Research on the adsorptive kinetic experiments on humus and its spacial variations in the Changjiang (Yangtze) estuary

In this paper, based on the adsorptive kinetic experiments and interfacial chemistry experiments, the adsorption mechanism and the factors influencing the adsorption of humus by HS-12 resin have been studied. Humus in the water of the Changjiang estuary w…     

The Cenomanian–Turonian Boundary Event (CTBE) on the southern slope of the Subalpine Basin (SE France) and its bearing on a probable tectonic pulse on a larger scale

The Cenomanian–Turonian Boundary Event (CTBE) event is not associated with a transgression on the southern margin of the Subalpine Basin, but with a steady shallowing-up trend beginning in the lower half of the δ¹³C positive shift. The SW–NE Rouaine Fault had a complex role, first in isolating a black shale basin to the west and a large, deep submarine plateau devoid of black shale to the east, then by a strike-slip movement that induced a forced progradation to the north of the southern platform in the eastern compartment. This compressive tectonic reactivation of the southern margin began around the deposition of the local equivalent of the Plenus bed of boreal basins, as shown by correlation supported by both isotope and palaeontological data. Other local data are pieced together to suggest that the whole of SE France underwent a short-lived transpressive tectonic pulse around the Cenomanian–Turonian boundary, probably connected with the early compressive movement of Africa vs. Europe. On a larger scale, other published data suggest that this pulse could be a global one. It is coeval with renewed thrust loading, volcanism and transgression in the North-American Western Interior, local emergences during the event along the eastern Atlantic margin, suggesting a slight tendency to inversion of the margin, and a tilting to the east of the North-Africa plate that could explain the large transgression recorded from Morocco to Tunisia on the Saharan Craton.New isotope and palaeontological (coiling ratio of Muricohedbergella delrioensis) data from SE France suggest that two coolings of suprabasinal importance occurred just before and during the build-up of the d¹³C shift, including the boreal “Plenus Marls“, especially its middle limestone bed and its SE France equivalent.Regarding the extinction of the genus Thalmaninella and Rotalipora and during the event, neither anoxia nor climate changes can fully explain the palaeontological crisis, given that Rotalipora cushmani crosses the first phase of anoxia without harm, as well as the two coolings, not only in SE France but on a large scale, as shown by the correlation of the published data. This extinction needs alternative explanations as we challenge both anoxia and climate as major causes.     

International Symposium on Geoscience of the Northern Qinghai-Tibet Plateau──Marking the 20~(th) Anniversary of the Sino-French Cooperative Research on Geoscience

Sponsored by the Ministry of Land and Resources of the People*s Republic of China, China Seismological Bureau, Ministere de Ia Recherche de Ia France and Ministere des Affaires etrangres de Ia France, the international symposium on Geoscience of the northern Qinghai-Tibet Plateau was held in Beijing on October 8-15, 2000. After the meeting in Beijing a field-work trip began from Dunhuang (Gansu province), Aksay, Dacaidan (Qinghai province), Golmud to Xidatang (near the Kunlun Shan…     

Preliminary Study on the Metallogenic System of Mafic Large Igneous Provinces (Mlips)

正Large igneous provinces(LIPs)generally refer to the different types of the igneous rocks,which intrude in a short time,ranging in area from 50000 to 100000 km~2(Sheth,2007;Bryan et al.,2008).While the mafic large     

A Raman spectroscopic study on the structural disorder of monazite–(Ce)

