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1.
Pevzner M. M. Lebedev V. A. Kuscheva Yu. V. Volynets A. O. Tolstykh M. L. Babansky A. D. 《Doklady Earth Sciences》2020,490(1):1-3
Doklady Earth Sciences - A first set of K–Ar isotopic ages obtained, which allowed to estimate the age of the largest volcanoes of the Anaunsky Dol (3.2, 2.2 and 1.9 Ma) and eruptive centers... 相似文献
2.
Hans-Jürgen F?rster Dieter Rhede Holly J. Stein Rolf L. Romer Gerhard Tischendorf 《International Journal of Earth Sciences》2012,101(1):57-67
We present geochronological data for late-Variscan magmatism in the Lausitz Block of the Saxo-Thuringian Zone, Germany. The
Th–U–total Pb age of uraninite and the Re–Os age of molybdenite from the composite biotite–monzogranite pluton of K?nigshain
overlap at the 2σ confidence limit: 328.6 ± 1.9 Ma (uraninite), and 327.0 ± 1.3 Ma and 327.6 ± 1.3 Ma (molybdenite), indicating
that crystallization of magmatic uraninite and deposition of molybdenite were nearly contemporaneous. These data imply that
magmatic processes in this part of the Variscan orogen already started in latest Visean time, about 10 Ma earlier than previously
assumed (315–320 Ma). The new ages correspond to ages for plutonic rocks in the Elbe Zone immediately west of the Lausitz
(around 335–325 Ma) and the bulk of late-Variscan igneous rocks in the Saxo-Thuringian Zone (335–320 Ma). 相似文献
3.
K–Ar dating of mineral separates extracted from various granitoid rock units of the eastern Pontides and central Anatolia,
Turkey, has provided some new insights unravelling various stages of the Neo-Tethyan convergence system, which evolved with
northward subduction between the Eurasian plate (EP) to the north and the Tauride-Anatolide platform (TAP) to the south along
the İzmir-Ankara-Erzincan suture (IAES) zone. Arc-related granitoid rocks are only encountered in the eastern Pontides and
yield K–Ar cooling ages of both Early Cretaceous (138.5 ± 2.2 Ma) (early arc), and Late Cretaceous, ranging from 75.7 ± 0.0
to 66.5 ± 1.5 Ma (mature arc), respectively. The multi-sourced granitoids of the eastern Pontides, with a predominant mantle
component and K–Ar ages between 40 and 50 Ma, are considered to be a part of post-collisional slab break-off magmatism accompanied
by tectonic denudation of pre-Late Cretaceous granitoid rocks following juxtaposition of the EP and the TAP around 55–50 Ma
in the eastern Pontides. The K–Ar cooling ages of collision-related S-, I- and A-type granitoids in central Anatolia reflect
good synchronism between 80 and 65 Ma, suggesting a coeval genesis in a unique geodynamic setting but with derivation from
various sources—namely, purely crustal, purely mantle and/or of mixed origin. This sort of simultaneous generation model for
these S-I-A-type intrusives seems to be consistent with a post-collisional lithospheric detachment related geodynamic setting.
I-type granodioritic to tonalitic intrusives with K–Ar cooling ages ranging from 40 to 48 Ma in east-central Anatolia are
interpreted to have been derived from a post-collisional, within-plate, extension-related geodynamic setting following the
amalgamation of the EP and the TAP in east-central Anatolia. 相似文献
4.
Martin J.S. Rudwick 《《幕》》2008,31(3):363-366
Bursting the Limits of Time by the distin- guished historian of geology Martin Rudwick is a massive, two-part book. The first part contains what he calls a synchronous history of what eventually became historical geology in western Europe between the time of de Sans- sure＇s epoch-making ascent of Mont Blanc in 1787 and the discovery of the Kirkdale hyaena cave by Buckland in the winter of 1821-1822, 相似文献
5.
The granitoids of the Dal’negorsk borosilicate deposit are ascribed mainly to the high-K metaluminous rocks of the calcic and alkali-calcic series. The thermo-baro-geo-chemical studies showed that they originated from melts with low contents of water (H2O < 3.5% H2O) and CO2 at 800–850°C and 65–90 MPa. The data on the average contents of elements in the rock-forming minerals and the estimated initial water content in the magma point to the absence of a genetic relation between the intrusion and boron mineralization. The granitoid magma was responsible for the skarn formation and for the mobilization and remobilization of boron under a favorable environment. The K/Ar dating (51.0 ± 10 Ma), the geochemical typification (signatures of within-plate, subduction, and collisional granitoids), and the low water content in the parental melts of the granitoids, in accordance with the scheme of the geodynamic evolution of the region, indicate their formation in the lithospheric plate sliding environment. 相似文献
6.
