THE MAIN FEATURES OF MORPHOSTRUCTURE OFTHE TRANSREGIONAL AMUR-SONGHUA-HUANGHEFAULT ZONE IN EAST ASIA

DuringthelastseveralyearstheRussian-Chinese~tivemorphOStructUralinvestigationswerecarriedoutalongthetransregionalfaultzonewhichstretcheSmorethan3000kin,fromlowerstreamoftheHuanghecaver,ac~theffehaho,Liaohedep~ion,thenalongthehahuaandthelowerAInurvalleystotheNorthffekhalinandprobablytothecentralPartofOkhotskAsbasin.It'soneofthelargestfaultzonesintheeasternrnalginofAsia.OntheterritoryofnortheasternChinathemostpinOfthiszoneiskno~asTall-L.faultzonewhichhasbeenstudiedbyChinesegeologistsform…     

Geochemical features of the Okhotsk Sea Cenozoic volcanism

Cenozoic volcanic rocks were discovered on major rises of the inner Okhotsk Sea. In this paper, these rocks are geochemically typified, and the geodynamic conditions of their formation reconstructed. For this purpose, mineralogical and geochemical analyses as well as radioisotope age determinations were carried out. The radioisotope age determinations show that the Cenozoic volcanic rocks were formed during the Paleogene–Pleistocene. Within this period, Eocene and Plio-Pleistocene volcanic complexes are particularly prominent. Mineralogical and geochemical analyses show that the rocks belong to the calc-alkaline volcanic series. The Eocene volcanic rocks were formed under subaerial conditions, whereas the Plio-Pleistocene volcanics were formed under submarine conditions. The results of the study suggest that the Okhotsk Sea Basin was formed during the destruction of the Asian continental margin, the Eocene volcanism reflecting subaerial, the Plio-Pleistocene volcanism submarine stages of the Okhotsk Sea evolution.     

Global hydrogeological systems and groundwater of the Pacific segment of the Earth

The paper presents the main results of almost half-century-long theoretical and applied studies by the late K.P. Karavanov dedicated to hydrogeological systems of continents and the oceanic floor as well as to the regional hydrogeology of the Pacific segment of the Earth. This research is not yet over; it is being developed by his followers and serves as a basis for the further study of the subsurface hydrosphere on land and the sea and ocean floor.     

Thermodynamic studies of pyrrhotite-pyrite equilibria in the Ag-Fe-S system by solid-state galvanic cell technique at 518-723 K and total pressure of 1 atm

The reaction FeS₂(cr) + 2Ag(cr) = ‘FeS’(cr) + Ag₂S(cr) was studied by measuring the temperature dependence of the electromotive force (EMF) of the all-solid-state galvanic cell with common gas space:

(-)Pt|Ag|AgI|Ag₂S,‘FeS’,FeS₂|Pt(+)     

Isotopic-geochemical study of nitrogen and carbon in peat from the Tunguska Cosmic Body explosion site

Isotopic-geochemical investigations were carried out on peat samples from the 1908 Tunguska Cosmic Body (TCB) explosion area. We analyzed two peat columns from the Northern peat bog, sampled in 1998, and from the Raketka peat bog, sampled during the 1999 Italian expedition, both located near the epicenter of the TCB explosion area. At the depth of the “catastrophic” layer, formed in 1908, and deeper, one can observe shifts in the isotopic composition of nitrogen (up to Δ¹⁵N = +7.2‰) and carbon (up to Δ¹³C = +2‰) and also an increase in the nitrogen concentration compared to those in the normal, upper layers, unaffected by the Tunguska event. One possible explanation for these effects could be the presence of nitrogen and carbon from TCB material and from acid rains, following the TCB explosion, in the “catastrophic” and “precatastrophic” layers of peat. We found that the highest quantity of isotopically heavy nitrogen fell near the explosion epicenter and along the TCB trajectory. It is calculated that 200,000 tons of nitrogen fell over the area of devastated forest, i.e., only about 30% of the value calculated by Rasmussen et al. (1984). This discrepancy is probably caused by part of the nitrogen having dispersed in the Earth’s atmosphere. The isotopic effects observed in the peat agree with the results of previous investigations [Kolesnikov et al 1998a], [Kolesnikov et al 1998b], [Kolesnikov et al 1999] and [Rasmussen et al 1999] and also with the increased content of iridium and other platinoids found in the corresponding peat layers of other columns [Hou et al 1998] and [Hou et al 2000]. These data favor the hypothesis of a cosmochemical origin of the isotopic effects.     

