基于GRACE卫星测量得到的中国及其周边地区陆地水量变化

GRACE卫星成功开辟了空间大地测量对地观测的新途径。利用GRACE卫星得到的时变地球重力资料,分析估计了中国及其周边地区陆地水量的变化趋势,较为清晰地揭示了该地区季节性变化特征。进一步采用13点滑动平均的方法扣除了季节性变化,提取了4个特征区域(喜马拉雅南部,新疆与西藏及其周边的亚洲高山区域,中国华北、东北地区和中国南部地区)的陆地水量变化特征信息,这4个区域陆地水量的变化趋势分别为-12.7±0.7、-60.4±2.7、-12.5±0.5和6.6±0.9 km³/a。其中：喜马拉雅南部和亚洲高山区域陆地水量呈现明显的衰减趋势,与Matsuo和Heki模拟冰川质量损失源得到的结果较为一致;但近10年来亚洲高山区域西北部冰川加速融化趋势并不明显。中国华北、东北地区和南部地区水量变化比较复杂,具不稳定的变化趋势。     

Estimating groundwater evapotranspiration rates using diurnal water-table fluctuations in a semi-arid riparian zone

In semi-arid climates, phreatophytes draw on shallow aquifers, and groundwater evapotranspiration (ET_G) is a principal component of groundwater budgets. Diurnal water table fluctuations, which often are a product of ET_G, were monitored in the riparian zone of Red Canyon Creek, Wyoming, USA. These fluctuations were higher in a riparian wetland (2–36 mm) than a grass-covered meadow (1–6 mm). The onset and cessation of water-table fluctuations correspond to daily temperatures relative to freezing. Spatial differences were due to vegetation type and specific yield, while temporal changes were due to vegetation dormancy. Ratios of ET_G to potential evapotranspiration (PET), K _c,GW, were similar to ratios of actual evapotranspiration (ET) to PET, K _c, in semi-arid rangelands. Before vegetation senescence, K _c,GW increased between precipitation events, suggesting phreatophytes pull more water from the saturated zone as soil moisture decreases. In contrast, K _c decreases with soil moisture following precipitation events as ET becomes increasingly water-limited. Error in ET_G is primarily from estimates of specific yield (S _y), which is difficult to quantify in heterogeneous sediments. ET_G values may be more reliable because the range of acceptable S _y is smaller than K _c and S _y does not change with vegetation type or soil moisture.     

复杂应力条件下掺砾黏土真三轴试验

采用新型真三轴仪器,对掺砾黏土进行了复杂应力条件下加载试验,近似模拟了土石坝填筑期心墙土体单元的加荷过程。试验结果表明,由于土体单元处于复杂应力状态,即使是单向加载这样的简单加荷应力路径,在不同应力方向上的应力和变形也都呈现显著的应力各向异性。土石坝应力变形分析中坝体单元处于三向应力条件下,由于加载引起的应力各向异性对心墙乃至整个坝体的应力变形规律都有较大影响,合理的本构模型应该能够反映并描述这种复杂应力状态下的应力各向异性。     

Groundwater chemistry and mass transfers in the Independence aquifer,central Mexico,by using multivariate statistics and mass-balance models

In the light of progressive depletion of groundwater reservoir and water quality deterioration of the Independence aquifer, an investigation on chemical data of dissolved major and minor constituents in 246 recent groundwater samples was performed. The main objective was the detection of processes responsible for the geochemical evolution and mineralization throughout the area. Multivariate techniques revealed different sources of solutes (a) dissolution of calcium and magnesium carbonate minerals, (b) weathering of acid volcanic minerals, (c) alteration of manganese containing alkaline silicates, (d) leaching of halite deposits of meteoric origin, (e) contamination from agricultural and urban wastewaters, and (f) evaporative effects due to intensive irrigation. Although nitrate contamination is associated with pollution from intensive cultivated areas, natural contamination plays an important role in the study area. The investigation reveals that weathering of acid volcanic rocks (rhyolite) and oxidation of arsenic bearing sulfide minerals are the responsible processes for high fluorine (up to 16 mg/l) and arsenic (up to 0.12 mg/l) contents, respectively, exceeding the Mexican maximum admissible concentration for drinking water. Except for kaolinite, all recharge processes are dissolution oriented (CO₂, calcite, dolomite, K-feldspar, plagioclase). Silicate precipitation (amorphous silica and chalcedony) is of growing importance in discharge zones. Cation exchange is not an important issue in the whole study area.     

