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1.
Bindheimite has been identified in specimens from the Lvov Lease, N.W. Queensland. Chemical, microscopic and X‐ray data are given for the mineral which was found to possess a cubic lattice with a unit cell dimension of 10–427 A.  相似文献   

2.
The Tongfeng mercury zone is an important producer of mercury in China.The underlying Lower Cambrian black rock series is strongly depleted in mercury and is thought to be the major source bed for mercury mineralization .The Catian deposit ,as the representative of the zone, was formed at low temperature,which is characterized by a meteoric chlorine-rich and sulfur-poor ore-forming solution of high salinity.A geochemical genetic model of buried hydrothermal explosion is proposed.  相似文献   

3.
Results of measurements of optical thickness of clouds over the West Siberian Plain taken with the help of the MERIS spectrometer onboard the European satellite ENVISAT are analyzed. The observational data for two summer periods of 2008–2009 are considered. It is found that the distribution function of the clouds’ optical thickness averaged over the territory is best presented as the sum of three logonormal distributions. The contribution from each of them to the total envelope, values of optical thickness logarithms for mode centers, and values of variances are given. It is shown that the distribution parameters are almost unchanged with conditional division of the plain’s territory into four zones. The total number of the studied cases exceeds 106.  相似文献   

4.
In order to examine the seasonal characteristics of the dust events over western parts of Iran, surface observations from 27 meteorological stations for the period 1951–2014 were analyzed to obtain spatial distributions and temporal variations and trend of dusty day frequency (DDF). Trends of DDF were analyzed by Mann–Kendall and Sen’s estimator of slope nonparametric statistics. Three meteorological stations were selected in north (Tabriz), middle (Kermanshah), and south of the study area (Ahwaz) as reference stations for detecting the regional differences of DDFs. The results showed that DDF is a variable season by season but in general, DDF increases from north to south and from east to west of Iran. The maximum of DDF is monitored in May, June, and July. There are tangible seasonal increasing–decreasing periods in which these changes are logically related with seasonal changes. Regardless of the existence of the maximum DDF in south and southwest of study area, the most intensive increasing DDF trend is calculated in west middle areas. The most widespread and intensive increasing DDF pattern in west of Iran is observed when it is spring. In this case, the dust storms replaced the rainfalls. Distance from dust sources, major movement ways of dust transporting synoptic systems, regional effective wind activity (such as Shamal wind), and arrangement of high mountains are the known factors affecting frequency variation, distribution, and rate of the trend of all the dust phenomena in west of Iran.  相似文献   

5.
Alizadeh  A.  Behyari  M.  Golandam  H. 《Geotectonics》2019,53(4):533-540
Geotectonics - The northeastern part of the Tabriz, Khaje area has been studied to determine the relationship between the orientation of local structures and regional tectonics, and the influence...  相似文献   

6.
The results of experimental studies on the macro- and microcomponent composition of the ion–salt complex of argillaceous siliceous rocks from the Bazhenov formation of West Siberia are presented. The studies were based on the analysis of samples using a high-resolution mass spectrometer with ionization in inductively coupled plasma, by the X-ray diffraction (XRD) method, and via the study of water and ammonium extracts from samples with a natural moisture content, as well as after drying. It was established that the composition of the solutions of water extracts from rocks with a natural moisture content belongs to the sulfate- sodium-bicarbonate type with increased content of dissolved silicic acid with weakly alkaline pH values (～9.5) and is considerably different from the content of water extracts from the samples after drying. Sodium dominates in the exchange complex; the cation exchange capacity is 14–19 mg-eq/100 g of rock. A sharp excess of the percentage abundance by 2–10 orders of magnitude was recorded for barium, boron, zinc, vanadium, uranium, and arsenic. The barium content in pore water exceeds the strontium content by a factor of 10, which is anomalous with respect to the reservoir formation waters in the majority of oil fields and to the ocean water.  相似文献   

7.
ＡＮＥＮＩＧＭＡ :ＥＸＴＩＮＣＴＩＯＮＯＦＤＩＮＯＳＡＵＲＴｈｅｓｔｒａｔａｒｅｃｏｒｄｔｈｅｈｉｓｔｏｒｙｏｆｔｈｅｅａｒｔｈ .Ｅｖｅｒｙｓｃａｌｅｃａｔａｓ ｔｒｏｐｈｉｃｅｖｅｎｔａｌｌｋｅｐｔｓｏｍｅｔｒａｃｅｉｎｔｈｅｓｔｒａｔｕｍ .Ｍａｎｙｅｎｉｇｍａｓｃａｎｂｅｒｅｖｅａｌｅｄｔｈｒｏｕｇｈｔｈｅｃｈａｒａｃｔｅｒｓｏｆｓｔｒａｔａａｎｄｔｈｅｆｏｓｓｉｌｓｉｎｔｈｅｓｔｒａｔａ .ＴｈｅｅｘｔｉｎｃｔｉｏｎｏｆｄｉｎｏｓａｕｒｉｓｏｎｅｅｎｉｇｍａｈａｐｐｅｎｅｄｉｎｔｈｅＣｒｅｔ…  相似文献   

