Distribution ofBe andBe in the Pacific Ocean     

M. Kusakabe  T.L. Ku  J.R. Southon  J.S. Vogel  D.E. Nelson  C.I. Measures  Y. Nozaki 《Earth and Planetary Science Letters》1987,82(3-4)

The vertical distributions of¹⁰Be and⁹Be at three locations in the Pacific (25°N, 170°E; 17°N, 118°W; 3°S, 117°W) are presented. The results show that both isotopes exhibit nutrient-like profiles. From the surface to the bottom, the increase for¹⁰Be is two- to threefold and that for⁹Be is about fivefold. While the inter-station variations in surface water concentrations may reach a factor of two, deep-water values tend to be much more uniform averaging about 2000 atoms/g for¹⁰Be and 30 pM for⁹Be. A similar situation applies to the¹⁰Be/⁹Be ratio; it varies approximately from 1 to 3 × 10⁻⁷ (atom/atom) at shallow depths but tends toward a value close to 1.1 × 10⁻⁷ in the deep ocean. The variation of¹⁰Be/⁹Be can be viewed as resulting from the fact that¹⁰Be in a given parcel of water consists of two components: recycled and primary. The recycled component is that part of¹⁰Be which has reached tracer equilibrium with⁹Be, as opposed to the primary component which, upon entering the sea from the atmosphere, has yet to equilibrate with⁹Be through particle cycling and mixing processes. It is estimated that 70% to nearly 100% of¹⁰Be at the three stations are being recycled, and the recycled beryllium bears an atomic ratio of¹⁰Be/⁹Be close to 1 × 10⁻⁷. The oceanic residence time of Be is of the order of 1000–4000 years, comparable to or slightly longer than the ocean mixing time.  相似文献   

Be in a deep-sea core: implications regardingBe production changes over the past 420 ka     

J.R. Southon  T.L. Ku  D.E. Nelson  J.L. Reyss  J.C. Duplessy  J.S. Vogel 《Earth and Planetary Science Letters》1987,85(4)

The influx of¹⁰Be into a globigerinid ooze core (CH72-02) from the eastern North Atlantic has been studied. This core contains a depositional record of the first 11 δ¹⁸O stages covering the last 423 ka. It is shown that the marine deposition of¹⁰Be is strongly influenced by the sedimentation of clays. Clay particles appear 10 times more efficient than the carbonate component as a carrier in bringing¹⁰Be to the bottom sediments. In core CH72-02, the deposition rates of¹⁰Be averaged over each oxygen-isotope stage for the past 11 stages show a scatter of ±40% about the mean value of 6.6 × 10⁸ atoms cm⁻² ka⁻¹. However, after correction for changes in lithology, the data show that the production rate of¹⁰Be over the same period has varied no more than ±25%, and the variations are not systematic in that high or low¹⁰Be production appear to be associated with either cold or warm climates. On the time scale of this investigation (intervals of ca. 50 ka over the last 420 ka, with resolutions as fine as 10 ka for portions of the record), it is unlikely that the shielding effect of the solar wind has deviated by more than ±25% or the geomagnetic field intensity has deviated by more than a factor of 1.6 from their long-term averages.  相似文献   

GPS控制测量和精密导线在隧道定向中的应用     

邹进贵  童魁  朱勇超 《测绘信息与工程》2014,(2):42-44

针对隧道测量中的难点问题,提出了运用GPS测量手段和精密导线测量的方法来解决特长隧道定向问题;依托全球卫星定位系统建立高等级控制网,得到准确的控制点坐标;研发的基于测量机器人的多测回测角软件用于隧道内导线测量,减轻隧道内作业强度,提高了测量精度。  相似文献   

地理学视角下土地利用/覆被分类发展探讨     

王志华  郜酷  杨晓梅  苏奋振  黄翀  石铁柱  颜凤芹  李贺  张慧芳  吕宁  潘婷婷 《地理研究》2022,41(11):2946-2962

随着对地观测和互联网技术的发展,地理大数据时代正在到来,其多尺度、长时序、多模态等海量“超”覆盖数据为土地利用/覆被（Land Use/Land Cover, 简称LULC）分类及变化检测带来巨大的机遇,支撑着新时代人、地两大系统相互作用关系的认知和实践。然而,多数地理学者认为地理学基本原理与核心思想并未因为大数据的到来而发生本质性变化。所以,从地理学基本原理角度理解LULC分类的发展,尤其在地理大数据时代的发展方向,不失为一条可行的途径。为此,本文从区域、尺度、综合三方面的地理学基本原理视角将LULC分类技术的发展划分为地球观测数据匮乏阶段、人类行为数据融合阶段以及地理大数据“超”覆盖阶段分别探讨分析,以期主动把握LULC分类技术及应用的未来发展趋势。研究结果显示：在地球观测数据匮乏阶段,LULC分类多以类型还不丰富的遥感数据源,在空间分辨率较低的像元尺度上,进行以地表覆被状态为主的分类;发展到人类行为数据融合阶段,LULC分类在城市区域率先出现了对地观测数据和人类行为数据相融合,在街区尺度上进行以空间功能异质性划分、识别为主导的城市功能区分类;在地理大数据“超”覆盖阶段,LULC分类将实现多尺度协同、面向全空间的功能异质性划分,并在主体功能的基础上融合“社会-经济-自然”多维定量属性,本文称之为“空间场景”。希望本文的探讨能够为地理大数据时代LULC分类的新技术发展和新产品应用提供有益启示。  相似文献   

