地幔柱和地幔流体作用与深部找矿应用研究

地球是一个复杂的系统,自形成以来,一直处于不停地运动、分异和演化过程;它不仅存在着圈层结构,而且伴随其自转和公转的离心力,以及核幔间的温度差、压力差、密度差、粘度差、速度差和放射性蜕变热等动热机制,同时存在着以地幔柱和地幔流体作用方式的物质垂向运动;这一过程,不仅直接向地壳带入核幔成矿物质,而且通过流体自身的超临界性质,将沿途活化已有初步富集的成矿物质转移至地壳适宜部位集中成矿。因此,大多与深大断裂有关的矿床,其成矿作用多与成矿物质的垂向运动密切相关,进而可能具备深部成矿的条件。研究从地幔柱和地幔流体作用入手,探讨了大型和超大型矿床形成的地球化学背景,揭示了开展深部找矿应用的前景。     

Ubinas: the evolution of the historically most active volcano in southern Peru

Ubinas volcano has had 23 degassing and ashfall episodes since A.D. 1550, making it the historically most active volcano in southern Peru. Based on fieldwork, on interpretation of aerial photographs and satellite images, and on radiometric ages, the eruptive history of Ubinas is divided into two major periods. Ubinas I (Middle Pleistocene >376 ka) is characterized by lava flow activity that formed the lower part of the edifice. This edifice collapsed and resulted in a debris-avalanche deposit distributed as far as 12 km downstream the Rio Ubinas. Non-welded ignimbrites were erupted subsequently and ponded to a thickness of 150 m as far as 7 km south of the summit. These eruptions probably left a small collapse caldera on the summit of Ubinas I. A 100-m-thick sequence of ash-and-pumice flow deposits followed, filling paleo-valleys 6 km from the summit. Ubinas II, 376 ky to present comprises several stages. The summit cone was built by andesite and dacite flows between 376 and 142 ky. A series of domes grew on the southern flank and the largest one was dated at 250 ky; block-and-ash flow deposits from these domes filled the upper Rio Ubinas valley 10 km to the south. The summit caldera was formed between 25 and 9.7 ky. Ash-flow deposits and two Plinian deposits reflect explosive eruptions of more differentiated magmas. A debris-avalanche deposit (about 1.2 km³) formed hummocks at the base of the 1,000-m-high, fractured and unstable south flank before 3.6 ka. Countless explosive events took place inside the summit caldera during the last 9.7 ky. The last Plinian eruption, dated A.D.1000–1160, produced an andesitic pumice-fall deposit, which achieved a thickness of 25 cm 40 km SE of the summit. Minor eruptions since then show phreatomagmatic characteristics and a wide range in composition (mafic to rhyolitic): the events reported since A.D. 1550 include many degassing episodes, four moderate (VEI 2–3) eruptions, and one VEI 3 eruption in A.D. 1667. Ubinas erupted high-K, calc-alkaline magmas (SiO₂=56 to 71%). Magmatic processes include fractional crystallization and mixing of deeply derived mafic andesites in a shallow magma chamber. Parent magmas have been relatively homogeneous through time but reflect variable conditions of deep-crustal assimilation, as shown in the large variations in Sr/Y and LREE/HREE. Depleted HREE and Y values in some lavas, mostly late mafic rocks, suggest contamination of magmas near the base of the >60-km-thick continental crust. The most recently erupted products (mostly scoria) show a wide range in composition and a trend towards more mafic magmas.Recent eruptions indicate that Ubinas poses a severe threat to at least 5,000 people living in the valley of the Rio Ubinas, and within a 15-km radius of the summit. The threat includes thick tephra falls, phreatomagmatic ejecta, failure of the unstable south flank with subsequent debris avalanches, rain-triggered lahars, and pyroclastic flows. Should Plinian eruptions of the size of the Holocene events recur at Ubinas, tephra fall would affect about one million people living in the Arequipa area 60 km west of the summit.Editorial responsibility: D Dingwell     

