宁芜火山杂岩中标准岩石的研究和意义

宁芜中生代火山杂岩覆盖面积约1200km~2,累计厚度1920m左右,分五组,经筛选得出各组的标准岩石共22块,分别从矿物学特征和岩石化学判据上建立了区分各火山岩组的判别模型。在此基础上,用“标准岩石-阶段成图法”测制的岩性图、相图和组图,能较准确地反映出古火山岩地喷构造特征。     

一种2 m温度误差订正方法在复杂地形区数值预报中的应用

利用模式三维预报变量,结合地面要素预报产品,采用2 m温度三维插值方法进行地形订正,以确保预报与观测三维空间上的一致性,在地形订正基础上,利用历史月均预报误差作为参考误差,剔除模式系统性误差,获取具备日变化特征的预报产品。基于陕西地区复杂地形条件下的典型观测站点,利用2016年8月28日48 h预报个例进行对比分析发现,三维插值方法有效改善了地形差异引起的评估误导问题,但无法改进模式预报的日变化趋势,进一步采用系统性误差订正后,日变化特征明显改善,特别是前24 h预报效果体现出与实况良好的一致性及更佳的预报技巧。通过2016年夏季统计评估表明,误差订正后的2 m温度预报产品有效改善了周期性误差振荡,均方根误差稳定在2 K左右,显示出明显的改进优势。     

Geochronology and geochemistry of the Nantianwan mafic–ultramafic complex,Emeishan large igneous province: metallogenesis of magmatic Ni–Cu sulphide deposits and geodynamic setting

The Nantianwan mafic–ultramafic complex is situated in the northwest part of the Panxi district, southwest China. It consists predominantly of gabbros, gabbronorites, and lherzolites. LA–ICP–MS U–Pb zircon dating of the gabbronorites yields an age of 259.7 ± 0.6 million years, consistent with the ages of other mafic–ultramafic intrusions in the Emeishan large igneous province (ELIP). Gabbronorites and lherzolites host Cu–Ni sulphide ores. Cumulus texture is pronounced in these rocks, containing magnesium-rich olivine (up to 81.4% forsterite). SiO₂ contents of the lherzolites range from 42.93 to 44.18 wt.%, whereas those of the gabbronorites vary between 44.89 and 52.76 wt.%. Analysed samples have low rare earth element (REE) contents (23.22–30.16 ppm for lherzolites and 25.21–61.05 ppm for gabbronorites). Both lherzolites and gabbronorites have similar chondrite-normalized REE patterns, suggesting that they are comagmatic. All samples are slightly enriched in large ion lithophile elements (LILEs, e.g. Rb, Ba, and Sr) relative to high field strength elements (HFSEs, e.g. Nb, Ta, and Ti), very similar to those of ocean island basalts (OIBs). The presence of cumulus textures and geochemical signatures indicates that fractional crystallization played an important role in the petrogenesis of these rocks. Initial (⁸⁷Sr/⁸⁶Sr) _t (t?=?260 Ma) ratios and ?_Nd(t) values of the mafic–ultramafic suite vary from 0.70542 to 0.70763, and??0.4 to 1.7, respectively. Compared to the Cu–Ni-bearing Baimazhai and Limahe intrusions in the ELIP, which were considerably contaminated by variable crustal materials, the Nantianwan complex exhibits much lower (⁸⁷Sr/⁸⁶Sr) _t . Their ?_Nd(t) versus (Th/Nb)_PM ratios also indicate that the ore-bearing magmas did not undergo significant crustal contamination. In combination with (Tb/Yb)_PM versus (Yb/Sm)_PM modelling, we infer that the magmas originated from an incompatible elements-enriched spinel-facies lherzolite that itself formed by interaction between the Emeishan plume and the lithospheric mantle. Most plots of NiO versus Fo contents of olivine suggest that sulphides are separated from the parental magma by liquid immiscibility, which is also supported by bulk-rock Cu/Zr ratios of the lherzolites (7.04–102.67) and gabbronorites (0.88–5.56). We suggest that the gabbronorites and lherzolites experienced undersaturation to oversaturation of sulphur; the latter may be due to fractional crystallization in a high-level magma chamber, accounting for the sulphide segregation.     