聚炳烯酰胺无固相冲洗液在复杂地层中的应用研究

根据多年对聚丙烯酰胺无固相冲洗液钻进技术在地质岩心钻探中的应用情况,进一步分析聚丙烯酰胺无固相冲洗液钻进所具有的技术优势,以及如何发挥其优势,利用聚丙烯酰胺无固相冲洗液钻进水敏地层及其它复杂地层,解决难以钻进的问题。同时,为进一步完善、选择适宜的钻井冲洗液提供一些可供借鉴的建议,使该技术的快速发展和地质岩心钻探钻进技术全面提高。     

EARLY PALEOZOIC SUBDUCTION-RELATED ACCRETIONARY COMPLEX IN WESTERN KUNLUN

EARLY PALEOZOIC SUBDUCTION-RELATED ACCRETIONARY COMPLEX IN WESTERN KUNLUN     

祁连山区大坂山隧道围岩的冻融状况分析

通过对严守地区隧道现场基本气象条件的分析,建立了隧道内空气与围岩对流换热及固体导热的综合模型;在隧道内空气以紊流为主的情况下,分析预报了祁连山区大坂山隧道开通运营后洞内温度及围岩冻结、融化状况,并与在隧道内空气以层流为主的情况下的已有结论进行比较。     

Huanggang Intrusive Complex in Northern Tongbai Area: Island-Arc Tectonic Environment and Its Geological Significance

ＩＮＴＲＯＤＵＣＴＩＯＮＲｅｃｅｎｔｇｅｏｌｏｇｉｃａｌｓｔｕｄｉｅｓｓｈｏｗｔｈａｔｔｈｅＥｒｌａｎｇｐｉｎｇｏｐｈｉ－ｏｌｉｔｅｆｒａｇｍｅｎｔｗａｓｆｏｒｍｅｄｉｎｂａｃｋ－ａｒｃｂａｓｉｎ（Ｓｕｎｅｔａｌ．,１９９６;Ｗａｎｇｅｔａｌ．,１９...     

大裂隙堵漏剂在神农架矿区复杂地层钻进中的试验应用

通过大裂隙堵漏剂在神农架矿区复杂地层钻进的试验应用,论述了该堵漏剂堵漏性能参数及堵漏机理,总结了用该堵漏剂堵漏的操作方法;简述了野外施工试验的应用过程及应用效果。     

钙贝塔石(Calciobetafite)在我国的发现

钙贝塔石发现于四川西昌的霓辉石-钠铁闪石脉中，与之共生的矿物是霓辉石，钠铁闪石，钠长石，铈磷灰石，硅钛铈矿，沥青铀矿，重晶石，方解石和彩钼铅矿等。钙贝塔石呈黑色，黑褐色，具八面体晶形，大小为2mm～8mm，条痕为黑色或黄褐色，油脂到沥青光泽，贝壳状断口。摩氏硬度为6．05～6．44(Hv=570．08kg／mm^2～689．06kg／mm^2)；无解理，比重4．51(扭力天平法测定)，反射率从406nm(13．53％)到659nm(11．87％)。经计算钙贝塔石的化学式为：(Ca，Na，U)2(Nb，Ti)2(0，OH)，。钙贝塔石的强X射线：2．975(10．222)，2．570(5．400)，1．816(9．440)，1．549(8．622)，1．050(6．844)，等轴晶系，α=1．029nm。