8.
Based on fission track dating of apatite, and measurement of vitrinite reflectance of rock samples from the Longmenshan (Longmen Mountain)area and the West Sichuan foreland basin and computer modelling it is concluded that (l)the Songpan-Garze fold belt has uplifted at least by 3-4 km with an uplift rate of no less than 0.3-0.4 mm/a since 10 Ma B.P.; (2) the Longmenshan thrust nappe belt has uplifted at least by 5-6 km with an uplift rate of more than 0.5- 0.6 mm /a since 10 Ma B.P.; (3) the Longmenshan detachment belt has uplifted by 1 - 2 km at a rate of 0.016-0.032 mm/a since 60 Ma B.P.; (4) the West Sichuan foreland basin has uplifted by 1.7-3 km at a rate of 0.028-0.05 mm/a since 60 Ma B.P.; (5) the uplift rate of the area on the west side of the Beichuan-Yingxiu-Xiaoguanzi fault for the last 10 Ma is 40 times as much as that on its east side; (6) the uplifting of the the Songpan - Garze fold belt and the subsidence of the West Sichuan foreland basin 60 Ma ago exhibit a mirro-image correlation, i.e  相似文献   

9.
Glancophane in Shuangjiang area, West Yunnan Province, supplies a chance for studying south segment of Lancangjiang tectonic zone. But people are at odds as to whether two-stage glaucophane exists or not, glaucophane is the result of dynamic metamorphism later, or indicates a high P/T metamorphic belt when Paleozoic Tethys Sea dosed. Authors discover in a recent research that there is only one-stage glaucophane in Shuangjiang area, and three blueschist belts are distributed near N-S-tending,and glaucophane in Shuangjiang area is related to the eastward subduction of Changning-Menglian basin.  相似文献   

10.
The paper presents the results of detailed paleomagnetic studies of the Paleogene-Neogene continental sediments stripped by borehole 8 in southwestern West Siberia (Russkaya Polyana district, Omsk Region), near the Kazakhstan frontier. According to the previous biostratigraphic data, the sediments under study formed from Rupelian to Ruscinian. The results of stepwise thermal demagnetization and alternating-field demagnetization were used to carry out a component analysis of natural remanent magnetization, which revealed characteristic (primary) remanent magnetization (ChRM). The compiled paleomagnetic section, which includes seven regional horizons and same-named formations (Oligocene Atlym, Novomikhailovka, and Zhuravka Formations and Neogene Abrosimovka, Beshcheul, Tavolzhan, and Novaya Stanitsa Formations), was compared with the Cenozoic polarity scale for the West Siberian Plate. This made it possible to assess the completeness of the geologic section of the Paleogene and Neogene continental sediments in borehole 8 and to record the magnetozones and their fragments missing from the magnetostratigraphic section (for some intervals, in absolute chronology). The comparison shows that the magnetostratigraphic section of the studied sediments at the edges of the Om’ basin is approximately twice shorter than that of the basin center.  相似文献   

11.
《Precambrian Research》2001,105(2-4):129-141
The Isua greenstone belt (Fig. 1) contains the oldest known, relatively well preserved, metavolcanic and metasedimentary rocks on Earth. The rocks are all deformed and many were substantially altered by metasomatism, but both the deformation and metasomatism were heterogeneous. Transitional stages can be seen from relatively well preserved primary volcanic and sedimentary structures to schists in which all primary features have been obliterated. Likewise different kinds, and different episodes, of metasomatic alteration can be seen that produced a diversity of different compositions and metamorphic mineral assemblages from similar protoliths. New geological mapping has traced out gradations between the best preserved protoliths and their diverse deformed and metasomatised equivalents. By this means, the primary nature of the schists that make up most of the Isua greenstone belt was reinterpreted, and a new map that better portrays the primary nature of the rocks has been produced. The previously mapped stratigraphy was found to be of little value in understanding the geology. Stratigraphic units were defined by different and diverse criteria, such as current composition, structure, metamorphic texture, and inferred protoliths. Much of this stratigraphy represents a misinterpretation of the primary nature of the rocks. The new work indicates that most of the Isua greenstone belt consists of fault-bounded rock packages, mainly derived from basaltic and high-Mg basaltic pillow lava and pillow lava breccia, chert–BIF, and a minor component of clastic sedimentary rocks derived from chert and basaltic volcanic rocks. A previously mapped, extensive, unit of felsic volcanic rocks was found to be derived from metasomatised basaltic pillow lava and pillow breccia intruded by numerous sheets of tonalite.  相似文献   

12.
Please refer to the attachment(s) for more details  相似文献   

13.
The traditional idea proposes that granites on the east and west coasts of the Pacific Ocean are different. According to field investigations of the geology of the western United States coupled with the authors' long-term studies on granites in South China, granites both in eastern China and in the western United States are similar.  相似文献   

