华北地区热均衡、重力均衡与深部构造

本文基于最新的全球重力场模型TopexV18.1数据,在区域背景尺度下,计算了华北地区的区域布格重力异常,并反演了Moho面分布特征;在此基础上结合区域地热流测量数据,讨论重力均衡和热均衡调整过程对现今地形的影响;最后,结合已有的速度结构模型和岩石圈热参数,对10个次级块体单元的热均衡特点开展了综合对比研究.研究结果表...     

Sampling strategy and climatic implications of tree-ring stable isotopes on the southeast Tibetan Plateau

We explore the potential of tree-ring cellulose δ¹⁸O and δ¹³C records for reconstructing climate variability in the southeast Tibetan Plateau. Our sampling strategy was designed to investigate intra and inter-tree variability, and the effects of the age of tree on δ¹⁸O variation. We show that intra-tree δ¹³C and δ¹⁸O variability is negligible, and inter-tree coherence is sufficient to build robust tree-ring δ¹⁸O or δ¹³C chronologies based on only four trees. There is no evidence of an age effect regarding δ¹⁸O, in contrast with tree-ring width. In our warm and moist sampling site, young tree δ¹³C is not clearly correlated with monthly mean meteorological data. Tree-ring δ¹⁸O appears significantly anti-correlated with summer precipitation amount, regional cloud cover, and relative humidity. Simulations conducted with the ORCHIDEE land surface model confirm the observed contribution of relative humidity to tree cellulose δ¹⁸O, and explain the weak correlation of δ¹³C with climate by the non-linear integration linked with photosynthesis. Altogether, the tree-ring cellulose δ¹⁸O is shown to be a promising proxy to reconstruct regional summer moisture variability prior to the instrumental period.     

Research on the stabilization treatment of clay slope topsoil by organic polymer soil stabilizer

The topsoil of clayey slope is easy to erosion because it is weak in its strength, water stability and erosion resistance. A new organic polymer soil stabilizer, which was developed for the stabilization treatment of clay slope topsoil and was named as STW, was introduced in this study. In order to understand the effect of STW on the stabilization of clayey soil, laboratory tests on the unconfined compressive strength, shear strength, water stability and erosion resistance of untreated and treated soil specimens are performed, The results indicated that STW soil stabilizer can significantly increased the unconfined compression strength, shear strength, water stability and erosion resistance of clayey soil. The unconfined compression strength increased with the increasing of curing time and the variation mainly occurs in the first 24-hour. With the addition amounts of STW increasing, the strength, water stability and erosion resistance increased at the curing time being 48 h, but in the case of friction angle, no major change was observed. Based on the scanning electron microscopy (SEM) analysis of the stabilized soil, the stabilization mechanisms of STW soil stabilizer in the clayey soil were discussed. Finally, a field test of the stabilization treatment of clay slope topsoil with STW was carried out, and the results indicated that the STW soil stabilizer on the stabilization treatment of clay slope topsoil is effective for improving the erosion resistance of slope topsoil, reducing the soil loss and protecting the vegetation growth. Therefore, this technique is worth popularizing for the topsoil protection of clay slope.     

Thermodynamic modeling of binary CH4-H2O fluid inclusions

This work reports the application of thermodynamic models, including equations of state, to binary (salt-free) CH₄-H₂O fluid inclusions. A general method is presented to calculate the compositions of CH₄-H₂O inclusions using the phase volume fractions and dissolution temperatures of CH₄ hydrate. To calculate the homogenization pressures and isolines of the CH₄-H₂O inclusions, an improved activity-fugacity model is developed to predict the vapor-liquid phase equilibrium. The phase equilibrium model can predict methane solubility in the liquid phase and water content in the vapor phase from 273 to 623 K and from 1 to 1000 bar (up to 2000 bar for the liquid phase), within or close to experimental uncertainties. Compared to reliable experimental phase equilibrium data, the average deviation of the water content in the vapor phase and methane solubility in the liquid phase is 4.29% and 3.63%, respectively. In the near-critical region, the predicted composition deviations increase to over 10%. The vapor-liquid phase equilibrium model together with the updated volumetric model of homogenous (single-phase) CH₄-H₂O fluid mixtures (Mao S., Duan Z., Hu J. and Zhang D. (2010) A model for single-phase PVTx properties of CO₂-CH₄-C₂H₆-N₂-H₂O-NaCl fluid mixtures from 273 to 1273 K and from 1 to 5000 bar. Chem. Geol.275, 148-160), is applied to calculate the isolines, homogenization pressures, homogenization volumes, and isochores at specified homogenization temperatures and compositions. Online calculation is on the website: http://www.geochem-model.org/.     

