Deep Structure and Dynamics of Passive Continental Margin from Shelf to Ocean of the Northern South China Sea

To study the deep dynamic mechanism leading to the difference in rifting pattern and basin structure from shelf to oceanic basin in passive continental margin,we constructed long geological sections across the shelf,slope and oceanic basin using new seismic data.Integrated gravity-magnetic inversion and interpretation of these sections were made with the advanced dissection method.Results show that the basement composition changes from intermediate-acid intrusive rocks in the sheff to intermediate-basic rocks in the slope.The Moho surface shoals gradually from 31 km in the sheff to 22.5 km in the uplift and then 19 km in the slope and finally to 13 km in the oceanic basin.The crust thickness also decreases gradually from 30 km in the northern fault belt to 9 km in the oceanic basin.The crustal stretching factor increases from the shelf toward the oceanic basin,with the strongest extension under the sags and the oceanic basin.The intensity of mantle upwelling controlled the style of basin structures from sheff to oceanic basin.In the Zhu 1 depression on the shelf,the crust is nearly normal,the brittle and cold upper crust mainly controlled the fault development;so the combinative grabens with single symmetric graben are characteristic.In the slope,the crust thinned with a large stretching factor,affected by the mantle upwelling.The ductile deformation controlled the faults,so there developed an asymmetric complex graben in the Baiyun (白云) sag.     

我国省域工业主导产业的遴选与发展

工业主导产业在国民经济发展中起着决定性和指向性的作用.主导产业的选择是经济发展阶段的重要课题.依据6个量化指标,从4个维度对“十一五”期间主导产业进行遴选,发现以能源及相关产业为代表的重化工业是各省的重点,高新技术产业成为主导产业的省份较少,劳动密集型产业依然是东部发达省市的重点,预期中的产业转移并未实现;以行业为变量对各省份的主导产业进行聚类分析,可将31个省份划分为5类,反映了我国各省份主导产业布局特点;在此基础上,依据产业生命周期理论和各地区“十二五”发展趋势,提出了相应的对策建议.     

Evaluation of water quality of the lower Mississippi River

Using the most recent hydrologic and water quality data issued by U.S. Geological Survey, this paper deals with the pollution of the lower Mississippi River for the 1978–1981 water years and compares the water pollution of this period with that of the 1973–1977 water years. The water quality of the lower Mississippi River has not been evaluated comprehensively. This paper utilizes the Cartesian coordinates approach in an appraisal of water quality of the Mississippi River for the first time. Thus, it provides a foundation for the further comprehensive evaluation of environmental quality and research of water resources.     

Reflection and transmission of seismic waves at an interface betwen two saturated soils

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基于“课程思政”的地理议题式教学设计研究——以“探究青藏高原的形成”为例

思政教育是德育工作的主渠道,围绕立德树人的教育目标,在地理议题式教学开放的环境中进行合作探究,把学生的思政教育融于教学内容,在探究活动的体验与感悟中,做到学用贯通、知行统一,在辩证与分析的过程中锤炼理性思维、培养有责任担当的优秀品质。     

Crustacean zooplankton distribution patterns and their biomass as related to trophic indicators of 29 shallow subtropical lakes

A comparative limnological study was carried out to present a snapshot of crustacean zooplankton communities and their relations to environmental factors to test whether there is a consistent relationship between crustacean biomass and trophic indicators among lake groups with similar trophic conditions. The study lakes showed a wide range of trophic status, with total phosphorus (TP) ranging from 0.008 to 1.448 mg L⁻¹, and chlorophyll a from 0.7 to 146.1 μg L⁻¹, respectively. About 38 species of Crustacea were found, of which Cladocera were represented by 25 taxa (20 genera), and Copepoda by 13 taxa (11 genera). The most common and dominant species were Bosmina coregoni, Moina micrura, Diaphanosoma brachyurum, Cyclops vicinus, Thermocyclops taihokuensis, Mesocyclops notius and Sinocalanus dorrii. Daphnia was rare in abundance. Canonical correspondence analysis showed that except for four species (D. hyalina, S. dorrii, C. vicinus and M. micrura), almost all the dominant species had the same preference for environmental factors. Temperature, predatory cyclopoids and planktivorous fishes seem to be the key factors determining species distribution. TP was a relatively better trophic indicator than chlorophyll a to predict crustacean biomass. Within the three groups of lakes, however, there was no consistent relationship between crustacean biomass and trophic indicators. The possible reason might be that top-down and bottom-up control on crustaceans vary with lake trophic state. The lack of significant negative correlation between crustacean biomass and chlorophyll a suggests that there was little control of phytoplankton biomass by macrozooplankton in these shallow subtropical lakes.     