Isotope systematics of noble gases in the Earth's mantle: possible sources of primordial isotopes and implications for mantle structure

The Earth's mantle contains a mixture of primordial noble gases, in particular solar-type helium and neon, and radiogenic rare gases from long-lived U, ²³²Th, ⁴⁰K and short-lived ¹²⁹I, ²⁴⁴Pu. Rocks derived from deep mantle plume magmatism like on Hawaii or Iceland contain a higher proportion of primordial nuclides than rocks from the shallow upper mantle, e.g. mid ocean ridge basalts (MORBs). This is widely regarded as the key evidence for survival of a less degassed and more “primitive” reservoir within the lower mantle. We present an evaluation of noble gas composition showing the shallow mantle to have about five times more radiogenic (relative to primordial) isotopes than Hawaii/Iceland-type plume reservoirs, no matter if short- or long-lived decay systems are considered. This fundamental property suggests that both MORB and plume-type noble gases are mixtures of: (1) a homogeneous radiogenic component present throughout most of the mantle and (2) a uniform primordial noble gas component with very minor radiogenic ingrowth. This conclusion depends crucially on the observed excess of radiogenic Xe in plume-derived rocks, and is only valid if this Xe excess is inherent to the plume sources.Possible sources of the primordial component of mantle plume reservoirs—and possibly also the MORB mantle—could be mantle reservoirs that remained relatively isolated over most of Earth's history (“blobs”, a deep abyssal layer, or the D” layer), but these need a considerable concentration of primordial gases to compensate U, Th, K decay over 4.5 Ga. Earth's core is evaluated as an alternative viable source feeding primordial nuclides into mantle reservoirs: even low metal-silicate partitioning coefficients allow sufficient primordial noble gases to be incorporated into the early forming core, as the undifferentiated proto-Earth was initially gas-rich. Massive mantle degassing soon after core formation then provides the opposite concentration gradient that allows primordial noble gases reentering the mantle at the core-mantle boundary, probably via partial mantle melts. Another possible source of primordial noble gases in Earth's mantle are subducted sediments containing extraterrestrial dust with solar He and Ne, but this supply mechanism crucially depends on largely unconstrained parameters. The latter two scenarios do not require the preservation of a “primitive” mantle reservoir over 4.5 Ga, and can potentially better reconcile increasing geochemical evidence of recycled lithospheric components in mantle plumes and seismic evidence for whole mantle convection.     

利用SAR图像制作正射影像图的研究

简要阐述了SAR图像几何处理的数学模型，着重对斜距投影公式进行了研究，并利用斜距投影公式进行单片空中三角测量解算。最后，用SIR－A获得的SAR影像制作了1：10万比例尺的正射影像图。     

Cause-Effect Models of Large Landslides

Within the scope of the International Decade ofNatural Disaster Reduction (IDNDR), cause-effectmodels of large landslides are being developed toestimate hazard. This work is based on a structuralexploration of the landslide areas mainly by seismicmethods. Information about the status of deformationis obtained by comparison of the actual topographywith a reconstruction of the original topography, byGPS, and by SAR interferometry. Geologic andgeomorphological evidence, as well as relevantinformation from other geo-scientific disciplines, isconsidered. The Finite Element Method is used to modelthe initial phase of a mass movement. Later on thismodeling will be extended to the quasi-stationarycreep phase and the transition from creeping to rapidsliding.Four large landslides within the crystalline rocks ofthe Eastern Alps have been investigated since 1997.Two of them are evaluated so far, and are presented inthis paper. The largest one is the Köfelslandslide with a total volume of 3.9 km³ and apotential energy release of 5 × 10¹⁶ Joule.Refraction and reflection multi-component seismictechniques were used to resolve structure and elasticparameters of the landslide masses. For the modelingof the initial phase of the landslides by the FiniteElement Method a strain softening behavior of the rockmass has been assumed. The development of softened orfractured zones was successfully simulated, inagreement with the structures obtained by the seismicmeasurements.     

