重磁异常界面反演中的计算方法

迭代法和子空间法为重力异常界面反演最优化求解计算的两种方法。传统的最优化计算立意虽然简单明确，但迭代计算过程中必须的简化使得求解不稳定，加进一些限制条件之后，使计算量明显增大，以致使求解变得困难。通过引入子空间计算在矩阵求解中减少了工作量，使得加约束的最优化计算变得容易实现。通过理论分析，表明利用子空间方法的解的计算结果准确且效率较高。     

Gravity data as a tool for landfill study

This paper shows the potential of gravity data to map a buried landfill bottom topography. To this end, a gravity inversion method is presented for estimating the landfill’s bottom depths at discrete points assuming a decrease of the density contrast with depth according to a hyperbolic law. The method’s efficiency was tested using synthetic data from simulated waste landfills, producing estimated bottom topographies very close to the true ones. The method’s potentiality has been further evaluated in applying it to the gravity data from the abandoned Thomas Farm Landfill site, Indiana, USA, whose bottom topography is known. The estimated topography showed close agreement with the known Thomas Farm Landfill’s bottom topography.     

Prokaryotes as a Source of Petroleum Hydrocarbons

Doklady Earth Sciences - The regularities of the distribution of aliphatic and cyclic petroleum hydrocarbon biomarkers in different individual prokaryotes and their communities are considered....     

Source of Strong Earthquake as a Geological Object

Geotectonics - The paper considers the results of a study of modern strong earthquakes (1991 Racha, 2006 Olyutor, 2003 Altai, and 2011–2012 Tuva) according to a single methodological plan....     

The Crossite Content of Ca-Amphibole as a Guide to Pressure of Metamorphism

A correlation between the crossite component (NaM₄) in Ca-amphiboleand pressure of metamorphism has long been recognized (Shido& Miyashiro, 1959), but only recently has the reaction beenidentified which buffers this aspect of amphibole composition(Brown, 1974): Ca-amphibole+iron oxide+albite+chloriteI+H₂O (±stilp,qtz) = crossite+epidote (±muscovite, qtz). The exact stoichiometry of the reaction depends on compositionalvariables in the minerals, especially Fe²⁺/Mg and Fe³⁺/Al. Ca-amphiboleshould have fixed NaM₄, at any given T and P, where it coexistswith iron oxide, albite, and chlorite. Comparison of Ca-amphibole composition with mineral assemblage,in rocks from Otago, N.Z., and elsewhere, supports this hypothesis.In any terrane NaM₄ is nearly constant at a particular metamorphicgrade where amphibole exists in the buffering assemblage, butvaries widely outside of this assemblage. Variations in Fe²⁺/Mgand Fe³⁺/Al in the amphibole have relatively little effect onNaM₄, but in high pressure amphiboles NaM₄ varies inverselywith Al^iv. Ca-amphiboles from high pressure areas have substantially moreNaM₄ (Otago, 0.6 of 2.0) than those from lower pressure areas(Sierra contact aureoles, 0.1). These relations suggest thatin the buffering assemblage, the NaM₄ content of Ca-amphiboleshould be a useful relative barometer for low to medium grademetamorphic rocks.     

The Role of Pressure in Producing Compositional Diversity in Intraplate Basaltic Magmas

Basaltic magmas found in intraplate suites appear to followmore than one differentiation trend. Many ocean island suitesfollow the ocean island tholeiitic trend, with the basalts differentiatingfrom olivine tholeiite through basaltic andesite, andesite,and dacite to sodic rhyolite. Many continental intraplate magmaticregimes, such as those of the Snake River Plain and the plutonicsequences associated with massif anorthosites, follow the potassicsilica-saturated alkalic trend, in which basalt differentiatesfrom olivine tholeiite through ferrobasalt (jotunite or ferrodiorite),Fe-rich intermediate rocks (trachybasalt or monzonite), andtrachyte (syenite) to potassic rhyolites and granites. Crystallizationexperiments on an olivine tholeiite from the Snake River Plainshow that the basaltic portions of the ocean island tholeiitictrend and the potassic silica-saturated alkalic trend (whichleads to strong alkali, P, Ti, and Fe enrichment and silicadepletion) can arise from the same ‘dry’ tholeiiticparental magma. These compositional differences are inducedby changes in phase equilibria as a function of pressure, withthe ocean island tholeiitic series arising from crystal–liquiddifferentiation at low pressure and the potassic silica-saturatedalkalic series arising via differentiation at elevated pressures. KEY WORDS: tholeiite differentiation; experimental petrology; phase equilibria; ferrodiorite; ferrobasalt     

Development of a Simple Mechanical Impact System as a Non-Explosive Seismic Source

A Simple Mechanical Impact System (SMIS) was developed recently as a non-explosive seismic source. The SMIS consists of an impact head, a steel rod with extensions, and an anchoring system. The system is small and simple, and can be conveniently installed in a shallow borehole oriented in any direction. The SMIS was developed to address two problems commonly associated with non-explosive seismic sources: insufficient seismic strength and lack of repeatability. Field tests have shown that it is possible to produce clear and repeatable signals with this system even when the SMIS is installed in a coal seam.     

