Two Genetic Types of Bauxites of the Central Deposit (Siberian Platform) and a Rare Metal Mineralization

Doklady Earth Sciences - The Central bauxite deposit on the territory of the Russian Federation is a unique geological object. It hosts both primary lateritic bauxites and products of their...     

利用地磁数据进行地震预报

利用地磁数据进行地震预报卡日莫娃Ｌ．，科斯卡耶娃Ｇ．，马斯科诺夫Ｓ．，马卡连柯Ｓ．（哈萨克斯坦共和国科学院，阿拉木图）ＡＢＯＵＴＥＡＲＴＨＱＵＡＫＥＰＲＥＤＩＣＴＩＯＮＢＹＧＥＯＭＡＧＮＥＴＩＣＤＡＴＡ￥ＫａｒｉｍｏｖａＬ．；ＫｕｒｓｋｅｙｅｖａＧ．...     

Geology, mineralogy, and genesis of PGE mineralization in the South Sopcha massif, Monchegorsk complex, Russia

New data are reported on the localization and genesis of PGE mineralization at the South Sopcha deposit situated in the southern framework of the Monchegorsk pluton. Disseminated PGE-Cu-Ni mineralization, the thickness of which in particular boreholes exceeds 100 m, is hosted in the zone of alternating peridotite, pyroxenite, norite, and gabbronorite. The PGE grade does not exceed 1?C2 gpt with Pd/Pt = 3?C4 at Ni and Cu contents from 0.2 to 1.5 wt %. The PGE contents up to 4?C6 gpt and Pd/Pt = 4?C8 are noted at local sites of hydrothermally altered rocks. Another type of PGE mineralization is established in the outcrops of the southeastern marginal group of the massif. Pyroxenite, norite, and gabbronorite fragments are incorporated here in the gabbroic matrix, making up a complex zone of magmatic breccia complicated by mylonites and late injections. Elevated PGE contents (1.0?C6.5 gpt) are detected in all types of rocks in the zone of brecciation, mainly in the matrix. Platinum-group minerals (PGM) occur in association with magmatic and late sulfides, amphibole, mica, and chlorite. PGM vary in composition depending on the petrographic features of rocks. In rocks of the layered series and in pegmatoid pyroxenite PGM are extremely diverse comprising PGE compounds with As, Sb, Bi, Te, Se, and S. In the brecciated rocks of the marginal group, Pd bismuthotellurides (mainly merenskyite), sperrylite, hollingworthite, and Pd- and Rh-bearing cobaltite and gersdorffite are predominant. The PGE mineralization in rocks of the layered series and pegmatoid pyroxenite was formed from the magmatic melt enriched in volatiles and with subsequent transformation of PGE assemblages under the influence of hydrothermal fluids at a lower temperature. In gabbroic rocks of the marginal group, PGM are associated with the latest sulfides (chalcopyrite, bornite, chalcocite), forming separate grains and thin veinlets in hydrothermally altered rocks. The gabbroic melt affected incompletely crystallized rocks of the layered series by formation of contact-type PGE mineralization, deposition and redeposition of ore matter.     

Observation of eddy structures in the Baltic Sea with the use of radiolocation and radiometric satellite data

The manifestations of mesoscale and submesoscale eddy elements in surface currents of the Baltic Sea in satellite images differing in physical nature and spatial resolution are considered. The investigation is based on the Envisat ASAR and ERS-2 SAR high-resolution radiolocation images (RLIs) obtained in 2008–2009 for different sites of the Baltic Sea water area and the use of the Envisat MERIS and Landsat ETM+ radiometric images of the visible spectrum. Possible mechanisms of the appearance of eddy structures in RLIs of the Baltic Sea water area are considered. Joint analysis of the mentioned data revealed specific features of the appearance of eddy structures in satellite images, taking into account the variability of optical characteristics of Baltic Sea surface waters during the summer blooming of cyanobacteria and the spring blooming of diatomic algae.     

Evaluating direct and indirect evidence of climatic change by Hölder regularity and order pattern in time series

The several competing reconstructions of Northern Hemisphere temperature variability exists with partly conflicting evidence. Here we considered a specific problem of choosing “the best” reconstruction, in a frame of assumptions, that they are produced by smooth dynamical system as well as instrumental time series. Using some sophisticated measures of similarity, we could not match to all existing hemispheric paleoclimate reconstructions with hypothesis about any deterministic system which can produced its as typical projection of their trajectories. The results cast doubt on the conventional techniques frequently used to reconstruct past climate variability.