Eocene oil shales from Jordan – Paleoenvironmental implications from reworked microfossils

Reworked microfossils, common in Paleogene sediments in Jordan, are here used to reconstruct the depositional environment. The reworked taxa, which include both calcareous nannofossils and foraminifera of Cretaceous and Paleocene age, were found in Eocene oil shales. The potential provenance of the reworked material and the underlying processes of the reworking are discussed. We differentiate between a subaerial erosion of exposed hinterland strata and a submarine abrasion of sediments.A total of 73 smear slides have been prepared to identify calcareous nannofossils, another fifteen samples were analyzed for foraminifera. The allochthonous calcareous nannofossil and foraminifera taxa can be linked to a lithified source, which was eroded and transported with both calcitic lithic fragments and organic matter. Multiple factors controlling the transport of the reworked taxa during the time of deposition have been investigated for the Jordanian oil shales. Climate changes are thought to be the cause for changes in the abundance patterns and in the composition of the reworked taxa. The input of common autochthonous components during arid phases and more allochthonous sediment particles during humid periods filled the Eocene sink. A fall in relative sea level, perhaps in combination with increased storm activity, caused a transport of reworked material to deeper parts of the Azraq Hamza Sub-basin. The relative sea level changes in turn were related to syndepositional movements, redefining the shape of the Azraq Hamza Sub-basin and its internal fault-block architecture.     

长白山区暗棕壤成土作用地球化学特征

以代表性暗棕壤垂直剖面土壤地球化学数据为依据,研究了长白山区特定的森林景观条件下成土过程中元素的分异与富集特征。研究结果表明,在岩石风化过程中主要以CaO、Na2O、Sr淋溶为主,有机酸淋溶过程中SiO2、Al2O3、K2O部分被淋溶,部分游离铁下渗到土体中下部氧化成铁锰胶膜;微量元素在风化过程中被次生黏土矿物吸附,不同程度地富集,在腐殖质积累过程中Cd、Zn、Pb、Mo、Hg、Co、Mn、Cr等亲生物元素进一步富集于表层土壤,Ce、Ni、Sb、Ti、V、Y、Zr在表生环境中地球化学性质稳定,残留富集于土壤表层。母质层继承和保留了基岩元素地球化学分布的基本特征。     

湖南锡田岩体的岩浆混合成因:岩相学､岩石地球化学和U-Pb 年龄证据

南岭中段的锡田岩体燕山期岩石以斑状黑云母二长花岗岩为主,岩体中广泛发育暗色微粒包体?暗色微粒包体为岩浆结构,大多数具有塑性外形,发育淬冷边?反向脉,存在多种不平衡结构和矿物组合,如钾长石环斑?石英眼斑?针状磷灰石等,显示岩浆混合特征?岩石地球化学方面,暗色微粒包体具有比寄主岩贫硅?贫碱,富K?Fe?Mg?Ca?Ti 特征;暗色微粒包体及寄主岩富集轻稀土元素(LREE/HREE=2.6~8.8),具有中-强的铕负异常(δEu=0.09~0.74)以及具有相似的稀土元素配分曲线和微量元素蛛网图;在主要氧化物含量Harker 图解中投点多呈直线变异趋势,反映了两者具有密切的亲缘关系,利用共分母和不共分母图解进行判别,暗色微粒包体与寄主岩具岩浆混合特征,在MgO-TFeO判别图解中也指示包体为岩浆混合成因?上述岩相学和元素地球化学特征表明暗色微粒包体是基性岩浆侵入到酸性岩浆中淬冷形成的,指示锡田岩体存在两种岩浆的混合作用?通过LA-ICP-MS锆石U-Pb 定年,得到寄主岩形成年龄(150.04±0.52)Ma,暗色包体形成年龄(145.09±0.63)Ma,二者年龄在测试误差范围内一致,显示岩浆混合作用发生的时间大致为晚侏罗世?     

Microbial Processes in Stratified Lake Doroninskoe(Transbaikal Region)

正In recent decades,meromictic ponds attract the attention of researchers in different directions,because here the character of the physical,chemical and biological processes differ from those of typical mixing waters(Kuznetsov,1970;Hutchinson,1969).In Transbaikalia widely distributed soda and salt lakes with different salinity.Notable among them is Lake Doroninskoye,which has a pronounced stratification for a     

墨绿色仿翡翠品的宝石学特征

我国玉器市场的繁荣发展,使得玉器优劣并存,导致大量墨绿色“石材”充斥市场,充当翡翠销售.在广东玉器加工批发集散市场上收集了多种墨绿色仿翡翠原料,挑选具有代表性的4件原料进行测试分析.通过宝石显微镜观察、折射率、密度以及红外光谱、X射线粉末衍射、偏光显微镜薄片鉴定等测试方法进行对比研究.该4件样品的密度、折射率与翡翠一致,红外反射光谱与绿辉石非常相似,但其结构特征、矿物组成明显区别于翡翠.综合国标判定,该4件样品均为仿翡翠品.笔者提醒,常规宝石学测试和红外光谱测试不易区分此类制品,而加强基础性研究、提高镜下鉴定能力是防范检测风险的有效途径.     

