基于农户调查的经济发达地区城郊农地流转 ——以广州市番禺区为例

农地流转是农户具有方向性选择的土地利用行为表现,按流转方向可分为转入与转出.为探讨不同流转方向的农户农地流转特征差异,以广州市番禺区467户农户调研数据为例,分析不同流转方向下的农地流转特征,并探讨不同流转方向下的流转价格影响因素。研究认为：①番禺区农地流转的特征在不同流转方向下具有一定差异,其中转出率高于转入率,转入规模大于转出规模,北部的转入和转出率均稍高于南部,但在流转价格、流转年限、契约方式、流转难易及交易时间等方面则差异不显著。②应用多元回归分析法对不同流转方向下的农地流转价格影响因素进行分析,发现转入模型回归效果比转出模型回归效果好,其中流转方式及流转花费时间两个因子在不同模型中的作用不同。研究表明,农地流转由于存在转入与转出方向的不同,流转特征会存在一定差异,开展该方面的研究应区别对待。     

Planktonic stages of the teleost family carapidae in eastern New Zealand waters

The occurrence of planktonic carapid eggs in Otago waters, of young stages of Echiodon rendahli off Castlepoint, and the possible presence of unrecorded members of the family Carapidae in New Zealand waters is discussed. Young E. rendahli possess a long spine which originates dorsally to a distinctive suspended gut.     

南京河西地区岩土体剪切波速与土层深度的关系

南京河西地区是南京市重点开发的新市区,该区域工程地质条件相似,主要为长江高河漫滩地质地貌单元。本文选取该地区47个典型钻孔的岩土体剪切波速资料,采用三种数学模型进行统计回归分析,运用相关系数R（或测定系数R^2）检验Vs-H之间的线性相关关系,并根据计算的SD值选择较优的数学模型。统计结果表明,该地区各类岩土体的Vs-H线性相关关系显著,说明采用上述数学模型进行Vs-H回归是可行的。对两个工程场地进行剪切波速预测,并对场地类别作出划分,检验结果表明,该地区各类岩土体的Vs-H经验关系是可靠的,符合当地岩土特征,在样本深度范围内有足够的工程应用精度,可以应用。     

城市边缘区空间发展探讨——以北京市海淀区为例

在快速城镇化时期,城市边缘区是城市扩张过程中空间结构变化最大、土地利用转变最快的地区,以过渡性、复杂性、动态性为突出特征。研究城市边缘区的空间演变对认识城镇化、优化城市空间结构等具有重要意义。本文在总结海淀区空间发展历史渊源的基础上,采用了RS/GIS技术对20世纪80年代以来海淀城市边缘区的范围、空间扩张进行了定量分析;并结合系统论方法,探索影响海淀城市边缘区空间演变的若干因素。研究发现：海淀城市边缘区空间发展有独特的地理优势和文化渊源,且在政策、经济、人口、交通等因素的综合作用下,处于不断动态变化之中;呈现出沿环线不规则分布、边界由清晰变模糊、整体向西北推移的空间特征;总面积逐渐增加、年扩张速率先升后降;1995-2007年以向外扩张为主,其他阶段以内部填充型发展为主;空间分布及扩张强度在不同乡镇街道具有区域差异性等。本文将RS/GIS技术与系统分析相结合,来研究城市边缘区相关问题的技术可行性。     

新疆石河子农区土壤含盐量定量反演及其空间格局分析

盐渍化严重威胁着土地持续耕作和粮食生产安全,土壤含盐量的快速反演和及时监测,对新疆石河子农区农业可持续发展有着重大意义。以Landsat-8 OLI遥感影像与野外采样测定的72个样点土壤含盐量为数据基础,引入土壤亮度指数、土壤湿度指数、土壤盐盖度指数和土壤辐射水平指数等构建的特征遥感指数定量反演新疆石河子农垦区土壤含盐量,并对其空间布局进行了分析。研究表明：① 利用遥感影像像元特征遥感指数值反演地面对应土壤含盐量的精度较好,反演方法可行,反演精度为66%;② 反演得到土壤含盐量空间分布图在空间上等级明显,层次分明,呈现出“一带一区”的格局,“一带”是玛纳斯流域形成的盐渍化程度较高的条带,“一区”是内在土质形成的严重盐渍化区域;③ 在新疆石河子农区中,35.40%的棉田适合耕作,64.60%的棉田耕地需要进行改良,农区土壤盐渍化治理仍十分紧迫。     

