Animal burrowing and associated formation of large desiccation cracks as factors of a rapid restoration of soil cover in flooded farmlands     

Nizamettin Kazanci  Omer Emre  M. Cihat Alcicek 《Environmental Geology》2001,40(8):964-967

The burrowing activity of annelids controls the spatial pattern and rapid formation of large desiccation cracks in the river flood-derived mud cover in recently inundated farmland areas in northwestern Anatolia, Turkey. The phenomenon is confirmed by laboratory experiments imitating the natural floodplain conditions.  相似文献   

离子色谱法测定水样中S~(2-)、SO_3~(2-)、SO_4~(2-)、S_2O_3~(2-)     

时艳  刘江潮 《吉林地质》2001,(2)

该种方法利用离子色谱仪的电导检测器与电化学检测器串联 ,十几分钟即可连续完成水中S2 - 、SO2 - 3 、SO2 - 4、S2 O2 - 3 的测定 ,方法具有快速、高效、方便、灵敏、选择性好等特点。方法的检出限分别为 :S2 - 12 5 μg/L ;SO2 - 3 2 2 4 μg/L ;SO2 - 45 0 μg/L ;S2 O2 - 35 0 μg/L。相对标准偏差在 1 5 %～ 6 9%之间 ,能够满足水中S2 - 、SO2 - 3 、SO2 - 4、S2 O2 - 3四种阴离子分析测试的需要。  相似文献   

Secondary dispersion from gold deposits in west Turkey     

Mi?raç Akçay  H.Mustafa Özkan  Charles J. Moon  Barry C. Scott 《Journal of Geochemical Exploration》1996,56(3):197-218

Orientation studies over the Sarpda? prospect in the Biga peninsula and the Arapdagi deposit near Izmir have provided elear evidence for elemental dispersion around west Turkish gold prospects. Although these deposits are of different types, silicification associated with the deposits results in the main part of both deposits forming topographic highs.At Sarpda? gold mineralisation is relatively weak compared with nearby prospects and associated with a silicified cap on the main hill. Comparison of coarse and fine fractions, based on a 190 μm size split of 8 kg of -2 mm material, suggests that gold disperses clastically on the steep slopes, probably within silica, but coarse grains break down giving Au concentrations in the finer fractions at the base of the main slope. Discrete gold grains, that can be panned, only occur 1–2 km downstream within the streams and heavy mineral concentrations are very limited. This interpretation of Au dispersion is consistent with the data from 1 kg samples collected at the higher primary grade, but more contaminated, Arapda?i prospect.Antimony is the most consistent pathfinder both for the silicified cap at Sarpda? and for gold-rich veins at Arpada?i. It gives high contrast anomalies. Arsenic is useful being more mobile than Sb, although contrast may be low. High resolution Ag data can be useful but base metal enrichments are also often associated with Ag anomalies. Most prospects have some base metal enrichments although they can be displaced from the main gold-rich parts of the deposit and anomalies may be weak. Lead and Cu are the more consistently useful elements.The use of large (> 8 kg of -2 mm material) samples produces consistent stream sediment data that can be used to reliably interpret single samples and quantify Au anomalies. A survey around the Halíköy Hg and Emirli Sb mines, using these large samples, confirmed the extension of the known gold-bearing Emirli structure. In contrast the major Hg-bearing Halíköy Fault is gold poor although a structure parallel to it is auriferous.  相似文献   

Histological bone structure of Lower Cretaceous dinosaurs from southwest Istria (Croatia)     

Z. Kozari?  M. Šparica  Z. Bajraktarevi? 《Cretaceous Research》1996,17(6):741-749

Recently discovered dinosaur bones in submerged near-shore deposits of southwest Istria include one vertebra, one femur, and two rib fragments. They all show well-developed vascularization. The large amounts of primary bone tissue in the vertebral and femoral compacta as well as in one rib fragment suggest that they belong to sub-adult animals which were growing rapidly. The structure of a second rib fragment differs in that it consists of secondary bone. The absence of lines of arrested growth is evident in all investigated bones. This suggests a sustained manner of bone deposition.  相似文献   

Book review     

W. E. Sharp  M. Dane Picard  Jean-Fran?ois Gaillard 《Mathematical Geology》1992,24(4):437-447

  相似文献   

Geodesic polygons on surfaces of revolution     

Walter K?hnlein 《Journal of Geodesy》1963,37(2):201-209

This paper presents a way for computing geodesic polygons on real surfaces of revolution with partly continuous curvature and gives an application to coordinate transformations in geodesic coordinate systems. The specific formulas for an ellipsoid of revolution are briefly mentioned.  相似文献   

Simultaneous determination of latitude, longitude and azimuth with a theodolite by photographing the star passages     

E. Kuntz  K. Schn?delbach 《Journal of Geodesy》1968,42(3):303-308

  相似文献   

Petrogenetic relationships of acid and basic rocks in iceland: Sr-isotopes and rare-earth elements in late and postglacial volcanics     

R.K. O&#x;Nions  K. Gr?nvold 《Earth and Planetary Science Letters》1973,19(4):397-409

Strontium isotope ratios and rare-earth element abundances have been measured in acid, intermediate and basic rocks from three late to postglacial volcanic complexes, and several other postglacial basalts in Iceland. Late and postglacial basalts in Iceland have been generated from a source region which is essentially homogeneous with respect to⁸⁷Sr/⁸⁶Sr. The mean⁸⁷Sr/⁸⁶Sr ratio for the basalts analysed is 0.70328 and the range is from 0.70317 ± 6to0.70334 ± 5 (2σ).Acid rocks from the Kerlinganfjöll and Namafjall volcanic complexes have⁸⁷Sr/⁸⁶Sr ratios which are indistinguishable from analysed basalts from the same complexes. However, intermediate and acid rocks from the Torfajökull complex have significantly higher⁸⁷Sr/⁸⁶Sr ratios and could not have been derived by fractional crystallization from basaltic magmas similar to those found in the same complex. These latter rocks have most probably been produced by remelting of Tertiary gabbroic rocks in Layer 3. Most of the basalts analysed have higher total rare-earth element abundances than typical dredged ocean-ridge tholeiites, and show less light rare-earth depletion. Intermediate and acid compositions show overall higher abundances and light rare-earth enrichments. The measured rare-earth abundances are compared with abundances generated by differential partial melting of various model source regions.It is shown that both the tholeiitic and alkali basalt compositions could be generated from the same source material by different degrees of partial melting. Variable partial melting of gabbroic material may account for the rare-earth element abundances of both the rhyolitic rocks (small degrees of melting) and the intermediate rocks (more extensive melting).  相似文献   

Investigation of Image Fusion Between High—Resolution Image and Multi—Spectral Image     

LlPingxiang WANGZhijun 《地球空间信息科学学报》2003,6(2):31-34

On the basis of a thorough understanding of the physical characteristics of remote sensing image,this paper employs the theories of wavelet transform and signal sampling to develop a new image fusion algorithm.The algorithm has been successfully applied to the image fusion of SPOT PAN and TM of Guangdong province, China The experimental results show that a perfect image fusion can be built up by using the image analytical solution and reconstruction in the image frequency domain based on the physical characteristics of the image formation.The method has demonstrated that the results of the image fusion do not change spectral characteristics of the original image.  相似文献   

An effective concept extraction method for improving text classification performance     

ZHANGYuntao GONGLing WANGYongcheng YINZhonghang 《地球空间信息科学学报》2003,6(4):66-72

  相似文献