中国泛滥平原沉积物中铂,钯丰度值及地球化学省的初步研究

根据中国泛滥平原沉积物中Ｐｔ、Ｐｄ的分析结果,求得泛监平原沉积物中的Ｐｔ、Ｐｄ近似丰度值分别为０．４６ｎｇ／ｇ和０．４０ｎｇ／ｇ。据泛监平原沉积物中Ｐｔ、Ｐｄ的空间分布模式初步圈出滇黔Ｐｔ、Ｐｄ地球化学省,新疆Ｐｔ、Ｐｄ地球化学省和西藏雅布江Ｐｔ、Ｐｄ地球化学省。     

Phase equilibria in the granite-H2O-HF system and effect of fluorine on granitic melt structure

Experiments carried out in the system granite-H₂O-HF at 0.1 GPa show that the crystal-liquid equilibrium temperature of quartz rises and that of alkali-feldspar goes down with increasing F content. The calculated results of quartz and alkali feldspar crystal-liquid equilibrium show that the activity of SiO₂ in melt increases and the activities of NaAlSi₃O₈(Ab) and KAlSi₃O₈(Or) decrease, with a greater decreasing extent for a _Ab ^L than a _Or ^L . These systematic changes are believed to be caused by F complexing with Al, Na, K, but not Si in the melt, and are consistent with F decomposing AlO ₂ ^? tetrahedra and more preferentially forming complexes with Na than K. The comparison between effects of F and H₂O on phase equilibrium suggests that the maximum difference affecting melt structure between F and OH is F complexing without Si and OH complexing with Si in granitic melt.     

Looking Down the Light Cone: Can Deep Redshift Surveys Alone Measure the Power Spectrum?

We analyse the window functions for the spherical harmonic mode estimators of all-sky, volume-limited surveys, considering evolutionary effects along the past light-cone which include the deviation of the distance scale from a linear relationship with redshift, linear peculiar velocity corrections, and linear evolution of the density perturbations. The spherical harmonic basis functions are considered, because they correspond most closely to the symmetries of typical survey geometries and of the light-cone effects we consider. Our results show substantial broadening of the windows over that expected by ignoring light-cone effects, indicating the difficulty of measuring the power spectrum independently from cosmology. We suggest that because of light-cone effects, deep redshift surveys should be analysed either in conjunction with CMBR data which determines the cosmological parameters, or by using a Bayesian likelihood scheme in which varying cosmological parameters and a simple parametrization of the primordial power spectrum are assumed as the priors, so that observed data can be mapped from redshift to real space. The derived power spectrum can then be compared with underlying models of fluctuation generation and growth in structure formation to evaluate both these models and the cosmological priors.     

内蒙白旗地区火山碎斑熔岩矿物红外光谱特征研究

正镶白旗碎斑熔岩和花岗斑岩中钾长石主要为高正长石和低透长石，有序度低，反映了白旗火山岩形成温度较高，钾长石有序度具明显的变化规律，反映了各相带岩石形成环境的差异性。各相带中石英的红外光谱反映了与钾长石相同的温度变化规律；岩石中锆石主要以晶质锆石为主；磁铁矿的红外光谱特征则表明碎斑熔岩形成于高氧化条件的侵出相环境。     

江西茅排金矿床含金韧性剪切带构造特征

茅排韧性剪切带是茅排金矿床主要控矿构造，属左行韧性平移剪切带，形成于加里东末期。带内剪切不协调褶皱，粘滞型石香肠，塑性流变组构、拉伸线理以及波状消光，拔丝构造等宏观及微观韧性变形组构十分发育。该剪切带控制了茅排金矿床的空间定位，金矿化局限于剪切带内，剪切热能是地层中金活化的重要动力源，剪切带为含金热液的运移和金的沉淀提供有利通道和空间，并为晚期脆性构造叠加形成富矿体创造了前提。     

