水库对海岸带海水入侵影响的数值模拟研究

修建海岸水库是满足滨海地区淡水资源的保障的一个重要方式,为了进一步分析海岸水库的建立对滨海含水层的海水入侵的影响,采用SUTRA(saturated-unsaturatedtransport)模型建立具有代表性的二维海岸模型开展定量和定性研究,结果表明:潮汐作用抑制底层盐水楔的入侵,加快海陆物质交换;实例中计算表明建坝后,海岸水库坝体的建立加剧了海水入侵;水库水位在平均海平面以下时,潮汐动力因素占主导,海水入侵严重且随着水位抬高,海水入侵程度基本保持不变,应注意海水入侵的防治;库区水位在平均海平面以上时,海水入侵程度随着库区水位的抬高而减少,可以调节水库水位进行滨海含水层的海水入侵的防控;海岸水库在建设中存在一个控制水位,当水库水位在控制水位以上,库区水体盐度和含水层淡水储量能得到保证;库区高水位时内陆物质运移时间较长,运移区域较广,氮类污染物易在库底含水层堆积,需重视含水层的地下水污染防治。     

北秦岭弧后盆地俯冲消减与陆壳物质再循环——桃园岩体和黄岗杂岩体的地球化学证据

对桐柏北部加里东期桃园岩体和黄岗杂岩体的地球化学研究表明, 桃园岩体形成于与洋壳消减作用有关的弧后盆地环境, 与二郎坪基性火山岩具有相同的岩浆来源.黄岗杂岩岩浆中含有一定比例的陆壳物质, 该物质来自俯冲板片上陆壳沉积物的再循环, 与二郎坪弧后盆地向北的俯冲消减有密切联系.      

鄂尔多斯盆地延长组致密砂岩孔喉结构与油藏物性表征

基于高压压汞和核磁共振测试方法,结合分形理论对鄂尔多斯盆地延长组致密砂岩孔喉结构与油藏物性进行了表征。采用毛管束模型和润湿相模型计算了高压压汞孔喉分形维数,利用核磁共振测试T₂谱分别计算了大孔、中孔、小孔以及总孔隙的分形维数;对各分形维数与油藏物性之间的关系进行了对比分析。研究表明：基于高压压汞曲线计算岩心分形维数时,相比于润湿相模型,毛管束模型计算得到的分形维数与油藏物性之间具有更好的相关性,随着分形维数增加,平均半径减小,孔喉结构非均质性增强,油藏物性变差。核磁总孔隙分形维数与油藏物性相关性较差,大孔和中孔的分形维数与油藏物性具有较好的相关性,其中随着大孔和中孔分形维数增加,岩心渗透率降低,油藏物性变差;与小孔相比,大孔和中孔的分形维数与油藏物性的相关性更强,表明致密砂岩储层物性主要受大孔和中孔控制,分形维数可以有效表征致密砂岩小孔、中孔和大孔对油藏物性的影响。     

山西省中生代侵入岩新认识

根据区域地质调查资料,对山西省中生代侵入岩进行分析研究,将其划分为3个岩浆系列: 碱性偏碱性系列、亚碱性(基性)中性—中酸性系列和A型花岗岩(酸性)系列。碱性偏碱性岩系列形成于后碰撞构造环境,亚碱性(基性)中性—中酸性岩系列为大陆边缘弧和大陆岛弧及后造山构造环境,A型花岗岩系列为板内大陆裂谷或与地幔热点(地幔羽)有关的构造环境,板块俯冲作用为其提供了热能和含水溶液。大地构造分区划分为华北陆块区构造岩浆省(Ⅰ级),其中包括3个岩浆带(Ⅱ级): 南兴蒙岩浆带、北秦岭岩浆带和华北东部岩浆带,每个岩浆带又可划分为2个岩浆亚带(2期岩浆作用)(Ⅲ级),各个岩浆亚带均具有板块俯冲造山带火成岩的特征和发育演化极性。该成果为解决板块构造登陆问题提供了借鉴。     

平度市海水入侵成因及防治对策

平度市北胶莱河沿岸由于遭受海水入侵的影响,给工农业生产和人民生活造成了严重的危害。通过调查分析平度市北胶莱河沿岸海水入侵的现状和特点;针对海水入侵的演化特征分析了海水入侵的形成原因,并分析海水入侵造成的危害,提出相应的防治对策。     

富水软弱带公路隧道支护技术研究

大奎隧道是炎汝高速公路炎陵至汝城段的一座公路隧道,地质条件极其复杂,隧道施工后,初期支护发生严重变形,钢支撑被压弯,下沉量严重侵入建筑限界。综合现场监测、地质雷达扫描结果,从涌水特征、地质情况和施工方法3方面出发,系统分析了大奎隧道富水软弱带初期支护后隧道严重变形的原因,并在此基础上,研究支护失效段和掌子面的支护设计及施工组织方案,提出三大治理措施：一是控制涌水,二是反压回填及加固围岩,三是优化施工工法。监测结果显示：上述措施实施后,取得了非常满意的效果,保证了复杂地质条件下隧道施工的安全。该成果对富水软弱地层隧道修建具有重要的指导作用和参考价值。     

