Geochemistry of pyrite and chalcopyrite from an active black smoker in 49.6°E Southwest Indian Ridge

Active hydrothermal chimneys, as the product of submarine hydrothermal activity, can be used to determine the fluid evolution and formation process of potential volcanic-hosted massive sulfide deposits. A hard-won specimen from an active hydrothermal chimney was collected in the 49.6°E ultraslow-spreading Southwest Indian Ridge (SWIR) field through a television-guided grab. A geochemical study of prominent sulfide (e.g., pyrite and chalcopyrite) included in this sample was performed using laser ablation inductively coupled plasma mass spectroscopy. The early sulfides produced at low temperature are of disseminated fine-grained anhedral morphology, whereas the late ones with massive, coarse euhedral features precipitated in a high-temperature setting. The systematic variations in the contents of minor and trace elements are apparently related to the crystallization sequence, as well as to texture. Micro-disseminated anhedral sulfides rich in Pb, As, Ni, Ba, Mn, Mo, U, and V were formed during the initial chimney wall growth, whereas those rich in Sn, Se, and Co with massive, coarse euhedral morphology were formed within the late metallogenic stage. The hydrothermal fluid composition has experienced a great change during the chimney growth. Such a conclusion is consistent with that indicated by using principal component analysis, which is a powerful statistical analysis method widely used to project multidimensional datasets (e.g., element contents in different mineral phases) into a few directions. This distribution pattern points to crystallographic controls on minor and trace element uptake during chimney growth, occurring with concomitant variations in the fluid composition evolutionary history. In this pyrite-chalcopyrite-bearing active hydrothermal chimney at the SWIR, the metal concentration and precipitation of sulfides largely occurred at the seafloor as a result of mixing between the upwelling hot hydrothermal fluid and cold seawater. Over the course of mixing, significant variations in metal solubility were caused by changes in temperature, pH, and redox conditions in the parental fluid phase.     

The X-ray bursts within the 2010 outburst of the accreting millisecond X-ray pulsar SAX J1748.9-2021

With the observations from Rossi X-ray Timing Explorer, we search and study the X-ray bursts of accreting millisecond X-ray pulsar SAX J1748.9-2021 during its 2010 outburst. We find 13 X-ray bursts, including 12 standard type-I X-ray bursts and an irregular X-ray burst which lacks cooling tail. During the outburst, the persistent emission occurred at \(\sim (1\mbox{--}5)\%{\dot{\mathrm{M}}_{\mathrm{Edd}}}\). We use a combination model of a blackbody (BB), a powerlaw, and a line component to fit the persistent emission spectra. Another BB is added into the combination model to account for the emission of the X-ray bursts due to the thermonuclear burning on the surface of the neutron star. Finally, we modify the combination model with a multiplicative factor \(f_{\mathrm{a}}\), plus a BB to fit the spectra during the X-ray bursts. It is found that the \(f_{\mathrm{a}}\) is inversely correlated with the burst flux in some cases. Our analysis suggests that the ignition depth of the irregular X-ray burst is obviously smaller than those of the type-I X-ray bursts. We argue that the detected type-I X-ray bursts originate from helium-rich or pure-helium environment, while the irregular X-ray burst originates from the thermonuclear flash in a shallow ocean.     

迁居意愿、地方依赖和社区认同——北京中关村地区居住选择调查分析

迁居行为及其意愿反映了城市居民对美好生活的向往,揭示了城市居住环境是否能够满足居民的需要。论文从迁居意愿的视角,将地方依赖和社区认同引入迁居研究中,并采用问卷调查和访谈相结合的方法来分析城市居民的居住选择。运用Williams量表,在292份调查问卷和52份深度访谈的基础上,对北京中关村地区展开了调查研究。结果表明：中关村周边社区居民对就业和子女教育具有明显的地方依赖和较高的社区认同感。在292名被调查者中,共有115名居民有迁居意愿,占被调查者总数的39.4%。其中,在就业和子女教育地方依赖程度较低的调查人群中,这一比例分别上升至47.2%和54.2%。此外,有迁居意愿的居民大多社区认同感不高,在115名有迁居意愿的居民中,仅有4人对所在社区具有强烈认同感。论文从地方感的角度丰富了居住空间的研究内容,为理解当代城市居住空间的特点、提升城市空间建设质量提供了参考依据。     

The response of spiders to less-focused non-crop habitats in the agricultural landscape along the lower reach of the Yellow River

Journal of Geographical Sciences - Non-crop habitats have been suggested to impact local biodiversity significantly in agricultural landscapes. However, there have been few studies of the effects...     

SLDZ-1数字化地下流体多测项综合观测仪的研制及试验观测

介绍SLDZ-1数字化地下流体多测项综合观测仪的主要结构和工作原理,以及该仪器的技术指标和功能。根据水位、水温、H2、CO2和CH4的试验观测结果,发现各测项数据的连续性、准确性和稳定性均较强,说明该监测仪器适用于地震地下流体微观和宏观监测、调查与核实等领域。     

Characteristics of Carbonate Reservoir and Its Forming Conditions in Continental Lake Basin of China