基于重磁数据梯度比值的深度学习技术实现场源位置反演方法

场源中心位置的计算是重磁数据反演的主要任务之一,现主要通过异常与场源位置之间的数学物理方程来估算地质体的位置.为了快速、准确获得地质体的位置信息,提出基于重磁梯度比值的深度学习技术实现场源位置的获取;其利用深度学习技术所建立的重磁梯度比值水平分布与地质体埋深、构造指数的关系,快速实现异常场源位置计算,且提出利用多个值的...     

Comparison of the Spatial Properties of Entrances to Black Holes and Wormholes

Astronomy Reports - The spatial properties of the entrances to spherically symmetric black holes and wormholes with zero and positive masses are compared. The properties were studied in terms of...     

Groundwater Discharge as a Source of Dissolved Carbon and Greenhouse Gases in a Subtropical Estuary

Groundwater may be highly enriched in dissolved carbon species, but its role as a source of carbon to coastal waters is still poorly constrained. Exports of deep and shallow groundwater-derived dissolved carbon species from a small subtropical estuary (Korogoro Creek, Australia, latitude ?31.0478°, longitude 153.0649°) were quantified using a radium isotope mass balance model (²³³Ra and ²²⁴Ra, natural groundwater tracers) under two hydrological conditions. In addition, air-water exchange of carbon dioxide and methane in the estuary was estimated. The highest carbon inputs to the estuary were from deep fresh groundwater in the wet season. Most of the dissolved carbon delivered by groundwater and exported from the estuary to the coastal ocean was in the form of dissolved inorganic carbon (DIC; 687 mmol m^?2 estuary day^?1; 20 mmol m^?2 catchment day^?1, respectively), with a large export of alkalinity (23 mmol m^?2 catchment day^?1). Average water to air flux of CO₂ (869 mmol m^?2 day^?1) and CH₄ (26 mmol m^?2 day^?1) were 5- and 43-fold higher, respectively, than the average global evasion in estuaries due to the large input of CO₂- and CH₄-enriched groundwater. The groundwater discharge contribution to carbon exports from the estuary for DIC, dissolved organic carbon (DOC), alkalinity, CO₂, and CH₄ was 22, 41, 3, 75, and 100 %, respectively. The results show that CO₂ and CH₄ evasion rates from small subtropical estuaries surrounded by wetlands can be extremely high and that groundwater discharge had a major role in carbon export and evasion from the estuary and therefore should be accounted for in coastal carbon budgets.     

地球微生物过程与潜在烃源岩的形成:钙质微生物岩

钙质微生物岩是各种微生物生命活动引起的特殊的碳酸盐建造, 主要集中发育在前寒武纪及显生宙等重大地质转折期, 在我国华北及华南地区有着广泛的分布.微生物岩中大量微生物化石的存在反映当时的海洋具有很高的初级生产力.明显偏低的钼同位素值显示在前寒武纪相当长的时期里, 海洋底部处于缺氧状态.Th/U值的急剧降低和黄铁矿在浅水台地区的广泛出现显示二叠纪大绝灭后, 海洋环境也同样呈现缺氧的还原状态.高生产力和还原的沉积环境为生物有机质的埋藏及烃源岩的形成创造了条件.前寒武纪及晚泥盆世微生物岩中沥青的发现, 进一步增加了钙质微生物岩作为潜在碳酸盐型烃源岩的可能性.      

深部重力、磁力测量数据子库

为了保证入库数据质量的可靠和所包含信息的完整,首先将入库的数据按照重磁数据入库技术规定的要求进行检查,对于符合重磁数据入库技术规定的数据才能入库.同时,为了对入库的数据进行有效的管理,建立了数据表.在深部重力测量和磁力测量数据子库中建立4个模块:浏览模块、维护模块、报表模块和数据处理与反演模块.文中对每个模块的功能加以了介绍.建立数据库的目的是为了用户能够使用它,并为自己的工作服务.为了便于用户使用,在深部重力测量和磁力测量数据子库中充分利用了ACCESS提供的窗体技术,并在窗体中显示大量的提示信息.由于采用了对用户友好的图形界面,用户可以很快地掌握并使用数据库.     