Experimental soft‐sediment deformation caused by fluidization and intrusive ice melt in sand

Identifying the driving mechanisms of soft‐sediment deformation in the geological record is the subject of debate. Thawing of ice‐rich clayey silt above permafrost was proved experimentally to be among the processes capable of triggering deformation. However, previous work has failed so far to reproduce similar structures in sand. This study investigates fluidization and intrusive ice formation from soil models in the laboratory. Experimental conditions reproduce the growth of ice‐cored mounds caused by pore water pressure increase during freeze‐back of sand in a permafrost context. Excess pore water pressure causes hydraulic fracturing and the development of water lenses beneath the freezing front. Later freezing of the water lenses generates intrusive ice. The main structures consist of sand dykes and sills formed when the increase in pore water pressure exceeds a critical threshold, and soft‐sediment deformations induced by subsidence during ice melt. The combination of processes has resulted in diapir‐like structures. The experimental structures are similar to those described in Pleistocene sites from France. These processes constitute a credible alternative to the seismic hypothesis evoked to explain soft‐sediment deformation structures in other European regions subjected to Pleistocene cold climates.     

Pore Structure Heterogeneity of the Xiamaling Formation Shale Gas Reservoir in the Yanshan Area of China: Evaluation of Geological Controlling Factors

Micro-heterogeneity is an integral parameter of the pore structure of shale gas reservoir and it forms an essential basis for setting and adjusting development parameters. In this study, scanning electron microscopy, high-pressure mercury intrusion and low-temperature nitrogen adsorption experiments were used to qualitatively and quantitatively characterize the pore structure of black shale from the third member of the Xiamaling Formation in the Yanshan area. The pore heterogeneity was studied using fractal theory, and the controlling factors of pore development and heterogeneity were evaluated in combination with geochemical parameters, mineral composition, and geological evolution history. The results show that the pore structure of the reservoir was intricate and complicated. Moreover, various types of micro-nano scale pores such as dissolution pores, intergranular pores, interlayer pores, and micro-cracks are well developed in member 3 of the Xiamaling Formation. The average porosity was found to be 6.30%, and the mean value of the average pore size was 4.78 nm. Micropores and transition pores provided most of the storage space. Pore development was significantly affected by the region and was mainly related to the total organic carbon content, vitrinite reflectance and mineral composition. The fractal dimension, which characterizes the heterogeneity, is 2.66 on average, indicating that the pore structure is highly heterogeneous. Fractal dimension is positively correlated with maturity and clay mineral content, while it is negatively correlated with brittle mineral content and average pore size. These results indicate that pore heterogeneity is closely related to thermal history and material composition. Combined with the geological background of this area, it was found that the pore heterogeneity was mainly controlled by the Jurassic magmatism. The more intense the magma intrusion, the stronger the pore heterogeneity. The pore structure and its heterogeneity characteristics present today are a general reflection of the superimposed geological processes of sedimentary-diagenetic-late transformation. The influence of magmatic intrusion on the reservoir is the main geological factor that should be considered for detailed evaluation of the Xiamaling Formation shale gas reservoir in the Yanshan area.     

西秦岭岗岔—克莫金矿区石英闪长玢岩多金属“珠滴构造”及其找矿意义

西秦岭造山带北缘之金属成矿带是我国重要的斑岩型Cu-Au远景区,该带的德乌鲁岩体及其接触带是重要找矿潜力区。最新的野外调查发现,德乌鲁岩体东南缘接触带的石英闪长玢岩中发育大量含有多种金属矿物的椭圆形或近球形“珠滴构造”,且其矿物组合非常类似于临近的岗岔—克莫金矿床矿石矿物组合,即“珠滴”内含有大量金属矿物黄铁矿、毒砂、黄铜矿、方铅矿、闪锌矿、磁黄铁矿、钛铁矿和辉砷钴矿等,此外还发育有绿泥石、绿帘石、方解石、钾长石、钠长石、石英、绢云母、电气石、葡萄石、磷灰石、榍石和金红石等复杂的非金属矿物组合。详细的矿物学和地球化学研究结果表明,“珠滴”与寄主岩石属同源产物。绿泥石温度计和二长石温度计显示“珠滴”形成温度范围在297～435 ℃,角闪石全铝压力计显示寄主岩石形成压力为1.02～2.28 kbar。因此推断,“珠滴”形成于深部富含金属的流体,金属物质依附气泡按照“浮选”机制随岩浆侵位上升。当载有金属物质的气泡随着岩浆侵位到浅部时便快速解耦,其流体相逃逸,“珠滴”则被冷凝固结在岩浆圈闭之中。依据上述分析结果,认为携带金属物质的气泡把成矿元素运移至石英闪长玢岩体内,其中一些气泡把金属物质卸载到浅部,而大量的金属物质可能仍然留在深部石英闪长玢岩内。“珠滴构造”可能是深部成矿的重要指示标志。