胶东燕山期大型超大型金矿集区形成的壳幔结构探讨：来自致矿火成岩(组合)的约束

大型超大型金属矿床形成的深部物质组成和壳幔结构一直是地学研究中被关注的焦点和难点问题。胶东地区发育很多(燕山期)的大型超大型的金矿,是我国著名的金矿集区。本文基于板块构造理论,通过揭示区域火成岩、致矿火成岩组合及其特征,探讨金矿发育时的深部物质组成和壳幔结构。区域上成矿前的侵入岩组合为含少量英云闪长岩+奥长花岗岩(TT)的花岗闪长岩+花岗岩(G1G2)组合;区域上发育的青山群为含有高镁安山岩(HMA)和镁安山岩(MA)的玄武安山岩安山岩英安岩流纹岩以及粗安岩玄粗岩粗面岩组合;矿集区的致矿火成岩组合为含有高Mg闪长岩类(HMgδ)+Mg闪长岩类(Mgδ)的宽谱系岩墙群(WSDS),岩性从基性到酸性均有。上述火成岩组合,以及TTG1、HMA与MA系列火山岩、HMgδ和Mgδ的存在,指示弧火成岩的组合,其各种岩石地球化学特征亦具有弧的特征,因此,上述火成岩及金矿形成于洋俯冲环境,具有俯冲带的壳幔结构和物质组成。各种不同的火成岩指示其可能分别来源于俯冲带不同部位的局部熔融,指示洋壳、上覆地幔楔以及上覆陆壳具有异常热的壳幔结构,即热的洋壳、热的上覆地幔(软流圈)、热的陆壳。致矿火成岩事件、成矿事件均在大规模的壳源(或壳幔)侵入岩浆活动之后。     

Metavolcanic host rocks,mineralization, and gossans of the Shaib al Tair and Rabathan volcanogenic massive sulphide deposits of the Wadi Bidah Mineral District,Saudi Arabia

The Wadi Bidah Mineral District of Saudi Arabia contains more than 16 small outcropping stratabound volcanogenic Cu–Zn–(Pb) ± Au-bearing massive sulphide deposits and associated zones of hydrothermal alteration. Here, we use major and trace element analyses of massive sulphides, gossans, and hydrothermally altered and least altered metamorphosed host rock (schist) from two of the deposits (Shaib al Tair and Rabathan) to interpret the geochemical and petrological evolution of the host rocks and gossanization of the mineralization. Tectonic interpretations utilize high-field-strength elements, including the rare earth elements (REE), because they are relatively immobile during hydrothermal alteration, low-grade metamorphism, and supergene weathering and therefore are useful in constraining the source, composition, and physicochemical parameters of the primary igneous rocks, the mineralizing hydrothermal fluid and subsequent supergene weathering processes. Positive Eu anomalies in some of the massive sulphide samples are consistent with a high temperature (>250°C) hydrothermal origin, consistent with the Cu contents (up to 2 wt.%) of the massive sulphides. The REE profiles of the gossans are topologically similar to nearby hydrothermally altered felsic schists (light REE (LREE)-enriched to concave-up REE profiles, with or without positive Eu anomalies) suggesting that the REE experienced little fractionation during metamorphism or supergene weathering. Hydrothermally altered rocks (now schists) close to the massive sulphide deposits have high base metals and Ba contents and have concave-up REE patterns, in contrast to the least altered host rocks, consistent with greater mobility of the middle REE compared to the light and heavy REE during hydrothermal alteration. The gossans are interpreted to represent relict massive sulphides that have undergone supergene weathering; ‘chert’ beds within these massive sulphide deposits may be leached wall-rock gossans that experienced silicification and Pb–Ba–Fe enrichment from acidic groundwaters generated during gossan formation.     

