Uncertainties of landslide susceptibility prediction:influences of different study area scales and mapping unit scales

This study aims to investigate the effects of different mapping unit scales and study area scales on the uncertainty rules of landslide susceptibility prediction(LSP).To illustrate various study area scales,Ganzhou City in China,its eastern region(Ganzhou East),and Ruijin County in Ganzhou East were chosen.Different mapping unit scales are represented by grid units with spatial resolution of 30 and 60 m,as well as slope units that were extracted by multi-scale segmentation method.The 3855 landslide locations and 21 typical environmental factors in Ganzhou City are first determined to create spatial datasets with input-outputs.Then,landslide susceptibility maps(LSMs)of Ganzhou City,Ganzhou East and Ruijin County are pro-duced using a support vector machine(SVM)and random forest(RF),respectively.The LSMs of the above three regions are then extracted by mask from the LSM of Ganzhou City,along with the LSMs of Ruijin County from Ganzhou East.Additionally,LSMs of Ruijin at various mapping unit scales are generated in accordance.Accuracy and landslide suscepti-bility indexes(LSIs)distribution are used to express LSP uncertainties.The LSP uncertainties under grid units significantly decrease as study area scales decrease from Ganzhou City,Ganzhou East to Ruijin County,whereas those under slope units are less affected by study area scales.Of course,attentions should also be paid to the broader representativeness of large study areas.The LSP accuracy of slope units increases by about 6%–10%compared with those under grid units with 30 m and 60 m resolution in the same study area's scale.The significance of environmental factors exhibits an averaging trend as study area scale increases from small to large.The importance of environmental factors varies greatly with the 60 m grid unit,but it tends to be consistent to some extent in the 30 m grid unit and the slope unit.

Movement Properties of Pipe Flow Along Granite Slope of Three Gorges Area of Yangtze River in China

It is well known that, in most cases, soil water doesn't move in the form of laminar flow as described by Darcy law. Only when Reynolds number ( Re ) is no more than 10, does water movement follow Darcy law. A soil profile with 2 9 m long and 2 13 2 60 m deep was excavated on a lower slope located at Zigui County, Hubei Province, China. Field observation found that soil pipes were mainly distributed in the transient layer between horizon B with higher degree of granite weathering and horizon C with lower degree of granite weathering. At the foot of the slope, about 5 7 soil pipes per meter were observed along the vertical direction of the slope. The observed results, obtained by continuous observation of soil pipes and pipe flow processes at granite slope for many rainfall events, indicate that the relationship between velocity of pipe flow and hydraulic gradient along the pipe is parabolic rather than linear. Based on the investigated data of soil, landform, and land use etc., combined with observed data of pipe flow derived from many rainfall events, a pipe flow model was developed. For velocity V p, discharge Q p of pipe flow and radius r of soil pipe, great similarity was found between simulated and observed values. Particularly, the simulated length of soil pipes reflects the great difference among soil pipes as a result of its different position in the soil profile. The length values of 4 soil pipes were estimated to be 98 1%, 27 6%, 11 0% and 3 0% of the longest distance of the catchment, respectively. As a special case of water movement, soil pipe flow follows Darcy Weisbach law. Discharge of pipe flow is much greater than infiltration discharge in common. Only when the depth of groundwater is more than the diameter of soil pipe and water layer submerges soil pipes during rainfall, may pipe flow occur. Under these circumstances, discharge of pipe flow is directly proportional to the depth of groundwater.

Study on Soil Erosion Model Under Different Slopes in Southwest Karst Mountain Area

The aim was to further research soil erosion characteristics and accurately predict soil erosion amount in karst areas. Based on field surveys and research achievements available, yellow soils, which are widely distributed, were chosen as test soil samples and slope, rain intensity, vegetation coverage and bare-rock ratio were taken as soil erosion factors. Artificial rain simulation instruments （needle-type） were made use of to simulate correlation of rain intensity, vegetation coverage, and bare-rock ratio with soil erosion quantity. Furthermore, multiple-factor linear regression analysis, stepwise regression analysis and multiple-factor non-linear regression analy- sis were made to establish a multiple-factor formula of soil erosion modulus with dif- ferent slopes and select regression models with high correlation coefficients. The re- sults show that a non-linear regression model reached extremely significant level or significant level （0.692〈FF〈0.988） and linear regression model achieved significant lev- el （0.523〈FF〈0.634）. The effects of erosion modulus changed from decreasing to in- creasing and the erosion factors from high to low were rain intensity, vegetation cov- erage and bare-rock ratio when slope gradient was at 6~, 16~, 26~ and 36~. The mod- el is of high accuracy for predicting gentle slope and abtupt slope, which reveals correlation of erosion modulus with erosion factors in karst areas.

