A Polychronous Locality of Megafauna on the Northwestern Coast of Lake Baikal     

Kalmykov  N. P.  Budaev  R. Ts. 《Doklady Earth Sciences》2018,483(2):1487-1490

Doklady Earth Sciences - Based on geochronological data, it is shown that the formation of sediments of a 50–80 m terrace of Lake Baikal occurred during the Middle Pleistocene and its top...  相似文献   

First Data on the Isotopic Age of Zircons from Rocks of the Roseta Ultramafic Massif,Southern Margin of the São Francisco Craton (Brazil)     

Lesnov  F. P.  Pinheiro  M. A. P.  Sergeev  S. A. 《Doklady Earth Sciences》2018,483(2):1510-1514

Doklady Earth Sciences - The results of isotope U–Pb dating of zircons from lherzolite and vein olivine orthopyroxenite composing the Roseta ultramafic massif are presented. The zircons...  相似文献   

Carbon Isotope Characteristics as Evidence of an External Source of High-Temperature Granitoids in Granulite Complexes     

Safonov  O. G.  Reutsky  V. N.  Shcherbakov  V. D.  Golunova  M. A.  Varlamov  D. A.  Yapaskurt  V. O.  van Reenen  D. D. 《Doklady Earth Sciences》2018,483(2):1515-1518

Doklady Earth Sciences - Data on the carbon isotope composition of graphite and CO2 from inclusions in quartz of granitoids of the Southern Marginal Zone (SMZ) of the Limpopo granulite belt, South...  相似文献   

Geochemical Specifics of Highly Differentiated Topaz-Bearing Granite of the Salmi Batholith     

Konyshev  A. A.  Chevychelov  V. Yu.  Shapovalov  Yu. B. 《Doklady Earth Sciences》2018,483(2):1542-1546

Doklady Earth Sciences - Two varieties of highly differentiated topaz-bearing granite of the Salmi Batholith are distinguished: Li-siderophyllite topaz-bearing granite (Li-Sdph) (Lupikko dome) and...  相似文献   

The Magmatic–Hydrothermal Transition and Origin of Brine in the Oceanic Core Complex of the Mid-Atlantic Ridge at 13° N     

Pertsev  A. N.  Bortnikov  N. S.  Prokofiev  V. Yu.  Aranovich  L. Ya.  Ageeva  O. A.  Beltenev  V. E.  Zhilicheva  O. M.  Kovalchuk  E. V. 《Doklady Earth Sciences》2018,480(1):661-665

New data on local mineral associations and the microheterogeneity of minerals and fluid inclusions in gabbro were obtained for the gabbro–peridotite oceanic core complex with a long-lived detachment fault controlling the hydrothermal activity. It is assumed that the hydrothermal hydrogen-bearing fluid with a NaCl content of >30 wt % is formed in the seawater/harzburgite (~1/5) reaction of serpentinization. The brine residual after serpentinization interacted with gabbro at the final stages of crystallization of an intrusion and assimilated some components (K, REEs, and Ba) from the residual melt. The interaction was resulted in metamorphic transformations of gabbro at decreasing temperature below 500°C. The reaction of the decomposition of magmatic titanomagnetite with the transition of iron reduced to Fe²⁺ into newly formed chlorinebearing amphibole at 540–450°C and logf(O₂) from–20 to–24 is shown.

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Ba同位素揭示上地幔中广泛存在再循环的沉积物     

Sune G.Nielsen  Tristan J.Horner  Helena V.Pryer  Jerzy Blusztajn  Yunchao Shu  Mark D.Kurz  Veronique Le Roux 《矿物岩石地球化学通报》2018,(4)

正Ba同位素由于具有在低温环境中分馏的特性,相比放射性同位素与微量元素,可以更好地示踪地球深部动力学过程中的再循环物质。研究表明沉积物与蚀变洋壳具有明显不同的Ba同位素组成(沉积物富集来自重晶石的Ba),使得Ba同位素成为研究表层与地幔储库间物质交换的有力工具。最近美国伍兹霍尔海洋研究所报道了来自全球洋中脊的21个MORB样品的Ba、Sr、Nd同位素和微量元素组成以及两个钻井中沉积物和蚀变洋壳  相似文献   

<Superscript>230</Superscript>Th/U Chronology and Geochemistry of Irinovskoe Hydrothermal Field (Mid-Atlantic Ridge)     

