2019年4—10月我国主要暴雨天气过程简述     

闵爱荣  廖移山  邓雯  张翠荣 《湖北气象》2020,39(5):539-548

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Time-mean precipitation and vertical motion patterns over the United States     

H. M. VAN DEN DOOL 《地球，A辑:动力气象学与海洋学》1990,42(1):51-64

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繁昌盆地张家冲铅锌矿地质特征及成矿规律     

洪东良  段留安  赵磊  邓江洪  陈四新 《安徽地质》2014,(2):103-107,118

长江中下游成矿带铜陵矿集区,长期以来为国内外研究的热点地区之一,但大都集中于研究Cu、Au、S、Fe等矿产,而铅锌矿的相关报道或科研工作相对较少。铜陵张家冲铅锌矿位于长江中下游成矿带繁昌盆地内,属次火山口控制的铅锌矿,是繁昌火山岩盆地内发现的第一个有色金属矿床,同时也是通过对盆地内硅化带的系统解剖发现的矿床,有着较高的科研和生产价值。笔者近年来组织了对该区的施工,提交(332+333)铅锌矿石资源量675.87×104t,Pb+Zn金属量11.90×104t。本文旨在通过对该区铅锌矿地质特征、矿床成因、找矿标志及成矿规律等进行总结,进一步丰富该地区成矿模式和理论,为本区乃至整个繁昌盆地下步找矿提供参考和借鉴。  相似文献   

Optical dating of relict sand wedges and composite-wedge pseudomorphs in Flanders, Belgium     

JAN-PIETER BUYLAERT  GUNTHER GHYSELS  REW S. MURRAY  KRISTINA J. THOMSEN  DIMITRI VANDENBERGHE  FRANS DE CORTE  IRENÉE HEYSE  PETER VAN DEN HAUTE 《Boreas: An International Journal of Quaternary Research》2009,38(1):160-175

We report on quartz Optically Stimulated Luminescence (OSL) dating of the infill of 14 relict sand wedges and composite-wedge pseudomorphs at 5 different sites in Flanders, Belgium. A laboratory dose recovery test indicates that the single-aliquot regenerative-dose (SAR) procedure is suitable for our samples (measured to a given dose ratio 0.980 ± 0.005; n =139). Completeness of resetting of the wedge infill of two samples was confirmed by single-grain analyses. The suite of optical ages indicates that repeated thermal contraction cracking, degradation and infilling with wind-blown sediment appear to have been commonplace in Flanders during the Late Pleniglacial (Oxygen Isotope Stage 2; OIS2); more specifically, around the Last Glacial Maximum (LGM, ∼21 kyr ago) and the transition period between the LGM and the start of the Lateglacial (∼15 kyr ago). Optical dating at one site has revealed two significantly older wedge levels, the younger inset into the older; the younger wedge has an age of 36 ± 4 kyr (Middle Pleniglacial; OIS3), the older wedge 129 ± 11 kyr, which points to formation during the Late Saalian (OIS6). Our OSL ages of the wedges and host sediments bracket formation of the BGB (Beuningen Gravel Bed: a widespread deflation horizon in northwestern Europe) at between ∼15 and 18 kyr; this is in good agreement with previous OSL dating studies. We conclude that optical dating using quartz SAR OSL establishes an absolute chronology for these periglacial phenomena and allows secure palaeoenvironmental reconstructions to be made.  相似文献   

浙江省地闪活动特征分析   总被引：2，自引：0，他引：2  

潘娅英  王亚云  周良女  邓霞君  史海峰 《亚热带资源与环境学报》2010,5(3):82-88

通过分析闪电定位所取得的2007—2009年的浙江省地闪资料,初步研究其地闪特征.地闪中绝大多数是负闪,其平均强度为33.2 kA,地闪出现最多的强度范围是20~40 kA.地闪活动具有明显的日变化,总体呈单峰形式,总地闪频次峰值和负闪频次峰值出现时段都在14:00—16:00,而正闪频次落后于总地闪和负闪峰值2~4小时,23:00至次日11:00平均地闪频次每小时20次以下.地闪的月变化也呈单峰型分布,其中1月份、12月份地闪极其稀少,主要集中在6—8月份,以8月份为最多,正闪和负闪的各月变化与地闪总数的各月变化一致.全省地闪密度集中区位于山脉的夏季风的迎风坡一侧.全省的地闪密度分布和同期雷暴日分布不一致,表明在评价雷电活动中仅用雷暴日有一定的局限性.  相似文献   

Modelling feedback mechanisms in the carbon cycle: balancing the carbon budget   总被引：2，自引：0，他引：2  