For decades of exploration, geologists have made great achievements in the exploration of lacustrine carbonate rocks. By dissecting four typical cases of lacustrine carbonate rocks, such as Lucaogou Formation of Permian in Junggar Basin, Da'anzhai Section of Jurassic in Sichuan Basin, Cretaceous in Yin'e Basin and Oligocene in Qaidam Basin, the reservoir characteristics, hydrocarbon generating capacity and reservoir forming model of source rocks were analyzed. The results show that: \mathrm{①} Lacustrine carbonate reservoirs are generally dense, with nano-micron reservoir space as the main reservoir space, including dolomite intergranular pore, organism cavity and accumulation pore, micro-fracture system and its corrosion expansion pore. Saline environment is beneficial to dolomitization and can improve the reservoir capacity of lacustrine carbonate rocks, but most of the permeability is less than 0.1 mD. \mathrm{②} Lacustrine carbonate rocks have not only reservoir capacity, but also can be used as source rocks. The abundance of organic matter is not high and the maturity is generally low. However, dispersed soluble organic matter in source rocks can generate and expel hydrocarbons in large quantities at low maturity stage, which has high liquid hydrocarbon yield. \mathrm{③} Oil and gas reservoirs are characterized by "high initial production, large reduction of production and long-term low and stable production", and are typical "fracture-pore" reservoirs. Fracture networks provide migration pathways in the process of primary migration and accumulation of oil and gas in geological history and oil and gas exploitation nowadays. \mathrm{④} Oil and gas reservoirs are "continuous" unconventional reservoirs, which often form regional oil and gas field groups together with conventional reservoirs in adjacent areas. The research results lay a theoretical foundation for re-evaluating the exploration potential of lacustrine carbonate rocks.     

Zircon saturation model in silicate melts: a review and update

Zircon stability in silicate melts—which can be quantitatively constrained by laboratory measurements of zircon saturation—is important for understanding the evolution of magma. Although the original zircon saturation model proposed by Watson and Harrison (Earth Planet Sci Lett 64(2):295–304, 1983) is widely cited and has been updated recently, the three main models currently in use may generate large uncertainties due to extrapolation beyond their respective calibrated ranges. This paper reviews and updates zircon saturation models developed with temperature and compositional parameters. All available data on zircon saturation ranging in composition from mafic to silicic (and/or peralkaline to peraluminous) at temperatures from 750 to 1400 °C were collected to develop two refined models (1 and 2) that may be applied to the wider range of compositions. Model 1 is given by lnC_Zr(melt) = (14.297 ± 0.308) + (0.964 ± 0.066)·M − (11113 ± 374)/T, and model 2 given by lnC_Zr(melt) = (18.99 ± 0.423) − (1.069 ± 0.102)·lnG − (12288 ± 593)/T, where C_Zr(melt) is the Zr concentration of the melt in ppm and parameters M [= (Na + K + 2Ca)/(Al·Si)] (cation ratios) and G [= (3·Al₂O₃ + SiO₂)/(Na₂O + K₂O + CaO + MgO + FeO)] (molar proportions) represent the melt composition. The errors are at one sigma, and T is the temperature in Kelvin. Before applying these models to natural rocks, it is necessary to ensure that the zircon used to date is crystallized from the host magmatic rock. Assessment of the application of both new and old models to natural rocks suggests that model 1 may be the best for magmatic temperature estimates of metaluminous to peraluminous rocks and that model 2 may be the best for estimating magmatic temperatures of alkaline to peralkaline rocks.

     

金伯利岩的卫星影像识别标志及应用实例

金刚石矿是我国的急缺矿种,具有很高的工业价值和经济价值。但是,过去的 50 年中国在寻找金刚石矿上始终没有取得突破。在科学理解金伯利岩火山地貌形态的基础上,利用卫星影像识别技术,建立一个地区金伯利岩的卫星影像识别标志,能够在金刚石矿靶区范围内有效地缩小目标。这些都是要建立在野外和室内的反复认证的基础之上。本文以世界著名的博兹瓦纳境内两个著名的金刚石矿,结合山东临沂和湖南常德地区的具体实例来推断金伯利岩的存在。在寻找金伯利岩时,理解金伯利质火山是玛珥-管道火山体是寻找金伯利质火山管道的基础,重视对低平圆形地质体成因的研究,建立一个地区的小型圆形地质体的卫星影像识别标准是一个野外和室内反复验证和积累经验的过程。     

淮南煤田刘庄煤矿深部煤层气地质特征

为了查明刘庄煤矿深部煤层气赋存及开发地质条件,在井田内实施了两口煤层气探井,并开展了系统的分析测试工作。结果表明:刘庄深部勘查区主要煤层孔隙度一般为4.14%~4.77%,比表面积集中在2.184~5.228m 2/g,13-1煤层、11-2煤层和8煤层试井渗透率分别为0.12mD、0.09mD和0.08mD,孔裂隙系统发育一般,属于渗透性差的储集层;储层压力梯度大于静水压力梯度,属高异常压力范畴;主要煤层兰氏压力平均为2.61MPa,兰氏体积平均为6.74m 3/t,吸附能力较低;LT-1井气测录井过程中共出现14层气测异常,异常层段全烃含量均较低,最大为3.701%(16-1煤);主要煤层的含气量分布在0.21~1.47m 3/t,平均0.65m 3/t,主要煤层含气饱和度均很低,最大值仅为18.0%。综合分析认为,刘庄煤矿深部主要煤层埋深大,孔裂隙系统发育差,渗透率低,而且具有低含气量和低饱和度的特征,煤层气勘探风险较高。     

Experimental study on the pile group-soil vibration induced by railway traffic under the inclined bedrock condition

Acta Geotechnica - The aim of this paper is to study the soil vibration response of a pile group induced by train traffic resting on the inclined bedrock condition. A series of model tests on the...