地质环境信息系统上线安全检测工作实践

本文针对地质环境领域业务系统的特点,提出了一种信息系统上线安全检测的方法,深入探讨了上线安全检测实践中的基本流程、测评方法与测评成果,为提升地质环境信息系统安全运行和服务能力提供了技术支撑.     

苍山5.2Ms级地震前后地震前兆综合危险度的变化

地震前兆综合危险度是以系统论为基础的一种综合地震预报的新方法。利用山东省每年年底的地震会商报告给出的地震前兆异常,而不是取震后的震例总结或论文给出的异常,通过“专家系统”的思想,对每一异常事件进行综合评估,计算出无量纲的、归一化的地震前兆综合危险度,分析了１９９５年９月２０日山东苍山５２Ｍｓ级地震前综合危险度的变化特征。震前综合危险度出现了一次明显的高值异常变化,震后危险度很快下降恢复到正常水平。     

Optimization of concurrent mining and reclamation plans for single coal seam: a case study in northern Anhui, China

The extraction of underground ore body inevitably causes a large amount of land subsidence. Current reclamation technologies in China mainly focus on stable subsided land, which means most of the affected lands are submerged into water because of the high groundwater table in some areas, leading to the loss of soils and inefficient reclamation. Therefore, a new technology for reclaiming unstable subsiding land is being studied for restoring farmland as much as possible, based on a case study in northern Anhui, China. In consideration of the mining plan, subsidence processes in various stages were analyzed and some related factors such as vertical subsidence, post-mining slope, water area, and land use condition were also simulated. Due to mining activities, useful farmland has gradually decreased to merely 14.4 % of the pre-mining area. In this study, the following stages were modeled from pre-mining to post-mining: (1) percentage of farmland was 100 % in stage (a) (pre-mining), (2) 72.5 % in stage (b), (3) 67.3 % in stage (c), and (4) 14.4 % in stage (d) (post-mining). The results show that 86.6 % of cultivated land was submerged into water and lost its capacity for cultivation after coal mining. Reclamation plans for stages (b), (c), and (d) were made by a traditional reclamation method called “Digging Deep to Fill Shallow”. Based on scenario simulation of reclamation, the farmland reclamation percentages were improved to 78.3, 73.3, and 40.70 %, respectively. Taking the percentage of reclaimed farmland as the preferred standard, concurrent mining and reclamation for stage (b) and (c) could increase farmland reclamation percentages to 37.6 and 32.6 %, respectively, compared with the farmland reclamation percentage of post-mining [reclaiming the land in stage (d)]. The results reveal that optimum reclamation time should be at stage (b). Therefore, under current technical conditions, concurrent mining and reclamation could enhance the quantity of cultivated land and provide better land protection and food security in the mined areas with high groundwater table.     

Magnetostratigraphy of the Red Beds in the Hengyang Basin

Abstract This paper discusses the Cretaceous-Tertiary magnetic polarity sequence of the the Hengyang Basin on the basis of magnetostratigraphic study. The age of each stratigraphic unit has been determined with the magnetic polarity time scale combined with ³⁹Ar/⁴⁰Ar dating, thus providing evidence for determining the geological ages of different formations. The authors assign the age of the Dongjing Formation of the Hengyang Basin to Early Cretaceous, the Shenhuangshan Formation to Early-Late Cretaceous, the Daijiaping Formation to Late Cretaceous, and the Dongtang and Xialiushi formations to Palaeocene.