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561.
Mn3O4was prepared with the chemical bath deposition(CBD) method. A Mn SO4 solution was obtained by the leaching and purifying of low-grade rhodochrosite ore(LGRO), which was used as raw material. The prepa ration procedures were studied and promoted. The result showed that the Mn3O4 with the highest purity and highes specific surface area could be obtained under the following processes. An Mn SO4 solution of 1.0 mol/L was added into a beaker under a flow rate of 30 m L/h. The p H of the reaction solution was adjusted to 10 using NH3 H2 O a80 °C. Then the solids were washed and dried at 200 °C fo2.5 h. The total Mn content(TMC) of Mn3O4 was 72.0 %The ionic distributions was formulated as [Mn2?[Mn2??0.3024Mn30.2937Mn4?h0.37860.0254]2O4. The average crys tallite size of Mn3O4 with a tetragonal hausmannite struc ture was found to be about 35 nm by X-ray diffraction(XRD) analysis. The BET specific surface area of the Mn3O4 measured was 32 m2/g. 相似文献
562.
<正>Dabashan complex tectonic belt is located in the junction of the Yangtze plate and North China plate,which is the composite products of the Indo-Chinese epoch,Yanshan epoch,Himalayan epoch thrust nappe.Experiencing multiphase complex structural movement,the tectonic belt has been regarded as a forbidden zone in the oil and gas exploration.And it is also a blank area of oil 相似文献
563.
Ecological patterns and processes in dune ecosystems have been a research focus in recent years, however information on how dune stabilization influences vegetation and soil at different spatial scales... 相似文献
564.
We selected four typical glaciers in the Qilian Mountains and investigated their movements and variation using advanced technologies such as remote sensing,photographic measurements,and global positioning systems.The velocity of glacier movements in the Qilian Mountains is relatively low,and there has been no significant variation during the past 50 years.Glacier motion has maintained a normal style.The movement velocity of Laohugou Glacier No.12 presented a decreasing trend(by 48%) from 1960 to 2012.The movement velocity of the Qiyi Glacier also presented a decreasing trend(by 48.1%) from 1958 to 2012; it decreased by 29.4% from 1958 to 1977 and by 26.5% from 1977 to 2012.Therefore,the Qiyi Glacier's movement velocity varied greatly over the earlier 20 years(1958–1977),but presented a small decreasing trend during the latter 30 years(1977–2012).By comparing the movement velocity variation of these typical glaciers,we determined that the extent of variation was consistent among large glaciers(such as Laohugou Glacier No.12) and small glaciers(such as the Qiyi Glacier and Yanglonghe Glacier No.5),despite their different sizes. 相似文献
565.
Hydraulic fracture (HF) propagation behavior is signi?cant when building enhanced geothermal systems (EGS). HF geometry is closely related to the structural planes (SPs) in hot dry rock (HDR), such as natural fractures (NFs), quartz veins (QVs) and lithologic interfaces (LIs). However, the HF behaviors in HDR have not been well understood, especially the influence of multiple SPs on the HF geometry. To clarify this mechanism, several groups of physical simulation experiments of hydraulic fracturing were conducted to investigate the intersection relationship between the HFs and the SPs. Results show that the HF geometry shows great differences when intersecting with different SPs. In summary, the HF geometry displays four basic patterns, namely, propagation along the SPs, branching, capture, penetration/non-dilation. The fluctuation degree of the pressure-time curve and the HF complexity show a positive correlation. The cementing strength of the SP and their different mechanical properties from rock matrix influence the HF behaviors significantly. Therefore, the HF shows diverse geometries when intersecting with the NFs and LIs, while propagating along the QV when intersecting with it. For the complex networks, it is favorable for the HF to penetrate through and dilate several SPs, rather than simply cross or propagate along the SP. 相似文献
566.
567.
In situ terrestrial cosmogenic nuclide (TCN) exposure dating using 10Be is one of the most successful techniques used to determine the ages of Quaternary deposits and yields data that enable the reconstruction of the Quaternary glacial history of the Tibetan Plateau and the surrounding mountain ranges. Statistical analysis of TCN 10Be exposure ages, helps to reconstruct the history of glacial fluctuations and past climate changes on the Tibetan Plateau, differences in the timing of glacier advances among different regions. However, different versions of the Cosmic‐Ray‐prOduced NUclide Systematics on Earth (CRONUS‐Earth) online calculator, which calculates and corrects the TCN ages of Quaternary glacial landforms, yield different results. For convenience in establishing contrasts among regions, in this paper, we recalculate 1848 10Be exposure ages from the Tibetan Plateau that were published from 1999 to 2017 using version 2.3 of the CRONUS‐Earth calculator. We also compare the results obtained for 1594 10Be exposure ages using different versions (2.2, 2.3 and 3.0) of the CRONUS‐Earth calculator. The results are as follows. (1) Approximately 97% of the exposure ages are less than 200 ka. A probability density curve of the exposure ages suggests that greater numbers of oscillations emerge during the Holocene, and the peaks correspond to the Little Ice Age, the 8.2 ka and 9.3 ka cold events; the main peak covers the period between 12 and 18 ka. (2) In most areas, the newer versions of the calculator produce older 10Be exposure ages. When different versions of the CRONUS‐Earth calculator are used, approximately 29% of the 10Be exposure ages display maximum differences greater than 10 ka, and the maximum age difference for a single sample is 181.1 ka. 相似文献
568.
