The human impact on the transformation of juniper forest landscape in the western part of the Pamir-Alay range (Tajikistan)

Detailed analyses were conducted of human impact on juniper forest landscapes occurring within the Zarafshan Range (Pamir-Alay). Juniperus seravschanica and J. semiglobosa belong to forest-forming species in Central Asia. At present, juniper forests all over Tajikistan are seriously threatened as a result of excessive logging and cattle grazing. The aim of this paper is to present juniper forest transformation as a result of human activities as well as the diversity of soil properties in the organic and humus horizons in the altitudinal system of soil zonation. Three groups of phytocoenoses were distinguished: those with a dominant share of Juniperus seravschanica; those with a dominant share of J. semiglobosa; and mixed. Associations with Juniperus seravschanica and J. semiglobosa feature several variants of phytocoenoses with dominant species: Artemisia lehmanniana, A. dracunculus, Eremurus olgae, Festuca sulcata, Ligularia thomsonii, Stipa turkestanica, Thymus seravschanicus, and Ziziphora pamiroalaica. The collected soil samples differ in their granulometric composition. Gravelly cobble fractions >2 mm are dominant; the share of sandy particles <2 mm is much lower (about 10–20%). Fraction 0.5–0.05 attains 35% on average. The Corg content of the soil varied from 0.26 to 11.40% in the humus horizon (A) and from 4.3 to 25% in the organic (O). Similar relationships were reported in the case of Ntot concentration. A clear relationship can be observed between concentrations of Corg and Ntot. Soil pH varied, ranging from very low acidic (pH 5.5) to neutral (pH 8.5). The content of available P varied; high concentrations were noted in organic (O) (40.46–211 mg kg^?1) and mixed horizons (OA) (2.61–119 mg kg^?1). Maximum accumulations of Pavail (1739.6 mg kg^?1) and Ptot (9696 mg kg^?1) were observed at a site heavily affected by intense grazing. Concentrations of Mgavail varied from 116 to 964 mg kg^?1. Most of the analysed soil profiles lacked an organic horizon; only thin humus occurred.     

Subsidence prediction method of solid backfilling mining with different filling ratios under thick unconsolidated layers

Solid backfill mining for coal pillar recovery in industrial squares has to ensure that the mine infrastructure, such as the shafts and substations, is not degraded or has its utility impaired by that mining. At the same time, it is important to recover as much coal as possible. As a result, it is necessary to predict mining subsidence during solid backfilling mining of coal pillars in industrial squares and to optimize the design of the working faces. At the Baishan coal mine in Anhiu province, China, there are thick layers of unconsolidated overburden above the coal seam so it is not appropriate to use the surface subsidence prediction method of equivalent mining height to predict subsidence during the mining of the coal pillars there. In order to find a reasonable coal pillar recovery scheme for the Baishan mine, a numerical simulation method is used to determine the relationships between the compression ratio of the backfilling material and the surface subsidence prediction parameters. Research was done to determine the appropriate parameters, and based on the final prediction parameters and taking the mandated protection standards for buildings and structures into account, surface subsidence is predicted and a backfill mining scheme for pillar recovery is proposed. The results show that of the six mining schemes considered, scheme 5 is the best scheme for coal pillar recovery in the industrial square at the Baishan mine. The research results are significant for similar mines with thick unconsolidated overburden anywhere in the world.     

Numerical investigation of slippage characteristics of normal and reverse faults under fluid injection and production

Nowadays, a great deal of petroleum geology and engineering projects associated with underground fluid injection and production (FIP) are widely conducted around the world. The FIP engineering may cause complex stress perturbation and trigger seismicity, which have been extensively reported and studied. In this paper, we investigated the fault slippage characteristics influenced by FIP. It reveals that for a fault (normal or reverse) that penetrating through the reservoir into the caprock and underburden, the footwall reservoir is the relatively stable one for fluid injection in a fluid FIP engineering. No matter it is a normal or a reverse fault, injecting fluid into footwall reservoir and producing fluid from the hanging wall reservoir can induce smaller fault slippage. After having determined the better fluid injection–production pattern, we studied the influence of three key factors of fault, i.e., dip, offset and depth, on fault stability. We found that, in our range of study, the influence of single action of fault dip, offset or depth on fault slippage in a FIP engineering was small. However, the influence of the combined effects of the factors may be large. Finally, we studied the effect of different pressure management scenarios on fault responses based on the specific fluid injection–production pattern. The results revealed that appropriate pressure management could effectively reduce fault slippage in a FIP engineering. However, inappropriate pressure management may cause much larger fault slippage. Given these concerns, it is therefore vital that the effect of pressure management scenario to be modeled prior to FIP.     