贵州台江县大塘铅锌矿找矿前景浅析

大塘铅锌矿位于黔东铅锌成矿带中段,区域性施洞口断裂北西侧,矿体及矿化体呈似层状、脉状和透镜状赋存于下寒武统清虚洞组及中寒武统石冷水组地层中,含矿岩系为角砾状白云岩,矿石矿物主要为闪锌矿、方铅矿及少量黄铁矿,脉石矿物主要为白云石及少量方解石。矿石结构以粒状结构和假象结构为主,矿石构造主要为浸染状、细脉状和角砾状构造。该类型铅锌矿矿床有一定的规模,找矿标志明显。黔东铅锌成矿带中段内有铅锌矿点和铅锌地球化学异常区多处,通过了解该类型铅锌矿床地质特征和找矿标志,可望找到更多、更大的铅锌矿。     

碎屑锆石对班公湖地区晚侏罗世-早白垩世沉积物源的制约

本文对班公湖地区中生代沙木罗组（J3—K1s）和日松组（J3r）地层的碎屑锆石进行了形态学及U-Pb年代学的研究。结果表明：锆石颗粒粒径约为100～150 μm,内部结构清晰,晶体为长柱状,自形程度较高,多数锆石不含暗色包体及浑圆形内核; 有些锆石颗粒有扇型分带结构。Th/U比值较大,多数大于0.1,均值约为0.86,说明岩浆的成因以锆石为主体,部分颗粒或晶体可能为变质成因; 锆石年龄主要分布在6个区间范围内： 1）180～100 Ma, 2）350～180 Ma, 3）600～450 Ma, 4）1100～600 Ma, 5）1800～1400 Ma, 6）2200～1800 Ma。锆石U-Pb年龄谱对应了羌塘地块经历的几次构造热事件,验证了晚侏罗世—早白垩世班公湖地区的物源主要来自其北部的羌塘地块。     

浙江萧山跨湖桥遗址动物骨骼表面微痕与人类行为特征

浙江跨湖桥遗址位于中国东南沿海,是距今约8000年左右的新石器时代遗址.遗址中出土有大量哺乳动物骨骼,通过显微观测和统计,发现遗址动物骨骼表面有丰富的人工改造痕迹,并有家畜狗的啃咬痕迹等.其中人工改造痕迹的比重,达到所观察标本总数的17.57%.人工改造痕迹的显微特征、排列规律、分布位置等,反映遗址古居民已熟练掌握了剥...     

甘肃省临夏盆地更新世早期湖泊沉积孢粉记录的古气候演化

根据孢粉组合特征,将临夏盆地早更新统东山组(2.50-1.76Ma)的孢粉划分为3个孢粉带(含6个亚带),即3个植被、气候阶段,第一阶段(2.50-1.91Ma,带Ⅰ),植被类型是以柏科、榆属和禾本科为优势种的温带森林,气候表现为温凉稍干,并有逐渐干旱化的趋势.第二阶段(1.91-1.80Ma,带Ⅱ)是以云杉属、榆属和...     

基于耦合关系的干旱绿洲区农村居民点整理分区研究——以张掖市甘州区为例

以张掖市甘州区为例,利用系统科学理论与方法,研究农村居民点整理与农村社会经济之间的动态耦合规律,并以甘州区18个乡镇为研究单元,构建了农村居民点用地整理分区评价指标体系,利用熵值法确定权重,计算农村居民点整理的综合评价值,运用层次筛选法将研究区划分为5个整理区。研究结果：①甘州区农村居民点与农村社会经济的耦合度演化分为3个阶段：1995—1997年,二者不甚协调;1998—2003年,二者都处于持续、稳定、最佳协调发展状态;2004—2007年,二者处于相对稳定协调状态;目前二者处于不甚协调发展阶段。②农村居民点整理分区包括优先整理区、强化整理区、适度整理区、一般整理区和完善整理区。     

The suitability of using leaf area index to quantify soil loss under vegetation cover

Soil erosion by water under forest cover is a serious problem in southern China. A comparative study was carried out on the use of leaf area index (LAI) and vegetation fractional coverage (VFC) in quantifying soil loss under vegetation cover. Five types of vegetation with varied LAI and VFC under field conditions were exposed to two rainfall rates (40 mm h⁻¹ and 54 mm h⁻¹) using a portable rainfall simulator. Runoff rate, sediment concentration and soil loss rate were measured at relatively runoff stable state. Significant negative exponential relationship (p < 0.05, R² = 0.83) and linear relationship (p < 0.05, R² = 0.84) were obtained between LAI and sediment concentration, while no significant relationship existed between VFC and sediment concentration. The mechanism by which vegetation canopy prevents soil loss was by reducing rainfall kinetic energy and sediment concentration. LAI could better quantify such a role than VFC. However, neither LAI nor VFC could explain runoff rate or soil loss rate. Caution must be taken when using LAI to quantify the role of certain vegetation in soil and water conservation.