Geochemical indices of soil development on basalt rocks in arid to sub-humid climosequence of Central Iran

Quantitative weathering indices are efficient tools in determining the soil development from the underlying rocks. In order to evaluate the effects of climate on the soils developed under an arid to sub-humid climosequence in central Iran, twenty soil-development indices were compared. Twentyfour samples from six pedons were analyzed for routine physico-chemical and geochemical analyses using X-ray fluorescence(XRF). The lowest and highest calculated soil development indices were observed in the arid and sub-humid regions respectively. Among the studied indices, fifteen indices showed similar trends concerning the intensity of weathering. The consistency of such trends reveals the feasibility of using these indices to evaluate basalt weathering rate and soil development in arid, semi-arid and sub-humid regions. This study demonstrated that, among the evaluated weathering indices, the Weathering Index of Parker(WIP) and mass transfer coefficient(τ) were the most proper indices for predicting basalt weathering intensity. This is due to the fact that these indices use the highly mobile earth elements which are the most sensitive elements in basalt chemical weathering. The calculated indices were subdivided into three subgroups including the ratios of mobile/immobile, mobile/mobile and immobile/mobile elements based on the elements used in their calculation. The state of soil evolution was more accurately predicted compared to the other subgroups using the mobile/immobile subgroup of indices. Overall, the weathering indices calculated using the mobile elements are better indicators of weathering intensity, soil formation and the exogenous processes across the arid to sub-humid climosequence.     

Effects of environmental factors on classification of loessderived soils and clay minerals variations,northern Iran

Land-use type under different topographic conditions and human activities affects soil development. We investigated the effects of land-use, topography and human activity on soil classification changes in the Toshan watershed in northern Iran. Seven representative pedons derived from loess parent materials were studied on different land-uses and topographic positions. The studied pedons in forest (FO) on backslopes and footslope were classified as Calcic Haploxeralfs and Typic Haploxeralfs, respectively. The soils in abandoned lands (AB) and orchards (OR), where formerly under natural forests, located on the shoulder and backslopes positions were classified as Calcic Haploxeralfs and Vertic Haploxeralfs, respectively. Well-developed argillic horizons as indicators for higher degrees of soil evolution were observed in more-stable areas under the natural forest or less disturbed areas. Clay lessivage through these soil profiles have led to formation of Typic or Calcic Haploxeralfs, while under croplands (CP) were classified as Typic Calcixerepts. Conversion of sloping deforested areas to CP along with inappropriate management have accelerated soil erosion, resulting in unstable conditions in which decalcification and formation of developed soils cannot occur. Paddy cultivation in flat areas has caused to reduced conditions and formation of Typic Haplaquepts. Because of unfavorable conditions for chemical weathering (e.g. lower water retention compared to more-stable areas) no vermiculite was detected in the CP. The results showed that evolution and classification of the studied soils were strongly affected by land-use type, topography and management.     

Identifying flow regime in the aquifer of fractured rock system in Germi Chai Basin,Iran

Considering the importance of fractured rock aquifers in the hydrogeologic process, this research aimed to analyze the flow regime, internal degree of karstification, and estimate storage volume in fractured rock aquifers of the Germi Chai Basin in northwest Iran, which is attributed to its active tectonics, erosion, and the lithological diversity. Given the geological setting, the hypothesis is that this basin is characterized by a high degree of karstification and diffuse or intermediate flow ...     

Sea surface height variations in the Mindanao Dome region in response to the northern tropical Pacific winds

Sea surface height (SSH) variability in the Mindanao Dome (MD) region is found to be one of the strong variations in the northern Pacific. It is only weaker than that in the Kuroshio Extension area, and is comparable to that in the North Pacific Subtropical Countercurrent region. Based on a 1.5-layer reduced gravity model, we analyzed SSH variations in this region and their responses to northern tropical Pacific winds. The average SSH anomaly in the region varies mainly on a seasonal scale, with significant periods of 0.5 and 1 year, ENSO time scale2-7years, and time scale in excess of 8 years. Annual and long-term variabilities are comparably stronger. These variations are essentially a response to the northern tropical Pacific winds. On seasonal and ENSO time scales, they are mainly caused by wind anomalies east of the region, which generate westward-propagating, long Rossby waves. On time scales longer than 8 years, they are mostly induced by local Ekman pumping. Long-term SSH variations in the MD region and their responses to local winds are examined and discussed for the first time .     