Geochemical data of altered wall rocks are important for the metallogenic prognosis of hydrothermal gold deposits. Indicator elements of altered wall rocks such as K, Al, As, Sb, and Hg have been successfully used to assess gold anomalies in lithogeochemical survey. However, such researches have rarely been done in stream sediment survey for the exploration of gold from various landscapes. On the basis of the geochemical analysis of altered wall rocks of gold deposits in the cold desert areas of Gansu (甘肃) Province in Northwest China, it is found that the combination of Al, K, and Sn could serve as an important indicator of hydrothermal gold deposits and can be used to evaluate the metallogenic prospective of gold anomalies in stream sediments. More studies performed in the cold grassland areas and the moderate-low relief mountainous areas showed that, both weak and strong geochemical anomalies can be extracted, if strictly abiding by the ways of calculation and addition of the binary values of the indicator elements with equal weight, and this provides the sound delineation of metallogenic perspective areas. 相似文献
7.
Wang Bixiang Li Zhaonai Zhao Guangzan Wang Fubao Zhang Shuizhe Fei Wenheng 《《地质学报》英文版》1990,64(1):55-67
The granitioids in question are located in the geosynclinal fold belt of the Northern Tianshan Mountains.The magmas are intruded into a Carboniferous marine volcanic-sedimentary rock series. forming a contempo-raneous. intermediate-basic to acid. composite intrusion. With a whole-rock Rb-Sr isochron age of 315.7 Ma. itis considered to be of middle Heicynian age. The granitoids have a SiO_2 content of 48-78%, a calc-alkali indexof 60 and silica-alkali indices ρ=2.2-2.4 and σ=1.5-2. From basic to acid compositions, the total REE con-tent increases from 38 to 143 ppm. δEu ranges from 0.47 to 0.86 and the Eu anomalies are negative. Thenormalized curves of REE of various rock types are very similar. These coupled with the characteristics of traceelement geochemistry show that the intrusion is an island arc-continental margin, calc-alkaline one. Theδ~(18)O values range from 5.8 to 8.9‰ and the ~(87)Sr/~(86)Sr initial ratio is 0.705. The materials of the intrusion arecomposed of a mixture of the magmas at the top of the upper mantle and in the lower crust, This indicates thatthe rocks might be consanguineous. differentiated and evolved products and possess the characteristics of Ⅰtype granites. 相似文献
8.
Liu Kuiwu 《《地质学报》英文版》1990,64(2):147-162
Apatites occurring in sedimentary rocks are carbonate fluorapatites (C-F apatites) with differentCO_2 contents. During diagenesis. the CO_2 in the C-F apatites gradually decreased with the increasing strengthof diagenesis. resulting in the systematic changes in refractive index. specific gravity, cell parameters and crystalchemistry of apatites. On the basis of X-ray diffraction and IR spectroscopic analyses, the author proposes twoparameters for determining diagenetic stages. i.e.. the crystallinity index (CR) and sharpness index (SH). Thesetwo parameters serve as new criteria for the determination. which due to the common existence of phosphorousnodules and bands and argillo-crystalline cement in sedimentary rocks, most likely have wide prospects for ap-plication. 相似文献
9.
N. A. Krivolutskaya 《Geology of Ore Deposits》2011,53(4):309-339
The timing of the emplacement of ore-bearing melts in the process of evolution of flood-basalt magmatism in the Noril’sk District
is discussed. The current models of ore formation consider the emplacement of ore-bearing intrusions either under the conditions
of a closed magmatic system as a product of a self-dependent magmatic event, or under the conditions of an open magmatic system,
where intrusions are parts of the conduits feeding lava flows. In both cases, the composition of the initial magma, the content
of volatile components therein, and the contribution of country rock assimilation are important for the development of a genetic
model. The relationships between lavas and intrusions are exemplified in the South Maslov intrusion, which cuts through the
rocks of the Nadezhdinsky Formation. No geological evidence for links of lavas to intrusions has been established. Substantial
difference in geochemistry (Ti contents, Gd/Yb and La/Sm ratios, etc.) of the tuff and lava sequence on the northern shore
of Lake Lama and the Maslov intrusions are demonstrated. It is concluded that the Noril’sk deposits were formed as products
of emplacement of self-dependent portion of magma in the post-lower Nadezhdinsky time. The melt composition determined from
melt inclusions in olivine corresponds to high-Mg tholeiitic basalt (up to 7–8 wt % MgO) containing up to 1 wt % H2O and 0.3 wt % Cl and undersaturated with sulfur. The fluid regime of flood-basalt volcanism had no anomalous features—the
fluid was aqueous-carbon dioxide. The melts of ore-bearing and barren intrusions had similar concentrations of volatile components.
