Discriminating characters of ore-forming intrusions in the super-large Chalukou porphyry Mo deposit,NE China     

Peixin Duan  Cui Liu  Xuanxue Mo  Jinfu Deng  Jinhua Qin  Yu Zhang  Shipan Tian 《地学前缘(英文版)》2018,9(5):1417-1431

The Chalukou porphyry Mo deposit, located in the Great Hinggan Range, is the largest Mo deposit in northeast China, although the age and genesis of the associated magmatic intrusions remain debated.Here we report zircon U-Pb ages and trace elements, whole rock geochemistry and Sre Nd isotope data with a view to understand the relationship between the magmatism and molybdenum mineralization.Zircon U-Pb analysis yield an age of 475 Ma for rhyolite in the older strata, 168 Ma for the premineralization monzogranite, and 154 Ma for the syn-mineralization granite porphyry. The granite porphyry and quartz porphyry are considered as the ore-forming intrusions. These rocks are peraluminous, alkali-calcic, and belong to high-K to shoshonitic series with a strong depletion of Eu. They also display characteristics of I-type granites. The rocks exhibit wide variations of(87 Sr/86 Sr)iin the range of 0.705426 -0.707363, and ε_(Nd)(t) of -3.7 to 0.93. Zircon REE distribution patterns show characteristics between crust and the mantle, implying magma genesis through crust-mantle interaction. The Fe_2O_3/FeO values(average 1) for the whole rock and EuN/Eu*Nvalues(average 0.45), Ce~(4+)/Ce~(3+) values(average 301)for zircon grains from the granite porphyry are higher than those from other lithologies. These features suggest that the ore-forming intrusions(syn-mineralization porphyry) had higher oxygen fugacity conditions than those of the pre-mineralization and post-mineralization rocks. The Chalukou Mo deposit formed in relation to the southward subduction of the Mongol-Okhotsk Ocean. Our study suggests that the subduction-related setting, crust-mantle interaction, and the large-scale magmatic intrusion were favorable factors to generate the super-large Mo deposits in this area.  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   

Shear Tectonic Fabric in the Atlantic Ocean and Its Relation to the Geodynamic Condition of the Upper Mantle and Intraplate Deformations     

S. Yu. Sokolov 《Doklady Earth Sciences》2018,480(2):715-719

The tectogenesis of the Atlantic Ocean segments is complicated by the axial difference in spreading half-velocities, which causes additional shear displacements between the lithospheric blocks along the transform faults. The intensity of these processes and density of the fault zones iis related to the presence of “cold” sublithospheric lenses along the MAR at a depth of 500 km.  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   

Occurrence Forms of Carbon,Sulfur, and Noble Metals in Deposits of the Black-Shale Formation by the Example of the Degdekan Gold-Ore Deposit (Northeastern Russia)     

V. L. Tauson  R. G. Kravtsova  V. V. Akimov  S. V. Lipko  A. M. Spiridonov  A. E. Budyak  I. Yu. Voronova  O. Yu. Belozerova  K. Yu. Arsentev 《Doklady Earth Sciences》2018,478(1):92-99

Pyrite crystals and ore-bearing shales of the Degdekan deposit were studied by means of XPS, SEM–EDX, EPMA, and AAS. Five peaks of carbon organic forms were identified, conforming to polymer compounds containing either double bonds of carbon or alkyne groups and compounds containing C–OH and C=O bonds, as well as, probably, small amounts of S-containing compounds and those with functional groups of carboxylic acids. Sulfate prevails over sulfite in pyrites; among the surface sulfide forms, disulfide prevails over monosulfide; the presence of polysulfide is registered. The occurrence of various chemical forms of sulfur on the surface might provide for concentrating of microelements including the noble metals (NMs) in their surface-bound forms. The regular behavior of NMs (Au, Pt, Pd, and Ru) depending on the grain sizes (specific surfaces) of pyrite crystals along with the narrow range of the ratios of structural and surface components of the concentrations of different NMs points to NM coprecipitation with pyrite during the same productive stage. No capture of NM-containing carbonaceous phases took place, which should violate the regularity of Au distribution in pyrites of the Sukhoi Log deposit.  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   

Arcanite from Fumarole Exhalations of the Tolbachik Volcano (Kamchatka,Russia) and Its Crystal Structure     

N. V. Zubkova  I. V. Pekov  D. A. Ksenofontov  V. O. Yapaskurt  D. Yu. Pushcharovsky  E. G. Sidorov 《Doklady Earth Sciences》2018,479(1):339-341

The crystal structure (R = 0.0194) of arcanite β-K₂SO₄ was studied on a single crystal from exhalations of the Arsenatnaya fumarole, Tolbachik Volcano (Kamchatka, Russia). The mineral crystallizes at a temperature of ≥350–430°C and associates with langbeinite, aphthitalite, hematite, tenorite, johillerite, and others. Arcanite is orthorhombic, Pnma, a = 7.4763(2) Å, b = 5.77262(16) Å, c = 10.0630(3) Å, V = 434.30(2) ų, Z = 4. Its structure contains isolated SO₄ tetrahedra, whereas K cations center ten- and nine-fold polyhedra.  相似文献   

First Results of U–Pb LA–ICP–MS Isotope Dating of Detrital Zircons from Arkose Sandstone of the Biryan Subformation of Zilmerdak Formation (Upper Riphean,South Urals)     

A. V. Maslov  Yu. V. Erokhin  A. Gerdes  Yu. L. Ronkin  K. S. Ivanov 《Doklady Earth Sciences》2018,482(2):1275-1277

Detrital zircons (DZs) from arkose sandstones of the Upper Riphean Zilmerdak Formation (Southern Urals) yielded ages in the range of 3039–964 Ma. Grains with Late Karelian and Early and Middle Riphean ages compose 35, 34, and 26% of the total number of the analyzed zircons, respectively. This is similar to the age spectra of the Vendian sandstones (Asha Group), but it differs significantly from the age distribution typical of the Riphean stratotype sandstones.  相似文献   

Chemical and Os-Isotopic Composition of Ru–Os Sulfides from the Verkh-Neivinsky Dunite-Harzburgite Massif (Middle Urals,Russia)     

K.?N.?MalitchEmail author  I.?Yu.?Badanina  E.?A.?Belousova  V.?V.?Murzin 《Doklady Earth Sciences》2018,483(1):1437-1441

  相似文献   

Cambrian Magmatism in the Northern Urals: New Data on the Age and Formation Conditions     

G. A. Petrov  Yu. L. Ronkin  A. Gerdes  A. V. Maslov 《Doklady Earth Sciences》2018,481(2):993-996

Cambrian igneous formations in the Northern Urals were identified and described for the first time. It was established that the Timanide orogeny terminated in the Early Cambrian and was followed by continental rifting above a mantle plume in the Late Cambrian.  相似文献