569.
LI Yilong WANG Guoqing XIAO Wenjiao ZOU Jing ZHENG Jianping Fraukje M. BROUWER 《《地质学报》英文版》2019,93(5):1228-1260
The Solonker suture zone has long been considered to mark the location of the final disappearance of the PaleoAsian Ocean in the eastern Central Asian Orogenic Belt(CAOB). However, the time of final suturing is still controversial with two main different proposals of late Permian to early Triassic, and late Devonian. This study reports integrated wholerock geochemistry and LA-ICP-MS zircon U-Pb ages of sedimentary rocks from the Silurian Xuniwusu Formation, the Devonian Xilingol Complex and the Permian Zhesi Formation in the Hegenshan-Xilinhot-Linxi area in central Inner Mongolia, China. The depositional environment, provenance and tectonic setting of the Silurian-Devonian and the Permian sediments are compared to constrain the tectonic evolution of the Solonker suture zone and its neighboring zones. The protoliths of the silty slates from the Xuniwusu Formation in the Baolidao zone belong to wacke and were derived from felsic igneous rocks with steady-state weathering, poor sorting and compositional immaturity. The protoliths of metasedimentary rocks from the Xilingol Complex were wackes and litharenites and were sourced from predominantly felsic igneous rocks with variable weathering conditions and moderate sorting. The Xuniwusu Formation and Xilingol Complex samples both have two groups of detrital zircon that peak at ca. 0.9–1.0 Ga and ca. 420–440 Ma, with maximum deposition ages of late Silurian and middle Devonian age, respectively. Considering the ca. 484–383 Ma volcanic arc in the Baolidao zone, the Xuxiniwu Formation represents an oceanic trench sediment and is covered by the sedimentary rocks in the Xilingol Complex that represents a continental slope sediment in front of the arc. The middle Permian Zhesi Formation metasandstones were derived from predominantly felsic igneous rocks and are texturally immature with very low degrees of rounding and sorting, indicating short transport and rapid burial. The Zhesi Formation in the Hegenshan zone has a main zircon age peak of 302 Ma and a subordinate peak of 423 Ma and was deposited in a back-arc basin with an early marine transgression during extension and a late marine regression during contraction. The formation also crops out locally in the Baolidao zone with a main zircon age peak of 467 Ma and a minor peak of 359 Ma, and suggests it formed as a marine transgression sedimentary sequence in a restricted extensional basin and followed by a marine regressive event. Two obvious zircon age peaks of 444 Ma and 280 Ma in the Solonker zone and 435 Ma and 274 Ma in Ondor Sum are retrieved from the Zhesi Formation. This suggests as a result of the gradual closure of the Paleo-Asian Ocean a narrow ocean sedimentary environment with marine regressive sedimentary sequences occupied the Solonker and Ondor Sum zones during the middle Permian. A restricted ocean is suggested by the Permian strata in the Bainaimiao zone. Early Paleozoic subduction until ca. 381 Ma and renewed subduction during ca. 310–254 Ma accompanied by the opening and closure of a back-arc basin during ca. 298–269 Ma occurred in the northern accretionary zone. In contrast, the southern accretionary zone documented early Paleozoic subduction until ca. 400 Ma and a renewed subduction during ca. 298–246 Ma. The final closure of the Paleo-Asian ocean therefore lasted at least until the early Triassic and ended with the formation of the Solonker suture zone. 相似文献
570.
Generally, nutrient cycle is closely related to the element distribution in biomass and the population dynamics in ecosystems. Carbon, nitrogen and phosphorus in Japanese anchovy (Engraulis japonicus) of different body lengths from the Huanghai Sea (Yellow Sea) were determined to better understand their variability and reasons during its life history. The mean content was 45.12%, 10.12% and 2.02% for C, N and P, respectively. Significant differences in C, N and P elemental composition were found among different sizes, which could be explained by varying proportions of storage compounds in whole body fish, and varying degrees of ossification. Considering abundant resources in Japanese anchovy, it was an important P-pool in the cycle of P. Moreover, the excreted N/P ratio was significantly different in fishes of different sizes, especially at high gross growth efficiency. In the past two decades, overexploitation tended to cause smaller body length in the community structure of anchovy, which presumably changed the nutrient cycle in food webs of the Huanghai Sea. Exptrapolation of the results indicates that Japanese anchovy may be important for conveying nutrient in the Huanghai Sea. 相似文献