Evapotranspiration and humidity variations in response to land cover conversions in the Three Gorges Reservoir Region

A new land cover classification system was established for the Three Gorges Reservoir Region (TGRR) after considering the continuity of inundation and the natural characteristics of land cover. The potential evapotranspiration (PET) was predicted using a modified Penman-Monteith (P-M) model. The region’s ratio of precipitation to evapotranspiration was calculated as the humidity index (HI). The data obtained was used to analyze climatic responses to land cover conversions from the perspectives of evapotranspiration and humidity variations. The results show that, from 1997 to 2009, the average annual PET increased in the early years and decreased later. In terms of overall spatial distribution, a significant reciprocal relationship appeared between annual PET and annual HI. In 1997, the annual PET was higher in the lower reaches than in the upper reaches of the TGRR, but the areas with high PET shifted substantially westward by 2003. The annual PET continued to increase in 2006, but the areas with high PET shrank by 2009. In contrast, the annual HI showed varying degrees of localized spatial variability. Over the three periods, the dominant forms of land cover conversions occurred from evergreen cover to seasonal green cover, from seasonal green cover to evergreen cover, and from seasonal green cover to seasonally inundated areas, respectively. These accounted for 48.0%, 38.4%, and 23.8% of the total areas of converted land covers in the three periods, respectively. During the period between 1997 and 2003, the main forms of land cover conversions resulted in both positive and negative growths in the average annual PET, while all of them pushed down the average annual HI. From 2003 to 2006, the reservoir region experienced neither a decrease in the annual PET nor an increase in the annual HI. The period between 2006 and 2009 saw a consistent downward trend in the annual PET and a consistent upward trend in the annual HI.     

准噶尔盆地腹部断裂和不整合面流体活动特征对比

断裂和不整合面是油气流体运移的良好通道,但对其流体活动特征的差异研究却不甚深入。以准噶尔盆地腹部地区为例,主要从流体活动的矿物岩石学记录入手,对断裂和不整合面的流体活动特征进行了对比研究。结果表明,断裂带流体活动复杂,在活动期均是油气流体运移的良好通道,并呈现出“幕式”特征,流体来源以深源含油气流体与大气降水影响为主。相比而言,不整合面之上流体来源较为单一,主要是含油气流体,而不整合面之下与断裂带地区类似,受到深源含油气流体与大气降水的复合影响。总体而言,断裂带流体活动强度要比不整合面上下的储层更强,断裂与不整合面纵横交叉之处是油气流体活动的有利通道,距不整合面越远,其流体活动强度越弱。这些认识可为区域油气勘探提供科学依据,也可供国内外同类研究类比参考。      

Implication of Surface Fractal Analysis to Evaluate the Relative Sensitivity of Topography to Active Tectonics,Zagros Mountains,Iran

Fractal geometry is increasingly becoming a useful tool for modeling and quantifying the complex patterns of natural phenomena. The Earth's topography is one of these phenomena that have fractal characteristics. This paper investigates the relative sensitivity of topography to active tectonics using ASTER Global Digital Elevation Model. The covering divider method was used for direct extraction of surface fractal dimension(D surf) to estimate the roughness-surface of topography with aid of geographic information system(GIS)techniques. This evaluation let us highlight the role of the geomorphic and tectonic processes on the spatial variability of fractal properties of natural landforms.Geomorphic zones can be delineated using fractal dimension mapping in which variability of surface fractal dimension reflects the roughness of the landform surface and is a measure of topography texture. Obtained results showed this method can be a quick and easy way to assess the distribution of land surface deformation in different tectonic settings. The loose alluvial deposits and irregularities derived by tectonic activity have high fractal dimensions whereas the competent formations and higher wavelength folded surfaces have lower fractal dimensions.According to the obtained results, the Kazerun Fault Zone has a crucial role in the separation of the Zagros Mountain Ranges into the different lithological,geomorphological and structural zones.     

Documentation of the Sirjan Orocline in the southeast Sanandaj-Sirjan Zone,Iran

At the southeastern part of the SanandajSirjan Zone of Iran, a group of structural elements outline a large-scale arc curvature around a vertical axis. This curvature comprises several elongated structural elements and their dividing faults, axialfold traces, layering, and foliation. The most frequent lithological units include Paleozoic metamorphic rocks, Mesozoic-Paleogene sedimentary rocks, and Mesozoic magmatic-ophiolitic complex disposed in several anticlines and synclines, forming a horseshoeshaped structure with a 240-km arc length and a 90-km wavelength. We name this structure the Sirjan Orocline, and characterize this structure here through field observations and satellite image analyses. The Sirjan Orocline formed during the late EoceneOligocene related to the most significant deformation event after regional metamorphism. The final form of this structural arc is affected by a younger tectonic event that compressed and transected this structure.     

