulder of the Vilyuy paleorift within the Vilyuy-Markha Middle Paleozoic Dyke Swarm. The field is unique in terms of spatial-temporal relationships between the basites and kimberlites. Most of the basic rocks predated the kimberlites. The emplacement of kimberlite bodies was followed by local manifestations of alkaline K-rich basic rocks accompanied by explosive breccias representing products of fluid-explosion disintegration of these basic rocks and enclosing sedimentary rocks. There is no agreement among researchers as to the genesis of explosive breccias. Some of them consider breccias and kimberlites to be consanguineous. The conducted study, however, did not confirm the consanguinity of basic, basic-carbonaceous and largely carbonaceous explosive breccias and kimberlites.

S.V. Kvashuk
Engineering and geological, and petrophysical features of rocks in the hypergenesis zone of Priamurye

The natural and climatic, and complex engineering and geological conditions of Priamurye influence substantially variations in the features of rocks in the hypergenesis zone. Characteristics of rocks at 18 sites have been studied aimed at revealing regularities in the development and distribution of the hypergenesis zone and the degree of its influence on the stability of engineering structures.