This study addresses whether Raman spectra can be used to estimate the degree of accumulated radiation damage in monazite-(Ce) samples whose chemical composition was previously determined. Our results indicate that the degree of disorder in monazite–(Ce), as observed from increasing Raman band broadening, generally depends on both the structural state (i.e., radiation damage) and the chemical composition (i.e., incorporation of non-formula elements). The chemical effects were studied on synthetic orthophosphates grown using the Li-Mo flux method, and non radiation-damaged analogues of the naturally radiation-damaged monazite–(Ce) samples, produced by dry annealing. We found that the “chemical” Raman-band broadening of natural monazite–(Ce) can be predicted by the empirical formula, $$ {\hbox{FWHM}} {\hbox{[c}}{{\hbox{m}}^{ - {1}}}{]} = {3}{.95} + {26}{.66} \times {\hbox{(Th}} + {\hbox{U}} + {\hbox{Ca}} + {\hbox{Pb)}} {\hbox{[apfu]}} $$ where, FWHM = full width at half maximum of the main Raman band of monazite–(Ce) (i.e., the symmetric PO₄ stretching near 970?cm^?1), and (Th+U+Ca+Pb) = sum of the four elements in apfu (atoms per formula unit). Provided the chemical composition of a natural monazite–(Ce) is known, this “chemical band broadening” can be used to estimate the degree of structural radiation damage from the observed FWHM of the ν₁(PO₄) band of that particular sample using Raman spectroscopy. Our annealing studies on a wide range of monazite–(Ce) reference materials and other monazite–(Ce) samples confirmed that this mineral virtually never becomes highly radiation damaged. Potential advantages and the practical use of the proposed method in the Earth sciences are discussed.     

Features of the Ore Forming Process on the Dvoinoye Epithermal Au–Ag Deposit (Western Chukotka)

The results of thermobaric geochemical study of ores of the Dvoinoye epithermal Au–Ag deposit are considered. Study of the fluid inclusions has shown that the ores were formed from low-salinity hydrothermal solutions with Na, Ka, and Mg chlorides and CO₂, HS^–, CH₄ trace fluxes at the time when the temperature dropped from 370 to 130°C. The results are compared with data obtained from the closely located Kupol and Sentyabr’skoye deposits.     

New Data on Diamond–Graphite Relationships in the Gneisses of the Kokchetav Massif (Northern Kazakhstan)

The results of studying an aggregate of graphite-and-diamond crystal in tourmaline 5 μm of the Kokchetav massif by the method of transmission electron microscopy are presented. The detail studies of the interface between the crystals of graphite and diamond have revealed the absence of disordered graphite that is detail partially graphitized diamond. Intense deformation changes in the graphite crystal occurred after it was captured by tourmaline at the regression stage, which led to considerable kinking of the graphite crystal along the a-axis. Thus, the coexistence of graphite and diamond crystals cannot be unambiguously interpreted as a product of partial diamond graphitization. Graphite could have crystallized syngenetic with a diamond crystal or at the retrograde stage in the graphite stability field.

     

On the nature of ore-bearing fluids on the Dal’negorskoe borosilicate deposit (Primor’e)

Doklady Earth Sciences -     

New data on the deep structure of the Northern Vent of the Great Tolbachik Fissure Eruption (1975–1976)

In order to restore the deep structure in the region of the Northern Vent (NV) of the Great Tolbachik Fissure Eruption (GTFE) (1975–1976), low-frequency microseismic sounding was applied. For this purpose accumulation of spectra of the microseismic field was performed in a wide frequency band in 29 points along a linear profile 14 km in length embedded transversely to the fissure eruption. A deep cross section of the Earth’s crust was constructed up to 20 km, reflecting the distribution of relative velocities of transverse seismic waves. The revealed structural heterogeneities were interpreted with consideration of previously known results of complex studies of the eruption. The existence of an abnormal structure at the depths of 2–3 and 7–8 km under the NV GTFE was confirmed, which could be low-depth magma chambers. Deep subvertical low-velocity structures were revealed and spatially registered, which probably feed the conduits of the eruption. It was demonstrated that the ways of possible magma supply to the peripheral chamber at the depth of 2–3 km could be various. For the first time for the zone of areal volcanism, variation of the character of magmatic intrusions was demonstrated at the transition from a crystalline basement to the near-surface depth: subvertical forms are replaced with a system of sills and interesting injections.     