吉林省辽吉台块中生代火山岩地球化学特征及构造环境

本区中生代火山岩可以分成偏碱性中性火山岩和酸性火山岩两类，二者之间表现出明显的成份间断，构成一个偏碱性中性－酸性双峰式岩系。偏碱性中性火山岩地球化学特征上与榄安粗岩相似，具有富碱（Ｋ２Ｏ＋Ｎａ２Ｏ），Ｋ２Ｏ／Ｎａ２Ｏ比值高以及富集大离子亲石元素（Ｒｂ，Ｓｒ，Ｂａ，Ｐ）等特征。本区火山岩形成大陆边缘拉张环境。     

北秦岭丹凤地区早古生代花岗岩的Pb、Sr、Nd同位素地球化学特征

通过对北秦岭丹凤地区早古生代花岗岩的Ｐｈ、Ｓｒ、Ｎｄ同位素地球化学特征的系统研究，结合元素地球化学特征，证明早古生代具成分极性的枣园、黄柏岔、石门花岗岩是由于秦岭群斜长角闪岩和黑云斜长片麻岩部分熔融，近俯冲带以熔体与熔体的混合、远离俯冲带是前者产生的熔体与后者熔融后的残留相以不同比例混合形成的。     

Biologischer Abbau von 2,4-Dinitrotoluol in einer kontinuierlich betriebenen Versuchsanlage und kinetische Untersuchungen

Biological Degradation of 2,4-Dinitrotoluene in a Continuous Bioreactor and Kinetic Studies Experimental results on the aerobic biological degradation with complete mineralization of 2,4-dinitrotoluene (2,4-DNT) are presented. A culture of Pseudomonas sp. DNT from Spain and Nishino was used. The degradation was examined with batch cultures for the determination of kinetic and stoichiometric coefficients. Further experiments were carried out with a continuous culture in a fixed-bed reactor with recirculation in order to obtain high degradation rates. The reactor was packed with ceramic Raschig rings (55 mL) and had a liquid reaction volume of 160 mL. The minimal salt media from Spanggord et al. with and without (NH₄)₂S)₄ as nitrogen source was used as substrate. 2,4-DNT was the sole source of carbon and energy. From batch experiments a yield coefficient Y_B/S = (0.30 ± 0.05) g g^?1 was calculated from a mass balance of the elements. This result was confirmed by calculations using literature data. Fitting the experimental data to the Monod equation, μ_max = 0.1 h^?1 and K_S = 0.01…0.03 mmol L^?1 were obtained. It was demonstrated by batch experiments that 2,4-DNT is not only used as the source of carbon and energy but also as the nitrogen source. In the fixed-bed reactor, a degradation of 92…97% was reached with a maximal 2,4-DNT load of 95 mg L^?1 h^?1. The rate of continuous degradation could be described by a pseudo-first-order reaction (k = 9.73 h^?1). The complete mineralization of 2,4-DNT was verified by the measurement of DOC and the formed nitrite and nitrate. The formed nitrite was nitrified simultaneously. It was demonstrated by these experiments that large scale biological treatment of industrial effluent containing 2,4-DNT may be successful.     

沉积岩系互稀释混合元素丰度关系

二元混合成国岩石元素丰度（ｘ，ｙ）遵守分式线性函数定律:式中ａ，ｂ，ｃ，ｄ为丰度关系常数，它们只和岩系中两个已知岩石（１和２）中元素丰度（ｘ_１，ｙ_１；ｘ_２，ｙ_２）有关，并等于其镜像∑变换（混合变换）（ａ，ｂ，ｃ，ｄ）＝∑∑|ｘ_１，ｙ_１；ｘ_２，ｙ_２|（２）元素丰度关系常数中，如果ｂ与Ｃ之比值小于零时，元素丰度ｙ＝Ｘ呈互稀释混合关系。