Exploring the hydrologic response to the urban building coverage ratio by model simulation

Theoretical and Applied Climatology - The increasing building coverage ratio accompanied by the increase in impervious surfaces during the urbanization process may change the flow concentration...     

商丹断裂带东段基性岩、超基性岩中的铁铬镍资源潜力预测

对商丹断裂带东段基性-超基性岩带（体）及其中的铁、铬等矿化特征作了概述,在岩带中圈出了A、B、C、D四个基性-超基性岩体集中区,对该带中铁铬镍等矿产资源潜力作了地质预测,认为该基性-超基性岩带是岩浆型铁、铬、镍等矿产的良好找矿远景区,提出了下步找矿工作思路、方法手段的建议.     

鱼耳石中锶和钡富集的影响因素及其环境响应

鱼耳石中元素锶和钡主要来源于鱼类生存的水体,这两种元素通过腮或肠进入内耳淋巴液,继而以类质同象的方式沉淀在耳石晶格内部空位和晶格间隙中。耳石结晶沉淀的整个过程不仅受生物的调控作用,而且还受到外界环境,如水体元素浓度、盐度、温度等因素的影响,因此耳石中某种元素的浓度与其在水体中的浓度之比(元素富集系数)与鱼类所生存的环境之间具有一定的响应关系。在以上各种因素中,水体元素浓度对耳石元素富集系数的影响最为显著。一般来说,耳石中某种元素的含量与水体中相应的元素浓度呈正相关关系,而水体中元素之间就耳石中的富集过程也存在一定的相互促进或抑制作用,如Sr对Ba为协同作用,Ca对Sr、Zn为拮抗作用。另外,水体盐度或温度与元素富集系数之间不存在简单的线性相关关系,而是因鱼种、水体综合环境及元素种类不同而有所差异。研究结果表明:鱼种一定的情况下,耳石中元素富集系数与水体盐度和温度存在良好相关关系。基于以上相关性分析,可以认为耳石中元素富集系数与环境因子(水体元素浓度、盐度、温度)之间存在响应关系。因此,可以选用那些受环境影响大但对自身调控影响小的元素(如:Sr、Zn、Pb、Mn、Ba、Fe、Li、Ni、Cd)来建立耳石与水体环境之间元素富集系数的定量化模型,并利用这种响应关系及定量化模型进行生态环境监测和渔业管理。     

橄榄岩中尖晶石的O同位素继承性与晶体结构转换

应用增量法计算的矿物对O同位素分馏曲线，得到正尖晶石-矿物对O同位素温度高于尖晶石在地幔中的熔点，而用反尖晶石-矿物对计算的O同位素温度低于尖晶石的熔点，较为合理。因此，地幔橄榄岩中镁铝尖晶石的O同位素组成可能继承了其母体反尖晶石特征，即使反结构尖晶石在发生相变作用变成正结构尖晶石时未发生O同位素再平衡。     

一个近地层中的三维随机扩散模式

利用横向Lagrange时间尺度T_(LY),与稳定度及高度的关系,本文建立了一个三维随机扩散模式,并用它模拟了近地层中地面源的扩散过程。模式计算结果表明:在稳定层结条件下该模式比取T_(LY)为常数得到的模式有明显的改进,而在不稳定条件下这一模式改进不大。     

Palynological constraints on the age of the Mississippi Valley-type Changdong Pb-Zn deposit,Sanjiang belt,West China

