Changes in chemical composition caused by water–rock interactions across a strike‐slip fault zone: case study of the Atera Fault,Central Japan

In some cases, water–rock interactions in fault zones can affect radionuclide migration. Here, we analyzed the chemical compositions of well‐exposed fault rocks from the strike‐slip Atera Fault, Central Japan, in order to understand the variability and behavior of major and selected trace elements. The fault zone has a 1.2‐m‐wide, smectite‐rich fault core and paired damage zones that developed within welded tuff on one side of the core and within granite on the other side. The 30‐cm‐wide, kaolinite‐rich fault gouge is developed in granite cataclasite, and it shows indications of the latest fault activity, while the 1.2‐m‐wide fault core appears to be older. Hydrogen and oxygen isotope ratios in the clay‐rich fault gouges, and carbon and oxygen isotope ratios in carbonates indicate that the two major clay‐rich zones formed in bedrock near the surface, consistent with observed deformation structures. Based on chemical analyses, we identified (1) a slight depletion in SiO₂, Na₂O, K₂O, and light rare earth elements at the edges of the 1.2‐m‐wide fault core, (2) a clear depletion in SiO₂, Na₂O, K₂O, and all rare earth elements except Eu in the 30‐cm‐wide fault gouge, and (3) an increase in CaO, MnO, and heavy rare earth elements across the entire 1.2‐m‐wide fault core. Findings (1) and (2) reflect water–rock interactions in the 1.2‐m‐wide fault core and in the 30‐cm‐wide fault gouge that resulted in the formation of smectite and kaolinite. Finding (3) reflects carbonate precipitation caused by the addition of basalt fragments from a nearby site to the 1.2‐m‐wide fault core during faulting, and subsequent sorption reactions of heavy rare earth elements via processes such as complexation with the carbonates.     

Rates of retrograde metamorphism and their implications for crustal rheology

The rate of reaction of a natural hornblende garnet granulite with water under a range of mid- to lower crustal conditions has been investigated experimentally. In runs of between 7 and 84 days small but measurable amounts of water were consumed, and sheet silicates (300°C, 300 MPa and 400°C, 400 MPa) and/or secondary actinolite (400°C, 400 MPa and 500°C, 500 MPa) were observed to have grown. When normalized to the surface area of the starting materials, hydration rates were in the range of 2–5 × 10⁻⁸ g m⁻² sec⁻¹. These reaction rates imply that a film of water that infiltrated a planar crack with a half width of 100 μm would be completely consumed within c. 100 years. These results imply that where water infiltrates the crust along faults or underlying shear zones in response to a deformation, it will remain as a free phase for only a finite period of time, which in some cases will be less than the repeat time for major earthquakes in the fault system. Thus, the rheology of fault zones and shear zones is likely to be cyclical, with the zone becoming stronger with time as water is consumed, and then weakened by infiltration of water after each rupture.     

Hydraulic observations from a 1 year fluid production test in the 4000 m deep KTB pilot borehole

A long‐term pump test was conducted in the KTB pilot borehole (KTB‐VB), located in the Oberpfalz area, Germany. It produced 22 300 m³ of formation fluid. Initially, fluid production rate was 29 l min^?1 for 4 months, but was then raised to an average of 57 l min^?1 for eight more months. The aim of this study was to examine the fluid parameters and hydraulic properties of fractured, crystalline crusts as part of the new KTB programme ‘Energy and Fluid Transport in Continental Fault Systems’. KTB‐VB has an open‐hole section from 3850 to 4000 m depth that is in hydraulic contact with a prominent continental fault system in the area, called SE2. Salinity and temperature of the fluid inside the borehole, and consequently hydrostatic pressure, changed significantly throughout the test. Influence of these quantities on variations in fluid density had to be taken into account for interpretation of the pump test. Modelling of the pressure response related to the pumping was achieved assuming the validity of linear Darcy flow and permeability to be independent of the flow rate. Following the principle ‘minimum in model dimension’, we first examined whether the pressure response can be explained by an equivalent model where rock properties around the borehole are axially symmetric. Calculations show that the observed pressure data in KTB‐VB can in fact be reproduced through such a configuration. For the period of high pumping rate (57 l min^?1) and the following recovery phase, the resulting parameters are 2.4 × 10^?13 m³ in hydraulic transmissivity and 3.7 × 10^?9 m Pa^?1 in storativity for radial distances up to 187 m, and 4.7 × 10^?14 m³ and 6.0 × 10^?9 m Pa^?1, respectively, for radial distances between 187 and 1200 m. The former pair of values mainly reflect the hydraulic properties of the fault zone SE2. For a more realistic hydraulic study on a greater scale, program FEFLOW was used. Parameter values were obtained by matching the calculated induced pressure signal to fluid‐level variations observed in the KTB main hole (KTB‐HB) located at 200 m radial distance from KTB‐VB. KTB‐HB is uncased from 9031 to 9100 m and shows indications of leakage in the casing at depths 5200–5600 m. Analysis of the pressure record and hydraulic modelling suggest the existence of a weak hydraulic communication between the two boreholes, probably at depths around the leakage. Hydraulic modelling of a major slug‐test in KTB‐HB that was run during the pumping in KTB‐VB reveals the effective transmissivity of the connected formation to be 1 to 2 orders of magnitude lower than the one determined for the SE2 fault zone.     