Sequence stratigraphy with emphasis on platform-related parasequences of the Zechstein 2 carbonate (Ca2) – the northern platform margin of the Southern Permian Basin (NE Germany)

Facies analysis combined with sequence stratigraphic interpretation of the Upper Permian carbonate (Ca2) of NE Germany (i.e. northern basin margin of the Southern Permian Basin) confirm the existence of a rimmed platform with a steep and tectonically structured slope. The karstified A1 platform is overlain by deposits of a thin transgressive systems tract (TST) and a thick highstand systems tract (HST) which shows two larger-scale regressive shallowing-upwards cycles (4th order) with typical stacking patterns of small-scale cycles (5th order). The TST consists of bitumen-rich mudstones with reworked clasts of anhydrite and early cemented wacke- to grainstones, and it shows two, probably 5th-order, deepening-upwards cycles. The first larger-scale shallowing-up cycle on the Ca2 platform (4th-order) is dominated by aggradation of the bar and shoal deposits, whereas the second one is dominated by progradation. The tops of both cycles are characterised by erosional and exposure surfaces. Various types of small-scale shallowing-upwards cycles (5th-order) are observed in the bar, in the intertidal and in the algal-dominated supratidal environment, showing pronounced transgressive boundaries. On the slope and in the basin, equally thick TST and HST are observed. These incorporate carbonate turbidites which indicate "highstand shedding" from the platform. Various orders of relative sea-level variations are discussed. Controlling factors include tectonics, climate, and eustatic processes. A combined carbonate and evaporite sequence was found on the upper Ca2 slope, which may indicate a Ca2-lowstand systems wedge.     

New data on palynostratigraphy of the Lipovtsy formation in the Razdol’naya coal Basin (Southern Primorye)

Palynological samples, plant megafossils, and fossil wood taken from the upper Lipovtsy Subformation (Porechye open-pit coal mine in the Il’ichevka coalfield, Razdol’naya River Basin, southern Primorye), as well as coal samples for determining coal-forming plants from dispersed cuticles are analyzed. The taxonomic composition of the identified palynomorphs from the coals and interstratal clastic sediments indicates the Aptian age of host deposits. The palynological spectra from the lower humic–rhabdopissite coal seam are dominated by Gleicheniaceae and Cyatheaceae accompanied by Dicksoniaceae and Ginkgocycadophytus. In the palynological spectra from the upper coal seam, the share of Gleicheniaceae substantially decreases, though they remain dominant; simultaneously, single angiosperm pollen grains appear in them. The spectra from the clastic rocks are dominated by Polypodiaceae and Cyatheaceae. The taxonomical composition of the gymnosperms is relatively diverse, although their abundance is low. The share of angiosperms increases with respect to both their diversity and abundance. The angiosperm pollen, found for the first time in the Aptian deposits of the Razdol’naya River Basin, provides grounds to assume that these pants appeared earlier than previously thought (early Albian). The coal-forming plants of the Il’ichevka coalfield are determined.     

A Review on the Taxonomic, Evolutionary and Phytogeographic Studies of the Lotus Plant (Nelumbonaceae: Nelumbo)

Nelumbo Adans. （Nelumbonaceae） is an important member of the early-diverging eudicots. It contains two extant species： N. nucifera Gaertn. （the Sacred lotus）, distributed in Asia and Australia and N. lutea Willd. （the American lotus）, occurring in North America. This paper reviews the taxonomic, evolutionary and phytogeographic studies of the genus Nelumbo, and also raises scientific questions about it in further paleobotanic research. There are about 30 fossil species of Nelumbo established since the Early Cretaceous. Based on fossil studies, the ancestors of the extant N. nucifera and N. lutea are respectively considered to be N. protospeciosa from the Eocene to Miocene of Eurasia, and N. protolutea from the Eocene of North American. However, molecular systematic studies indicate that N. nucifera and N. lutea are probably split from a common ancestor during the Late Miocene to Early Pliocene, or even the Pleistocene, rather than separate relicts from extinct species on different continents. The characters of lotus stomatal development, seedling morphology as well as its flowering, pollination and fertilization in air reveal that it evolves from the land plants. Fossil data of Nelumbo indicates that the genus first occurs in mid-latitude area of Laurasia in the Early Cretaceous, then becomes widespread in North America and Eurasia and expands into Africa and South America during the Late Cretaceous; the genus probably colonizes the Indian Subcontinent from Asia during the Early Eocene after the collision of India and the Asian plates; the genus becomes extinct in Europe, but survives in Asia and North America during the Quaternary Ice Age, and later forms the present East Asia and North Australia-North America disjunctive distribution.     