Types,Characteristics and Significances of Migrating Pathways of Gas-bearing Fluids in the Shenhu Area,Northern Continental Slope of the South China Sea

The first marine gas hydrate expedition in China has been conducted by Guangzhou Marine Geological Survey in the Shenhu Area, northern continental slope of the South China Sea. Previous study has analyzed the P-T conditions, geophysical anomalies and saturation calculations of these gas hydrates, but has not documented in detail the migration of gas-bearing fluids in the study area. Based on the interpretations of 2D/3D seismic data, this work identified two types of migration pathways for gas-bearing fluids in the Shenhu area, i.e., vertical and lateral pathways. The vertical pathways（largescale faults, gas chimneys and mud diapirs） presented as steep seismic reflection anomalies, which could be traced downward to the Eocene source rocks and may penetrate into the Late Miocene strata. The deeper gases/fluids might be allowed migrating into the shallower strata through these vertical conduits. However, the distributions showed distinct differences between these pathways. Large-scale faults developed only in the north and northeast of the Shenhu area, while in the drilling area gas chimneys were the sole vertical migration pathways. Since the Pliocene, normal faults, detachment faults and favorable sediments have constituted the lateral pathways in the Shenhu gas hydrate drilling area. Although these lateral pathways were connected with gas chimneys, they exerted different effects on hydrate formation and accumulation. Gas-bearing fluids migrated upward along gas chimneys might further migrate laterally because of the normal faults, thereby enlarging the range of the chimneys. Linking gas chimneys with the seafloor, the detachment faults might act as conduits for escaping gases/fluids. Re-deposited sediments developed at the early stage of the Quaternary were located within the gas hydrate stability zone, so hydrates would be enriched in these favorable sediments. Compared with the migration pathways（large-scale faults and mud diapirs） in the LW3-1 deep-sea oil/gas field, the migration efficiency of the vertical pathways（composed of gas chimneys） in the gas hydrate drilling area might be relatively low. Description and qualitative discrimination of migration pathways in the Shenhu gas hydrate drilling area are helpful to further understand the relationship between good-quality deep source rocks and shallow, mainly biogenicallyproduced, hydrates. As the main source rocks of the Baiyun sag, lacustrine mudstones in the Wenchang and Enping Formations may provide thermogenic methane. Gas chimneys with relatively low migration efficiency created the vertical pathways. Caused by the Dongsha tectonic movement, the release of overpressured fluids might reduce the vertical migration rates of the thermogenic methane. The thick bathyal/abyssal fine-grained sediments since the Late Miocene provided migration media with low permeability. These preconditions may cause carbon isotopic fractionation ofthermogenic methane during long-distance vertical migrations. Therefore, although geochemical analyses indicate that the methane forming gas hydrate in the Shenhu area was mainly produced biogenically, or was mixed methane primarily of microbial origin, thermogenic methane still contribute significantly.

The Relationship between Tectonic Subsidence and BSR of Upper Neogene in the Deep-Water Area of the Northern Continental Slope, South China Sea

BSR （Bottom Simulating Reflector） occurs widely in the strata since the late Miocene in the deep-water area of the northern continental slope of South China Sea （SCS）. It is an important seismic reference mark which identifies the gas hydrate and its distribution influenced by the tectonic movements. Single-point basin modeling was conducted using 473 points in the study area. To discuss the relationships between the tectonic subsidence and BSR, the volume and rate of tectonic subsidence in each geological time have been simulated. The results show that there are three tectonic accelerate subsidence processes in the study area since the late Miocene, especially since 1.8Ma the tectonic subsidence accelerates more apparently. Since the Late Miocene to Pleistocene, the rate of tectonic subsidence in deep-water underwent a transformation from weak to strong. The ratio of tectonic subsidence to the total subsidence was relatively high （65-70%）. Through the superposition of the BSR developed areas and the contours of tectonic subsidence in this area, it was discovered that more than 80% of BSR tend to be distributed at the slope break or depression-uplift structural transfer zone and the average tectonic subsidence rate ranges from 70 m/Ma to 125 m/Ma.

