Response to the comment by V. Neck on “Hydrolysis of neptunium(V) at variable temperatures (10-85 °C)”, Geochimica et Cosmochimica Acta 68, 4821-4830     

Linfeng Rao  Thandankorai G. Srinivasan  PierLuigi Zanonato  Plinio Di Bernardo 《Geochimica et cosmochimica acta》2006,70(17):4556-4562

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Deformability characteristics of brazilian laterites     

Jacques De Medina  Laura M. G. Motta  João D. G. Dos Santos 《Geotechnical and Geological Engineering》2006,24(4):949-971

This paper summarizes the resilient and permanent deformation characteristics of laterite gravels, determined by cyclic loading in triaxial tests of compacted specimens. A study of laterite pavements was carried out on eight paved road sections in the state of Mato Grosso. Also reported is the influence of fine sand admixture, specimen size and soaking in two laterite samples from Roraima and Rondônia in the North of Brazil. The experimental relationships of resilient moduli against applied stresses are interpreted empirically for models what may be incorporated in a structural analysis of full depth of laterite pavement.  相似文献   

内蒙古西辽河流域特种玉米品种特性及气候区划   总被引：3，自引：0，他引：3  

白美兰刘兴汉  邸瑞琦杨丽桃 冯晓晶 《气象科技》2005,33(5):437-441

基于玉米本身的特性和用途的不同,将玉米分为高油型玉米、高淀粉型玉米、高赖氨酸型玉米和甜玉米四大类型.根据每种玉米品种对气候条件、土壤类型、地形特征等的不同需求,以通辽地区作为内蒙古东部西辽河流域玉米主产区的示范区,提出了特种玉米的区划指标,并利用GIS技术进行适宜种植区域划分.内蒙古通辽地区大部分农区适宜种植特种玉米,最适宜区、适宜区基本上均位于通辽南部和中部农业区.  相似文献   

K 近邻非参数回归概率预报技术及其应用   总被引：7，自引：1，他引：7       下载免费PDF全文

翟宇梅赵瑞星  肖仁春王力维 《应用气象学报》2005,16(4):453-460

针对参数回归技术制作概率预报存在拟合好、但预报结果不稳定的现象, 提出了用K近邻非参数回归技术制作概率预报的新途径。K 近邻非参数回归技术包括历史样本数据库、近邻子集生成和优化以及预报量估计4 个主要部分。利用该技术进行了单要素概率预报(主要包括云量和降水)和多维联合概率预报(降水、总云量、风速和气温)试验, 并对试验结果进行了检验。实例研究结果表明:该文所给出的计算方案预报稳定性好, 准确率较高,具有良好的业务应用价值。  相似文献   

河南省洛阳—三门峡铝土矿地质特征及其勘查开发前景   总被引：8，自引：0，他引：8       下载免费PDF全文

陈全树  何文平  周迪 《地质找矿论丛》2002,17(4):252-256,270

河南省洛阳-三门峡的铝土矿，是赋存于中石炭统本溪组的一水硬铝石型沉积铝土矿。本区不仅蕴藏量多，而且有相当数量的富铝土矿，勘查开发潜力大，前景广阔。  相似文献   

Thermal and rheological structures of the Xisha Trough, South China Sea   总被引：8，自引：0，他引：8  

Xiaobin Shi  Di Zhou  Xuelin Qiu  Yixiang Zhang 《Tectonophysics》2002,351(4)

The Xisha Trough, located in the northwest of the South China Sea (SCS) mainly rifted 30 Ma ago, has been a failed rift since the cessation of the seafloor spreading of the NW subbasin. Based on the velocity–depth model along Profile OBH-4 across the Xisha Trough, a seven-layer density–depth model is used to estimate density structure for the profile. The relationship between seismic velocity and radiogenic heat production is used to estimate the vertical distribution of heat sources in the lower crust. The 2-D temperature field is calculated by applying a 2-D numerical solution of the heat conduction equation and the thermal lithosphere thickness is obtained from the basalt dry solidus (BDS). The rheology of the profile is estimated on the basis of frictional failure in the brittle regime and power-law steady-state creep in the ductile regime. Rheological model is constructed for a three-layer model involving a granitic upper crust, a quartz diorite lower crust and an olivine upper mantle. Gravity modeling supports basically the velocity–depth model. The Moho along Profile OBH-4 is of relatively high heat flow ranging from 46 to 60 mW/m² and the Moho heat flow is higher in the trough than on the flanks. The depth of the “thermal” lithospheric lower boundary is about 54 km in the center, deepens toward two sides, and is about 75 km at the northern slope area and about 70 km at the southern Xisha–Zhongsha Block. Rheological calculation indicates that the two thinnest ductile layers in the crust and the thickest brittle layer in the uppermost mantle lie in the central region, showing that the Xisha Trough has been rheologically strengthened, which are mainly due to later thermal relaxation. In addition, the strengthening in rheology during rifting was not the main factor in hampering the breakup of the Xisha Trough.  相似文献   

