Coal facies evolution of the main minable coal-bed in the Heidaigou Mine,Jungar Coalfield,Inner Mongolia,northern China     

Dai  ShiFeng  Ren  DeYi  Li  ShengSheng  Zhao  Lei  Zhang  Yong 《中国科学:地球科学(英文版)》2007,50(2):144-152

The No. 6 Coal-bed from the Heidaigou Mine, Jungar Coalfield, Inner Mongolia is a super-large Ga deposit. The dominant carrier of Ga is boehmite in coal. The study of coal facies may provide genetic enrichment information of Ga and its carrier (boehmite) in the Ga deposit. On the basis of study on coal petrology and mineralogy, it was found that the No. 6 Coal-bed from the Heidaigou Mine of Jungar was enriched in inertinites and the microlitho-types were dominated by clarodurite. The maceral morphological features and association indicate that the coal-bed was formed in a dry sedimentary environment or in a periodic dry sedimentary environment caused by the alternating variations of groundwater level. The optimum conditions for the enrichment of Ga and its particular carrier (boehmite) were dominated by four transitional conditions: (1) the upper delta plain which was the transitional zone between alluvial and lower delta plains, (2) the transitional zone between the dry and wet forest swamps, being slightly apt to the dry one, (3) the transitional tree density between the thick and loose ones, and (4) the low moor that was the transitional zone between two high moors during peat accumulation.

  相似文献   

Export stoichiometry and migrant-mediated flux of phosphorus in the North Pacific Subtropical Gyre     

Cecelia C.S. Hannides  Michael R. Landry  Claudia R. Benitez-Nelson  Renée M. Styles  Joseph P. Montoya  David M. Karl 《Deep Sea Research Part I: Oceanographic Research Papers》2009,56(1):73-88

Export processes play a major role in regulating global marine primary production by reducing the efficiency of nutrient cycling and turnover in surface waters. Most studies of euphotic zone export focus on passive fluxes, that is, sinking particles. However, active transport, the vertical transfer of material by migrating zooplankton, can also be an important component of carbon (C) and nitrogen (N) removal from the surface ocean. Here we demonstrate that active transport is an especially important mechanism for phosphorus (P) removal from the euphotic zone at Station ALOHA (Hawaii Ocean Time-series program; 22°45′N, 158°W), a P-stressed site in the North Pacific Subtropical Gyre. Migrant excretions in this region are P-rich (C₅₁:N₁₂:P₁) relative to sinking particles (C₂₅₀:N₃₁:P₁), and migrant-mediated P fluxes are almost equal in magnitude (82%) to P fluxes from sediment traps. Migrant zooplankton biomass and therefore the importance of this P removal pathway relative to sinking fluxes has increased significantly over the past 12 years, suggesting that active transport may be a major driving force for enhanced P-limitation of biological production in the NPSG. We further assess the C:N:P composition of zooplankton size fractions at Station ALOHA (C₈₈:N₁₈:P₁, on average) and discuss migrant-mediated P export in light of the balance between zooplankton and suspended particle stoichiometries. We conclude that, because active transport is such a large component of the total P flux and significantly impacts ecosystem stoichiometry, export processes involving migrant zooplankton must be included in large-scale efforts to understand biogeochemical cycles.  相似文献   

A GIS-based Tupu Analysis of Dynamics of Saline-alkali Land in Western Jilin Province     

REN Chunying ZHANG Bai WANG Zongming SONG Kaishan LIU Dianwei LIU Zhiming 《中国地理科学(英文版)》2007,17(4):333-340

Based on Tupu theory, this paper studied the dynamic changes, conversion modes, expansion intensity and landscape attributes of the saline-alkali lands in Changling County, Zhenlai County and Da'an City of the western Jilin Province in 1980-2000 with the help of GIS. The results show that the saline-alkali land rather sharply increased in Da'an during 1995-2000; the main conversion processes in the three counties were from grassland to saline-alkali land and from saline-alkali land to grassland; and the typical shapes, spatial expansion speed and mode, and landscape attributes of the saline-alkali land were different in the three counties, which were closely related to local topography, predominant wind orientation, water resources distribution, etc. The corresponding spatial expansion mode was marginality in Changling, random in Zhenlai and more kernels in Da'an, respectively. Landscape attributes also responded to the spatial-temporal dynamic changes of the saline-alkali land and the landscape indices of Da'an fluctuated greatly. The frame of this research may provide fundamental reference for landscape analysis and give some suggestions for regional sustainable development.  相似文献   

Predictive Models for Permeability of Cracked Rock Masses Based on Support Vector Machine Techniques     

Ma  Guotao  Chao  Zhiming  He  Kun 《Geotechnical and Geological Engineering》2021,39(2):1023-1031