Mineralogical,petrographic and fluid inclusion evidence for the link between boiling and epithermal Ag-Au mineralization in the La Luz area,Guanajuato Mining District,México

Theoretical, experimental and observation data provide strong evidence that boiling is the dominant depositional mechanism in many low to intermediate sulfidation epithermal precious metals deposits. Textural and petrographic features that are evidence for boiling in the epithermal environment include the presence of coexisting liquid-rich and vapor-rich fluid inclusions, assemblages consisting of only vapor-rich fluid inclusions, colloform quartz, adularia and bladed calcite. We have examined 213 samples collected from surface outcrops, underground workings and drill cores from the central part of the La Luz vein system in the Guanajuato mining district, Mexico. In each sample, the various features that are evidence of boiling have been recorded. These observations have been quantified using a Boiling Confidence Factor that provides a means of scoring and rating each sample or area relative to the likelihood that boiling occurred.Homogenization temperatures of liquid-rich fluid inclusions within assemblages of coexisting liquid-rich and vapor-rich fluid inclusions have been measured to estimate the depth of trapping of the inclusions, and these data have been used to estimate the depth to the 300 °C isotherm along the La Luz vein system.Fluid inclusions and mineral textural features show strong evidence of boiling in the deepest levels sampled in the La Luz system. This observation suggests that the bottom of the boiling zone is at some depth beneath the deepest levels explored and opens the potential for additional resources at depth.     

河套永济灌域土壤酸碱性与养分元素的关系

为了探讨干旱区灌区不同土地利用方式下盐碱化土壤剖面pH值与土壤水分和养分之间的关系,测定河套永济灌域荒地、林地、农田3种土地利用方式下0~20、20~40、40~60、60~80、80~100 cm剖面土壤pH值、含水率（SMC）、有机质（OM）、总氮（TN）、Zn、Cu的含量。结果表明：土壤pH值平均值为9.13;土壤含水率2.96%~31.35%;土壤OM、TN含量平均值分别为11.30、0.49 g·kg^-1;微量营养元素Zn、Cu平均值分别为107.20、32.78 mg·kg^-1,是相应背景值的1.9、1.7倍;3种土地利用方式下,土壤pH值差异性极显著（P<0.001）,高低顺序为荒地 > 农田 > 林地,在垂直剖面含量差异并不显著（P>0.05）;3种土地利用方式下,土壤pH值主要受TN含量的影响,回归方程为Y_pH=9.336-0.409X_TN（P=0.001）;表层（0~40 cm）土壤pH值在一定程度上受Cu含量的影响,回归方程为Y_pH=0.018 X_Cu+8.523（P=0.003）。在河套永济灌域,一方面土壤碱化会导致土壤养分含量的贫瘠,另一方面施肥等农业活动在一定程度上降低了土壤表层碱性,同时造成微量元素的累积,加重土壤碱性的作用也非常显著,因此在增加农业投入的同时应合理科学地施用农药化肥。     

河口三角洲地区宜居人口容量估算 ——以广州原南沙区为例

近年来,不断有位于河口三角洲区域的县区升级为国家级新区,科学地估算这些县区的宜居人口容量是新区规划的前提。文章通过选取河口区人居自然环境主导因子、提取人口承载区和参考同类区域平均人口密度和相关国家标准等环节,构建了一种基于人居环境适宜性的河口三角洲地区人口承载力的估算方法,并估算了广州原南沙区宜居人口容量。结果显示：原南沙区宜居人口容量为87万人,宜居人口密度为2 776人/km²,其中,南沙街23万人,黄阁镇21万人,万顷沙镇为19万人,横沥镇为13万人,珠江街为11万人。考虑到地基和经济发展差异,南沙区宜居人口密度与上海浦东新区、天津滨海新区之间和美国首都华盛顿特区的人口密度有较好的可比性。文章所用方法突出了水文与地质条件的约束作用,可用于估算河口三角洲地区人口容量。