18 December 2014, Volume 32 Issue 35

    

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  Importance of Salt Studies in Planetary Science

  KONG Weigang, ZHENG Mianping

  Science & Technology Review. 2014, 32(35): 15-21. https://doi.org/10.3981/j.issn.1000-7857.2014.35.001

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  Salts were found on Mars, Europa, and Enceladus, and were indicated to exist on Ganymede, Callisto, thus the salts might be common on planetary bodies. Salt studies are, therefore, important for the planetary science. First, the spectroscopic studies of salts serve references for the phase identifications by the analysis of the mission data, and the stability properties of salts can help identify the possible salt phases when the mission data do not give clear indications. Second, salts are the products of interaction between spheres of a planet, thus studies of planetary salts can provide rich information on the geological history of a planet. On the basis of their different origins, salt studies can help understanding the planetary interior, the surface aqueous processes, and the atmosphere. In addition, the origin of salts is the foundation for life occurrence, thus the planetary salt studies are one of the key steps for searching extraterrestrial life. Since 2008, Chinese scientists have carried out analogue studies on Martian salts, thus in this paper, we make a brief review of the analogue studies in the world.
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  Canonical Correspondence Analysis for Distribution of Extant Ostracodes and Environmental Factors in the South of Northern Tibet

  SONG Gao, WANG Hailei, ZHENG Mianping

  Science & Technology Review. 2014, 32(35): 22-28. https://doi.org/10.3981/j.issn.1000-7857.2014.35.002

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  Canonical correspondence analysis (CCA) is a direct sequencing method which can reflect the relationship among communities, distributions of species and environment factors in a simple way, and be used to study the relationship between the biology distribution and the environment factors effectively. It has been used in the biology and the ecological environment widely. In this paper, 49 surface sediment samples are collected to study the ecological distribution of extant ostracodes and their environmental implications for water bodies in south of northern Tibet in 2012. Total of 10 genera and extant ostracodes of 22 species are identified, among which, Limnocythere dubiosa, Ilyocypris bradyi and Candona candida are the common species with high occurrence frequency of 19, 13 and 9, respectively in Ali and Naqu regions, Tibet. CCA reveals a correlation coefficient of more than 80% between the extant ostracodes distribution and the eight environmental factors, suggesting that the distribution of many species is highly related to environmental changes. Among eight environmental factors, the conductivity, the pH value and the nitrite content are the most affective variables on the species occurrence. Eucypris rischtanica, Leucocythere dilitata, Cypricercus moguntiensis and Limnocytherellina kunlunensis have relatively strong adaptability to the water environment. The high occurrence frequency of Leucocythere postericosta, Limnocytherellina bispinosa and Candona houae corresponds to a high water conductivity and nitrite content, as the distribution of these species positively correlates with the water conductivity and the nitrite content, suggesting that the three species are good indicators for the water conductivity and the nitrite content. On the other hand, Ilyocypris bradyi and Candona candida are good indicators for the low conductivity. As for Limnocythere dubiosa, the most frequently occurred ostracode in Ali and Naqu regions, is a good indicator for the high pH value.
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  Lake Level Changes Indicated by Grain-size of Core SL-1 Sediments Since 5.33 ka BP in Selin Co, Central Qinghai-Tibetan Plateau

  WANG Hailei, ZHENG Mianping

  Science & Technology Review. 2014, 32(35): 29-34. https://doi.org/10.3981/j.issn.1000-7857.2014.35.003

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  This paper studies the chronology and the grain-size of core sediments retrieved from deep area of Selin Co, central Qinghai-Tibetan Plateau (QTP), to reconstruct the lake level changes since 5.33 ka BP. Lake level changes of Selin Co are in several distinct stages: 5.33-4.25 ka BP sees a continuous high lake level with tiny fluctuations; the lake level goes down during the period of 4.25-2.20 ka BP, and the wind contributes much to the sedimentary of Selin Co; 2.20-1.90 ka BP is a stable low lake level period; 1.90 ka BP-present sees a high lake level since 5.33 ka BP with several short and fast fluctuations. 0.1 ka and 0.2 ka cycles are recovered during this period. The low lake level usually lasts for only 20-50 a. The 0.20 ka cycle, which can also be seen in the temperature sequence recorded in the ice core from the QTP, goes through the whole period since 5.33 ka BP, indicating that on the centennial scale, the air temperature is important for the lake level variations of Selin Co.
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  Late Holocene Climatical and Environmental Evolutions Inferred from Mineralogical Records in Selin Co, Central Qinghai-Tibetan Plateau

  LIN Yongjie, ZHENG Mianping, WANG Hailei

  Science & Technology Review. 2014, 32(35): 35-40. https://doi.org/10.3981/j.issn.1000-7857.2014.35.004