气候变化对天山伊犁河上游河川径流的影响

用水量平衡模型研究气候变化对天山降雪比较丰富的伊犁河上游山区河川径流的影响。研究表明，作为西北干旱区水资源主要形成区的山区，由于气温较低和降水丰富，未来气候变化对水资源量的影响将主要取决于降水量的变化，气温升高的影响相对较小。气候的变暖，一方面使径流的年内分配发生变化，月径流峰值减少，时间提前，春季径流增加，而其余季节径流减少，其中夏季减少最多；另一方面将使年径流量的变率增大，这对水资源的利用极淡     

扬子地台西南缘铜金铅锌银成矿预测研究

扬子地台西南缘位于滨西太平洋成矿域、特提斯成矿域和秦祁昆成矿域的结合部位，是中国最重要的成矿带之一，具广阔的找矿前景。本次采用系统论、信息论、控制论并结合区内的成矿系列和成矿特征，共预测出Ⅰ级成矿带６个，Ⅱ级成矿远景区带６个，Ⅲ级重点普查区１２个。在此基础上，依据矿种急缺度、成矿条件有利度、预测依据充分度、预测矿床规模大小度、预测靶区可利用度、交通方便度、区位条件有利度以及经济和社会效益度８原则，且分别赋值进行半定量评价，从而优选出十佳找矿靶区并进行了排序。这些找矿靶区都转入普查，经过部分工程验证，得到了证实，开拓了科研找矿，理论找矿，与生产实际相结合的一条新路子。     

祁连山北坡河川径流变化的分析及趋势预测

本文结合大气环流及山区内,外气温和降水的年际变化,分析了径流变化与气候变化的关系。分析指出:山区东段河流的枯水年段与欧亚地区中高纬度纬向环流的加强有一定关系;山区对流性降水对本区河流年径流的变化有不可忽视的影响。用时间序列分析方法模拟了年径流的变化规律,并预测未来5—10年径流的变化趋势。     

Stable Strontium Isotopic Fractionation During Chemical Weathering in Drainage Basins: Mechanisms and Applications

The new non-traditional stable strontium (Sr) isotope has aroused great attention from academic scholars in terms of the continental weathering and marine Sr cycle. The analytical precision of stable Sr isotope using mass spectrometry is better than 0.03‰. The compiled δ⁸⁸/ ⁸⁶Sr values vary from -3.65‰ to 1.68‰ in natural reservoirs. Recent findings indicate that multiple processes can cause stable Sr isotope fractionation in Earth surface, including the incongruent dissolution of primary minerals, the formation and adsorption of secondary minerals, the precipitation of calcium carbonate, and the biological cycling. These processes lead to higher δ⁸⁸/ ⁸⁶Sr in the liquid phase and lower δ⁸⁸/ ⁸⁶Sr in the solid phase, and thus result in different geochemical behavior of stable Sr isotopes in water and sediment during the weathering processes. The δ⁸⁸/ ⁸⁶Sr values of river sediment decrease with the increase of weathering intensity, which has the potential to indicate chemical weathering intensity. Meanwhile, further study on the fractionation mechanisms and constraints of stable Sr isotopes in river water plays an important role in tracing chemical weathering processes within the watershed, which will lead to a better understanding of the global ocean Sr cycle.     

Ophiolites from the Mianlue Suture in the Southern Qinling and Their Relationship with the Eastern Paleotethys Evolution

The Mianlue suture extends from Derni-Nanping-Pipasi-Kangxian to the Lueyang-Mianxian area, then traverses the Bashan arcuate structure eastward to the Huashan region, and finally to the Qingshuihe area of the southern Dabie Mountains. From east to west, with a length of over 1500 km, the ophiolitic melange associations are distributed discontinuously along the suture. The rock assemblages include ophiolite, island-arc and oceanic island rock series, indicating that there existed a suture zone and a vanished paleo-ocean basin. The Mianliie paleo-ocean basin experienced its main expansion and formation process during the Carboniferous-Permian and closed totally in the Triassic. It belongs to the northern branch of the eastern paleotethys, separated from the northern margin of the Yangtze block under the paleotethys mantle dynamic system.