Natural Evaporation of Dangxiongcuo Salt Lake Spring Brine in Tibet,China

正1 Introduction Dangxiongcuo salt lake(Figure 1),which is located in the southwest of Tibet,China,is rich in valuable mineral elements like lithium,potassium,boron,rubidium,caesium     

新疆山区低层云水资源时空分布特征

采用云与地球辐射能量系统(CERES)2003～2007年的CERESSSF Aqua MODIS云资料,选取新疆阿尔泰山、天山和昆仑山三大山区,通过考察云量和云液态水柱含量分析了低层云水资源的多年空间分布和季节变化特征。结果表明,三大山区多年平均的云量年平均区域值在24.4%～27.5%之间,云液态水柱含量在51～56.3g/m2之间。三大山区低层云量和云液态水柱含量有明显的季节变化特征。综合云量和云水柱含量来看,春季是三大山区低层云量资源最丰富的季节,冬季是三大山区低层云中的含水量最丰富的季节。     

Anti-clockwise P–T paths in the lower crust: an example from a kyanite-bearing regional aureole, George Sound, New Zealand

The George Sound Paragneiss (GSP) represents a rare Permo-Triassic unit in Fiordland that occurs as a km-scale pillar to gabbroic and dioritic gneiss of c . 120 Ma Western Fiordland Orthogneiss (WFO). It is distinguished from Palaeozoic paragneiss common in western Fiordland (Deep Cove Gneiss) by SHRIMP and laser-ablation U–Pb ages as young as c . 190 Ma and ¹⁷⁶Hf/¹⁷⁷Lu >0.2828 for detrital zircon grains. The Mesozoic age of the GSP circumvents common ambiguity in the interpretation of Cretaceous v. Palaeozoic metamorphic assemblages in the Deep Cove Gneiss. A shallowly dipping S₁ foliation is preserved in the GSP distal to the WFO, cut by 100 m scale migmatite contact zones. All units preserve a steeply dipping S₂ foliation. S₁ staurolite and sillimanite inclusions in the cores of metapelitic garnet grains distal to the WFO preserve evidence for prograde conditions of T  <   650 °C and P <  8 kbar. Contact aureole and S₂ assemblages include Mg-rich, Ca-poor cores to garnet grains in metapelitic schist that reflect WFO emplacement at ≈760 °C and ≈6.5 kbar. S₂ kyanite-bearing matrix assemblages and Ca-enriched garnet rims reflect ≈650 °C and ≈11 kbar. Poorly oriented muscovite–biotite intergrowths and rare paragonite reflect post-S₂ high- P retrogression and cooling. Pseudosection modelling in NCKFMASH defines a high- P anti-clockwise P–T history for the GSP involving: (i) mid- P amphibolite facies conditions; preceding (ii) thermal metamorphism adjacent to the WFO; followed by (iii) burial to high- P and (iv) high- P cooling induced by tectonic juxtaposition of cooler country rock.     

Reactive flow of mixed CO2–H2O fluid and progress of calc-silicate reactions in contact metamorphic aureoles: insights from two-dimensional numerical modelling

Previous models of hydrodynamics in contact metamorphic aureoles assumed flow of aqueous fluids, whereas CO₂ and other species are also common fluid components in contact metamorphic aureoles. We investigated flow of mixed CO₂–H₂O fluid and kinetically controlled progress of calc‐silicate reactions using a two‐dimensional, finite‐element model constrained by the geological relations in the Notch Peak aureole, Utah. Results show that CO₂ strongly affects fluid‐flow patterns in contact aureoles. Infiltration of magmatic water into a homogeneous aureole containing CO₂–H₂O sedimentary fluid facilitates upward, thermally driven flow in the inner aureole and causes downward flow of the relatively dense CO₂‐poor fluid in the outer aureole. Metamorphic CO₂‐rich fluid tends to promote upward flow in the inner aureole and the progress of devolatilization reactions causes local fluid expulsion at reacting fronts. We also tracked the temporal evolution of P‐T‐X_CO2conditions of calc‐silicate reactions. The progress of low‐ to medium‐grade (phlogopite‐ to diopside‐forming) reactions is mainly driven by heat as the CO₂ concentration and fluid pressure and temperature increase simultaneously. In contrast, the progress of the high‐grade wollastonite‐forming reaction is mainly driven by infiltration of chemically out‐of‐equilibrium, CO₂‐poor fluid during late‐stage heating and early cooling of the inner aureole and thus it is significantly enhanced when magmatic water is involved. CO₂‐rich fluid dominates in the inner aureole during early heating, whereas CO₂‐poor fluid prevails at or after peak temperature is reached. Low‐grade metamorphic rocks are predicted to record the presence of CO₂‐rich fluid, and high‐grade rocks reflect the presence of CO₂‐poor fluid, consistent with geological observations in many calc‐silicate aureoles. The distribution of mineral assemblages predicted by our model matches those observed in the Notch Peak aureole.     