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  The X-ray diffraction (XRD) analysis of the core SL-1, collected from Selin Co, the climate sensitive regions in the central Qinghai-Tibetan Plateau, reveals that the minerals in the core mainly include aragonite, calcite , hydromagnesite, dolomite, gypsum and clastic materials such as quartz, muscovite, chlorite, feldspar, etc.. Based on the mineralogy of the sediments, three climate evolution stages are identified in Selin Co area since 5090 a BP, i.e. , 5090-2900 a BP; 2900-1135 a BP; 1135-0 a BP. The climate was changed from cool dry at 5090-2900 a BP to cold dry 1135 a BP-present, with a transition during 2900-1135 a BP. Meanwhile, several cold events are also retrieved in the late Holocene, according to the accumulation of hydromagnesite in the lower part of the core.
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  Cambrian Salt- forming Environment in Northeastern Sichuan Basin and Its Significance for Finding Potash

  WANG Shuli, ZHENG Mianping

  Science & Technology Review. 2014, 32(35): 41-49. https://doi.org/10.3981/j.issn.1000-7857.2014.35.005

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  Cambrian evaporites are in a wide distribution and the brine with high salinity was found in northeastern Sichuan basin. The thick layer of halite and gypsum in Qinjiamiao formation of Middle Cambrian was found in Jiannan area. Well Jianshen 1 encounters the thick halite layer, with accumulative thickness of up to 120 m, with thin-bedded gypsum, and with the single –layer thickness of halite reaching a maximum of 80 m (might be thickened by squeezing), which overturns the previous conclusion that this area has not reached the halite deposition stage. The bromine to chlorine ratio is analyzed for halite debris (it is not easy to determine whether the halite debris is primary or secondary) and the Br × 10³/Cl value ranges mostly from 0.05 to 0.22, indicating that the seawater has not reached the stage of sylvite deposition. Comparing the percentages of the water-soluble and acid-soluble potassium ions, the potassium ion content of acid-soluble is found to be about 1.3-2.0 times higher than that of the water-soluble, and this may because the rock salt debris contains water insoluble potassium-bearing minerals. There are several wells that encounter the high salinity brine in northeastern Sichuan basin, with the K⁺, Br^-, and Li⁺ concentrations up to 4.6 g/L, 886 mg/L and 148 mg/L, respectively for well Tian 2 in Wuxi. In addition, this study reveals that the high Li⁺ content in the brine is neither from the concentration of sea water, nor from the leaching of salts. It may be related to the water/rock interaction, the volcanic activity or other hot water of deep sources. A comprehensive evaluation of sylvinite forming conditions in this area and the wide distribution of Cambrian salt-bearing basins in Asia indicate that the exploration in this area should be strengthened in the future.
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  Characteristics and Forming Process of Juhongtu Boron Deposit in Yashatu, Qinghai Province

  QI Lujing, ZHENG Mianping, WU Guopeng, ZHANG Xuefei, DU Shaorong

  Science & Technology Review. 2014, 32(35): 50-60. https://doi.org/10.3981/j.issn.1000-7857.2014.35.006

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  The situation of boron resources is not promising in our country, so it is urgent to find alternative exogenous boron deposits. The Huke basin is located in the northern edge of the Qaidam basin, belonging to a "resource prospecting" area. The NWNWW Piedmont thrust and the NE fault control the formation and the distribution of the boron deposits and the mineralization points in Juhongtu and surrounding areas. The regional rock, the sedimentary and the water content have obvious positive anomalies of B, and the water is rich in B, Li and poor in Br, I, and the Σ^Ce Σ^Y ratio is close to that of the earth's crust, reflecting that the metallogenic source comes from the groundwater and the boron source rock. From the Juhongtu boron ore and the typical exogenous boron deposit, it is found that the boron ore is distributed in the upper Pleistocene series on fine grained sediments, reflecting stable sedimentary environments; the sediments show a positive change in the portrait with the granularity of clastic particle size from coarse to fine, the change of B₂O₃ containing grades from low to high and the change of the depression from the center to the edge. The strata thickness is gradually punched out from the middle to the sides. It is the first time to show that the deposit is formed in the late Pleistocene, 28 ka BP; the silicon is transformed into low temperature quartz and C opal and dilute alkali elements Li > Rb > Cs, which shows that the sinter has undergone a long-term "dehydration". Based on the carbonate sediment isotope and XRD analysis, the Juhongtu boron ore forming process is divided into three stages: I-early silicon tufa deposition stage; II- the lower boron ore initial sedimentary stage; and III-main boron ore deposition stage. The study of the formation mechanism of boron deposits in Qilian mountain area helps understanding of metallogenic processes.
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  Simulation Experiments on the Uraniferous Possibility of Peripheral Rock Series and Sediment from Gasikule Salt Lake, Western Qaidam Basin

  YE Chuanyong, WANG Zhiming, ZHENG Mianping, HAO Weilin, LIN Xiaobin, HAN Jun

  Science & Technology Review. 2014, 32(35): 61-70. https://doi.org/10.3981/j.issn.1000-7857.2014.35.007