The distribution of major and trace elements in intrusive rocks of the contact zone with the lower part of the Nadezhdinsky
Formation characterized by high (La/Sm)N ratio in comparison with gabbroic rocks (2.8–2.3 and 1.3–1.6, respectively), indicates that contamination of the initial
melt only took place in a narrow (1 m) contact zone or did not develop at all. New data on isotopic compositions of Sr (87Sr/86Sr)251 = 0.7089 and Pb (206Pb/204Pb = 20.877–24.528 in anhydrite confirm that local assimilation did not play a substantial role in the formation of rock and
ores. On the basis of chemical composition of ore-forming intrusions, their isotopic characteristics, and the composition
of melt inclusions in olivine, it is suggested that the lower crustal rocks were a major source of ore-bearing magmas. 相似文献
10.
With increasing high-quality geological and geophysical data it becomes clear that seismicity of the continents is characterized by linear patterns which are closely associated with tectonic features. The aim of this paper is to give reasonable interpretation for the earthquake distribution in the contiguous continent of the United States. Seismic lines and earthquake concentrated zones are defined, which reflect the characteristics of the continental seismotectonics. Similarities and differences in seismotectonics between the continental part of China and the contiguous continent of US are analysed. It is demonstrated that the spatial distribution of earthquakes can provide the information of the active structures in the earth's crust. The authors consider that the patterns of continental seismotectonics are not only controlled by the pre—existing tectonic frameworks and the current boundary dynamic conditions, but also possibly affected by dynamic factors of global tectonics at a higher level. 相似文献
11.
《《地质学报》英文版》1993,67(2)
Acta Geologica Sinica (hereinafter referred to as the Acta) starting publication in 1922, is a quaterly academia periodical sponsored by the Geological Society of China (GSC). It has been one of the science and technology periodicals in China with the longest history. 相似文献
12.
Liu Zhaojun Wang Dongpo Liu Li Liu Wanzhu Wang Pujun Du Xiaodi Yang Guang Changchun University of Earth Sciences Changchun Jilin Sun Sheping 《《地质学报》英文版》1993,67(2):167-180
The rupture of the lithosphere in Late Jurassic brought about the eruption of basaltic magma in the Songliao Basin. The evolution of the basin in Cretaceous progressed through six stages: pre-rift doming, extensional fracturing, fault subsidence, fault downwarping, downwarping and shringkage, resulting in the deposition of terrstrial facies nearly 10,000 m thick. There are different depositional sequences in these stages: the depositional period of the Early Cretaceous Shahezi and Yincheng Formations is the development stage of the down-faulted basin, forming a volcanic rock-alluvial fan-fan delta-lacustrine (intercalated with episodic turbidites)-swamp facies sequences; the period of the Early Cretaceous Dengluku Formation is the transformation stage of fault subsidence into fault downwarping of the basin, forming a sequence mainly of alluvial plain-lacustrine facies; the depositional period of the Early Cretaceous Quantou Formation-Late Cretaceous Nenjiang Formation is the downwarping stage of the basin, forming an alluvial plain-delta-lacustrine facies sequence; the period of the Late Cretaceous Sifangtai Formation-Mingshui Formation is the shringkage stage of the basin, forming again a sequence mainly of alluvial plain-alluvial fan and small relict lacustrine facies. These vertical depositional sequences fully display the sedimentary characteristics of a failed continental rift basin. Many facts indicate that the two large-scale lake invasions, synchronous with the global rise of sea level, which took place in the downwarping stage of the basin development, led to the connection between the lake and sea. 相似文献
13.
Shinji Sakurai Yoko Fujikawa Masami Fukui Masumi Kakumoto Tatsuhide Hamasaki Masataka Sugahara Yuko Abe Takahisa Shinjo 《中国地球化学学报》2006,25(B08):118-118
Livestock wastes applied to agricultural land are potential sources of steroidal hormones （estradiol （E2）, estrone （E1）, and estriol （E3）） that can adversely affect the aquatic ecosystem as endocrine disruptors. But the effects of plants on the fate of estrogen in the environment are not clearly known. In the present report, the behavior of E1, E2 and E3 added to the rhizospheric soil in various concentrations and its effect on plant growth were examined by estrogen batch sorption test, plant pot test and estrogen extraction test. Trifolium repens was grown on the soil spiked with E2 or a mixture of E1, E2 and E3. Pots without plant were prepared as controls. All pots were watered in 50 ml dose almost every day, and the rhizosheric soil and plant body were collected 7, 19, 26, 33 days after planting. The soil was sequentially extracted with Milli-Q water, and methanol / 1M acetic acid solvent followed by methanol wash at the solid to liquid ratio of 1 ： 4 （g/mL）. Extracts were analyzed for El, E2 and E3 using a Shimadzu GCMS-QP5050. Plant dry weight （4 hours, 105 ℃） was measured as an indicator of plant growth. In batch sorption tests, E1 and E2 concentrations in the liquid phase significantly decreased within 24 hours after the addition of estrogen. The sum of methanol / 1M acetic acid extractable E 1 and E2 in the soil decreased to half of the initial added amount within 7 days. Reduction in total estrogenic activity of the soil extracts （estimated as 0.01CE1＋CE2＋0.1CE3 where CE1, CE2 and CE3 are respective El, E2 and E3 concentrations per unit soil weight） continued for 1 month due to slow oxidation of E2 to E1. Desorption of E2 from soil during the pot experiment was higher than expected from the sorption experiment. 相似文献
14.
