南京太平门地段雪松树年轮及其根土中化学元素含量的相关性研究   总被引：6，自引：0，他引：6  

钱君龙  柯晓康 《地理科学》1998,18(4):374-378

１９９４年在南京市太平门街道采集了五株雪松的年轮样及其根部土壤（黄棕壤ｐＨ＝６．６８）,分别测定了Ｌｉ、Ａｌ、Ｐ、Ｋ、Ｍｎ、Ｃｏ、Ｃｕ、Ｚｎ、Ｃｄ、Ｂａ和Ｐｂ等１１种化学元素含量,实测结果验证了雪松年轮与其根部当年土壤中化学元素含量满足对数线性相关模式;ｌｇＣ′（Ｚ,ｔ）＝ａ（Ｚ）＋ｂ（Ｚ）ｌｇＣ（Ｚ,ｔ）。根据年轮元素含量Ｃ（Ｚ,ｔ）可以重建过去根土中元素含量Ｃ′（Ｚ,ｔ）,即反映环境（土壤）中元素含量的逐年演变的年份序列。利用Ｃ（Ｚ,ｔ）中最低含量可估算该地段黄棕壤的土壤元素背景值。  相似文献   

四川南部珙县早侏罗世一新蜥脚类恐龙   总被引：3，自引：0，他引：3  

何信禄  王长生  刘尚忠  周凤云  刘图强  蔡开基  代兵 《四川地质学报》1998,(1)

简介在珙县下侏罗统自流井组东岳庙段中,发现的原始蜥脚类恐龙化石的一新属种石碑珙县龙。成年个体长约１４ｍ。化石材料相当丰富,除头骨不完全外,其他部分乃至全部均保存完好。它是早期的原始的蜥脚类,但又和蜥脚类有不少共同点。它对研究蜥脚类的起源和进化,具有重要意义  相似文献   

利用空间测地技术结果估计地球平均下地幔粘性(英)     

杨志根  真锅盛二  黄山一  河野宣之 《天文学报》1998,(3)

基于IEC－4G冰期后地壳反弹模型,和地球上Laurentia,Fennoscandia,Antarctica,andGreenland四大冰盖最近21000年以来的冰融参数,计算了对地球最大主转动惯量的影响△I33,并进而由现代空间测地技术观测资料分析得到的地球自转非潮汐加速项为约束,估计了地球平均下地幔（670km以下）粘性vLM为（0．9～2．5）·1022Pas,这个结果表明了vLM应具有1022Pas量级．  相似文献   

CO Clouds around SNR G21.8-0.6 and G32.8-0.1     

Jian-Jun Zhou Xi-Zheng Zhang Hong-Bo Zhang Jarken Esimbek Ju-Yong Zhang Bing-Gang Ju 《中国天文和天体物理学报》2007,7(5):705-711

We made the first CO(I—0) mapping to SNR G21.8-0.6 and SNR G32.8-0.1, both associated with OH 1720 MHz maser.Based on the morphological correspondence and velocity and position agreement between the radio remnant and the CO clouds,we tentatively identify the clouds that are respectively interacting with the two SNRs.  相似文献   

Historical Evidence for the Birth of the Newly Discovered Pulsar PSR J1833-1034     

Zhen-Ru Wang  Min Li  Yi Zhao Astronomy Department  Nanjing University  Nanjing  Institute of Chinese Classics  Nanjing University  Nanjing 《中国天文和天体物理学报》2006,6(5)

Stimulated by the recent discovery of PSR J1833-1034 in SNR G21.5-0.9 and its age parameters presented by two groups of discovery, we demonstrate that the PSR J1833-1034 was born 2053 years ago from a supernova explosion, the BC 48 guest star observed in the Western Han (Early Han) Dynasty by ancient Chinese. Based on a detailed analysis of the Chinese ancient record of the BC 48 guest star and the new detected physical parameters of PSR J1833-1034, agreements on the visual position, age and distance between PSR J1833-1034 and the BC 48 guest star are obtained. The initial period P0 of PSR J1833-1034 is now derived from its historical and current observed data without any other extra assumption on P0 itself, except that the factor PP is a constant in its evolution until now.  相似文献   

Géomorphologie de Tromelin,océan Indien     

Nick Marriner  Max Guérout  Thomas Romon  Philippe Dussouillez 《Comptes Rendus Geoscience》2010,342(10):766-777

Tromelin is a small coral reef island (1 km²) located in the Indian Ocean, approximately 440 km east of Madagascar and 580 km north of La Réunion. Despite the presence of a permanent Météo France weather station on Tromelin since the 1950 s, a detailed geomorhological study of the island has never been undertaken. In this paper, we describe results from the 2008 field season, which enabled us to map and describe seven geomorphological zones on the atoll. (1) Tromelin's bathymetry is characterised by a pronounced submarine slope, which attains depths of 1000 m at only 2.5 km from the island's coastline. This geomorphology is typical of volcanic hotspots. (2) A coral platform borders the emerged crown of the island. This platform is exposed at low tide and has been fashioned in an ancient Pleistocene substratum. The substratum has been eroded by abrasive marine action to its present shape since the stabilisation of relative sea level around 6000 years ago. Erosion of the reef yields most of the biogenic sediment supply to the island. (3) The upper foreshore is characterised by outcrops of beachrock. These formations show a stratfication in slabs and dip gently towards the sea in the same manner as the contemporary clastic sediments. (4) Tromelin's beaches are divided into three sub-units, which reflect the different energy dynamics around the island, in addition to the transfer of sediment from the windward to the leeward side: (i) the southern storm beaches are characterised by coral blocks reworked during episodic high-energy events; they form boulder ramparts. Four perched rampart ridges have been recorded at ∼1 m, ∼3 m, ∼4.5 m and ∼7 m above mean sea level; (ii) transitional beaches are observed between the south and the north, constituting storm blocks and coarse sands and gravels; and (iii) sandy beaches are noted on the northern leeward side, comprising rounded gravels and coarse sands. The northern tip of the island is characterised by a sand spit (∼125 × ∼225 m), whose geometry varies based on the seasonal and meteo-marine contexts. (5) On Tromelin, a number of dune formations are observed. These are best developed in the north of the island due to the south-north translation of clastic sediments by aeolian wind action, and the trapping of sands by the well-developed vegetation. The height of the dunes varies between 10 cm (the southern micro-dunes) to 250 cm in the Northeast of Tromelin. (6) Exceptional waves have deposited storm tracts up to 250 m from the foreshore zone, comprising coarse gravels and coral blocks. The storm tract deposits are most prevalent on the windward side of the island, due not only to the high-energy dynamics, but also to the absence of vegetation cover in this area. (7) The southern depression covers an area of ∼40,000 m². At its lowest point it is only 1.2 m above sea level.  相似文献   