Structural Characteristics and their Significance for Hydrocarbon Accumulation in the Northern Slope of the Central Sichuan Paleo-uplift

Based on 2D and 3D seismic data,the latest drilling data and field outcrop data of the northern slope of the Central Sichuan paleo-uplift,the structural analysis method is used to analyze unconformity development characteristics and fault characteristics during the key structural transformation period,discussing the influence of the structural characteristics on the hydrocarbon accumulation of deep carbonate rocks.The results show that:(1)The two key unconformities of the Tongwan and Caledonian periods were primarily developed in deep carbonate rocks.Firstly,Tongwan’s unconformities are characterized by regional disconformities between the second and third members of the Dengying Formation,the top formation of the Sinian and the lower Cambrian,strips of which zigzag through the north and south sides of the study area.Secondly,the Caledonian unconformity is characterized by a regional unconformable contact between the lower Permian and the ower Paleozoic strata.From NE to SW,the age of the strata,which were subject to erosion,changes from new to old,the denudation distribution showing as a nose-shaped structure which inclines towards the ENE.(2)Boundary fault and transtensional strike-slip faults developed in the Sinian to Paleozoic strata.In profile,there are three types of structural styles:steep and erect,flower structures,’Y’and reversed’Y’type faults.In plane view,the Sinian developed extensional boundary faults extending in an almost NS direction,strike-slip faults developing and extending linearly in approximately EW,WNW and NE strikes in the Cambrian,with characteristically more in the south and less in the north.(3)The faults in the northern slope show obvious zonal deformations in transverse view as well as significant stages and stratified activity in a longitudinal direction.Among them,the activity of faults in the Sinian was the strongest,followed by the activity in the Cambrian period,the activity intensity of faults in the Permian period being the weakest.This fault activity can be divided into four periods:Sinian,Cambrian-Permian,the early Indosinian period and the late Indosinian-Himalayan period,the transtensional strikeslip faults being the products of oblique extensions of pre-existing weak zones in the Xingkai and Emei taphrogenesis,with a particular inheritance in the main faults.(4)Combined with hydrocarbon accumulation factors,it is considered that the epigenetic karstification of the Tongwan and Caledonian unconformities in the northern slope controlled the formation and distribution of carbonate karst reservoirs over a large area,also acting as a good pathway for oil and gas migration.The extensional faults developed at the margin of the NS trending rift,controlling the sag-platform sedimentary pattern in the Dengying Formation of the Sinian.Strike-slip faults in NE,WNW and ENE directions may control the microgeomorphological pattern inside the platform and intensify the differential distribution of grain beach facies.The multi-stage hereditary activity of strike-slip faults not only improved the porosity and permeability of the reservoirs,but also acted as the main channel of oil and gas migration,providing favorable conditions for the development of the current multi-layer gasbearing scenario in the northern slope of the Central Sichuan Basin.

Monitoring the Cultivated Slope Land in the Three Gorges Reservoir Area Based on Remote Sensing and GIS

By means of combining auto-extraction with manual interpretation, the current distribution information about cultivated land is obtained. The distribution information of 1992 is extracted from the dynamic polygons of 2002. The monitoring mini-system of the cultivated slope land is established. In the system, detailed surveys, focused on the resources of cultivated slope land, are carried out. The results indicate that the area of the cultivated slope land is very large. Meanwhile, there are lots of cultivated steep slopes with gradient above 35°. The areas of steep land cultivated had been slowly reduced from 1992 to 2002. At the same time, the pressures of returning farm land to forestry are great in all counties. The conflicts between population growth, insufficient grain supply and stagnant economic development sharpen increasingly. It is inevitable to improve the agricultural structure.

