中太平洋地区两个铁锰结壳的生长幕研究   总被引：1，自引：0，他引：1  

武光海  周怀阳  张海生  Irine PULYAEVA  凌洪飞  刘捷红 《地质学报》2006,80(4):577-588

通过对3块中太平洋铁锰结壳样品进行的生物地层学及其结构构造、元素地球化学剖面的综合研究发现,铁锰结壳的生长主要集中于两个形成环境存在差异分别由不同因素控制的形成阶段,一个是约25Ma以来其形成环境氧化程度由南极底层流(AABW)控制的对应于结壳新壳层的生长幕,另一个是渐新世之前其形成环境氧化程度由环赤道表中层洋流和高密度温盐表层水下沉控制的对应于结壳老壳层的生长幕,而在早、中渐新世处于两种环境的转换期,也正好是海退期、大洋低生产力期、低CCD和生物碳酸盐低产率期,形成结壳生长的主要生长间断。该研究成果对于进一步了解太平洋的古海洋、古环境演变有一定意义。  相似文献   

Metal flux as an alternative parameter in evaluating the resource potential for co-rich ferromanganese crusts     

Hisaaki Sato 《Marine Georesources & Geotechnology》2018,36(7):768-780

We propose a geochemical parameter, “metal flux” in evaluating hydrogenetic Co-rich ferromanganese crust deposits in the Pacific seamount area, that is based on physical, chemical, and geological characterization of the integrated growth piles of crusts. We calculated the metal flux for fifteen sites from different depths ranging between 900-6000m from different seamounts. The secular and areal variations of metal flux indicate a strong geological controls, and also can be a reliable tool for estimating an economic potential of the crusts. The Co flux decreases with increasing water depth, followed by almost constant flux of Ni and Mn. The Al and Fe fluxes vary with regions, indicating higher values in the western regions near the island arc probably related to a supply from the Asian continents. The results imply that Co, a redox sensitive metal element, is controlled by redox conditions of seawater, while Fe and Al are by terrigenous input. The metal flux reflects global and regional conditions and controls the compositional diversity of metals, thus consequently, the parameter can be a reliable powerful tool to estimate or single out more potential areas.  相似文献   

Low-temperature alteration of oceanic island basalts and their contribution to transition metal circulation of the ocean     

BU Wenrui  SHI Xuef  PENG Jiantang  LIU Jihu  Zhang Mingjie  QI Liang 《海洋学报(英文版)》2008,27(2):35-54

The major elements, rare earth elements （REE） and trace elements of four basalt samples from central and western Pacific ferro- manganese crust provinces have been analyzed using chemical methods and ICP - MS, respectively. The results indicate that the samples have been extensively altered and that the contents of their major elements have changed significantly. However, the similarity of REE partition patterns and trace element contents of basalt samples to those of fresh oceanic island basalts （OIB） indicate that the basalt samples originated as OIB. Because of low-temperature alteration, the contents of A1203 , Fe203 , MnO, K20 and P205 increased, while MgO and FeO decreased. Active components, such as magnesium and iron, were leached from OIB resulting in the relative enrichment of SiO2. The leaching of active components can cause the relative enrichment of REE, while the precipitation of LREE-rich ferromanganese oxides in vesicles and fissures not only causes an increase of REE contents, but also induces ＂fractionation＂ of LREE and HREE. Based on the enrichment mechanism of REE contents, the theoretical quantities of precipitated ferromanganese oxides and the depleted quantities of active components are calculated ： the depleted quantities of active components for the unit mass of fresh basalts vary in the range of 0.15 ～ 0. 657, and the precipitated quantities of ferromanganese oxides for the unit mass of fresh basahs vary in the range of 0. 006 ～ 0. 042. Of the major elements, the two most depleted are iron, and magnesium, with 18.28% ～ 70.95% of iron and 44.50% ～ 93.94% of magnesium in the fresh basalts was leached out. Theoretical calculation and geochemistry results both indicate that low-temperature alteration of basalts can supply abundant amount of metals to seawater, and may play an important role in ocean metal circulation.  相似文献   

西太平洋Kocebu海山铁锰结壳稀土元素地球化学特征     

刘凯  王珍岩 《海洋地质与第四纪地质》2021,41(1):210-222

西太平洋麦哲伦海山区是全球重要的铁锰结壳资源分布区,具有丰富的稀土元素资源潜力.本文对采自麦哲伦海山区Kocebu海山的11个铁锰结壳表层样(<1 mm)进行稀土元素地球化学研究,探讨其含量特征、成因和影响稀土元素富集的环境因素.结果表明:Kocebu海山铁锰结壳表层样品ΣREY(Rare earth elements...  相似文献   

A numerical survey of neutron star crustal density profiles     

B. Datta  A. V. Thampan  D. Bhattacharya 《Journal of Astrophysics and Astronomy》1995,16(3-4):375-391

An accurate numerical survey of the density profiles corresponding to the crusts of neutron stars for representative equation of state models is presented. This will find application in calculations of thermal and magnetic evolution of neutron stars.  相似文献   

俄罗斯大洋固体矿产资源调查研究进展   总被引：5，自引：0，他引：5  

许东禹 《海洋地质前沿》2002,18(10):21-28

介绍了俄罗斯的海洋多金属结核、铁锰结壳、热液硫化物和磷钙土资源调查研究活动概况和发展趋势。  相似文献   

Soil sealing and soil water content under no‐tillage and conventional tillage in irrigated corn: Effects on grain yield     

María Concepcin Ramos  Evangelina Pareja‐Snchez  Daniel Plaza‐Bonilla  Carlos Cantero‐Martínez  Jorge Lampurlans 《水文研究》2019,33(15):2095-2109

