应用宇宙成因核素10Be和26Al估算剥蚀面的暴露时间及剥蚀速率和剥蚀厚度

宇宙成因核素10 Be和2 6Al的浓度记录着岩层剥蚀面的暴露时间和岩石剥蚀速率等信息。利用数学换算法分析影响10 Be和2 6Al浓度的因素 ,并利用10 Be和2 6Al的半衰期的近似倍数关系建立联立方程组 ,从理论上得到了年轻地质体中遭受快速埋藏的剥蚀面的暴露时间和剥蚀速率的估算公式。在此基础上 ,对整个剥蚀区不同位置剥蚀速率进行了分析。通过分析可以更准确地估算出整个剥蚀区不同位置的剥蚀厚度 ,从而可恢复剥蚀面的古地貌。     

原地宇生核素^26Al和^10Be剖面定年及其在早期人类遗址年代研究中的应用前景

中、早更新世人类遗址年代的确定对于人类起源与演化的研究具有重要意义。原地宇生核素^26Al和^10Be浓度剖面定年法可用来测定百万年尺度河流阶地沉积物的同位素年龄,积极开展该法测年研究有望填补我国早期人类遗址如许家窑、郧县曲远河口等地点同位素地质年代研究的空白。本文简述该法的基本原理并展望其应用前景。     

宇宙成因核素10Be,26Al:原理及其在地表过程中的应用

地表岩石中宇宙成因核素10Be和26Al含量是侵蚀速率和辐射时间的函数,通过对岩石中10Be和26Al含量的测定能反映较长时间(103～107a)和较大空间尺度上的侵蚀作用大小和过程.根据10Be含量估算出长江中下游地区平均侵蚀速率为30～60 m·Ma-1,攀枝花至三峡长江流域内地表平均侵蚀速率为200m·Ma-1.     

宇宙成因核素10Be,26Al:原理及其在地表过程中的应用

地表岩石中宇宙成因核素10Be和26Al含量是侵蚀速率和辐射时间的函数,通过对岩石中10Be和26Al含量的测定能反映较长时间(103~107a)和较大空间尺度上的侵蚀作用大小和过程.根据10Be含量估算出长江中下游地区平均侵蚀速率为30~60m·Ma-1,攀枝花至三峡长江流域内地表平均侵蚀速率为200m·Ma-1.     

东南极拉斯曼丘陵友谊峰基岩^10Be暴露年龄及其地质意义

东南极沿海拉斯曼丘陵地区缺乏末次冰盛期(约20ka)的冰碛物堆积，冰川擦痕的保存以及冰退后海岸线的卸载反弹也很不明显，因此该地区末次冰盛期是否覆盖巨厚冰川存在分歧．已有的^14C测年结果显示拉斯曼丘陵至少部分地区在末次冰盛期无冰，冰退初始时间约在44ka前．利用原地生成宇宙成因核素^10Be测定了拉斯曼丘陵地区米洛半岛友谊峰的基岩暴露年龄，结果表明友谊峰基岩的^10Be最小暴露年龄约40ka，考虑到基岩存在侵蚀实际暴露年龄可能要略早．友谊峰基岩^10Be最小暴露年龄表明友谊峰末次冰退时间要明显早于末次冰盛期，约40ka前友谊峰以北米洛半岛大部分地区已基本无冰．友谊峰东南约400m的106峰峰顶漂砾的^10Be暴露年龄为8．8ka，表明冰盖边缘位置曾长时间位于友谊峰和106峰之间，冰川边缘从友谊峰退到106峰的过程历时30ka以上．     

厦门地区^7Be和^210Pb的大气沉降通量

^7Be和^210Pb是大气中天然存在的放射性核素．本文测定了2001年8月至2002年8月间厦门地区^7Be和^210Pb大气沉降通量，平均值分别为1．90和0.41Bq m^-2d^-1．对^7Be和^210Pb的沉降特征及其影响因素进行了探讨，表明降雨是影响沉降通量的主要因素，两个核素的沉降通量之间存在较好线性相关性．     

《石油大学学报(自然科学版)》2004年第28卷总目录

石油地质与勘探·应用宇宙成因核素10 Be和2 6 Al估算剥蚀面的暴露时间及剥蚀速率和剥蚀厚度李储华 ,纪友亮 ,张世奇 ,赵俊青 (1- 1)……………………………………………………………………准噶尔盆地三个泉地区下白垩统沉积相特征高　雷 ,朱筱敏 ,吕雪雁 (1- 5 )………………………………准噶尔盆地南缘古近系新近系异常高压系统与油气成藏机理张卫海 ,查　明 ,曲江秀 (1- 10 )…………深盆气圈闭判识方法与应用宫广胜 ,庞雄奇 ,马新华 ,姜振学 ,金之钧 (1- 13)……………………………熵权非均质综合指数算法及其应用杨少春 ,杨兆林 ,胡红…     