A nonlinear data‐driven model for synthetic generation of annual streamflows

A hybrid model that blends two non‐linear data‐driven models, i.e. an artificial neural network (ANN) and a moving block bootstrap (MBB), is proposed for modelling annual streamflows of rivers that exhibit complex dependence. In the proposed model, the annual streamflows are modelled initially using a radial basis function ANN model. The residuals extracted from the neural network model are resampled using the non‐parametric resampling technique MBB to obtain innovations, which are then added back to the ANN‐modelled flows to generate synthetic replicates. The model has been applied to three annual streamflow records with variable record length, selected from different geographic regions, namely Africa, USA and former USSR. The performance of the proposed ANN‐based non‐linear hybrid model has been compared with that of the linear parametric hybrid model. The results from the case studies indicate that the proposed ANN‐based hybrid model (ANNHM) is able to reproduce the skewness present in the streamflows better compared to the linear parametric‐based hybrid model (LPHM), owing to the effective capturing of the non‐linearities. Moreover, the ANNHM, being a completely data‐driven model, reproduces the features of the marginal distribution more closely than the LPHM, but offers less smoothing and no extrapolation value. It is observed that even though the preservation of the linear dependence structure by the ANNHM is inferior to the LPHM, the effective blending of the two non‐linear models helps the ANNHM to predict the drought and the storage characteristics efficiently. Copyright © 2007 John Wiley & Sons, Ltd.     

井间地震层析成像技术的应用

阐述了井间地震层析成像的正反演技术——基于最短路径法的射线追踪正演技术和基于LSQR算法的反演技术的原理,并且通过数值模型对正反演算法进行了较细致的研究,重建了地下构造原像,效果较好。结合工程应用实例,进一步表明井间地震层析成像技术能够更清晰、更客观地反映出地下构造情况,为地质结构研究和后期施工提供更详实的资料。最后,对层析成像的分辨率进行了探讨,指出了层析成像质量的影响因素。     

河南洛宁太华变质杂岩区早元古代变质作用P-T-t轨迹及其大地构造意义

太华变质杂岩广泛出露于华北克拉通南缘,总体呈SW-NE向展布.在河南洛宁地区,太华变质杂岩以TTG片麻岩、斜长角闪片麻岩和变泥质片麻岩为主.斜长角闪片麻岩中可识别出三个阶段的变质矿物组合:进变质阶段矿物组合(M1)为石榴子石变斑晶内部的包裹体矿物组合( Amp1+ Pl1+Qtz),变质高峰期矿物组合(M2)为石榴子石变斑晶边部和基质矿物组合( Grt2+ Amp2+ Pl2+ Qtz),退变质阶段矿物组合(M3)为“白眼圈”状后成合晶组合(Amp3+ Pl3+ Qtz).运用矿物温度计与压力计估算三个阶段的P-T条件分别为:进变质阶段约600 ～ 680℃/7.0～ 7.6kbar,变质高峰期为680 ～ 790℃/9.5 ～10.7kbar,退变质阶段为580～720℃/6.5 ～7.6kbar.变泥质片麻岩中保留了进变质阶段(M1)包裹体矿物组合(Bt1+Pl1+Qtz)和峰期变质阶段(M2)矿物组合(Grt2 +Bt2+Pl2 +Qtz)两个阶段.其中未发现后期退变质反应结构,石榴子石中也未发现成分环带.P-T条件估算结果分别为:M1阶段620 ～ 710℃/4.9 ～5.6kbar,M2阶段710～760℃/7.3～8.3kbar.洛宁地区太华变质杂岩记录了顺时针的近等温降压型的P-T轨迹,可能经历了与华北中部造山带其它杂岩类似的变质演化过程,推测其形成于华北克拉通东部陆块和西部陆块沿中部造山带的拼合过程中.SIMS与ICP-MS锆石U-Pb定年表明,斜长角闪片麻岩记录了1938～1967Ma的变质事件,比华北中部造山带其它变质杂岩区所广泛记录的～1850Ma变质事件早了约100Ma,暗示中部造山带的拼合可能是一个长期的、复杂的过程.     

西藏扎北盐湖秋季卤水(硫酸钠亚型)5℃等温蒸发实验研究

西藏扎北盐湖硫酸钠亚型卤水中富含元素Li、B、K和微量元素Rb、Cs等.为了更好地了解卤水在自然条件下的蒸发结晶规律,需对相应卤水进行低温室内等温蒸发实验研究.本文对该盐湖卤水进行了5℃等温蒸发试验,并利用Na+、K+、Mg2+//Cl-、SO42--H2O五元水盐体系0℃相图,构筑了从干基立体图Na2SO4角顶的放射...     

科学发展观视域下的生态城市建设路径探讨

作为世界上人口最多又处在城市化高峰期的中国,要注重城市的生态化发展,按照生态建设的要求和理念,建设可持续、生态型的城市。     

Changes of residential land density and spatial pattern from 1989 to 2004 in Jinan City,China

Urban sprawl is driven by a myriad of factors, the predominant one of which is the development of residential land. Selecting part of Jinan City for a case study, we use the landscape metric of percent of landscape (PLAND) to capture residential land growth and density changes in 1989, 1996 and 2004 to illuminate the dynamic process of residential land development. The results indicate that the moving window method and the landscape metrics method are efficient ways to describe residential land density. The residential land showed the greatest change among the built-up land with 1995.68 ha from 1989 to 2004, which is mainly transformed from agriculture land and green space. The urban center area of study area is primarily covered with medium density residential land, and surrounded by high density residential land. The development pattern of residential land exhibited both fill-in (new growth occurs through infilling the free spaces within the developed area) and sprawl processes, influenced by a series of factors, such as urban development policy, conservation of springs, recreational and aesthetic amenities. The findings of the study will help to guide urban planning with a focus on the management and protection of the environment and resources.