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81.
82.
由于地质过程的复杂性及成矿过程的多期次叠加性,原始重磁异常往往是多种地质因素的混合信息,既包含区域背景异常信息,也包含与矿床(体)、矿化蚀变带以及隐伏岩体等与找矿密切相关的地质要素所引起的局部重磁异常.如何从复杂的叠加重磁异常中分离出具有找矿意义的局部异常,是当前矿产勘查和资源潜力评价工作中面临的难题之一.采用经验模态分解(EMD)方法来分解重磁异常,为提高分解的稳健性提出了用双调和样条插值(BSI)进行包罗面插值的新方法,并以云南个旧地区重磁数据为例,对其进行非线性多尺度分解,实现对区域异常与局部重磁异常的分离,揭示了深层次找矿信息并拓宽了经验模态分解方法的应用领域. 相似文献
83.
84.
辽西建昌碱性粗面岩的年代学及岩石成因研究 总被引:1,自引:0,他引:1
义县组火山岩在辽话分布广泛,研究区碱性粗面岩位于建昌地区义县组火山岩的顶部,详细的年代学及地球化学研究表明,锆石u—Pb年龄为(120.3±1.5)Ma,具有较高的SiO2:和碱含量,ω(SiO2)=63.52%~65.94%,ω(Na20+K2O)=9.63%一10.15%,ω(Na20)/ω(K20)为0.96~1.08,属于高钾碱性岩系列,同时具有较低的ω(MgO)(0.75%~1.05%),稀土配分模式为轻稀土富集,重稀土亏损的右倾型模式(La/Yb)n=8.96~12.02),较弱的正Eu异常(δEu=1.07—1.16),相容元素Cr(1.46×10^6~4.15X10^6)、c0(19.8X10^6。~45.9X10^6)和Ni(0.100x10^6~1.55×10^6)含量低。微量元素蛛网图显示明显的Ba和Pb正异常,以及Sr、Ti和Y负异常,此外,zr和Hf显示一定的正异常。认为碱性岩形成于拉张的构造环境,且来源深度较大,是壳幔相互作用的结果,研究区火山岩是经过强烈橄榄石、斜方辉石和单斜辉石结晶分异的富集地幔岩浆上升底侵至下地壳,并经历同化混染和部分熔融,然后沿着深大断裂喷发至地表。 相似文献
85.
为了研究黏土体积变形的微观结构变化特征,选取上海第4层淤泥质黏土为研究对象,分别采用各向等压和K0压缩两种方法制备体积变化率相同的土样,经冷冻真空干燥后对土样进行压汞试验并测定土中孔隙大小分布状况。压汞试验结果表明:试验黏土中孔隙可分为大孔隙、中孔隙、小孔隙和微孔隙,小孔隙占据土中孔隙的大部分空间,且其变化能够反映微观结构的主要特性;在各向等压应力状态下,随着压应力增高、体积压缩量增大,黏土颗粒发生空间平移使颗粒间变得更为紧密,孔隙分布曲线变化以孔隙波峰往孔隙变小方向偏移为主要特征,孔隙尺寸变小而孔隙形态基本不变;在K0压缩应力状态下,随着压应力增高,黏土颗粒发生旋转使孔隙变得扁平,表现为孔隙波峰位置基本不发生偏移,而以峰值降低为主要特征,孔隙结构形态明显改变 相似文献
86.
辽宁猫岭金矿床地质特征及成因探讨 总被引:1,自引:0,他引:1
本文将猫岭金矿床划分为沉积变质、变质热液和交代重熔岩浆热液三个成矿期。由硫、氢、氧同位素,稀土元素特征及包裹体成分研究结果表明变质热液期为主成矿期,主要成矿物质来自围岩,矿床属变质热液成因。 相似文献
87.