基于GIS的区域地质调查数字制图--以1∶5万<里庄幅>为例     

廖忠礼  刘晓蓉  陈乔  廖光宇  朱弟成 《沉积与特提斯地质》2002,22(3)

本文以 1∶5万里庄幅为例 ,阐述了运用GIS系统对区调过程中各种资料的处理与编辑方法 ,并介绍了数字制图方法及工艺流程 ,提出了GIS系统在 1∶5万区调工作中的应用前景  相似文献   

PHREEQC and PHREEQCI: Geochemical Modeling with an Interactive Interface     

Laura Toran  David Grandstaff 《Ground water》2002,40(5):462-464

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Crystal-rich mass flow deposits related to the eruption of a sublacustrine silicic cryptodome (Early Permian Collio Basin, Italian Alps)     

Christoph Breitkreuz  Lucio Cortesogno  Laura Gaggero   《Journal of Volcanology and Geothermal Research》2002,114(3-4)

Sedimentological, granulometric and petrographic data are presented from a detailed study on a crystal-rich mass flow deposit, which is presumably related to the eruption of a sublacustrine cryptodome. The deposit forms a prominent intercalation in the Lower Permian Collio Formation in the Italian Alps north of Brescia. Outcrops of the 10–20-m-thick volcaniclastic deposit (Dasdana I Beds, DB) can be traced over 12 km from east to west. The DB consists of a thick, crystal-rich, sandy–gravelly lower subunit representing a sequence of amalgamated Bouma-a(b) divisions overlain by a thin, well-bedded, sandy–muddy subunit that is rich in outsize porphyritic silicic fragments. Modal and computer-aided image analyses reveal that the crystal-rich lower subunit contains up to 80% of volcanogenic crystals. Some samples contain up to 60% of porphyritic fragments, which have a phenocryst content of about 20%. The wide textural range from cryptocrystalline, poikilomosaic, to rarer medium-grained granophyric groundmass, the irregular to lensoid shapes of the porphyritic fragments, and the presence of basement and sedimentary clasts suggest that the DB originated from a sublacustrine eruption of a partially extrusive cryptodome (ca. 1.6 km³). Two other porphyritic felsic cryptodomes (Dosso dei Lupi, Dosso del Bue), described briefly here, emplaced into the Collio Formation sometime after the DB event, and expose flat bases and tilted sediments at their sides. Textures observed in these domes are comparable to those found in the DB porphyritic fragments.  相似文献   

Genesis of chlorine and sulphur in fumarolic emissions at Vulcano Island (Italy): assessment of pH and redox conditions in the hydrothermal system     

V. Di Liberto  P. M. Nuccio  A. Paonita   《Journal of Volcanology and Geothermal Research》2002,116(1-2)

Chlorine- and sulphur-bearing compounds in fumarole discharges of the La Fossa crater at Vulcano Island (Italy) can be modelled by a mixing process between magmatic gases and vapour from a boiling hydrothermal system. This allows estimating the compounds in both endmembers. Magma degassing cannot explain the time variation of sulphur and HCl concentrations in the deep endmember, which are more probably linked to reactions of solid phases at depth, before mixing with the hydrothermal vapours. Based on the P–T conditions and speciation of the boiling hydrothermal system below La Fossa, the HCl and S_tot contents in the hydrothermal vapours were used to compute the redox conditions and pH of the aqueous solution. The results suggest that the haematite–magnetite buffer controls the hydrothermal fO₂ values, while the pH has increased since the end of the 1970s. The main processes affecting pH values may be linked to Na–Ca exchanges between evolved seawater, feeding the boiling hydrothermal system, and local rocks. While Na is removed from water, calcium enters the solution, undergoes hydrolysis and produces HCl, lowering the pH of the water. The increasing water–rock ratio within the hydrothermal system lowers the Ca availability, so the aqueous solution becomes less acidic. Seawater flowing towards the boiling hydrothermal brine dissolves a large quantity of pyrite along its path. In the boiling hydrothermal system, dissolved sulphur precipitates as pyrite and anhydrite, and becomes partitioned in vapour phase as H₂S and SO₂. These results are in agreement with the paragenesis of hydrothermal alteration minerals recovered in drilled wells at Vulcano and are also in agreement with the isotopic composition of sulphur emitted by the crater fumaroles.  相似文献