Causes and effects of the catastrophic flooding on the Siret River (Romania) in July–August 2008

Natural Hazards - As a result of the massive deforestation and windfalling in Romania last year, catastrophic floods frequently occur with historic high-water marks only to be registered every 500...     

Geochemical controls on the formation of unconformity-type Au–U deposits (Northern Transbaikalia)

This study provides geochemical, mineralogical, and isotope data for rocks and ores from Lower Proterozoic black shale formations of the Kodar–Udokan structural and formational zone, which host the Khadatkanda gold—uranium deposit. The results indicate that the uranium and gold mineralizations were formed at different times in relation to different geodynamic settings. The gold mineralization is associated with the inception of the Syulban fault and has a juvenile source. The later Th–U mineralization originated during tectonic rejuvenation of the Syulban fault zone, while the sources of radioactive elements were presumably the underlying sediments of the Kodar Group, which are widespread throughout the area of the Baikal mountain region (BMR). Based on the above results, the Au–U mineralization in the study area can be recognized as unconformity-type deposits, analogous to the well-known deposits of Australia and Canada. In this connection, the Baikal mountain region has a good potential for the discovery of Au—U deposits.     

Chemical and tectonic controls on the formation of sparry magnesite deposits — the deposits of the northern Greywacke Zone (Austria)

The sparry magnesite deposits of the northern Greywacke Zone are situated at the base of thrust sheets. Model calculations and natural examples suggest that an inverse temperature gradient can only be established at the base of a thrust sheet if thrusting is so rapid as to be geologically unrealistic. Independently of this thrusting induces a fluid flow from the lower units to the front of the moving thrust sheet. Stability data of magnesite and dolomite in contact with fluids with different Ca/(Ca+Mg) ratios suggest that this tectonically induced fluid flow produce magnesite from preexisting dolomite by metasomatism.

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Zusammenfassung Die Spatmagnesitvorkommen der Nördlichen Grauwackenzone liegen innerhalb von Deckengrenzen. Modellberechnungen zeigen, daß ein inverser Temperaturgradient sich nur dann an der Basis von Decken einstellen kann, wenn die Überschiebungsgeschwindigkeit so groß wird, daß sie geologisch unglaubwürdig ist. Deckenüberschiebungen erzeugen aber in jedem Fall in der überschobenen Einheit einen zur Deckenfront hin gerichteten Fluidstrom. Eine Betrachtung der Stabilitätsdaten für Magnesit und Dolomit im Gleichgewicht mit einer fluiden Phase mit unterschiedlichen Ca/(Ca+Mg)-Verhältnissen zeigt, daß durch einen solchen Fluidstrom metasomatisch Magnesit aus Dolomit gebildet werden kann.

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Résumé Les dépôts de magnésite spathique de la Grauwacken Zone septentrionale sont situés à la base d'unités charriées. Un calcul de modélisation et des exemples naturels montrent qu'un gradient inverse de température ne peut s'établir à la base d'une unité charriée qu'à la condition d'admettre une vitesse de charriage tellement élevée qu'elle est irréaliste. D'autre part, le phénomene de charriage induit un déplacement de fluide depuis les unités inférieures vers le front de la nappe. Les données relatives aux conditions de stabilité de la magnésite et de la dolomite en présence de fluides de divers rapports Ca/Ca+Mg permettent de déduire que le flux ainsi engendré par la tectonique peut engendrer la magnésite par métasomatose à partir de dolomite préexistante.

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. , , , , . . , Ca/(Ca+Mg) , , , , , , - .

     

Seismic stratigraphy of the Upper Quaternary deposits on the northeastern slope of the Ceará Rise (Central Atlantic)

This study is focused on interpretation of ultrahigh-resolution seismoacoustic data from the northeastern slope of the Ceará Rise (Central Atlantic) acquired using the SES 2000 deep parametric narrow-beam subbottom profiler during cruise 35 of RV Akademik Ioffe in 2011. The geologic nature of most of the detected reflectors is constrained by correlation of the results of seismoacoustic profiling with core data collected in frame of the Ocean Drilling Program (ODP site 929A-E). Detailed seismostratigraphic study of the Upper Quaternary deposits in the study area has implications for better understanding of the role of gravity flows and bottom currents in sedimentation on the NE slope of the rise for the past 1.2 Myr.