Quantitative analysis of biotechnical reinforcement for a steep slope consisting of composite coal-gangue-soil medium adjacent to a mined-out area

The engineering and geological characteristics of a steep slope consisting of coal gangue, rock and soil medium in Huating coal mine have been comprehensively investigated. Owing to humid weather, heavy rainfall, vegetation and porous characteristics of the soil and rock mass, the steep slope will be destabilized and induce mud-rock flow or derive hazard easily. Firstly, based on the classical slope reinforcement theory, some regularity between the shear and displacement in the destabilized zone of the slope with or without root strength contribution is presented. Then, based on the experimental and statistical analysis of root strength, hydrological characteristics and stability status, etc., some possible biotechnical techniques for reinforcement of the steep slope have been suggested. These methods are important for quantitative analysis of destabilization of the slope and design of the biotechnical reinforcement.

An analysis of oasis stability in arid areas:a case study in the northern slope areas of the Tianshan Mountains

This paper discusses oasis stability at regional scale with a case study in the northern slope areas of the Tianshan Mountains (NSTM). The results showed certain significant aspects. (1) As long as water resources in the oasis keep stable and their utilization efficiency can be maintained or gradually increased, the primary productivity could be continuously increased and the natural primary productivity keeped relatively stable. In this case, it is considered that the oasis is stable and its sustainable development can be achieved at regional scale. (2) Considering the availability of water resources in the oases, the oases on the alluvial-diluvial fans are highly stable. In the alluvial plain downstream of the groundwater overflowing zones the oases are moderately stable and in the lacustrine deltas or dry lacustrine deltas the oases are lowly stable. (3) Enlargement of oases and the increase of water resources and vegetation coverage in the oasis will certainly enhance the 'cold-island effect' of the oasis and increase the stability of oases.

Reservoir controlling differences between consequent faults and antithetic faults in slope area outside of source: A case study of the south-central Wenan slope of Jizhong Depression, Bohai Bay Basin, East China

The control effects of different occurrence faults on oil and gas accumulation and distribution in the outer slope area of oil and gas reservoirs were studied taking the south-central Wen’an slope of the Jizhong depression in the Bohai Bay Basin as an example.Based on 3D seismic data and the distribution of oil and water,the controlling differences between consequent fault and antithetic fault were analyzed and compared from the formation and evolution rule of faults and the formation mechanism of fault traps,including development positions of the consequent fault traps and antithetic fault traps,oil and gas distribution horizon adjusted by fault and formation period of fault traps.The differences between consequent faults and antithetic faults in controlling reservoirs have three main aspects:(1)Consequent fault traps and antithetic fault traps are in different positions,the consequent fault traps are at the segmented growing point in the hanging wall of"hard-linkage"faults,while the antithetic fault traps are developed in the position with the largest throw in the footwall because of tilting action;(2)The two kinds of faults result in different oil and gas distribution vertically,oil and gas adjusted by consequent faults is distributed in a single layer or multi-layers,while oil and gas adjusted by antithetic faults occur in single layers;(3)The two kinds of fault traps are formed in different periods,the consequent fault traps are formed at the time when the related faults enter the stage of"hard-linkage",while the antithetic fault traps are formed at the beginning of the fault active period.

Analysis on Variations of the Temperature and Precipitation in North Slope Area of the Western Tianshan in Recent 50 Years

[Objective] The research aimed to analyze variation characteristics of the temperature and precipitation in north slope area of the Western Tianshan in recent 50 years.[Method] According to temperature and rainfall data from 1961 to 2010 at three meteorological stations in north slope area of the Western Tianshan,climate change in the zone in recent 50 years was analyzed by using linear trend analysis method and 5-year sliding average method.[Result] The temperature in north slope area of the Western Tianshan showed significant warming trend.The annual average temperature significantly increased at 0.3 ℃/10 a in recent 50 years.But rise rates of the temperature in different seasons were different:autumn> winter> spring> summer.The annual rainfall in north slope area of the Western Tianshan in recent 50 years overall presented relative increase trend.Seen from annual rainfall,it significantly increased at 16.9 mm/10 a.Seen from seasonal rainfall,except in autumn,rainfalls in other three seasons in the past 50 years all showed significant increase trends,with amplitude of 3.2-11.2 mm/10 a.The largest increase amplitude was in summer.After a small precipitation peak in the 1980s,autumn rainfall slightly declined in the past 20 years.[Conclusion] The climate in north slope area of the Western Tianshan become warm and wet.