穆格莱德盆地凯康坳陷西斜坡地层剥蚀与埋藏史研究

为深入了解穆格莱德盆地凯康坳陷西斜坡地区地层沉积和埋藏史情况,根据回剥法改进的"刘景彦模型",消除多剥蚀面盆地内上覆地层压实作用影响,并利用声波时差计算各剥蚀面剥蚀厚度,在综合分析地层残余厚度与剥蚀厚度的基础上恢复了研究区埋藏史.结果表明:①Baraka与Amal间剥蚀厚度最大,Abu Gabra与Bentiu间剥蚀厚度最小;②斜坡西部与南部剥蚀量大,东部与北部小;③受区域构造运动和沉降速率影响,北部地区沉降速度和沉积速率小,地层埋藏较浅,断层规模小,密度大,发育大量小型断块圈闭;④南部地区沉降速度和沉积速率较高,各组地层埋藏较深,烃源岩进入生油窗时间更早,大型同生断层发育,多见大型断块和断鼻圈闭,石油地质条件优于北部地区.     

地层结构外延法在塔中隆起古生界多期剥蚀量估算中的应用

许多常用的剥蚀量估算方法存在着局限性.这些方法通常只能估算某一界面的总剥蚀量或者在单期构造活动区估算剥蚀量.采用地层结构外延法,探讨具有多期剥蚀历史的剥蚀量估算.地震剖面综合研究揭示,塔中地区存在3个主要剥蚀界面.对3个主要构造变革期剥蚀量的剖面和平面分布特征的分析表明,塔中地区剥蚀量的分布主要受构造控制;不同时期的剥蚀量分布差异,反映了该区的古剥蚀地貌特征和构造发育演化过程.     

三峡地区极短周期内剥蚀速率、下切速率及地表隆升速率对比研究

通过河流输沙量计算出三峡地区短周期的剥蚀速率为0.084 mm/a,将剥蚀速率、下切速率以及隆升速率对比研究,确定了长江流域三峡段极短周期内下切速率与地表隆升速率之间的线性关系,并得出侵蚀基准面及气候变化的约束系数大约是0.4.基于前人对三峡地区一级阶地的数据,计算出一级阶地的下切速率约为3.025 mm/a.现代地壳变形测量和GPS测量结果,发现黄陵穹隆现今地表相对于周边地区其地表隆升速率最大可达5～10 mm/a.取其平均值7.5 mm/a作为三峡地区极短周期的地表隆升速率,对比分析三峡地区剥蚀速率、下切速率与隆升速率,结果该区隆升速率大于剥蚀速率,大约是剥蚀速率的89倍;下切速率也大于剥蚀速率,大约是剥蚀速率的36倍;隆升速率同样大于下切速率,大约是下切速率的2.5倍.三峡地区隆升大于剥蚀,也大于下切速率,三峡地区地表仍然在不断地升高;而地表剥蚀速率小于下切速率,地表切割进一步加深,因此地貌出现高低起伏、山高谷深的形态,并有进一步加剧的趋势.     

中国水土流失地区土壤沟蚀的研究进展

为了解决土壤侵蚀制约着社会、经济、环境的协调发展的环境问题.采用野外调查综和分析方法研究该问题,侵蚀沟径流冲刷是土壤侵蚀产沙的主要来源.论述了中国土壤沟蚀研究的主要方法,分析了土壤从细沟侵蚀-浅沟侵蚀-切沟侵蚀-冲沟侵蚀的演变机理,评述了细沟侵蚀、浅沟侵蚀、切沟侵蚀的研究进展,提出沟蚀过程中有待加强的研究领域,对科学地指导水土保持措施配置有重要的实践意义.     

Relationship between the geometric features of carbon steel cavitation erosion debris and the cavitation erosion stages

The debris produced in vibration cavitation tests of three kinds of carbon steel were collected. Their geometric features were analyzed quantitatively and observed respectively by a profilometer and a scanning electronic microscope (SEM) with reference to the investigation of the cavitation damaged surface by SEM and X-ray diffraction (XRD). It was found that among the debris produced in all cavitation erosion stages, more than 45% were platelets because of the occurrence of dislocation and cleavage fracture, and only less than 25% were strands. The number of granule was small in the first cavitation erosion stage and increased rapidly to the number comparable with that of platelets in the next stage, and then reduced in the third stage. The sphericity values of the debris varied in accordance with the stages of cavitation damage, which were 0.3―0.4 in the incubation stage, 0.5―0.7 in the acceleration stage and not less than 0.5 in the maximum rate stage, although a slight decrease occurred in the third stage.     

Particle erosion of infrared materials

Erosion test of some infrared (IR) optical crystals (Ge, ZnS, MgF₂, and quartz) was conducted with a number of different erodents (glass bead, and angular SiC, SiO₂, Al₂O₃) by a homemade gas-blasting erosion tester. The influence of impact angle, impact velocity, erodent, and erosion time on the erosion rate and the effect of erosion on their IR transmittance were studied. The dam- aged surface morphology was characterized by scanning electron microscopy, and the erosion mechanism was explored. All of the materials show the maximum in wear versus impact angle at 90°, confirming their brittle failure behavior. It is found that the erosion rate is dependent on the erodent velocity by a power law, and it is highly correlated to the hardness of the erodent. The erosion rate-time curves do not show an incubation state, but an accelerated erosion period followed a maximum erosion (steady state). The decrease of IR transmittance is direct proportion to the erosion rate. Although the material loss occurs primarily by brittle process, ductile behavior is clearly an important feature, especially for MgF₂ and ZnS.     

