小尺度网格层析速度建模方法在低幅构造区时深转换中的应用

渤海M油田区浅层多发育低幅构造,低幅构造区的地震数据对常规层析成像不够敏感,导致常规速度反演方法很难保证低幅构造速度建模的准确性,从而给时深转换工作带来较大误差.本文提出一种小尺度网格层析速度建模方法,该方法基于低幅构造的薄层信息,在有薄层信息的地层加密网格分布,从而实现根据地质条件划分网格的策略,进而通过解析矩阵方程实现速度模型的迭代更新.通过实际数据应用证明,对于渤海M油田利用本文提出的高精度网格层析速度建模方法是有效可行的,该方法能够有效提高低幅构造区速度建模的精度,利用该方法得到的速度模型能够大幅提高时深转换的精度,从而指导构造解释及成图工作.     

滇东北下寒武统黑色岩系钼、镍矿床特征及找矿前景

滇东北地区钼镍多金属矿床主要产于下寒武统筇竹寺组黑色页岩、黑色粉砂岩地层中,矿体与围岩界线明显,呈似层状、层状产出,为层控矿床。矿体厚度薄、品位高,但往深部有变富、变厚的趋势.     

Subsurface thermal and hydrothermal characterization based on geothermal resources map, drill hole thermal gradients, Curie point depths and hypocenter distribution — Examples of Tohoku district, Japan

Subsurface thermal structure in Tohoku district are characterized by existing data such as geothermal resources maps, drill hole thermal gradients, Curie point depths and hypocenters distribution maps. The collected data are registered in a database system, then, compared in plan view, cross-section and bird's-eye pictures. The comparison indicates that subsurface temperatures extrapolated from drill hole thermal gradients are generally concordant to the Curie point depth, assumed to be 650 °C. Tohoku district is generally divided into 5 type areas; fore arc lowland, fore arc mountain country, Quaternary volcanic terrain, back arc lowland and back arc mountain country. The surface thermal manifestations in Quaternary volcanic terrain are mainly controlled by the magma chambers as heat sources, while, surface thermal features such as hot springs in non-volcanic areas are controlled by degrees of heat flows, and hydrothermal flows in permeable Cenozoic formations and along permeable fault zones.     

Metamorphic petrology and zircon geochronology of high-grade rocks from the central Mozambique Belt of Tanzania: crustal recycling of Archean and Palaeoproterozoic material during the Pan-African orogeny

New data on the metamorphic petrology and zircon geochronology of high‐grade rocks in the central Mozambique Belt (MB) of Tanzania show that this part of the orogen consists of Archean and Palaeoproterozoic material that was structurally reworked during the Pan‐African event. The metamorphic rocks are characterized by a clockwise P–T path, followed by strong decompression, and the time of peak granulite facies metamorphism is similar to other granulite terranes in Tanzania. The predominant rock types are mafic to intermediate granulites, migmatites, granitoid orthogneisses and kyanite/sillimanite‐bearing metapelites. The meta‐granitoid rocks are of calc‐alkaline composition, range in age from late Archean to Neoproterozoic, and their protoliths were probably derived from magmatic arcs during collisional processes. Mafic to intermediate granulites consist of the mineral assemblage garnet–clinopyroxene–plagioclase–quartz–biotite–amphibole ± K‐feldspar ± orthopyroxene ± oxides. Metapelites are composed of garnet‐biotite‐plagioclase ± K‐feldspar ± kyanite/sillimanite ± oxides. Estimated values for peak granulite facies metamorphism are 12–13 kbar and 750–800 °C. Pressures of 5–8 kbar and temperatures of 550–700 °C characterize subsequent retrogression to amphibolite facies conditions. Evidence for a clockwise P–T path is provided by late growth of sillimanite after kyanite in metapelites. Zircon ages indicate that most of the central part of the MB in Tanzania consists of reworked ancient crust as shown by Archean (c. 2970–2500 Ma) and Palaeoproterozoic (c. 2124–1837 Ma) protolith ages. Metamorphic zircon from metapelites and granitoid orthogneisses yielded ages of c. 640 Ma which are considered to date peak regional granulite facies metamorphism during the Pan‐African orogenic event. However, the available zircon ages for the entire MB in East Africa and Madagascar also document that peak metamorphic conditions were reached at different times in different places. Large parts of the MB in central Tanzania consist of Archean and Palaeoproterozoic material that was reworked during the Pan‐African event and that may have been part of the Tanzania Craton and Usagaran domain farther to the west.     