Slope runoff study in situ using rainfall simulator in mountainous area of North China

Simulated rainfall is a valid tool to examine the runoff generation on the slope.13 simulated rainfall experiments with different rainfall intensities and durations are completed in a 5 m ×10 m experimental plot in mountainous area of North China.Simultaneously,rainfall,surface runoff,soil-layer flow,mantel-layer flow and soil moisture are monitored respectively.From the results,it is found that the hydrographs in all layers have the characteristics of rapid rise and fall.The recessions of surface flow and soil-layer flow are much faster than that of mantel-layer flow.Surface flow,the main contributor,makes up more than 60% of the total runoff in the study area.It even exceeds 90% in the cases of high intensity rainfall events.Runoff coefficient(ratio of total runoff to rainfall amount) is mainly influenced by rainfall amount,rainfall intensity and antecedent soil moisture,and the relationship can be well expressed by a multiple linear regression function α = 0.002P + 0.182i + 4.88Wa-0.821.The relation between the rainfall intensity and the lag time of three flows(surface runoff,soil-layer flow and mantel-layer flow) is shown to be exponential.Then,the result also shows that the recession constant is 0.75 for surface runoff,is 0.94 for soil-layer and mantel-layer flow in this area.In this study area,the dominant infiltration excess runoff is simulated by Horton model.About 0.10 mm/min percolation is observed under the condition of different rainfall intensities,therefore the value is regarded as the steady infiltration rate of the study area.

Tectonic analysis and petroleum significance of Cenozoic faults in Dongping-Niuzhong area in Altyn slope

The evolution process and petroleum significance of two groups of fault structures,the NW-SE trending and near EW trending ones in the Cenozoic of Dongping-Niuzhong area of the Altyn slope,Qaidam Basin,were investigated using high precision 3-D seismic data.The NW-SE faults were generated in Oligocene,causing the formation of a series of folds related to transpression faults in the Niuzhong and Dongping area.After the Miocene,with the continuous extension of the Altyn Tagh strike-slip fault zone,the EW trending faults began to develop massively in Altyn slope.The activity of near EW trending faults and large-scale uplift of the bedrock in the northern Niuzhong area shared most of the compression torsion in Niuzhong and Dongping area,consequently,the activity of NW-SE trending faults weakened significantly after the Miocene.Then good hydrocarbon source rocks developed in the inherited Jurassic sags.The faults were effective pathways for oil and gas migration in Dongping and Niuzhong areas,and the oil and gas charging time matched well with the formation period of the NW-SE trending faults and their related structures,making the fault-related anticlines favorable targets for oil and gas accumulation.The Niuzhong area has been less affected by the Cenozoic movement after the Miocene,and thus has better conditions for gas reservoir preservation.

昆仑山北坡水资源科学考察初报

2021年10月首批启动了第三次新疆科学考察——“昆仑山北坡水资源开发潜力及利用途径科学考察”。结合多源遥感信息和2022—2023年野外科考工作,对昆仑山北坡的水文水资源变化和水资源利用进行了调查研究。结果表明:(1)1990—2020年,昆仑山北坡山区的气温、降水分别以0.14℃·(10a)^(-1)和6.53 mm·(10a)^(-1)幅度增加。(2)冰川变化相对稳定,积雪面积和积雪深度表现为略微增加。(3)永久性水体和季节性水体面积分别显著增加79.89%和144.49%。(4)东昆仑-库木库里盆地的阿牙克库木湖和阿其克库勒湖两大湖泊的水域面积分别增加了68.91%和58.22%,盆地内多条河流具备水资源开发潜力。(5)昆仑山北坡陆地水储量总体呈增加趋势,表现为从西向东增加趋势越加显著。(6)昆仑山北坡的主要河流和田河、克里雅河和车尔臣河年均径流量2010—2023年较1957—2023年分别增加了20.24%、27.85%和45.17%。(7)基于不同气候变化情景模拟预测至21世纪中后叶,主要河流径流量将保持上升态势,区域水资源量总体呈增加趋势。昆仑山北坡的水资源禀赋可为区域绿色高质量发展提供有利的水资源保障条件。