Water resource management in the intermountain Izeh Plain, Southwest of Iran

Ever growing demand for water for agricultural activities in the Izeh Plain has enhanced the use of groundwater. Due to enormous groundwater abstraction since 1985, the overall static water level has receded by more than 5 meters reflecting that the aquifer is under stress condition. As a result, interest is focused on application of artificial recharge as an option for groundwater management to augment water supply in this area. Therefore, in the present investigations, suitable sites for artificial recharge were selected by an integrated surface and sub-surface assessment of the area. On the basis of the data collected from four target points, it was realized that the selected sites for artificial recharge could not meet water demand of the area. In this study attention was also paid to utilization of the existing Miangran Lake water as an alternative to combat water shortage for irrigation. The study further indicated that the available Miangran Lake water could be used for irrigation of the reclaimed agricultural land and enabling to convert 20o0 hectares of rain-fed land into irrigation. The total cost to utilize lake water is US$ 2,756,729 and it was estimated that the project could recoup the investment within 5 years which is quite reasonable in this water scarcity prone area.     

Dynamics and responses of vegetation to climatic variations in Ziya-Daqing basins,China

Examining the direct and indirect effects of climatic factors on vegetation growth is critical to understand the complex linkage between climate change and vegetation dynamics. Based on the Moderate Resolution Imaging Spectroradiometer(MODIS) Normalized Difference Vegetation Index(NDVI) data and meteorological data(temperature and precipitation) from 2001 to 2012, the trend of vegetation dynamics were examined in the Ziya-Daqing basins, China. The path analysis was used to obtain the information on the relationships among climatic factors and their effects on vegetation growth. It was found that the trends of growing season NDVI were insignificant in most plain dry land, while the upward trends were significant in forest, grass and dry land in Taihang Mountains. According to the path analysis, in 23% of the basins the inter-annual NDVI variation was dominated by the direct effect of precipitation, in 5% by the direct effects of precipitation and temperature, and in less than 1% by the direct effect of temperature or indirect effects of these two climatic factors. It indicated that precipitation significantly affected the vegetation growth in the whole basins, and this effect was not regulated by temperature. Precipitation increase(especially in July, August and September) was favorable to greenness enhancement. Summer temperature rising showed negative effect on plant productivity enhancement, but temperature rise in April was beneficial for the vegetation growth. When April temperature increases by 1℃, the onset date of greenness for natural vegetation will be 2 days in advance. There was a lag-time effect of precipitation or temperature on monthly NDVI for all land use types except grass.     

Evidence of the formation of landslide-dammed lakes in the Zagros Mountains range,Iran

Alternation of high and low resistance sedimentary beds,active tectonics,large rivers,and slope erosion in valleys consequently resulted in landslide in dammed lakes within the Zagros range.This study presents the results in the analysis of geological and topographic data,satellite imageries,morphotectonics and hydrodynamics of drainage networks about the landslide dammed lakes.There are four landslides in central Zagros(Zagros FoldThrust Belt,ZFTB)which have formed five dammed lakes named,Seymareh,Jaidar,Shur,Shimbar,and Godar.According to the results,damming landslides occurred in the active-tectonic regions on the slopes of anticlines and in valleys with undercutting effects of rivers on their slopes consisting of alternations of loose and resistant beds.The studied landslide dams in narrow valleys are formed as a result of blocking river by sliding debris slopes and rock slides.This study also indicates the formation of Jaidar and Godar in one stage and the presence of Lake Terrace sequence in Seymareh,Shur and Shimbar lakes.The observed sequences of terrace formation in these lakes are caused by four Seymareh Landslides followed by the three-stage excavation of Shur andShimbar lakes.     

