江西省铅山地区硅灰石矿地质特征及找矿远景

铅山地区除金属矿产外,非金属矿产也较多,其中硅灰石矿分布广泛。铅山硅灰石矿赋存于燕山早期侵入形成的葛仙山花岗岩体的外接触带400~500 m范围的下二叠统栖霞组含燧石灰岩和中厚层状夹硅质条带灰岩及硅质页岩、石英砂岩中。矿体多呈透镜状、囊状、不规则条带状等产出,矿体走向长50~100 m,厚度2~30 m。矿石中主要矿物为硅灰石、石英、方解石,硅灰石含量一般60%~70%,矿石化学成分主要为S iO2和C aO。区内燧石灰岩提供了硅灰石形成的硅钙质组合、中深成岩浆岩为钙硅化学合成硅灰石提供了反应热能,属层控热变质交代型矿床。区内同类型硅灰石矿化普遍,具有较好的成矿潜力。     

南海北部边缘盆地油气勘探现状与深水油气资源前景

自20世纪60年代初开展浅海油气苗调查及浅井钻探以来,南海北部边缘盆地迄今在陆架浅水区已勘探发现多个油气田,建成了一定储量规模的油气产能,基本构成了南海北部油气富集区的格[JP2]局。然而,如何保持油气可持续发展,尽快寻找油气储量接替的新领域,这是该区油气勘探所面临的关键问题。南海北部陆坡深水区与世界深水盆地一样,颇具油气资源潜力和勘探前景,近期LW311深水探井钻探的新发现表明,其应是该区油气资源接替非常现实的战略选区和勘探靶区。     

Three‐dimensional time‐harmonic fundamental solutions for a fluid‐saturated poroelastic half‐space with partially permeable free surface

By virtue of a pair of scalar potentials for the displacement of the solid skeleton and the pore fluid pressure field of a saturated poroelastic medium, an alternative solution method to the Helmholtz decomposition is developed for the wave propagation problems in the framework of Biot's theory. As an application, a comprehensive solution for three‐dimensional response of an isotropic poroelastic half‐space with a partially permeable hydraulic free surface under an arbitrarily distributed time‐harmonic internal force field and fluid sources is developed. The Green's functions for the poroelastic fields, corresponding to point, ring, and disk loads, are reduced to semi‐infinite complex‐valued integrals that can be evaluated numerically by an appropriate quadrature scheme. Analytical and numerical comparisons are made with existing elastic and poroelastic solutions to illustrate the quality and features of the solution. Copyright © 2016 John Wiley & Sons, Ltd.     

河北平原土壤有机碳储量及固碳机制研究

利用2005年多目标区域土壤地球化学调查及20世纪70年代末全省第二次土壤普查土壤有机碳数据,对河北平原土壤有机碳密度及碳储量的时空变化规律、固碳机制及固碳潜力等问题进行了研究。结果表明,全省第二次土壤普查时土壤有机碳储量124．86Mt,2005年为176．08Mt,26年中增加了41．02％,表现出“碳汇”效应。据...     

Piezomagnetic fields produced by dislocation sources

Tectonomagnetic modeling based on the linear piezomagnetic effect is reviewed with special attention to dislocation models. Stacey's scheme was the prototype for such modeling, as proposed in his first seismomagnetic calculations in 1964. The linear piezomagnetic law is presented, in which the stress-induced magnetization is expressed as a linear combination of stress components. The Gauss law for magnetic field and the Cauchy-Navier equation for static elastic equilibrium are combined through linear piezomagnetism and the Hooke law to yield the basic equation for piezomagnetic potential. A representation theorem for its solution is given by surface integrals of the displacement and its normal derivative over the strained body.A Green's function method is developed to compute the piezomagnetic field produced by a dislocation surface in an elastic half-space. Volterra's formula for piezomagnetic potential is derived by modifying Stacey's scheme for tectonomagnetic modeling. The Green's functions for the problem are called elementary piezomagnetic potentials, which are defined as potentials produced by elementary dislocations. Special consideration is required to construct the elementary piezomagnetic potentials, because the stress field around a point dislocation has a singularity of orderr ^–3. The integral representing elementary piezomagnetic potentials is not uniformly convergent. Owing to inappropriate convergency, the Green's functions obtained in an earlier study led to a puzzling outcome. Revised Green's functions give consistent results with those obtained so far by numerical integrations. Generally the piezomagnetic field produced by dislocation sources is weak in the case of a homogeneous earth model. Two enhancement effects for piezomagnetic signals are suggested: one due to inhomogeneous magnetization and the other via bore-hole observations.     

