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881.
通过采样过程和模数转换对记录影响的分析,讨论了数字地震仪记录的动态范围,以及如何使用谱分析方法去除仪器对最终记录的影响,以便获取“真实地面运动”的近似。 相似文献
882.
冀东地区长城系高于庄组岩相古地理及黄铁矿生物成因探讨 总被引:5,自引:0,他引:5
冀东地区中元古界长城系高于庄组可划分为7个自然岩性段,硫等赋矿层位为其2~5段,由含锰页岩 含锰白云岩 含锰页岩 含锰白云岩组成二个正旋回。高于庄组沉积早期(即下旋回第2段),在遵化 北汤道河水下高地的阻隔下,形成了蓟县 迁西泻湖,属封闭的还原环境,控制了“蓟县式”锰方硼石矿床。高于庄组沉积晚期(即上旋回第4段和第5段)沉积时期,高板河泻湖形成,由于泻湖南侧受北东东向同生断裂控制,北侧又受生物礁制约,在生物作用及滞流的还原环境下,形成了“高板河式”黄铁(铅锌)矿床。上旋回生物礁相和泻湖相区是寻找黄铁(铅锌)矿的靶区。 相似文献
883.
南沙北部伸展构造的基本特征及其动力学意义 总被引:16,自引:2,他引:14
南沙地块辫啊以中南-美洲断裂为分界,其东、西两侧伸展构造的几何学与运动学表明,晚白垩世至早渐新世,其伸展作用以纯剪切为主;中渐新世至早中新世,伸展带东段转换为简单剪切,西段剪切渐停。伸展作用的主要动力来源于陆缘俯冲板片的拆沉、软流圈地幔热物质乘隙上拱和部分熔融作用及周边板块的相互作用。 相似文献
884.
Mingcai Yan Chunshu Wang Tiexin Gu Qinghua Chi Zhong Zhang 《Geostandards and Geoanalytical Research》1998,22(2):235-246
Unlike the situation for other elements, few reference materials certified for the platinum-group elements are currently available. Therefore, the GPt1-7 series of PGE geochemical CRMs, prepared by the IGGE, represent an important addition and comprise a range of matrix types, including a soil, stream sediment, Mg-rich ultramafic rock, Fe-rich ultramafic rock, platinoid ore depleted in Cu, Ni and Fe, and a chromitite. The concentration of PGE in these samples ranges over 4-5 orders of magnitude and the samples were shown to have good homogeneity as assessed by a variance test. Analytical methods based on different principles were used in sample certification, including several fire assay and wet chemical procedures used for decomposition and preconcentration. Certified values for the elements Pt, Pd, Os, Ru, Ir, Rh and Au were determined by AAS, catalytic colourimetry (COL), catalytic polarography (POL), atomic emission spectrometry (AES), ICP-MS and NAA. Recently, the GPt1-7 samples were approved as national primary CRMs by the State Bureau of Technical Supervision of China. 相似文献
885.
CONCEPTIONSOFHEAVYFLOODSCAUSINGLAND┐SLIDE/SLIDETherearemanydisasters/hazardsoccuringontheearth’ssurface.Theseeventspresenteda... 相似文献
886.
887.
888.
Drop calorimetric measurements of HT-H273 are reported for glassy and liquid albite and potassium tetrasilicate for the temperature interval 600–1500 K. Analysis of these observations as well as data for 13 other stable and supercooled silicate liquids suggests strongly that the isobaric heat capacities of stable and supercooled liquids are equal and thus temperature independent. Available evidence indicates that the isochoric heat capacities of liquid alkali silicates are also temperature independent within present experimental uncertainties. 相似文献
889.
890.
Pierre Schiano Bernard Bourdon Robert Clocchiatti Dominique Massare Maria E. Varela Yan Bottinga 《Earth and Planetary Science Letters》1998,160(3-4):537-550
The study of glass inclusions inside mantle minerals provides direct information about the chemistry of naturally occurring mantle-derived melts and the fine-scale complexity of the melting process responsible for their genesis. Minerals in a spinel lherzolite nodule from Grande Comore island contain glass inclusions which, after homogenization by heating, exhibit a continuous suite of chemical compositions clearly distinct from that of the host basanitic lava. The compositions range from silicic, with nepheline–olivine normative, 64 wt% SiO2 and 11 wt% alkali oxides, to almost basaltic, with quartz normative, 50 wt% SiO2 and 1–2 wt% alkali oxides. Within a single mineral phase, olivine, the inferred primary melt composition varies from 54 to 64 wt% SiO2 for MgO content ranging from 8 to 0.8 wt%. An experimental study of the glass and fluid inclusions indicates that trapped melts represent liquids that are in equilibrium with their host phases at moderate temperature and pressure (T≈1230°C and P≈1.0 Gpa for melts trapped in olivine). Quantitative modelling of the compositional trends defined in the suite shows that all of the glasses are part of a cogenetic set of melts formed by fractional melting of spinel lherzolite, with F varying between 0.2 and 5%. The initial highly silicic, alkali-rich melts preserved in Mg-rich olivine become richer in FeO, MgO, CaO and Cr2O3 and poorer in SiO2, K2O, Na2O, Al2O3 and Cl with increasing melt fractions, evolving toward the basaltic melts found in clinopyroxene. These results confirm the connection between glass inclusions inside mantle minerals and partial mantle melts, and indicate that primary melts with SiO2 >60 wt%, alkali oxides >11%, FeO <1 wt% and MgO <1 wt% are generated during incipient melting of spinel peridotite. The composition of the primary melts is inferred to be dependent on pressure, and to reflect both the speciation of dissolved CO2 and the effect of alkali oxides on the silica activity coefficient in the melt. At pressures around 1 GPa, low-degree melts are characterized by alkali and silica-rich compositions, with a limited effect of dissolved CO2 and a decreased silica activity coefficient caused by the presence of alkali oxides, whereas at higher pressures alkali oxides form complexes with carbonates and, consequently, alkali-rich silica-poor melts will be generated. 相似文献