Indexing the engineering properties of residual soils in the southern slopes of Mashhad,NE Iran

Residual soils are weathering products of rocks that are commonly found under unsaturated conditions. The properties of residual soils are a function of the degree of weathering. A series of index properties, engineering properties and geophysics survey examinations were performed on residual soils from two major geological formations in Iran. In the present research, the index properties of residual soils in the south of Mashhad city in Iran are investigated.Natural and artificial trenches were analyzed for evaluating the weathering profiles and collecting soil samples. Disturbed and undisturbed samples were obtained from each of the soil profile horizons resulting from weathering of different parent rocks.Subsequently, physical properties and mechanical properties of the soil samples were determined in accordance with ASTM standards. Also, the mineralogical composition, chemistry, and texture of the soil were evaluated in 51 profiles. The field observations showed the difference in the weathering profile of residual soils deposited on various rocks(igneous, sedimentary, and metamorphic). These profiles mainly consisted of two horizons includingresidual soil on top and saprolite at the bottom. The results of laboratory tests and geotechnical data showed that the properties of residual soil samples change by depth. Moreover, depending on the type of origin rock, the properties are different in various types of residual soils. In most of the samples, the moisture content of soil horizons was also increased by depth. Based on the unified soil classification(USCS), the soils of the upper horizons appeared to be classified as ML(Lean silt) and CL(Lean clay) while the soils of the lower horizons(saprolite zone) fall in SC(clayey sand), SM(silty sand), and SW(wellgraded sand) classes. Moreover, the results demonstrated that the particle size of the soil was increased by depth. Comparison of results of the geotechnical tests showed that properties of residual soils are changed by variations of depth, weathering level, and type of parent rock. Considering the concentration of the number of lines and the concentration of the points of intersection, the length and dimension fractal of lineaments in the southeastern part of the study area, it is evident that this zone possesses weathering severity and soil thickness. Fieldwork data from this zone have also verified the severity of weathering conditions. The analysis of lineaments trends in different parts of the study area indicated that the lineaments with the NW-SE trend have a strong effect on weathering development. The weathering depth depends on the orientation of bedding joints with respect to the slope in the study area. Slope inclination and soil thickness are controlled by weathering and erosion processes.     

云南昌宁柯街断裂带温泉水化学特征

通过对柯街断裂带上2个温泉(梁园温泉和大地温泉)水样的阴阳离子分析,正确划分了温泉水的水化学类型;同位素
数据表明,2个样品的δD和δ18O值均在大气降水线附近,且未显示δ18O值向右漂移现象,说明该区地下热水具有现代大气降水
的氢氧同位素组成特征,推断温泉形成与火山、岩浆型热源没有直接关系。大气降水的同位素组成与海拔高程之间的耦合关系,
证明了地下热水补给源区位于西部山区;通过采用SiO₂ 温标计算得出了温泉的热储温度和热水循环深度。梁园温泉热储温度为
100.1℃,热水循环深度是1643.3m,大地温泉热储温度为79.8℃,热水循环深度是1237.2m。柯街断裂带的构造特征及岩性特
征与地下热水的水化学组成、深循环机制和冷热水的混合机制有着本质的联系。      

沂沭断裂带西缘昌乐县中部地区地热成热地质条件分析

通过对地质资料的分析,认为该区理论上具有较好的地热生成环境和赋存条件。重点围绕鄌郚葛沟断裂两侧,综合运用地质调查、测温、物探、钻探等手段,对成热地质条件进行调查分析,圈定淳于地热异常区和梁家庄地热异常区2个异常区,分析并初步确定热源为地壳深部的热流,导水导热通道为鄌郚葛沟断裂及其次级断裂,热储为深循环对流型带状热储,热储岩性为白垩纪青山群安山岩,埋深1400~2000m,盖层为新近纪、古近纪及白垩纪粘土岩、砂岩等。结合区域地质资料,建立地热资源概念模型,并据此确定了3处拟井位置及孔深。     

Determinants of Adaptation to Climate Change:A Case Study of Rice Farmers in Western Province,Iran

The decisions made by agricultural households to adjust to climate change(CC)in Iran are not well known.This study is intended to investigate the influence of perceptions and socioeconomic,institutional features on farmers’adaptation decisions about CC,which constitute the hypothetical statements of the study.We undertook a survey of 200 farm householders from 31 villages of Ilam Province,situated in the western Iran,as randomly selected.The result discloses that the proposed discriminant model matches the dataset well,with a strong effect size of partial eta-squared(η²=0.38).The analysis further signals that adapters are younger and more welleducated than non-adapters.Adapters are also knowledgeable about CC risks and institutional policy barriers.The adapters have subsidiary work,better access to credit,and have good contacts with expansion agents and specialists.The paper concludes that government authorities should provide farmers with the enriched capabilities and competencies enabling them to adapt to CC.     