A rigorous Hamiltonian approach to the rotation of elastic bodies

When the problem of the rotation of a non-rigid body is studied, the usual procedure consists of adding perturbations to the Hamiltonian of the rigid solid. In some cases, as occurs with the centrifugal deformation, the new perturbations contains potentials which depend on the velocity, but usually one alter neither the definition of the canonical variables nor the method for obtaining the Hamiltonian. Although this procedure gives good estimates and its formulation is simpler, it is incorrect from a theoretical point of view.In this paper we rigorously develop a Hamiltonian formulation of the problem, considering potentials that depend on the velocity. Thus the differences between the two procedures are clearly shown, giving special emphasis to the case of the elastic Earth, for which we show that the differences obtained cannot be ignored within the accuracy limits at present required.     

内蒙古四子王旗小南山地区镁铁质-超镁铁质岩体岩石成因及含矿性评价

内蒙古四子王旗小南山铜镍矿床及外围分布几处镁铁质- 超镁铁质岩体,其成因联系及成矿潜力尚不清晰,制约了该地区铜镍硫化物矿床的找矿工作。本文对小南山、土脑包和白音敖包岩体开展了年代学、岩石学及地球化学研究,结果显示,小南山地区存在两类镁铁质- 超镁铁质岩：小南山、土脑包含铜镍硫化物岩体由辉长岩、辉石岩组成,矿物组合以斜长石、单斜辉石为主,含少量斜方辉石和橄榄石,发育次闪石化、滑石化和绿泥石化;而白音敖包辉长岩不含铜镍硫化物,矿物组合以斜长石、单斜辉石为主,发育绿泥石化和钠黝帘石化,白音敖包辉长岩锆石U- Pb年龄为277. 2±7. 3 Ma,与小南山岩体(272. 7±2. 9 Ma)同期。此外,小南山和土脑包辉长岩Mg#值为0. 56～0. 67,m/f值为1. 25～1. 98,MgO与Ni、Co负相关,Ni与Cu/Zr值正相关,稀土元素配分曲线为右倾型;白音敖包辉长岩Mg#值为0. 50～0. 51,m/f值为0. 97～1. 02,MgO与Ni、Co相关性不明显,Cu/Zr值集中在1附近,稀土元素配分曲线为平坦型。岩石地球化学数据指示小南山和土脑包岩体是源自流体交代岩石圈地幔部分熔融,原生岩浆为高镁拉斑玄武质岩浆,岩浆上升过程受到10%～20%陆壳混染,外来硫的加入和分离结晶作用导致硫化物熔离成矿;白音敖包辉长岩由派生岩浆结晶形成,其岩浆源区受到交代作用不明显,岩浆上升过程仅受到5%左右的地壳物质混染,钻探验证没有发现矿体。     

东天山二叠纪大草滩地区镁铁-超镁铁质岩体的岩浆演化过程和含矿性

大草滩地区位于新疆东天山土墩-黄山-图拉尔根镁铁-超镁铁质岩带西侧,觉罗塔格构造带中段,区域构造环境主要受康古尔塔格-黄山深大断裂控制。本次研究的大草滩地区一、二号岩体形成于早二叠纪, SIMS法锆石U-Pb年龄分别为279±2Ma和278±2Ma。2个岩体主要由橄榄岩和辉长岩组成,全岩稀土总量较低,具LREE轻微亏损至平坦的分配型式。全岩Sr-Nd同位素与微量元素组成显示两个岩体的母岩浆来自软流圈地幔,其成分与N-MORB相似,在上升过程中经历了较低程度(1%~5%)的同生A型花岗岩混染。由于低程度的部分熔融(10%~15%)导致硫化物残留在地幔源区,导致母岩浆强烈亏损铂族元素,因此大草滩地区一、二号岩体可能不具有形成具经济价值铜镍硫化物矿床的潜力。     

Non-Integrability and Structure of the Resonance Zones in a Class of Galactic Potentials

The structure of the resonance zone in nearly integrable Hamiltonian systems is studied by a more general method than the pendulum approximation. This method applies to the case of a non-degenerate integrable part in the Hamiltonian. This problem may be overcome in a class of galactic-type polynomial potentials, in the case where the higher-order term is by itself integrable. An illustrative example is worked out.     

Stability of axial orbits in galactic potentials

We investigate the dynamics in a galactic potential with two reflection symmetries. The phase-space structure of the real system is approximated with a resonant detuned normal form constructed with the method based on the Lie transform. Attention is focused on the stability properties of the axial periodic orbits that play an important role in galactic models. Using energy and ellipticity as parameters, we find analytical expressions of bifurcations and compare them with numerical results available in the literature.