Mississippi Valley-type(MVT)Pb-Zn deposits serve as the world’s major supply of Pb-Zn resources.However,the age constraint of MVT Pb-Zn deposits has long been a big challenge,due to the lack of minerals that are unequivocally related to ore deposition and that can be used for radioisotopic dating.Here we show sporopollens can provide useful chronological information on the Changdong MVT Pb-Zn deposit in the Simao basin,Sanjiang belt,West China.The Pb-Zn ores in the Changdong deposit are hosted by internal sediments in paleo-karst caves of meteoric origin.Sphalerite and galena occur as replacements of carbonate minerals and void infillings in the internal sediments.The relations suggest that the Pb-Zn mineralization occurred after the deposition of the internal sediments.A palynological assemblage mainly composed of angiosperm pollen dominated by Castanea,Quercus,and Carya and fern spores dominated by Polypodiaceae,Pteris,and Athyriaceae was identified.These pollen and spores place the ore-hosting internal sediments and the Changdong paleo-karst at early to middle Oligocene.Consequently,the Changdong Pb-Zn deposit must have formed after the early Oligocene(~34 Ma).These age constraints,together with the geological characteristics,indicate that the Changdong Pb-Zn deposit is a paleo-karst-controlled MVT deposit related to fold-thrust systems in the Sanjiang belt.The Changdong deposit is similar to other MVT Pb-Zn deposits in the northern part of the Sanjiang belt,making it possible to extend this Pb-Zn belt 500 km further to the South.Results presented here highlights the potential of sporopollens in dating the age of MVT deposits related to paleo-karst formation in young orogenic belts.     

Magma underplating and Hannuoba present crust-mantle transitional zone composition: Xenolith petrological and geochemical evidence

Studies on the deep-seated xenoliths from global volcanoes reveal that the present petrological crust-mantle boundary between the lower crust and the upper mantle actually is a transitional layer from mainly mafic granulites to ultramafic spinel lher-zolites[1,2], i.e. a transitional zone distinctive from the seismological Moho[3]. Oceanic lithosphere crust- mantle transitional zone can be established from the study on the exposed ophiolites. However, as for the continental lithosphere, since …     

Thermal simulation of basic volcanic fluid influence on different source rocks

Based on thermal simulation experiment, interactions between volcanic fluids and source rocks were studied. Gas generations in the dry system and fluid system under different temperatures were analyzed. The results showed that the various types of source rocks are similar in composition, containing gaseous C1-C5 hydrocarbons, H2 and CO2 whose gas yields increase with increasing temperature. The gas yield of source rocks of type I is the high- est, followed by type II, and that of source rocks of type III is the lowest, indicating that the yield of hydrocarbon gases is related to their hydrocarbon generating potential. Although the generating potential of type III is the lowest, it can still be regarded as a useful gas source when it is buried deeply enough. The basic volcanic fluid restrains the generation of gaseous hydrocarbons in different types of source rocks, but promotes the generation of inorganic gases.     

煤岩的显微构造特征及其与瓦斯突出的关系——以南桐鱼田堡煤矿为例

煤瓦斯突出与煤岩显微结构构造密切相关。除部分显微结构构造与成煤阶段的环境等有关外,大部分都是构造变形的结果。因此,我们从构造变形类型和特点来划分煤岩显徽构造类型,既简便又利于应用。根据四川南桐鱼田堡煤矿4号及6号煤层的扫描电子显微镜研究,可将煤岩划分成5类:非构造煤、微裂隙煤、微劈理煤、碎裂构造煤和糜棱构造煤。文中详述了各类煤的特点,指出它们所代表的构造意义,并讨论了它们与瓦斯突出的关系。还特别提出糜棱构造煤的一系列塑性变形特征。得出结论:若其他条件均具备,有糜棱构造煤产出的地段,就可能是瓦斯突出最危险的部位。此外,根据观察煤瓦斯突出后的煤岩显微构造变化,提出有关瓦斯突出的过程,并探讨了煤瓦斯突出机理。在瓦斯突出过程中,已经历过塑性变形的煤岩又叠加了脆性变形,因而发生大量煤“粉尘”随突出而抛出。     

地震自相似现象初探

依据破裂过程和震源物理参数相似性,给出了自相似震源椭球体三轴之比约为a:b:c=1:0.2:0.2。基于分维理论和方法,讨论了自相似的地震时空分布的分维和强震前的降维现象。由前兆展布范围,大震前区域地震活动特征以及地震空区等可导出近源前兆(红肿)区线性尺度约为震源区的5倍。