N. I. Golubeva L. V. Burtseva G. G. Matishov G. V. Il’in 《Doklady Earth Sciences》2013,453(1):1090-1093
By experimental data on the concentration of toxic microelements (Pb, Cd, Cu, Zn, Ni, Co, and Cr) in atmospheric aerosols over the White and Norwegian Seas in winter-spring period of 2009–2010, the contamination of air environment over two sea basins, significantly different by geographical conditions but being heavily impacted by North-European industrial centres, including the impact of the largest in the European Arctic Kola industrial centre, has been analyzed. It has been indicated and described that the air basin over the White Sea water area, when compared to the Norwegian Sea, is under a significantly greater impact of the emission sources of heavy metals, located on the Kola Peninsula. 相似文献
15.
Doklady Earth Sciences - Based on atomistic modeling data, various schemes of the isomorphic incorporation of K+ and Na+ ions into the crystal structures of CaSiO3 and MgSiO3 in the pressure range... 相似文献
16.
This paper discusses the Cretaceous-Tertiary magnetic polarity sequence of the the Hengyang Basin on the basis of magnetostratigraphic study. The age of each stratigraphic unit has been determined with the magnetic polarity time scale combined with 39Ar/40Ar dating, thus providing evidence for determining the geological ages of different formations. The authors assign the age of the Dongjing Formation of the Hengyang Basin to Early Cretaceous, the Shenhuangshan Formation to Early-Late Cretaceous, the Daijiaping Formation to Late Cretaceous, and the Dongtang and Xialiushi formations to Palaeocene. 相似文献
17.
18.
It has been shown from petrologic,geochemical,trace element and REE evidence that the gran-ite intrusions at Sikongshan,Anhui Province,can be assigned to two distinct types which are radically different in age and origin.The Precambrian gneissic granited resulted from remelting of old continental crust while the Mesozoic granites were derived ,also through remelting,from low-Rb/Sr rocks at greater depths.Granite masses at Tiantangzhai and Zhoujiawan in the Dabieshan Mountains are also dicussed. 相似文献
19.
V. G. Klochkova V. E. Panchuk N. S. Tavolzhanskaya I. A. Usenko 《Astronomy Reports》2014,58(2):101-111
Multiple observations of the yellow hypergiant ρ Cas obtained in 2007–2011 in a wide wavelength range with spectroscopic resolving power R ≥ 60 000 have enabled studies of features of its optical spectrum in detail and brought to light previously unknown characteristics of the star’s extended atmosphere. The radial velocity measured from symmetric absorption lines of metals varies with an amplitude of about ±7 km/s around the systemic velocity V sys = ?47 km/s, due to low-amplitude pulsations of the atmospheric layers near the photosphere. At some times, a velocity gradient was observed in deep atmospheric layers of the star. A slight velocity stratification in the stellar atmosphere was detected for the first time, manifest as a difference of 3–4 km/s in the velocities measured from absorption lines of neutral metals and of ions. The long-wavelength components of split absorption lines of BaII, SrII, TiII, and other strong lines with low excitation potentials for their lower levels are distorted by nearby emission lines. It is suggested that the short-wavelength components, whose locations correspond to the narrow velocity range V r (blue) from approximately ?60 to ?70 km/s, are formed in a circumstellar envelope; one component of the D NaI doublet and the emission components of the FeII 6369.46 and 6432.68 Å ions are also formed there. 相似文献
20.
Liu Shaofeng Li Sitian Zhuang Xinguo Jiao Yangquan Lu ZongshengChina University of Geosciences Wuhan 《《地质学报》英文版》1996,70(3):233-245
Characteristics of deformation in the thrust belt and sequence stratigraphic framework in the foreland basin, structural features of the basin margin, and the episodic thrusting are studied in this paper by combining the eastern Qilian thrust belt and the Late Triassic foreland basin on the southwestern margin of Ordos. On this basis, a geological model and a mechanical model of coupling mechanism were established for the pair of thrust belt and foreland basin, and the subsidence and deposition process of the foreland basin were simulated on given parameters. 相似文献