Evolution of the mass function of dark matter haloes

We use a high-resolution ΛCDM numerical simulation to calculate the mass function of dark matter haloes down to the scale of dwarf galaxies, back to a redshift of 15, in a  50 h ⁻¹ Mpc  volume containing 80 million particles. Our low-redshift results allow us to probe low-σ density fluctuations significantly beyond the range of previous cosmological simulations. The Sheth & Tormen mass function provides an excellent match to all of our data except for redshifts of 10 and higher, where it overpredicts halo numbers increasingly with redshift, reaching roughly 50 per cent for the  10¹⁰–10¹¹ M_⊙  haloes sampled at redshift 15. Our results confirm previous findings that the simulated halo mass function can be described solely by the variance of the mass distribution, and thus has no explicit redshift dependence. We provide an empirical fit to our data that corrects for the overprediction of extremely rare objects by the Sheth & Tormen mass function. This overprediction has implications for studies that use the number densities of similarly rare objects as cosmological probes. For example, the number density of high-redshift  ( z ≃ 6) QSOs  , which are thought to be hosted by haloes at 5σ peaks in the fluctuation field, are likely to be overpredicted by at least a factor of 50 per cent. We test the sensitivity of our results to force accuracy, starting redshift and halo-finding algorithm.     

Constraining the cosmological baryon density with X-ray clusters

We study the properties of X-ray galaxy clusters in four cold dark matter models with different baryon fractions Ω_BM, ranging from 5 to 20 per cent. By using an original three-dimensional hydrodynamic code based on the piecewise parabolic method, we run simulations on a box with a size of 64  h ⁻¹ Mpc and we identify the clusters by selecting the peaks in the X-ray luminosity field. We analyse these mock catalogues by computing the mass function, the luminosity function, the temperature distribution and the luminosity–temperature relation. By comparing the predictions of the different models to a series of recent observational results, we find that only the models with low baryonic content agree with the data, while models with larger baryon fraction are well outside the 1σ error bars. In particular, the analysis of the luminosity functions, both bolometric and in the energy band [0.5–2] keV, requires Ω_BM ≲ 0.05 when we fix the values h  = 0.5 and n  = 0.8 for the Hubble parameter and the primordial spectral index, respectively. Moreover we find that, independently of the cosmological scenario, all the considered quantities have very little redshift evolution, particularly between z  = 0.5 and 0.     

光学卫星常态化相对辐射定标方法研究

相对辐射定标是获得各类光学遥感卫星传感器的高精度观测产品的必备条件,由于受发射震动、在轨空间环境变化等因素以及传感器自身衰减的影响,传感器在轨响应状态会随时间发生衰减和漂移,单一相对辐射定标方法无法保障卫星传感器在特定时间的探元响应一致性。本文以光学卫星传感器全生命周期影像辐射质量保障为目标,主要研究了光学卫星传感器在轨生命周期内高频率、高定标精度的常态化相对辐射定标方法,并总结了当前常用的相对辐射定标精度评估方法,评估了各定标方法的指标以及应用场景。利用珞珈一号01星（LJ1-01）夜光传感器获取的影像进行在轨暗电流、和在轨均匀场地定标实验和验证,珠海一号02组高光谱卫星影像被用来实施和验证统计定标和偏航辐射定标方法,并耦合多种定标方法实现常态化辐射定标。实验结果表明：各种定标方法处理后影像的条纹系数小于0.25%,图像相对标准差均优于3.00%;多种定标方法相互结合的常态化辐射定标方法实现了多种定标方法的优势最大化,完成常见传感器的高精度在轨标定。     

Short time-scale fluctuations in the difference light curves of QSO 0957+561A,B: microlensing or noise?

From optical R -band data of the double quasar QSO 0957+561A,B, we made two new difference light curves (with an overlap of about 330 d between the time-shifted light curve for the A image and the magnitude-shifted light curve for the B image). We observed noisy behaviours around the zero line and no short time-scale events (with a duration of months), where the term 'event' refers to a prominent feature that may be a result of microlensing or another source of variability. Only one event lasting two weeks and rising −33 mmag was found . Measured constraints on the possible microlensing variability can be used to obtain information on the granularity of the dark matter in the main lensing galaxy and the size of the source. In addition, one can also test the ability of the observational noise to cause the rms averages and the local features of the difference signals. We focused on this last issue. The combined photometries were related to a process consisting of an intrinsic signal plus a Gaussian observational noise. The intrinsic signal has been assumed to be either a smooth function (polynomial), a smooth function plus a stationary noise process, or a correlated stationary process . Using these three pictures without microlensing, we derived some models totally consistent with the observations. We finally discussed the sensitivity of our telescope (at Teide Observatory) to several classes of microlensing variability.