Alessandro Amorosi Luigi Bruno Bruno Campo Bianca Costagli Wan Hong Vincenzo Picotti Stefano Claudio Vaiani 《Sedimentology》2021,68(1):402-424
Despite increased application of subsurface datasets below the limits of seismic resolution, reconstructing near‐surface deformation of shallow key stratigraphic markers beneath modern alluvial and coastal plains through sediment core analysis has received little attention. Highly resolved stratigraphy of Upper Pleistocene to Holocene (Marine Isotope Stage 5e to Marine Isotope Stage 1) alluvial, deltaic and coastal depositional systems across the southern Po Plain, down to 150 m depth, provides an unambiguous documentation on the deformation of previously flat‐lying strata that goes back in time beyond the limits of morphological, historical and palaeoseismic records. Five prominent key horizons, accurately selected on the basis of their sedimentological characteristics and typified for their fossil content, were used as highly effective stratigraphic markers (M1 to M5) that can be tracked for tens of kilometres across the basin. A facies‐controlled approach tied to a robust chronology (102 radiocarbon dates) reveals considerable deformation of laterally extensive nearshore (M1), continental (M2 and M3) and lagoon (M4 and M5) marker beds originally deposited in a horizontal position (M1, M4 and M5). The areas where antiformal geometries are best observed are remarkably coincident with the axes of buried ramp anticlines, across which new seismic images reveal substantially warped stratal geometries of Lower Pleistocene strata. The striking spatial coincidence of fold crests with the epicentres of historic and instrumental seismicity suggests that deformation of marker beds M1 to M5 might reflect, in part at least, syntectonically generated relief and, thus, active tectonism. Precise identification and lateral tracing of chronologically constrained stratigraphic markers in the 14C time window through combined sedimentological and palaeoecological data may delineate late Quaternary subsurface stratigraphic architecture at an unprecedented level of detail, outlining cryptic stratal geometries at the sub‐seismic scale. This approach is highly reproducible in tectonically active Quaternary depositional systems and can help to assess patterns of active deformation in the subsurface of modern alluvial and coastal plains worldwide. 相似文献
88.
随着预应力锚索在湿陷性黄土边坡加固工程中的广泛应用,其耐久性问题就变得日益突出,湿陷性黄土边坡预应力锚索出现了较多因预应力损失而引起的失效事故。基于湿陷性黄土边坡预应力锚索运行现状进行研究,研究表明:黄土腐蚀性对边坡预应力锚索耐久性影响微弱,黄土湿陷性和地质条件变化对边坡预应力锚索耐久性影响显著;通过采用加强排水措施、提升浅部注浆工艺和注重运行维护等措施可以改善湿陷性黄土边坡预应力锚索耐久性;改善后的预应力锚索在监测期内处于平稳波动的服役状态,运行效果良好。本研究以期为湿陷性黄土边坡预应力锚索的设计、施工和运行维护等提供借鉴。 相似文献
89.
高围压下冻土强度弱化的机理分析 总被引:2,自引:5,他引:2
围压作用下,影响冻结砂土强度弱化的主要原因是孔隙冰的压融,矿物颗粒细化的微裂隙的发育。影响冻结粉质粘土强度弱化的主要原因是孔隙冰的压融和微裂隙的发育,这些过程是不独立存在的,而是共同影响,共同作用,从而导致了冻土强度的弱化。 相似文献
90.
Hong LuPaul Greenwood Tengshui ChenJinzhong Liu Ping’an Peng 《Organic Geochemistry》2011,42(6):700-706
The mechanism of thermochemical sulfate reduction (TSR) was investigated by separately heating n-C24 with three different sulfates (CaSO4, Na2SO4, MgSO4) in sealed gold tubes at 420 °C and measuring the stable carbon isotope values of hydrocarbon (C1-C5) and non-hydrocarbon (CO2) products. Extensive TSR was observed with the MgSO4 reactant as reflected by increasing concentrations of H2S, 13C depleted CO2 and relatively low concentrations of H2 (compared to the control). H2S yields were already very high at the first monitoring time (12 h) when the temperature had just reached 420 °C, suggesting that TSR had commenced well prior to this temperature. Only trace amounts of n-C24 and secondary C3-C5 alkanes were detected at 12 h, reflecting the efficient TSR utilization of the reactant and lower molecular weight alkane products. Ethane levels were still relatively high at 12 h, but declined thereafter as it was subject to TSR in the absence of higher molecular weight alkanes which had already been utilized. Methane yields were consistently high throughout the 48 h MgSO4 treatment. The temporal decrease in the concentrations of alkanes available for TSR may also contribute to the sharp enhancement of CO2 after 36 h. Absence or dampening of the molecular and isotopic trends of MgSO4 TSR was observed with Na2SO4 and CaSO4 respectively, directly reflecting the levels of TSR reached using these sulfate treatments.For all treatments, the δ13C values of C1-5n-alkanes showed an increase with both molecular weight and treatment time. MgSO4 TSR led to a 5-10‰ increase in the δ13C values of the C1-C5 hydrocarbons and a 20‰ decrease in the δ13C value of CO2. The significant 13C depletion of the CO2 may be due to co-production of 13C enriched MgCO3, although this remains unproven as the δ13C of MgCO3 was not measured. The difference in the δ13C values of ethane and propane (Δδ13CEP) increased in magnitude with the degree of TSR, and this trend could be used to help evaluate the occurrence and extent of TSR in subsurface gas reservoirs. 相似文献