一种便携式重力取样器的研制

在对湖泊或水库等浅层水域的环境变化研究和环境污染检测中,浅层水域的淤泥质沉积物取样是一项必不可缺的工作.在综合比较国内外常用重力取样器优缺点的基础上,提出了一种能够获取水库、湖泊等水域浅层淤泥质原状沉积物的重力式取样器,并详细介绍了其工作原理及其各组成机构的功能.通过现场试验情况证明,该取样器具有结构简单、操作方便的优点.     

卫星重力与地球重力场的文献计量分析

卫星重力与地球重力场研究是国际大地测量学的重要研究领域,不仅带动了大地测量学本身的发展,也在其他相关研究领域取得了重要的科学应用.以2000年1月至2020年9月的20年Web of Science核心合集数据库中关于该领域的科学论文为研究对象,使用文献计量的方法,应用CiteSpace软件对当前研究现状、近年来发展脉络以及研究热点进行分析.结果 表明,关于卫星重力和地球重力场的文献数量总体上逐年上升,2016年以来维持较高的水平,其中美国、德国以及中国的发文量位居前三位;发文量排名前三的研究机构分别为中国科学院、加州理工学院和美国国家航空航天局;我国在卫星重力及地球重力场领域的研究力量相对集中,中国科学院、武汉大学以及中国科学院大学发文数占中国总数的75.36％;利用GRACE数据和球谐函数构建高精度地球重力场模型,反演局部质量变化是当前国际研究热点.得益于卫星重力观测数据,全球重力场模型得到了实质性改进.     

Source depth as a useful parameter in the discrimination of earthquakes and underground explosions

In order to identify whether observed seismic signals are generated by an underground nuclear explosion or an earthquake, it is adequate to rely on one efficient identifier that provides a reasonably good clue in an unambiguous way. Although it is generally accepted that multi-station, multi-parameter discrimination can provide separation between explosions and earthquakes, it has been observed that cases do arise where signal characteristics cannot be established distinctly and satisfactorily. In the so-called “difficult” cases which are associated with some ambiguity in deducing the nature of the source using single-station seismograms, it is shown in this paper that a reliable estimate of source depth proves extremely useful. Out of the eleven typical examples of “not-easy-to-discriminate” events recorded at the Gauribidanur short-period seismic array in Southern India, seven could be successfully identified as earthquakes and the remaining four as probable underground explosions on the basis of focal-depth estimates from multi-station data.     

Serpentinized Peridotite as Source of Aeromagnetic Anomalies

The source of long-wavelength aeromagnetic anomalies appears to originate from the eartlrs deep crust. Constrained by previous studies on geochemical, petrologic analysis, the eclogite and serpentinized peridotite samples from drill hole ZK703 at Donghai in the western Sulu ultrahigh-pressure (UHP) terrane, East China, were unambiguously exhumed from the lower crust and the upper mantle, providing significant information about the magnetic properties of rocks at a deeper part of the crust. Results show that the serpentinization process favors the neoformation of nearly stoichiometric magnetite, resulting in the enhancement of its magnetization up to 8.6 A/m, which is sufficient enough to contribute to some magnetic anomalies. In contrast, eclogite samples have only weaker magnetization (generally less than 0.05 A/m) compared to serpentinized peridotite. Nevertheless, experiments under the lower crustal conditions are necessary to further support these conclusions.     

Slab Melt as a Potential Source of Profiling Elements of Gold and Heavy Metal Deposits

Spatial/genetic control by slab magma products at gold deposits is shown in this paper by the example of granitoids in the Ust’-Kara area of the Eastern Trans-Baikal Region. The investigation performed makes it possible to take a fresh look at the problem of metal sources in the East Trans-Baikal gold deposits and to relate their formation to material flow from the oceanic lithosphere in the subduction zone, material conservation within the subcontinental mantle, and possible remobilization under large tectonic reconstructions.     

压力对未熟烃源岩低温催化脂肪酸酯水解的影响

选择十八烷酸甲酯为模型化合物,以 7种抽提有机质的未熟烃源岩为载体考察了压力对未熟烃源岩矿物催化脂肪酸酯水解反应的影响。结果表明,在未熟烃源岩低温催化脂肪酸酯的水解反应中,压力是重要的影响因素,压力效应不可忽视。7种未熟烃源岩产生了不同的压力效应,并因此引起了水解率的升高或降低。文中对压力效应产生的原因进行了探讨,认为观测到的压力效应是压力对反应促进和抑制作用共同作用的结果。     

压力对烃源层演化及产烃影响的模拟实验

压力对烃源层演化及产烃影响的模拟实验解启来，范善发，周中毅，潘长春（中国科学院广州地球化学研究所．广州５１０６４０）关键词准噶尔盆地，压力，模拟实验按照现行的成油模式，一般认为石油是在１５００～４０００ｍ范围内生成和保存的，超过４０００ｍ石油将裂解成...