东濮凹陷文70断裂带构造与油气富集规律研究     

吴超  朱俊强  王宁  王库  吴信龙 《华北地质》2014,37(3)

文70断裂带位于东濮凹陷中央隆起带文留构造带南部,油藏受文东、文70和文147三条东倾的断层控制,为东倾的断层和一系列西倾的断层形成的断块。断层切割关系复杂,造成断层组合多解性强;另外油藏含油层系多,油藏较小,油水关系复杂,油藏成因、富集规律及控制因素不明确,油藏动用困难。针对区带存在问题,运用精细地层划分与对比、RFT测试资料、HDT测井资料和三维地震解释等新技术和新方法,在强调整体解释的基础上,重点解剖了文70断裂带各断层的空间展布及组合关系,落实了构造形态和圈闭特征,并对所形成构造圈闭的含油气性及潜力进行了详细分析。结果认为,文70断裂带油气成藏主要受构造控制,发育下生上储、自生自储和古生新储三种成藏组合模式。  相似文献   

Geological evolution of the Gulf of Saros,NE Aegean Sea     

Çağatay  M. N.  Görür  N.  Alpar  B.  Saatçılar  R.  Akkök  R.  Sakınç  M.  Yüce  H.  Yaltırak  C.  Kuşcu  I. 《Geo-Marine Letters》1998,18(1):1-9

 The Gulf of Saros is an Upper Miocene transtensional basin in NW Anatolia, formed by the interaction between the North Anatolian Fault and the N-S extensional tectonic régime of the Aegean. The present configuration of the basin evolved mainly during the Plio-Quaternary under the increased activity of the North Anatolian Fault. During the late Miocene-late Quaternary, no sedimentation took place on the shelves. After this long hiatus, an important change in tectonic style about 0.2 Ma BP allowed sedimentation to resume in the gulf. Received: 14 February 1997 / Revision received: 12 November 1997  相似文献   

Gas seepage, pockmarks and mud volcanoes in the near shore of SW Taiwan   总被引：2，自引：0，他引：2  

Song-Chuen Chen  Shu-Kun Hsu  Ching-Hui Tsai  Chia-Yen Ku  Yi-Ching Yeh  Yunshuen Wang 《Marine Geophysical Researches》2010,31(1-2):133-147

In order to understand gas hydrate related seafloor features in the near shore area off SW Taiwan, a deep-towed sidescan sonar and sub-bottom profiler survey was conducted in 2007. Three profiles of high-resolution sub-bottom profiler reveal the existence of five gas seeps (G96, GS1, GS2, GS3 and GS4) and one pockmark (PM) in the study area. Gas seeps and pockmark PM are shown in lines A and C, while no gas venting feature is observed along line B. This is the first time that a gas-hydrate related pockmark structure has been imaged off SW Taiwan. The relatively high backscatter intensity in our sidescan sonar images indicates the existence of authigenic carbonates or chemosynthetic communities on the seafloor. More than 2,000 seafloor photos obtained by a deep-towed camera (TowCam) system confirm the relatively high backscatter intensity of sidescan sonar images related to bacteria mats and authigenic carbonates formation at gas seep G96 and pockmark PM areas. Water column gas flares are observed in sidescan sonar images along lines A and C. Likewise, EK500 echo sounder images display the gas plumes above gas seep G96, pockmark PM and gas seep GS1; the gas plumes heights reach about 150, 100 and 20 m from seafloor, respectively. Based on multichannel seismic reflection (MCS) profiles, an anticline structure trending NNE-SSW is found beneath gas seep G96, pockmark PM and gas seep GS2. It implies that the gas venting features are related to the anticline structure. A thermal fluid may migrate from the anticline structure to the ridge crest, then rises up to the seafloor along faults or fissures. The seafloor characteristics indicate that the gas seep G96 area may be in a transitional stage from the first to second stage of a gas seep self-sealing process, while the pockmark PM area is from the second to final stage. In the pockmark PM area, gas venting is observed at eastern flank but not at the bottom while authigenic carbonates are present underneath the pockmark. It implies that the fluid migration pathways could have been clogged by carbonates at the bottom and the current pathway has shifted to the eastern flank of the pockmark during the gas seep self-sealing process.  相似文献