V. Yu. Kuznetsov  E. V. Tabuns  G. A. Cherkashev  V. E. Bel’tenev  F. E. Maksimov  K. A. Kuksa  L. I. Lazareva  S. B. Levchenkoa  I. E. Zherebtsov 《Doklady Earth Sciences》2018,478(1):26-30

The results of ²³⁰Th/U dating and mineralogical–geochemical studies of sulfide ores from the Irinovskoe hydrothermal field and the Severo-Zapadnoe ore occurrence (Mid-Atlantic Ridge) are presented. Sulfides are represented primarily by copper–sulfide ores with 12–30% Cu content; sulfur- and zinc-sulfide ores are distributed less frequently. The analysis of a change in the composition of sulfides over time has made it possible to identify three stages of formation. Each stage assumes that mineral associations are changed from high-temperature (sulfur and copper sulfide) to medium temperature (Zn–Cu and Zn-sulfide) sulfide ores. The whole age range of formation of the hydrothermal deposits falls within the time interval of about 58000–8000 for the Irinovskoe field and 69000–11000 years ago for the Severo-Zapadnoe ore occurrence.  相似文献   

The Late Silurian Age of the Reference Aralaul Granosyenites–Granite Massif (Northern Kazakhstan)     

K. E. Degtyarev  A. A. Tretyakov  A. B. Kotov  E. B. Salnikova  M. V. Luchitskaya  V. P. Kovach  K.-L. Wang 《Doklady Earth Sciences》2018,479(1):275-278

This work presents the results of U–Pb geochronological studies of alkaline granites of the Aralaul complex of Northern Kazakhstan, which allow one to substantiate their Late Silurian (420 ± 4 Ma) age. Taking into consideration the previously obtained data, we propose a new development scheme of Paleozoic granitoid magmatism in Northern Kazakhstan, which includes Late Ordovician granite–granodiorite (Zerenda and Krykkuduk), Early Silurian granite–leucogranite (Borovoe and Karabulak), Late Silurian granosyenites–granite (Aralaul), and Early Devonian (Balkashino and Orlinogorsk) complexes.  相似文献   

Redkinian Biota of Macroscopic Fossils from the Northwestern East European Platform (South Ladoga Region)     

E. Yu. Golubkova  E. A. Kushim  A. B. Kuznetsov  A. S. Yanovskii  A. V. Maslov  S. D. Shvedov  Yu. V. Plotkina 《Doklady Earth Sciences》2018,479(1):300-304

The stratigraphic distribution of microfossils and macroscopic fossil biota in Vendian deposits of the South Ladoga region (northwestern East European Platform) is analyzed. In the sequence of the Shotkusa- 1 well, three taxonomically heterogeneous microfossil assemblages are distinguished: two of them refer to the Redkinian age (Starorusskaya Fm.) and one to the Kotlinian age (Vasileostrovskaya Fm.). Deposits of the Starorusskaya Fm. contain Redkinian biota of macroscopic fossils, of which the most characteristic representatives are Chuaria circularis, Doushantuophyton lineare, Morania zinkovi, Orbisiana simplex, and Redkinia spinosa. These new findings expand the paleontological characteristics of Upper Vendian deposits, also providing additional criteria for distinguishing the Redkinian horizon in the northwestern East European Platform.  相似文献   

First Data about Mercury in Modern Hydrothermal Process in the Ocean,Juan de Fuca Ridge     

Yu. I. Konovalov  L. N. Luchsheva  V. B. Kurnosov 《Doklady Earth Sciences》2018,480(1):575-579

The results of studying Hg in an underwater hydrothermal system in the ocean using the Middle Valley of the Juan de Fuca ridge as an example are presented. A significant part of Hg is accumulated in the basalt fundament (Holes 858F, G), forming anomalously high concentrations (up to 29.30 ppm) in certain parts. The high Hg contents were established in metalliferous sediments (323 ppm) of the sedimentary cover (Hole 858D) and in sulfide deposits (up to 10.30 ppm). In other parts of the section, Hg content is 0.02–0.76 ppm (Holes 858B, D, F), background Hg contents in sediments—0.08–0.28 ppm and in basalts—0.17–0.31 ppm (Holes 855A, C, D).  相似文献