A hydrochemical and dye- tracing investigation in the Posht-e-Naz Karstic Aquifer, Alburz Mountain, Northern Iran

A hydrochemical and tracer study (uranine injection) was conducted in Jurassic limestone of the Posht-e-Naz area in the Alborz belt to evaluate hydraulic relations between a large diameter (about 100 m) sinkhole and springs and aquifer parameters. A main goal of the project was to find out the source of turbidity of the Emarate drinking water supply spring (SP4) in rainy season. Springs discharge were measured and hydrochemical investigation were carried out. The uranine tracer was injected and eight springs, three wells and the Neka River were selected and totally 989 samples in 107 days were collected. Hydrochemical data demonstrated a relative connection between sinkhole (Sh1) and spring (SP4). The results of the tracing by sampling water indicated only a hydraulic connection between Sange- Nou spring (SP8) and injection point, while the charcoal packets analysis revealed tracer exits from spring numbers SP1, SP3, SP4, SP5, SP8, in wells W1 and W2, and in the Neka River. The concentration — time curves of charcoal packets for qualitative analysis and exit tracer for quantitative analysis is also assessed.     

Seismotectonics and consequences of the 1930s large earthquakes in eastern Mazandaran,north of Iran

Early in the 1930s,two relatively large earthquakes (Kosout,magnitude 6.8,and Talarrud,magnitude 5.8) shook the eastern Mazandaran,northern Iran.Despite the his...     

Spatial variations of bacterial community composition in sediments of the Jiaozhou Bay,China

Spatial variations of sediment microbes pose a great challenge for the estimation of anthropogenic influence on biogeochemical processes, yet remain very unclear in coastal ecosystems. Surface sediments in 9 stations from the eutrophic Jiaozhou Bay, China, were sampled, DNA was extracted within the sediments, and the 16 S rDNA was sequenced with the Illumina Hiseq sequencing. Results reveal considerable heterogeneity of sediment bacteria in the Jiaozhou Bay, of which Proteobacteria and Bacteroidetes accounted for over 75%. Bacterial alpha-diversity indices decreased generally from the outside to the inner part of the bay and from the offshore to the nearshore area. Bacterial community structures of S3, S4, S7, and S8 clustered, those of S5, S13, and S14 grouped together, while those of S6 and S10 were distinct from each other and from those of the other stations. Major class Gammaproteobacteria were more abundant at the stations with mesoeutrophic to eutrophic levels(S4, S5, S8, and S10) and less abundant at oligotrophic stations(S6, S13, and S14), while Deltaproteobacteria had an opposite distribution pattern. Overall, bacterial community composition transitioned from being Xanthomonadales-dominant at S4 and S8 to being unidentifed_Gammaproteobacteria-dominant at S5, S6, S13, and S14, while in other stations there were comparable orders. The biogeochemical processes correspondingly changed from being nitrogen cycling-dominant at S4 and S8 to being sulfur cycling-dominant at S5, S6, S13, and S14. The bacterial distribution patterns were especially affected by the factors(dissolved organic phosphorus, DOP) in the overlying seawater due to the habitat status of P-insu fficiency in the bay. Both orders Xanthomonadales and Alteromonadales could serve as bioindicators of anthropogenic pollution to different pollution types. At last, divergent distribution patterns of individual bacterial populations in the bay were revealed, the influential environmental gradients were clarified, and the uncertainty of microbes was reduced, helping to predict environmental functions in coastal areas.     

An assessment of variations in mercury deposition to Antarctica over the past 34,000 years

We performed a comparison analysis of the variations .in Mercury ( Hg) concentrations and the precipitation proxies ( e. g. , 18 O values and 10 Be concentrations) in the Dome C ice core. The results showed that there were significant correlations between Hg and δ 10O values, 10Be concentrations, indicating that the accumulation rate in Dome C is one of the key factors controlling the variations of Hg concentrations in the past 34 ,000 years, and implying that Hg concentrations in ice core can be used as another reliable proxy of precipitation rate in Antarctica. Based upon the high-resolution δ 18O values, we estimated the variations in mercury deposition flux to Antarctica over the past 34,000 years. The highest mercury deposition flux is about 3. 80 pg cm-2 yr-1 during the Last Glacial Maxium (LGM) as high as 3. 5 times of the mercury deposition flux ( about 1. 08 pg cm -2 yr -1) in Holocene due to the fluctuations in natural mercury emissions such as the oceanic biological emissions.