In this study, a database developed from existing literature about permeability of cracked rock was established. The performance of Support Vector Machine (SVM) combined with optimisation algorithms: Genetic Algorithm (GA) and Particle Swarm Optimisation Algorithm (PSO) in predicting the permeability of cracked rock masses (CRM) is evaluated. Also, the sensitivity analysis of the influence factors to the permeability of CRM is conducted. The results indicate that the hybrid GA–SVM and hybrid PSO–SVM models can accurately predict the permeability of CRM in terms of the statistical performance criteria: Coefficient of Determination R², Regression Coefficient R and Mean Residual Error (MSE); Additionally, optimisation algorithms: PSO and GA can improve significantly the predictive performance of the SVM model. Based on the sensitivity analysis, crack angle is the most important factor to change the permeability of CRM, followed by confining pressure.

  相似文献   

Assessing crop yield and crop water productivity and optimizing irrigation scheduling of winter wheat and summer maize in the Haihe plain using SWAT model          下载免费PDF全文

Chen Sun  Li Ren 《水文研究》2014,28(4):2478-2498

Haihe plain is an important food production area in China, facing an increasing water shortage. The water used for agriculture accounts for about 70% of total water resources. Thus, it is critical to optimize the irrigation scheduling for saving water and increasing crop water productivity (CWP). This study first simulated crop yield and CWP for winter wheat and summer maize in historical scenario during 1961–2005 for Haihe plain using previously well‐established Soil and Water Assessment Tool model. Then, scenarios under historical irrigation (scenario 1) and sufficient irrigation (scenario 2) were, respectively, simulated both with sufficient fertilizer. The crop yield in scenario 2 was considered as the potential crop yield. The optimal irrigation scheduling with sufficient fertilizer (scenario 3) was explored by iteratively adjusting irrigation scheduling based on the scenario 1 and previous studies related to water stress on crop growth. Results showed that net irrigation amount was, respectively, reduced 23.1% and 18.8% in scenario 3 for winter wheat and summer maize when compared with scenario 1. The CWP was 12.1% and 8.2% higher with very slight change of crop yield. Using optimal irrigation scheduling could save 8.8 × 10⁸ m³ irrigation water and reduce about 16.3% groundwater over‐exploitation in winter wheat growth period. The corresponding yield was 18.5% and 12.9% less than potential yield for winter wheat and summer maize but using less irrigation water. Therefore, it could be considered that the optimal irrigation was reasonable, which provided beneficial suggestions for increasing efficiency of agricultural water use with sustainable crop yield in Haihe plain. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Use of stable water isotopes to assess sources and influences of slope groundwater on slope failure     

Tsung‐Ren Peng  Chung‐Ho Wang  Shih‐Meng Hsu  Nai‐Chin Chen  Tai‐Wei Su  Jiin‐Fa Lee 《水文研究》2012,26(3):345-355

This study employs stable oxygen and hydrogen isotopes as natural tracers to assess the headwater of a landslide next to a drainage divide and the importance of the slope's headwater in the study area. The study is undertaken near Wu‐She Township in the mountains of central Taiwan. Because a reservoir is located on the other side of the divide, this study evaluates the relationship between the reservoir water and headwater of the landslide as well. Over a 1‐year period, water samples from September 2008 to September 2009, including local precipitation (LP), Wu‐She Reservoir's water (WSRW), slope groundwater (SGW), upper‐reach stream water (USTW), and down‐reach stream water (DSTW), were analysed for deuterium (δD) and oxygen (δ¹⁸O) stable isotopes. Results indicate that WSRW is the predominant component in SGW: approximately 70% of SGW originates from WSRW and 30% from LP based on a two end‐member mass‐balance mixing model for δ¹⁸O. The similar two end‐member mixing model is also employed to assess the contributions of USTW and SGW to DSTW. Model results indicate that SGW is the major source of DSTW with a contribution of about 67%. Accordingly, about 47% of DSTW sources from the WSRW. In short, owing to reservoir leakage, WSRW contributes the greater part of both SGW and DSTW. Plentiful WSRW in SGW threatens the stability of the slope in the divide area. To avoid subsequent continuous slope failure, necessary mitigation steps are required. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Factors controlling spatial and seasonal distributions of precipitation δ18O in China     

Liangju Zhao  Honglang Xiao  Maoxian Zhou  Guodong Cheng  Lixin Wang  Li Yin  Juan Ren 《水文研究》2012,26(1):143-152