新疆乌孙山1号金矿床的发现及其地质特征

新疆乌孙地区１号金矿是在对化探综合异常的查证过程中发现的。是伊什基里克山金、铜成矿带内发现的新类型金矿床。产于华力西中期花岗杂岩体的内外接触带附近的构造破碎带内,是构造蚀变岩型金矿床。矿化严格受断裂构造带和花岗杂岩体的控制。放体具规模较大、连续性良好,产状稳定及贫硫化物特征。     

宁东枣泉煤矿矿井水文地质类型划分探讨

通过对枣泉煤矿矿井水文地质条件、矿井充水因素、矿井涌水量、矿井受水害影响程度及防治水难易程度等方面分析,以实际资料为依据,结合对《煤矿防治水规定》的理解,提出枣泉煤矿矿井水文地质类型为复杂型的结论,从而分析和评价矿井水害危害程度,经济合理地搞好矿井防治水工作提供了基础资料。     

实现复频移完全匹配层吸收边界条件的递推卷积方法

完全匹配层吸收边界（PML）已经被证明是非常有效的边界吸收技术,对体波和面波的吸收都具有非常好的效果,已经被广泛应用于弹性波的数值模拟中。但是在某些情况下传统的PML技术还是存在一定的问题,比如对掠射情况下的体波和窄区域自由表面条件下的面波的吸收等等。在坐标变换中采用复频移拉伸函数的复频移PML可以有效地改善PML边界条件的吸收性能。基于弹性波一阶速度-应力方程,推导了复频移PML的递推卷积实现方法,并采用交错网格高阶有限差分法对其进行了数值模拟,与传统的PML进行了对比。结果表明：传统的PML对掠射情况下的体波和窄区域自由表面条件下的面波吸收不足,会产生虚假反射,影响真实波场;而基于递推卷积的复频移PML算法能够有效地改善困难情况下的吸收效果,并且在实现过程中不用分裂变量,应用更加方便简单。计算卷积时采用递推的形式,推导过程直观易懂,易于编程,而且不会增加计算量,存储量也没有太大的变化。     

赣东北双层复合逆冲推覆构造研究

赣东北多期造山带发育一种双层复合逆冲推覆构造,它是由下部的登山—横峰逆冲断层系和上部的葛源逆冲推覆构造共同构成。地质年代学及运动学研究表明,登山—横峰逆冲断层系形成于加里东期,自南东向北西运移达３０ｋｍ以上,应变速率ε＝２．４×１０－１２／ｓ。葛源逆冲推覆构造则形成于印支期,自北西向南东运移至少５０ｋｍ。     

基于GMS的石羊河流域含水层空间结构变化的可视化研究

石羊河流域作为我国西北内陆河流域之一,由于长期过量开采地下水资源,使地下水位大幅度下降,并引发一系列生态环境问题.在现实环境中,地下水含水层系统是由多个子含水层系统叠加得到的多层结构,并且子含水层系统之间有弱含水层系统或不完整隔水层系统的存在,而作为揭示地层信息的钻孔数据,具有一定的有限性,这直接制约着含水层空间可视化...     

基于洪水预报系统误差反演的多河段联合校正方法

提出一种基于洪水预报误差系统反演的多河段联合校正方法.采用马斯京根法矩阵方程描述多河段多区间入流的河道汇流过程,基于动力系统反演理论建立洪水预报误差的递推方程,最后利用修正后的多河段状态变量经演算得到预报断面的洪水过程,进而达到多河段联合校正目的.对大渡河上游的应用示例结果表明：多河段联合校正方法考虑了河系中断面间的水力联系及预报误差在时程上的传递规律,可充分利用上游多断面实测和校正信息进行下游预报断面的误差修正,因此具有更高的校正精度和稳定性.