Centroid sliding pyramid method for removability and stability analysis of fractured hard rock

This paper proposes a new method using centroid sliding pyramid (CSP) to identify the removability and stability of fractured hard rock in tunnel and slope engineering. The new method features two geometrical and topological improvements over the original key block method (KBM). Firstly, all the concave corners are considered as starting points of cutting process when a concave block is divided into a set of convex blocks in the original KBM. Only the concave corners formed by two joint planes are used for partitioning a concave block in the presented method and concave corners with free planes are excluded. Secondly, joint pyramid for removability computation in the original KBM is generated using all of the joint planes, while CSP is calculated only from the joint planes adjoining the free planes. The cone angle θ of CSP is the vectorial angle formed by the two candidate sliding surfaces of this CSP. Removability analysis of a block is transformed into calculating the cone angle of CSP. The geometrical relationship is simplified, and data size for removability computation is reduced compared with the original KBM. The provided method is implemented in a computer program and validated by examples of fractured rock slopes and tunnels.     

<Superscript>230</Superscript>Th/<Superscript>238</Superscript>U dating of hydrothermal sulfides from Duanqiao hydrothermal field,Southwest Indian Ridge

Duanqiao hydrothermal field is located between the Indomed and Gallieni fracture zones at the central volcano, at 50°28′E in the ultraslow-spreading Southwest Indian Ridge (SWIR). Twenty-eight subsamples from a relict chimney and massive sulfides were dated using the ²³⁰Th/²³⁸U method. Four main episodes of hydrothermal activity were determined according to the restricted results: 68.9–84.3, 43.9–48.4, 25.3–34.8, and 0.7–17.3 kyrs. Hydrothermal activity of Duanqiao probably started about 84.3 (±0.5) kyrs ago and ceased about 0.737 (±0.023) kyrs ago. The periodic character of hydrothermal activity may be related to the heat source provided by the interaction of local magmatism and tectonism. The estimated mean growth rate of the sulfide chimney is <0.02 mm/yr. This study is the first to estimate the growth rate of chimneys in the SWIR. The maximum age of the relict chimney in Duanqiao hydrothermal filed is close to that of the chimneys from Mt. Jourdanne (70 kyrs). The hydrothermal activity in Dragon Flag field is much more recent than that of Duanqiao or Mt. Jourdanne fields. The massive sulfides are younger than the sulfides from other hydrothermal fields such as Rainbow, Sonne and Ashadze-2. The preliminarily estimated reserves of sulfide ores of Duanqiao are approximately 0.5–2.9 million tons.     

全球实施碳税政策对碳减排及世界经济的影响评估

该研究模拟了全球各区域2008-2050年的经济发展和碳排放状况,并将该模拟结果设定为基准情景。在基准情景中全球GDP随时间增长,而全球的碳排放同样表现出增长趋势。为了模拟碳税政策的减排效应及其对经济的影响,本文构建了其他3种碳税政策情景。情景1,将碳税收入作为一般性财政收入,此时全球升温减缓,世界碳排放下降显著,但中国、印度、俄罗斯、马来西亚和印度尼西亚等发展中国家经济发展严重受创,世界经济不均衡加剧。情景2,将各区域的碳税收入汇总之后按照比例统一分配,该情景下,世界碳减排规模较情景1略有下降,但世界各区域的经济较基准情景得到更好的发展。情景3,碳税税率随时间阶段性增长,此时,碳税政策对全球升温的控制更显著;世界各区域,尤其是发展中国家（地区）,经济增长更迅速。另外,碳税收入用来提升区域技术进步,在一定程度上促进了产业的优化升级。碳税政策与技术进步的协同减排政策,考虑了区域经济发展的不均衡性,兼顾了气候治理的公平性,是一种有效、可行的全球气候治理政策。     

临震天体引潮力和地面长波辐射OLR异常

利用天体引潮力周期变化模型和地面长波辐射(OLR)数据资料,分析2010~2011年云南、西藏地区的4次M5.0以上地震震前OLR异常,探讨了诱发地震的外部因素,即天体引潮力周期与红外异常发展的关联特征。结果显示:以临近发震时刻所在周期引潮力值最低点日期为OLR参照背景,获取的地震前后NOAA长波辐射OLR日增量分布图像显示:震中附近热异常明显,异常受构造控制,且其分布与断裂关系密切;异常演化经历起始-加强-高峰-衰减-再增强-发震-平静的过程,符合岩石因应力增加而破裂的规律。一方面表明地应力的临界状态演化过程可通过OLR辐射变化来反映。另一方面表明引潮力可以改变构造内部地应力的状态。