白银厂黄铁矿型铜、多金属矿床综合勘查模型

在综合以往大量资料的基础上，补做钻孔原生晕、物性和物化探综合剖面工作，经理论模型正演，归纳概括出白银厂黄铁矿型铜、多金属矿床、矿田地质—地球物理—地球化学综合勘查模型，并对矿床、矿田按剥蚀程度不同分别提出预测标志。     

云县邦撒铁锰矿矿床成因探讨

铁锰矿产于新糖房背斜西翼南延澜沧江群中上部绢云石英片岩地层中,似层状、透镜状、囊状产出,矿床成因为沉积、变质铁锰矿床,其富集与表生氧化作用关系密切。     

Polymetallic (Pb-Zn-Cu-Ag ± Au) vein-type deposits in brittle-ductile transtensional shear zones,Eastern Sierras Pampeanas (Argentina): Age constraints and significance for the Late Paleozoic tectonic evolution and metallogenesis

This paper discusses new structural, kinematic and geochronological data from polymetallic (Pb-Zn-Cu-Ag ± Au) vein-type deposits hosted in the metamorphic basement of the southern Sierras de Córdoba. A Carboniferous age was established for the hydrothermal event between ∼329 and 315 Ma (Late Mississippian-Early Pennsylvanian) by the K/Ar fine-fraction dating method of sericitic alteration related to metallic ore deposition in the Las Guindas and Oro districts. The obtained ages postdate the spatially associated Devonian magmatism and overlap the A-type Early Carboniferous magmatism defined for the Eastern Sierras Pampeanas. The presence of non-exhumed granitic bodies at shallow depths, possibly related to mineralization, is supported by available geophysical and field evidence.The strain fabric and 3-D kinematic analyses constitute first kinematic data for the Carboniferous basement of the Southern Sierras Pampeanas demonstrating that mineralization was controlled by NNW- and ENE-trending brittle-ductile transtensional shear zones that overprint the earlier high-strain deformation fabrics of the basement. Transtensional deformation has accommodated large amounts of strike-slip movements and subordinated extensional components. The calculated kinematic axes indicate a coherent kinematic pattern of the mineralized systems in the two studied districts, with a maximum extension direction oriented NNE- to NE and maximum shortening direction oriented WNW- to NW. This deformation regime, active during mineralization, point to a non-compressive setting at the Late Mississippian-Early Pennsylvanian boundary. In line with other regional evidence, we propose a distinctive Carboniferous deformational phase in the Eastern Sierras Pampeanas, dominated by transtension. This period would have occurred after the transition with the Devonian compressional/transpressional orogenic regime.     

富宁微细浸染型金矿及远景

富宁金矿地处著名的滇黔桂“金三角”成矿带上,金矿资源远景与地层、构造、岩浆岩建造有显著内在联系,地球物理、化学性质有着突出表现特征,金矿床在规模、数量和资源量上都有极大潜力。     

北秦岭瓦穴子—乔端断裂带的构造特征及形成温度—压力条件探讨

瓦乔(瓦穴子—乔端)断裂带是北秦岭尤为重要的断裂带之一,该带经历了长期的变质变形作用,记录了二郎坪弧后盆地向华北板块南缘俯冲消亡的信息。本文运用多种方法,对瓦乔断裂带几何学、运动学及形成温压条件进行研究和探讨,得出以下几点认识:①瓦乔断裂带产状基本倾向NNE,带内线理发育,表现为由N向S逆冲的运动学特征,且存在左旋剪切的分量;②瓦乔断裂带变形岩石显微构造特征明显,反映了挤压应力下塑性流变的特征;③运用角闪石全铝压力计,得到瓦乔断裂带形成压力为0.64GPa。越靠近瓦乔断裂带中心,压力逐渐变大,位于断裂带中心压力达到0.68GPa,已达到中压相系环境;④运用角闪石—斜长石地质温压计算得瓦乔断裂带形成温度范围500～550℃,属中温环境。     

An infrared and <Superscript>1</Superscript>H MAS NMR investigation of strong hydrogen bonding in ussingite,Na<Subscript>2</Subscript>AlSi<Subscript>3</Subscript>O<Subscript>8</Subscript>(OH)

The mineral ussingite, Na₂AlSi₃O₈(OH), an interrupted tectosilicate, has strong hydrogen bonding between OH and the other nonbridging oxygen atom in the structure. Infrared spectra contain a strongly polarized, very broad OH-stretching band with an ill-defined maximum between 1500 and 1800 cm^–1, and a possible OH librational bending mode at 1295 cm^–1. The IR spectra confirm the orientation of the OH vector within the triclinic unit cell as determined from X-ray refinement (Rossi et al. 1974). There are three distinct bands in the ¹H NMR spectrum of ussingite: a predominant band at 13.5 ppm (TMS) representing 90% of the structural hydrogen, a second band at 15.9 ppm corresponding to 8% of the protons, and a third band at 11.0 ppm accounting for the remaining 2% of structural hydrogen. From the correlation between hydrogen bond length and ¹H NMR chemical shift (Sternberg and Brunner 1994), the predominant hydrogen bond length (H...O) was calculated to be 1.49 Å, in comparison to the hydrogen bond length determined from X-ray refinement (1.54 Å). The population of protons at 15.9 ppm is consistent with 5–8% Al–Si disorder. Although the ussingite crystal structure and composition are similar to those of low albite, the bonding environment of OH in low albite and other feldspars, as characterized through IR and ¹H NMR, is fundamentally different from the strong hydrogen bonding found in ussingite.