Utilising datasets from the Global Network of Isotopes in Precipitation of the International Atomic Energy Agency, and previous isotopic studies, we investigated δ¹⁸O spatial and temporal patterns in Chinese precipitation. Significantly positive relationships existed between precipitation δ¹⁸O and air temperature above the north of 35°N and in high altitude regions above 32°N. Significantly negative relationships between precipitation δ¹⁸O and the precipitation amount existed below south of 35°N. These temperature and precipitation effects became stronger with increasing altitude except in high altitude regions between 32°N and 35°N. The NCEP/NCAR reanalysis data from 1980 to 2004 showed that variations in spatial and seasonal wind fields at 700 hpa and total precipitable water from the ground to the top of the atmosphere were correlated with the monthly spatial distribution of precipitation δ¹⁸O. Basing on this relationship, we established quantitative correlations between the mean monthly precipitation δ¹⁸O and both latitude and temperature in different seasons. We found that spatial variations in precipitation δ¹⁸O could be described well using the Bowen–Wilkinson model and second‐order equations developed during the present study only in winter (from December to February). During the rest of the year, patterns were too complex to predict using simple models. The results suggest that it is difficult to demonstrate variations of precipitation δ¹⁸O throughout the year and for all regions of China using a single model. Moreover, the new models for the relationships among precipitation, latitude, and temperature were better able to depict the variations in precipitation δ¹⁸O than the Bowen–Wilkinson model. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Experimental investigation of propagation and run-up of rockslide- generated impulse waves in a curved mountain reservoir     

Han  Linfeng  Wang  Pingyi  Mu  Ping  Ren  Qingyang  Liu  Yun 《Natural Hazards》2022,111(2):1375-1399

Natural Hazards - Propagation and run-up of impulse waves generated by rockslides in curved channels are investigated by carrying out three-dimensional laboratory tests. The objective is to study...  相似文献   

Petrological and chronological characteristics of medium-high grade metamorphic rocks in Gonjo area,southeastern margin of Qamdo block,eastern Tibet.SCIEI北大核心CSCD     

唐渊  秦雅东  王冬兵  李勇  巩小栋  王保弟  任光明 《岩石学报》2022,(11):3302-3320

青藏高原东缘的昌都地块是连接青藏高原腹地和藏东南三江-印支地区的关键区域,发育有较完整的晚古生界,以三叠系、侏罗系-白垩系广泛分布为特色;但其前寒武纪基底岩系出露较少,主要以宁多岩群(Pt_(1-2)Nd.)和草曲群(Pt_(3)C)为代表。本文针对昌都地块东南缘贡觉地区出露的一套被前人称为“宁多岩群”的中深变质岩系,开展了系统的野外地质调查、显微薄片分析、锆石U-Pb年代学等研究工作,认为该套中深变质岩系属于一套变质杂岩,其岩石组合既包括了原岩沉积时代不早于奥陶纪的片麻岩、变粒岩和大理岩等副变质岩,又包含了原岩时代分别为中二叠世的斜长角闪岩和中三叠世花岗质片麻岩等正变质岩。其原岩时代特征与昌都地块北缘的宁多岩群有较大差别,不应当归属为昌都地块的前寒武纪结晶基底。结合片麻岩的变质新生云母类矿物Ar-Ar测年数据和变质后期侵入的闪长玢岩脉锆石U-Pb年龄,认为贡觉地区出露的中深变质岩的变质时代为ca.260~244Ma(P_(2)-T_(2))。该期发生在昌都地块东南缘的角闪岩相变质作用,是金沙江古特提斯洋向西俯冲-碰撞的构造响应。  相似文献   

西昆仑甜水海黄羊沟闪长玢岩年代学、地球化学特征及构造背景     

张博文  苏春媚  冯汉清  任文林 《吉林大学学报(地球科学版)》2022,52(5):1575-1593

黄羊沟闪长玢岩岩体侵位于甜水海—喀喇昆仑地块上侏罗统红其拉甫组灰岩地层中,为了厘定其形成时代,揭示岩石成因以及构造背景,对黄羊沟闪长玢岩岩体进行了LA-ICP-MS锆石U-Pb年代学及全岩地球化学分析研究。岩石地球化学研究结果表明,该岩体锆石U-Pb年龄为(159.9±1.4) Ma,形成于碰撞后伸展环境,源区具幔源特征,有地壳物质同化混染参与,形成条件为低压、强氧化环境,经历中等分异作用。该岩体具低硅（w(SiO₂)=56.11%~57.36%）、高钙（w(CaO)=4.29%~6.59%）、富碱（w(Na₂O+K₂O)=6.00%~7.96%）特征,属准铝质（A/NCK=0.79~0.95）岩石,且富集大离子亲石元素K、Rb、Ba、Th、U及亏损高场强元素Nb、Ta、Zr、Hf等,具微弱Eu负异常,δEu均值为0.97。通过区域岩浆活动对比研究,认为黄羊沟岩体与班—怒缝合带革吉地区的帕阿岩体I型花岗岩体具有很强的亲缘性,且与班—怒缝合带内的岩浆岩时限一致,表明甜水海地体南部的黄羊沟闪长玢岩是班—怒缝合带以北区域中、新特提斯洋向南俯冲的岩浆作用响应。  相似文献