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  In order to explore the uraniferous possibility in different parts of China, the leaching experiments of peripheral rock series and the equilibration experiment of sediment from Gasikule Salt Lake located in the western margin of Qaidam Basin are conducted in this paper. It is shown that the leachate has similar hydrochemical characteristics of three types of rock series (old strata, Pliocene salt-bearing strata and Quaternay sediment) around Gasikule Salt Lake. The hydrochemistry of Gasikule Salt Lake basin is deeply influenced by peripheral rock series and characterized by re-dissolved salt obviously. Three types of rock series suffer severely from eluviations, and the leaching trend is in the order of Quaternay sediment > Pliocene salt- bearing strata > old strata. In the equilibration experiment, the uranium concentration in the suspension decreases first and then slowly increases against the balance time. However, the uranium concentration in the sediments sees a reverse trend, which illustrates that the uranium has a rapid exchange between the suspension and the sediment. The uranium in the suspension absorbed by the sediment may be accounted for the decrease of the uranium concentration in the suspension at the first stage of the equilibration experiment. During Neogene and early Quarternary, the uranium in Gasikule Salt Lake's brine and sediment mainly comes from the chemical weathering in the peripheral old strata. However, the Pliocene salt-bearing strata and the deep water contain the majority of uranium sources during late Quaternary, coupled with sediment and old strata weathering, this period enjoys larger uranium supplementary amount than that in the periods of Neogene and early Quarternary.
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  Characteristics and Resource Prospection of Hydrocarbon Source Rocks in Ordovician Salt-bearing Strate in Ordos Basin, China

  XING Enyuan, ZHANG Yongsheng, SU Kui, PAN Wei, JIANG Suyang

  Science & Technology Review. 2014, 32(35): 72-77. https://doi.org/10.3981/j.issn.1000-7857.2014.35.008

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  The sedimentary environment of salt-bearing strate is more advantageous than the source rock, and there are many kinds of other minerals. The vertical continuous 551 hydrocarbon source rock continuous geochemical data for Well Zhenjia1 are obtained by the pyrolysis experiments, and by the degradation ratio method after restoring the organic carbon, combined with a comprehensive analysis of the single well facies display, it is shown that the geochemical indicators of Majiagou Formation source rock in Well Zhenjia1 are in overall low,a part of the samples are in normal- good level, mostly in the 5^th Majiagou member. The organic abundance as well as the TOC averaged value are 0.18%, the TOC of the 2^nd Majiagou member is the highest, with the average value of 0.28%, and the 5^th Majiagou member has the highest value of 1.04%. The types of organics in Well Zhenjia1 are mainly type III kerogen, with type I and II kerogen, distributed in the M₄ and M₅ in the source rock in some parts of the well. On the whole, the maturity of the source rock of Majiagou Formation is over-high, and the main production is gas. The lagoon facies is most conducive to the development of hydrocarbon source rocks, and the open platform facies takes the second place. Relatively high TOC value is usually seen in the dark grey micritic limestone-(gypsum) penecontemporaneous gray dolomite-in smoke gray halite evaporation cycle, which is a common phenomena in the 5^th Majiagou member. With respect to the vertical variation characteristics of organic parameters of hydrocarbon source rocks, it is shown that the 5^th Majiagou member is the most favorable strata for development of source rocks, at the same time, this layer is also the most favorable strata for potash and halite deposits. Coupling of multiple potential mineral resources indicate that the 5^th Majiagou member is a favorable metallogenic strata for gas, halite and potash, which provides some hints for future investigations of mineral resources.
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  Sequence Variations of the Maize ELM1 Gene and Their Association with Plant Types and Ear Traits

  YANG Zefeng, ZHANG Enying, XU Shuhui, MAO Beili, PAN Liang, CHEN Qing, XU Chenwu

  Science & Technology Review. 2014, 32(35): 78-84. https://doi.org/10.3981/j.issn.1000-7857.2014.35.009

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  With the deficiency of the synthesis for the phytochromechromophore in the maize elm1 mutant, the phytochrome activity might be reduced and the mutant plant might show characteristics of light insensitivity. In order to reveal the nucleotide polymorphisms in the maize ELM1 gene and their associations with important agronomic traits, the sequences of the maize ELM1 gene are captured in 80 inbred lines in the present study, and the associations between the sequence variations of this gene and 2 plant types (including plant height and ear height) and 7 ear traits (ear length, ear diameter, cob diameter, ear weight, kernels per row, rows per ear and kernels per ear) are determined. A total of 85 variants, including 73 SNPs and 12 indels, are detected from the full sequences of this gene in the tested inbred lines. Although in the coding regions, the indel is not included, with the SNPs of CDS sequences, the maize ELM1 gene can be classified into 7 haplotypes, which encode 6 different ELM1 proteins. There are significant differences among inbred lines for all 9 plant types and ear traits. According to the results of the association analysis, one nonsynonymous SNP is found to be associated with the ear height, while two other nonsynonymous SNPs are associated with the kernels per row.