The main objective of this research was to analyse the effect of soil management on soil sealing and on soil water content under contrasting tillage practices and its influence on corn yield. The experimental research was carried out in a field cultivated with irrigated corn differentiated into three zones representing a gradient of soil texture (Z1, Z2, and Z3, i.e., increasingly coarser). Two plots under different soil management practices (conventional intensive tillage, CT, and no‐tillage, NT) were selected in each zone. The susceptibility to sealing of each soil and the steady infiltration rates were evaluated in the laboratory subjecting the soils to rainfall simulation applied at an intensity of 25 mm h^?1. In addition, soil porosity under each treatment was quantified. Soil water content (0–90 cm depth) was determined gravimetrically at the beginning and the end of the growing cycle and at the surface (0–5 cm) during three growing seasons and continuously at two depths (5–15 and 50–60 cm) during the last growing cycle. Soil water content was simulated using the SIMPEL model, which was calibrated for the experimental conditions. Corn yield and above‐ground biomass were also analysed. Significant differences in soil sealing among zones, with decreasing soil sealing for coarser textures, and treatments were observed with infiltration rates that were near twice in NT than in CT, being the effect of soil cover significant in the reduction of soil detachment and soil losses. NT showed higher soil water content than CT, especially in the surface layers. Above‐ground biomass production was smaller in CT than in NT, and in the areas with higher sealing susceptibility was 30% to 45% smaller than in other zones, reaching the smallest values in Z1. A similar reduction in corn yield was observed between treatments being smaller in CT than in NT. No‐tillage has been confirmed as an effective technique that benefits soil physical properties as well as crop yields in relation to CT, being its impact greater in soils susceptible to sealing.  相似文献   

影响生物土壤结皮在沙丘不同地貌部位分布的风因子讨论   总被引：1，自引：1，他引：0  

吴永胜  哈斯  屈志强 《中国沙漠》2012,32(4):980-984

 生物土壤结皮广泛分布于干旱和半干旱区,它的形成和发育对荒漠生态系统修复过程产生重要的影响。采用野外观测的方法,测定了固定沙丘纵断面表面气流和生物土壤结皮的发育特征。结果发现,近地表气流在迎风坡坡脚部位最低,丘顶最高,从坡脚到丘顶呈增加的趋势。近地表气流在背风坡中上部急剧下降,中下部位有所增加,到坡脚部位又呈减少的趋势,但后者均远低于丘顶的风速。各观测点不同高度风速放大率不尽相同。生物土壤结皮发育特征的测定结果显示,其厚度、抗剪强度和细颗粒物含量均从沙丘底部向中上部呈减少的趋势,表现出风速较高区域生物土壤结皮的发育程度较低,风速较低区域生物土壤结皮的发育程度较高的特点,说明生物土壤结皮在沙丘不同地貌部位的分布与由地形差异导致的气流变化之间具有密切的关系。  相似文献   

The factors influencing the abrasion efficiency of saltating grains on a clay‐crusted playa     

Christopher A. Houser  William G. Nickling 《地球表面变化过程与地形》2001,26(5):491-505

The entrainment and subsequent transport of PM₁₀ (particulate matter <10 µm) has become an important and challenging focus of research for both scientific and practical applications. Arid and semi‐arid environments are important sources for the atmospheric loading of PM₁₀, although the emission of this material is often limited by surface crusts. It has been suggested that the primary mechanisms through which PM₁₀ is released from a crusted surface are abrasion by saltating grains or disturbance by agricultural and recreational activities. To examine the importance of saltation abrasion in the emission of PM₁₀, a series of field wind tunnel tests were conducted on a clay‐crusted surface near Desert Wells, Arizona. In a previous part of this study it was found that the emission rate varies linearly with the saltation transport rate, although there can be considerable variation in this relationship. This paper more closely examines the source of the variability in the abrasion efficiency, the amount of PM₁₀ emitted by a given quantity of saltating grains. The abrasion efficiency was found to vary with the susceptibility of the surface to abrasion, the ability of the sand to abrade that surface and the availability of material with a caliper size <10 µm within the crust. Specifically, the results of the study show that the abrasion efficiency is related to the crust strength, the amount of surface disturbance and the velocity of the saltating grains. It is concluded that the spatial and temporal variability of these controls on the abrasion efficiency imposes severe contextual limitations on experimentally derived models, and can make theoretical models too complex and impractical to be of use. Copyright­© 2001 John Wiley & Sons, Ltd.  相似文献   

贵州中三叠统上部垄头组的沉积性质——再论其钙结壳的成因   总被引：4，自引：0，他引：4       下载免费PDF全文

范嘉松  吴亚生 《地质学报》2004,78(2):149-155

钙结壳是土壤层之下的岩石在出露地表渗流带环境内受大气雨水的溶解,并通过上覆土壤层的淋滤而成的产物。由于雨水的不断的溶解,使原始的岩石或沉积物发生破裂,从而形成各种大小的砾块或砾石。随着雨水不断的溶解,雨水逐渐增加 CaCO_3的含量。这些富含碳酸钙的雨水,当它流到位于潜水面之上的下渗流带时,就在土壤层之下、原来岩石之上沉积了特殊的、层纹状方解石胶结物。它们往往覆盖岩石表面或沿着砾石的外缘、呈包覆状沉积,从而形成典型的层纹状钙结壳。渗滤豆粒的外皮也属于层纹状钙结壳的性质,这些外皮有向下方加厚的趋势,这表明渗流带的含碳酸钙的雨水,受重力作用影响下,具有往下悬垂现象,类似于洞穴内的钟乳石。豆粒之间的相互衔接呈多边形构造,也表明它是受重力作用而形成的构造。  相似文献