J. ROTMANS  M. G. J. DEN ELZEN 《Tellus. Series B, Chemical and physical meteorology》1993,45(4):301-320

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Juvenile CO₂ in enderbites of Tromøy near Arendal, southern Norway: a fluid inclusion and stable isotope study     

A. M. VAN DEN. KERKHOF  J. L. R. TOURET  R. KREULEN 《Journal of Metamorphic Geology》1994,12(3):301-310

The enderbites from Tromøy in the central, granulite facies part of the Proterozoic Bamble sector of southern Norway contain dominantly CO₂ and N₂ fluid inclusions. CO₂ from fluid inclusions in quartz segregations in enderbites was extracted by mechanical (crushing) and thermal decrepitation and the δ¹³C measured. Measurement was also made on samples washed in 10% HCl, oxidized with CuO at high temperatures, and step-wise extracted with progressive heating. Results between the different techniques are systematic. The main results show δ¹³C of -4.5±1.5% for crushing and -7±2% for thermal decrepitation. δ¹³C is about constant for CO₂ extracted at different temperatures and points to a homogeneous isotopic composition. Due to the presence of carbonate particles and/or induced contaminations for the extraction by thermal decrepitation, the results for the crushing experiments are assumed the most reliable for fluid-inclusion CO₂. Very low values of δ¹³C have not been found in enderbite samples and δ¹³C combined with δ¹⁸O of the host quartzes (8-11%) indicates juvenile values. In addition, the fluid inclusions were examined by microthermometry and Raman analysis and host quartz by acoustic emission and cathodoluminescence. CO₂ fluid inclusions have varying densities with a frequency maximum of 0.92 g cm^-3 and generally do not concur with trapping densities at granulite conditions. Textures show that CO₂ must have been trapped in fluid inclusions in one early event, but transformed to different extents during late isothermal uplift without important fractionation of isotope compositions. The present data support a model of intrusion and crystallization of a CO₂-rich enderbitic magma at granuiite conditions.  相似文献   

Modeling shoreline sand waves on the coasts of Namibia and Angola     

Francesca RIBAS  Albert FALQUS  Niels VAN DEN BERG  Miquel CABALLERIA 《国际泥沙研究》2013,28(3):338-348

The southwestern (SW) coast of Africa (Namibia and Angola) features long sandy beaches and a wave climate dominated by energetic swells from the Southsouthwest (SSW), therefore approaching the coast with a very high obliquity. Satellite images reveal that along that coast there are many shoreline sand waves with wavelengths ranging from 2 to 8 km. A more detailed study, including a Fourier analysis of the shoreline position, yields the wavelengths (among this range) with the highest spectral density concentration. Also, it becomes apparent that at least some of the sand waves are dynamically active rather than being controlled by the geological setting. A morphodynamic model is used to test the hypothesis that these sand waves could emerge as free morphodynamic instabilities of the coastline due to the obliquity in wave incidence. It is found that the period of the incident water waves, T_p, is crucial to establish the tendency to stability or instability, instability increasing for decreasing period, whilst there is some discrepancy in the observed periods. Model results for T_p = 7–8 s clearly show the tendency for the coast to develop free sand waves at about 4 km wavelength within a few years, which migrate to the north at rates of 0.2–0.6 km yr^?1. For larger T_p or steeper profiles, the coast is stable but sand waves originated by other mechanisms can propagate downdrift with little decay.  相似文献   

南海地震研究的基本思路与构想     

刘武忠  李海华 《华南地震》1994,14(1):64-69

南海有丰富的海洋资源和矿藏资源，开发南海是２１世纪的战略目标之一．开展南海地震研究有重大的现实意义和深远意义．阐明了南海地震研究的基本任务和科学问题，进而提出了若干具体构想和措施．  相似文献   

锡铁山矿床中石膏、菱铁矿成因研究与意义   总被引：4，自引：0，他引：4  

祝新友  樊俊昌  邓吉牛 《矿产与地质》2006,20(3):205-210

锡铁山矿床地表及上部中段的近矿围岩中发育大量的石膏和含锌菱铁矿,长期以来主要作为喷流沉积或后期改造的产物。同时,地表的褶皱构造在深部却不发育,其原因一直存在争议。在对这些石膏、含锌菱铁矿及相关地质现象研究的基础上指出,锡铁山矿床近地表部分存在强烈的氧化作用与岩溶作用,石膏、含锌菱铁矿的主体是大气降水条件下原生矿石氧化形成的,而非形成于喷流沉积作用。同时,强烈的岩溶塌陷改变了部分地质体的产状,这可能是形成地表矿体附近“褶皱构造”的主要原因。  相似文献