Breaking the Grenville–Sveconorwegian link in Rodinia reconstructions

The Grenville, Sveconorwegian, and Sunsas orogens are typically inferred to reflect collision between Laurentia, Baltica, and Amazonia at ca. 1.0 Ga, forming a central portion of the Rodinia supercontinent. This triple‐junction configuration is often nearly identical in otherwise diverse Rodinia reconstructions. However, available geological data suggest that although the Grenville and Sveconorwegian provinces shared a similar tectonic evolution from pre‐1.8 to ca. 1.5 Ga, they record distinctly different tectonic histories leading up to, during, and possibly following Grenville–Sveconorwegian orogenesis. Moreover, palaeomagnetic data suggest the two continents were separated at peak orogenesis, further invalidating any direct correlation. A number of possible interpretations are permissible with available geological and palaeomagnetic data, of which a “classic” triple‐junction configuration appears least likely. In contrast to the commonly inferred intertwined Proterozoic evolution of Baltica and Laurentia, the possibility remains that they were unrelated for a billion years between 1.5 and 0.45 Ga.     

Water in Parental Basaltic Magmas of Menshyi Brat Volcano (Iturup Island,Kurile Islands)

Doklady Earth Sciences - Data from the study of minerals of the liquidus association (olivine and spinel) from high-Mg basalts (up to 10 wt % MgO) of Menshyi Brat Volcano (Iturup Island) are...     

远震数据显示贝加尔裂谷带北穆伊斯克(Severomuysk)段地壳和上地幔的精细结构

通过贝加尔裂谷系统北穆伊斯克(Severomuysk)段的密集地震台站线性网络获得的远距离强震记录,并利用P波接收函数技术,揭示了地壳和上地幔顶部的复杂分层块状结构。横波速度的分布表明构成北穆伊斯克地壳的地块具有不同性质。这些地块的西部聚散和地壳下部的分层证实了该地区隆起的堆积-碰撞起源。位于西伯利亚克拉通变薄的倾斜边缘上的北穆伊斯克段解释了该地区地壳碰撞效应的强度。2015年地震的震中深度与Muyakan 凹陷地壳上部的明显速度差异存在令人信服的相关性。     

Application of machine learning to characterize gas hydrate reservoirs in Mackenzie Delta (Canada) and on the Alaska north slope (USA)

Computational Geosciences - Artificial neural network-trained models were used to predict gas hydrate saturation distributions in permafrost-associated deposits in the Eileen Gas Hydrate Trend on...     

Determination of the equilibrium fO2 in bulk samples of H,L, and LL ordinary chondrites by solid‐state electrochemistry

High‐temperature solid‐state electrochemistry techniques (EMF method) were used to measure the oxygen fugacity (fO₂) of the ordinary chondrites Ochansk (H4), Savtschenskoje (LL4), Elenovka (L5), Vengerovo (H5), and Kharkov (L6). The fO₂ results are presented in the form of the following equations: It was found that fO₂ regularly increases from H chondrites to LL chondrites. Measured fO₂ are ~1.5 higher than those previously calculated from mineral assemblages. Kharkov (L6) is a little more oxidized than Elenovka (L5) in agreement with the progressive oxidation model. At the same time, Ochansk (H4) is more oxidized than Vengerovo (H5) and exhibits a slightly different slope compared to other chondrites and at T > 1200 K, becomes more reduced than Kharkov (L6) or Elenovka (L5). Measured oxygen fugacity values of meteorites fall within (0.1–1.0)·log fO₂ of one another. The possible explanation of discrepancies between measured and calculated values is discussed.