川东红星地区中上二叠统页岩气勘探成果及方向展望

基于构造、岩心、测井等资料,采用电镜扫描、低温N_(2)吸附实验、高压压汞实验、盆地模拟等手段,系统分析了川东红星地区中上二叠统页岩的沉积演化、储层特征及页岩气富集模式,明确了勘探有利区,总结了勘探成果及意义。研究结果表明:(1)红星地区中上二叠统的沉积演化表现为:栖霞组—茅口组三段为开阔台地相;茅四段底部为台地-陆棚相,相带变化快,茅四段顶部为斜坡-陆棚相,地层被剥蚀、南厚北薄;吴家坪组一段(吴一段)底部为海陆过渡滨岸沼泽-潟湖相,吴一段顶部为台地-斜坡-陆棚相,斜坡-陆棚相带分布范围小、相变快;吴二段为斜坡-陆棚相沉积,从早至晚依次受控于古气候、火山活动和古气候、火山活动,沉积中—晚期古生产力较高,TOC均值大于8.00%。(2)研究区茅四段及吴二段陆棚相区发育2套优质页岩,具有“高有机碳-高灰质”的特征,富有机质页岩厚度分别为19 m和25 m,孔隙类型以有机孔为主,结构以微孔和介孔为主;富碳凝灰岩薄夹层混合质页岩岩相、高碳凝灰岩薄夹层硅质页岩为优质岩相,孔隙度分别为6.27%和6.43%,TOC值分别为10.11%和9.35%,含气饱和度分别为92.59%和91.81%,脆性指数分别为55.24%和61.19%,是地质和工程的双“甜点”段。(3)研究区二叠系广泛发育的层状藻为主要有机质来源;在侏罗纪主排烃期,其构造稳定、二叠系烃源岩排烃较少,中侏罗纪—早白垩纪早期为主生气期,构造活动较弱,页岩气的保存条件好,现今已完成生气过程,处于成熟—过成熟阶段,Ro值约2.1%,勘探潜力巨大。(4)建南、龙驹坝、三星区块为有利勘探区,其中建南区块潜力最大;茅四段(3)小层及吴二段(3)小层为优质层系的靶窗层段。

玛西斜坡区风城组高含盐致密储集层流体识别

准噶尔盆地玛西斜坡区二叠系风城组发育碱湖沉积的高含盐致密储集层,其油水关系复杂,流体识别难度大。利用岩性扫描测井资料构建饱含盐水地层热中子宏观俘获截面,并利用测井热中子宏观俘获截面与饱含盐水地层热中子宏观俘获截面的差值构建含油性敏感因子,再利用氯元素相对产额与总孔隙度比值构建含盐度敏感因子,将含油性敏感因子与含盐度敏感因子交会形成流体识别图版。实例应用表明,利用该流体识别图版可以对储集层流体性质进行准确判断,为试油选层提供依据。

渭北黄土台塬区水库水下岸坡稳定形态预测模型研究

黄土地区水库塌岸预测仍以卡丘金法等经验图解法为主,此类方法预测结果的准确性取决于对岸坡剖面形态的准确描述。为了提高黄土地区水库塌岸宽度预测的准确性,选取渭北黄土台塬区选择典型水库进行现场调查,对原河道岸坡形态与蓄水后岸坡形态进行对比分析,在此基础上建立了水下岸坡形态预测模型。结果表明,渭北黄土台塬区水库岸坡塌岸稳定后,水上岸坡呈直立状,高度可达30 m以上,水下岸坡呈曲线形,受水深和岸坡高度共同影响,塌落物可能露出水面。在此基础上基于对数螺线方程建立了水下岸坡形态预测模型,并与经典图解法所用直线型岸坡进行对比,误差分析结果表明采用对数螺线方程进行水下岸坡形态预测时堆积体积误差为4.50%~39.70%,均值为12.64%,而直线型岸坡的预测误差为25.75%~124.69%,均值为75.69%。即采用对数螺线方程可以更好的测水下岸坡形态及水下堆积量。相关研究成果对黄土台塬区水库塌岸预测方法的改进,以及黄河流域的渭北黄土台塬区的环境保护与高质量发展具有实际意义。