14.
In this paper the results of magnetostratigraphic studies of the Upper Cretaceous penetrated by two wells (S-124 and S-114) drilled in the Tomsk structural-facies zone (Bakchar iron ore deposit) are presented. The obtained biostratigraphic data show that the sediments formed in the Campanian–Maastrichtian time interval. The high-temperature component of the remanent magnetization identified in the rocks allowed us to compile paleomagnetic columns for each well and correlate the columns, using paleontological data, with each other and with the general magnetostratigraphic and magnetochronological scales. In magnetostratigraphic sections of two wells, the Campanian reverse-polarity Slavgorod Formation (R(km)) with a normal-polarity horizon is correlated with Chron C33(r) (top) and C33(n) (bottom) of the Gradstein scale, and the Maastrichtian normal-polarity Gan’kino Formation with a thin reverse-polarity horizon (N(mt)) is correlated with Chron C30 of this scale.  相似文献   

15.
A collection of 235 samples were taken from 115 sites (representing a density of 1 sampling site ca. 130 km2) on rural soils derived from the major rock types in the southern Iberian Massif. The geochemical baselines of selected trace elements (As, Co, Cr, Cu, Ni, Pb and Zn) were determined on the < 2 mm soil fraction. The sampling sites were not directly influenced by external pollution. Soil geochemical baseline and threshold values were calculated for each element in two geologically different zones: the Ossa-Morena Zone (OMZ) and the South-Portuguese Zone (SPZ).  相似文献   

16.
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17.
Typomorphic features of native gold and its contents in complex Ti–Zr placers in the southern West Siberian Plain are reported. Three of the placers are of littoral-marine genesis, and two formed under conditions of an alluvial piedmont plain. Native gold from the studied Ti–Zr placers occurs mainly as flattened thin (?0.1 mm) particles which underwent mechanical action. It is marked by wide fineness variation and the abundance of a very fine (990–1000‰) variety. Most likely, this is chemically transformed clastogenic metal. The gold content of the productive bed (5–30 mg/m3 native gold and 8–140 ppb bulk gold) is consistent with the dispersion of heavy ore and accessory minerals during mechanical migration in water flows simultaneously with their concentration on geochemical barriers. The native-gold content of complex Ti–Zr placers shows a higher negative correlation with the primary source–placer distance than those of Ti and Zr minerals and a positive correlation with the degree of hydrodynamic reworking (gravity concentration) of transit terrigenous material. On the southern framing of the West Siberian Plain, some regions of northern Kazakhstan are promising for gold of complex Ti–Zr placers as well as fine- and thin-gold placers, gold-bearing weathering crusts, and primary gold deposits.  相似文献   

18.
INTRODUCTIONWestYunnanProvince ,locatedattheconjoinedre gionbetweenGondwanaandYangtzeblock ,isacollisionorogenicbeltduetoPaleozoicTethysSeaclosedinIndo Chinastage .Shuangjiangtectonicm啨ｌａｎｇｅｚｏｎｅｂｅｌｏｎｇｓｔｏｓｏｕｔｈｓｅｇｍｅｎｔｏｆＬａｎｃａｎｇｊｉａｎｇｔｅｃｔｏｎｉｃｚｏｎｅｉｎＬｉｎｃａｎｇShuangjiangarea .WestYunnanProvince ,composedofophioliteimplicatingresidualoceaniccrust,passive activecontinentalmarginsediments ,metamorphicbasementandcontinentalmarginarct…  相似文献   

19.
The West Spitsbergen Fold Belt, together with the Eurekan structures of northern Greenland and Ellesmere Island, are suggested to be the result of Late Cretaceous-Palaeocene intracontinental compressional tectonics. The Late Palaeozoic –Mesozoic rocks of western Spitsbergen are characterized by near-foreland deformation with ramp-flat, top-to-the east thrust trajectories, whereas structurally higher nappes involving Caledonian complexes are typified by more listric thrusts and mylonite zones. A minimum of 40 km of shortening is estimated for the northern part of the West Spitsbergen Fold Belt. The axial trends in the West Spitsbergen and the North Greenland Eurekan fold belts parallel the principal fault zones which accommodated the separation of Greenland and Svalbard after Chron 25/24. In northern Greenland, north directed Eurekan thrusts associated with mylonites and cleavage formation represent at least 10 km of shortening. Between 50 and 100 km of shortening is estimated for the markedly arcuate Eurekan Fold Belt of Ellesmere Island, but the principal tectonic transport is eastwards. Kinematic reconstructions suggest that Svalbard was linked to North America before the opening of the Eurasian Basin and Norwegian — Greenland Sea. In the Late Cretaceous — Palaeocene interval, the relative motion between Greenland and North America was convergent across the Greenland — Svalbard margin, giving rise to the West Spitsbergen Fold Belt and the Eurekan structures of North Greenland.  相似文献   

20.
Doklady Earth Sciences - The morphology of archaeocyaths from the Oldynda Formation of the Uda–Vitim lithofacial zone and the Aikta Formation of the Birami–Yanguda Zone of West...  相似文献   

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