Tourmaline from the Archean G.R.Halli gold deposit,Chitradurga greenstone belt,Dharwar craton （India）： Implications for the gold metallogeny     

Susmita Gupta  ;M. Jayananda  ;Fareeduddin 《地学前缘(英文版)》2014,5(6):877-892

Tourmaline occurs as a minor but important mineral in the alteration zc,ne of the Archean orogenic gold deposit of Guddadarangavanahalli （G.R.Halli） in the Chitradurga greenst~ne belt of the western Dharwar craton, southern India. It occurs in the distal alteration halo of the G.R.Halli golcl deposit as （a） clusters of very fine grained aggregates which form a minor constituent in the natrix of the altered metabasalt （AMB tourmaline） and （b） in quartz-carbonate veins （vein tourmaline）. ~[＇he vein tourmaline, based upon the association of specific carbonate minerals, is further grouped as （i） albite-tourmaline-ankerite-quartz veins （vein-1 tourmaline） and （ii） albite-tourmaline-calcite-quartz veins （vein-2 tourmaline）. Both the AMB tourmaline and the vein tourmalines （vein-I and vein-2） belong to the alkali group and are clas- sified under schorl-dravite series. Tourmalines occurring in the veins are zoned while the AMB tour- malines are unzoned. Mineral chemistry and discrimination diagrams 1eveal that cores and rims of the vein tourmalines are distinctly different. Core composition of the ve：n tourmalines is similar to the composition of the AMB tourmaline. The formation of the AMB tourmaline and cores of the vein tour- malines are proposed to be related to the regional D1 deformational event associated with the emplacement of the adjoining ca. 2.61 Ga Chitradurga granite whilst rims of the vein tourmalines vis-a- vis gold mineralization is spatially linked to the juvenile magmatic accretion （2.56-2.50 Ga） east of the studied area in the western part of the eastern Dharwar craton.  相似文献   

冰后回弹对全球及中国参考框架的影响分析     

于男  程鹏飞  成英燕  李兵 《测绘科学》2014,39(12)

文章利用ICE-5G模型发布的最新预报值,计算分析了冰后回弹对全球和中国区域的影响,发现冰后回弹不仅会引起垂直方向的地壳运动,而且还会引起水平方向的地壳运动,但是水平方向的量级要明显小于垂直方向.全球范围内最大回弹区域位于加拿大,大约为16mm/a,而由冰后回弹所引起的地壳水平方向运动达3mm/a.这个回弹量级对于维持毫米级ITRF的稳定所造成的影响是不容忽视的.中国范围内回弹值大概在0～0.7mm/a,这个量级对于参考框架的影响基本可以忽略.  相似文献   

Characteristics of the supernova remnant G351.7+0.8 and a distance argument against its association with PSR J1721−3532     

W. W. Tian  M. Haverkorn †  H. Y. Zhang 《Monthly notices of the Royal Astronomical Society》2007,378(4):1283-1286

New images of the supernova remnant (SNR) G351.7+0.8 are presented based on 21-cm H  i -line emission and continuum emission data from the Southern Galactic Plane Survey. SNR G351.7+0.8 has a flux density of 8.4 ± 0.7 Jy at 1420 MHz. Its spectral index is 0.52 ± 0.25 ( S = v ^−α) between 1420 and 843 MHz, typical of adiabatically expanding shell-like remnants. H  i observations show structures possibly associated with the SNR in the radial velocity range of −10 to −18 km s⁻¹, and suggest a distance of 13.2 kpc and a radius of 30.7 pc. The estimated Sedov age for G351.7+0.8 is less than  6.8×10⁴ yr  . A young radio pulsar PSR J1721−3532 lies close to SNR G351.7+0.8 on the sky. The new distance and age of G351.7+0.8 and recent proper motion measurements of the pulsar strongly argue against an association between SNR G351.7+0.8 and PSR J1721−3532. There is an unidentified, faint X-ray point source 1RXS J172055.3−353937 which is close to G351.7+0.8. This may be a neutron star potentially associated with G351.7+0.8.  相似文献   

基于3G与3S集成的土地利用执法检查应用     

董廷旭  王建华  陈朝镇  张新合 《地球信息科学学报》2011,13(2):260-265

土地卫片执法检查是政府实施土地严格管理的重要手段.本文以绵阳市2009年度遥感土地执法检查为例,选用2008年和2009年两个时相的中巴资源卫星02B遥感图像作为信息源,对3G与3S集成技术在土地利用执法检查中应用方法进行了研究.该方法利用RS获取土地利用变化信息,利用VRS-GPS技术采集变化图斑空间与属性特征信息,...  相似文献