气体地球化学勘查在巴—麦地区砂岩型铀矿找矿中的应用

塔里木盆地内部砂岩型铀矿找矿十分迫切。针对该盆地地质构造相对复杂、沉积地层厚度大、勘查手段受到沙漠-荒漠地貌的限制、勘查程度较低和地表成矿信息弱的特点,在巴楚隆起—麦盖提斜坡带地区(巴—麦地区)开展能指示深部地层环境的H_(2)S、CH_(4)、H_(2)、CO_(2)和4He气体地球化学区域测量研究。结果表明,几种土壤气体浓度能够较为清晰地显示各自异常分布范围,并指示盆地地层中可能的铀异常信息,气体地球化学测量方法是一种相对高效的盆地区域地表勘查方法。在综合测区断裂分布、油气藏、水文等地质条件和气体化学反应性质的基础上,分析气体浓度异常成因及分布综合特征,测区东北部、东南部及色力布亚断裂和巴什托断裂所夹持部分地段具有几种气体组份浓度异常叠加,地层中可能发育氧化-还原地球化学障,是有利的找矿预测区,为该地区砂岩型铀矿勘查提供参考依据。

准噶尔盆地环东道海子凹陷侏罗系煤层气成藏条件及勘探方向

为了明确准噶尔盆地环东道海子凹陷侏罗系煤层气勘探方向,开展了煤层连井对比、井-震标定和地震资料解释以及煤层测、录井资料分析。研究结果表明:①准噶尔盆地侏罗系西山窑组和八道湾组煤层发育,厚度较大,分布稳定,其中西山窑组发育2~3层煤层,累计最大厚度为20 m,八道湾组发育2~4层煤层,累计最大厚度为29 m。煤岩含气性好,录井气测异常明显。②环东道海子凹陷内中下侏罗统煤系烃源岩为中等—好烃源岩,Ro为0.6%~0.8%,处于低成熟—成熟阶段,具有较好的生气能力;天然气碳同位素分析结果显示,煤层气亦可来源于深部高成熟腐殖型有机质。③研究区西山窑组煤岩为中—低孔、低渗储层,孔隙度为7.0%~20.8%,渗透率为0.32~8.67 mD;八道湾组煤岩为低孔、中—低渗储层,孔隙度为5.6%~7.8%,渗透率为2.30~13.83 mD;煤层夹于泥岩之间且煤层之上区域性泥岩盖层分布广泛,封盖保存条件好。④研究区存在凹陷区源内煤层气富集成藏和凸起区深部外源气富集成藏等2种模式。环东道海子凹陷煤层气勘探潜力较大,特别是凹陷北东方向斜坡区和凹陷北部斜坡—滴南凸起区。

边坡监测与治理技术在高寒矿区露天煤矿生态修复中的应用研究

边坡治理是露天矿山生态修复中的重要内容之一。以青海木里矿区聚乎更区为例,针对高寒矿区露天煤矿的边坡问题识别、监测和治理开展了系统研究,通过遥感、物探、钻探及地表测量等手段研究了矿区内不稳定边坡发育特征及稳定性。研究结果表明:建立了以遥感技术为核心,辅以常规的地表监测、地质调查、物探及钻探等手段的“天空地时”一体化不稳定边坡探查监测体系,确定矿区内不稳定边坡发育特征及稳定性,为矿山修复治理针对性开展边坡治理提供依据;采用高危渣山降高减载和边坡减坡治理技术,对边坡台阶进行清坡处理,消除浮石和崩塌等灾害,对渣山削坡卸载,使采坑边坡和渣山边坡达到稳定状态;并以聚乎更4号井南渣山为例,根据高密度电法探测和钻探验证,识别出了常年冻土上限和渣土层与原采坑基岩界线两个滑移面,确定后缘载荷过大是导致滑坡的主要因素,采取“后缘降高减载+边坡减坡+水系连通+综合监测”的治理方案,治理后既消除了对边坡前缘的载荷,又为后期植被复绿提供了稳定的立地条件。多期次动态监测表明边坡后缘已趋于稳定;边坡监测及治理技术在木里矿区生态修复治理中得到广泛使用,治理后的渣山边坡坡度控制均小于26°,有效消除了不稳定边坡对修复治理的影响,保障了矿山生态修复治理成效。