长春-吉林经济带的形成与空间结构特点研究

文章通过对经济带概念的分析,构建经济带的形成和演进理论,认为经济带有等级、层次之分,其时空演进的理论为增长极理论——点一轴发展理论——梯度推移理论。在此基础上,论证长春—吉林经济带的存在性,分析其结构、功能及空间联系形式。作者认为,长春—吉林经济带目前是一个弱经济带,其扩散效应较弱,随着其扩散效应的增强,长春—吉林经济带将能够从整体上带动和促进吉林省的经济发展。     

Pollution effects of place-based policy: Evidence from China's development-zone program

Environmental externalities of place-based policy have generally been overlooked despite their welfare consequences. This paper studies the air-pollution effect of development zones in urban China using a geo-coded data set of 2720 counties from 1998 to 2016. By adopting the generalized difference-in-difference framework to resolve the problem of endogenous locational selection for place-based policies, we find that development zones reduce ambient PM_2.5 concentration by around 1.8%, leading to a total social gain of $7.75 billion USD. The environmental benefit varies by the zone's dominant industry, geographical region, administrative affiliation and time of establishment. We further show that development zones are comparably cleaner due to the incentives of central and local governments, manifested by the desire to administratively promote development zones, the attempt to satisfy residential demands for higher quality-of-life cities, and the employment of the national environmental monitoring system.     

藏北无人区的三大动物家族

藏北无人区是野生动物的天然保护区,那里繁衍生息着许多高原特有的珍稀动物。在无人区的动物种类中,最大的群落要数藏羚羊、藏野驴和野牦牛三种。它们是动物王国里名声显赫的“三大家族”。     

广州市商业功能区空间结构研究

商业功能区是城市商业多种业态和功能在不同地域的反映,其形成环境和演化过程深刻地影响着城市商业空间结构的发展走势。下文通过分析广州市商业功能区的空间分布特征、形成机制及演化趋势,探讨城市商业功能区的发展规律。     

县域主体功能区划分研究——以广东省云安县为例

采用GIS,以云安县为例,以100m×100m格网作为评价单元,根据格网内的环境特征,选用对区域开发建设影响较大的自然生态、生态服务、灾害风险等作为生态敏感性评价条件,约束区域的发展;在分析经济社会发展空间格局的基础上,采用资源承载力、社会支撑力、经济发展力、集聚辐射力、区位支撑力和外部推动力综合评价了经济社会综合发展潜力,作为区域发展的推动力,综合考虑生态敏感性和社会经济综合发展力,划分了主体功能区,并分析了各区的发展方向主要功能和管制措施。     

西安高新区经济发展水平及其竞争力分析

为揭示西安高新区经济发展水平在全国高新区中的地位,首先采用聚类分析及因子分析方法对53个国家级高新区经济发展状况进行了分析,西安高新区的经济发展水平处于前十名,处于发展良好的一类;接着从高新区企业平均经济规模、人均工业总产值、企业市场竞争力、参与国际竞争能力及技术转化能力五个方面对包括西安高新区在内的发展较好以上的30个高新区作了进一步分析,指出了虽然从整体来看西安高新区的经济发展在人力资源、科技创新、产品开发等方面存在的优势,但与成都、武汉等高新区相比,其优势并不明显;最后提出了西安高新区应该从产业环境、招商引资和软硬环境等方面提高其竞争力的政策建议。     

江苏省海岸带可持续发展初探

在海洋经济区中,海岸带具有一定的特殊性。虽然其资源丰富且种类繁多,但由于受到多种作用力的交互影响,而客观上存在各种灾害频繁、生态环境脆弱等问题,因此迫切需要实施可持续发展。江苏是海洋资源大省,海涂面积占全国海涂总面积高达30%左右,大陆海岸线长度约占全国大陆海岸线总长度的5.3%,但却又是海洋经济弱省,其海洋产业产值仅占全国海洋产业总产值的4.4%,与广东(21.71%)、山东(14.14%)、浙江(14.05%)、福建(12.68%)相比存在很大差距,已经成为江苏区域发展中必须正视和急于解决的突出问题。本文从可持续发展原理出发,通过分析江苏省海岸带的特点及其开发利用现状与存在问题,提出了实施其可持续发展的战略选择以及所应采取的主要措施。