ATMP、硫脲缓蚀性能的研究

利用 DJS- 2 92型恒电位仪分别测定了不同浓度的 ATMP、硫脲以及二者复配后在1 mol.dm-3硫酸溶液中的阴阳极极化曲线。实验结果表明 :ATMP、硫脲对碳钢的腐蚀有较强的抑制作用 ;浓度对二者的缓蚀性能有一定影响 ;ATMP、硫脲复配后缓蚀作用比单独使用两者中的任一种强。本文对 ATMP、硫脲的缓蚀机理进行了初步探讨 ,同时初步分析了二者复配后缓蚀性能增强的原因。     

Decoupling of erosion and precipitation in the Himalayas

The hypothesis that abrupt spatial gradients in erosion can cause high strain rates in active orogens has been supported by numerical models that couple erosional processes with lithospheric deformation via gravitational feedbacks. Most such models invoke a 'stream-power' rule, in which either increased discharge or steeper channel slopes cause higher erosion rates. Spatial variations in precipitation and slopes are therefore predicted to correlate with gradients in both erosion rates and crustal strain. Here we combine observations from a meteorological network across the Greater Himalaya, Nepal, along with estimates of erosion rates at geologic timescales (greater than 100,000 yr) from low-temperature thermochronometry. Across a zone of about 20 km length spanning the Himalayan crest and encompassing a more than fivefold difference in monsoon precipitation, significant spatial variations in geologic erosion rates are not detectable. Decreased rainfall is not balanced by steeper channels. Instead, additional factors that influence river incision rates, such as channel width and sediment concentrations, must compensate for decreasing precipitation. Overall, spatially constant erosion is a response to uniform, upward tectonic transport of Greater Himalayan rock above a crustal ramp.     

基于GIS的泥石流侵蚀特征分析——以文家沟为例

5.12汶川地震导致四川部分地区大规模泥石流爆发,其爆发规模和特征都不同于以往的泥石流,为了进一步研究震后泥石流的特征并揭示其现象,选取了位于绵远河流域的文家沟作为研究对象。主要利用ARCGIS平台对灾前灾后DEM数据进行对比,从主沟道的坡度及下切深度、沟谷形态的变化和区域侵蚀三个方面来分析文家沟泥石流的特征,解释了文家沟泥石流侵蚀过程和深切拉槽现象,为今后泥石流灾害评估、侵蚀过程分析及防治工程提供依据。     

黄土地貌区水力侵蚀敏感性分析：以山西省五寨县为例

在自然与人为因素的干扰下,黄土高原地区常年遭受较为严重的水力侵蚀。为了减缓水力侵蚀进程并避免对人类生命财产的损害,对其进行敏感性分析是具有重要意义的。从CSLE模型出发,以地貌单元作为评价单元,对降水侵蚀力因子、土壤可蚀性因子、坡长坡度因子、生物/耕作措施因子以及工程措施因子分别进行正向化处理与熵值法确权叠加后建立了一个水力侵蚀敏感性评价模型,借助面积-高程积分对该模型进行评价后,利用该模型对研究区进行水力侵蚀敏感性分析。结果表明：在区域尺度下,文中提出的水力侵蚀敏感性评价模型的评价因子为0.61,相对优于作为对比验证的CSLE模型,因此可以利用该模型对研究区进行水力侵蚀敏感性评价;水力侵蚀敏感性值在不同地貌单元之间表现为：大起伏山地>洪积平原>黄土塬>黄土梁峁>中起伏山地>冲积洪积平原;为了避免对人类生命财产造成损害,北部冲积洪积平原与中起伏山地相交地带、南部大起伏山地的清涟河流域应重点进行治理。该文提出的方法有效解决了黄土地貌区的水力侵蚀敏感性分析问题。     

Stabilizing feedbacks in glacier-bed erosion

Glaciers often erode, transport and deposit sediment much more rapidly than nonglacial environments, with implications for the evolution of glaciated mountain belts and their associated sedimentary basins. But modelling such glacial processes is difficult, partly because stabilizing feedbacks similar to those operating in rivers have not been identified for glacial landscapes. Here we combine new and existing data of glacier morphology and the processes governing glacier evolution from diverse settings to reveal such stabilizing feedbacks. We find that the long profiles of beds of highly erosive glaciers tend towards steady-state angles opposed to and slightly more than 50 per cent steeper than the overlying ice-air surface slopes, and that additional subglacial deepening must be enabled by non-glacial processes. Climatic or glaciological perturbations of the ice-air surface slope can have large transient effects on glaciofluvial sediment flux and apparent glacial erosion rate.