福建黄地金-多金属矿床地质特征

黄地金-多金属矿床严格受黄地逆冲推覆断层控制,矿脉(体)赋存于由推覆体构造带上下盘岩石所形成的碎裂岩化、糜棱岩化带中,并且金、铅、锌在空间上具有分段富集的特点.矿石为动力变质多金属硫化物蚀变岩型,主要有自形-半自形、他形粒状,包含、碎裂等结构,块状、浸染状、角砾状等构造.金属矿物主要有黄铁矿、磁黄铁矿、方铅矿、闪锌矿以及银金矿和自然金,非金属矿物主要为石英和绢云母.自然金主要产于黄铁矿的晶洞中,少部分包裹于非金属矿物中.成矿作用可分为岩浆接触交代期、气-水热液矿化期和氧化期,其中气-水热液矿化期的早期石英-硫化物阶段为主成矿阶段,成矿物质主要来源于动力变质作用所形成的深部矿化热液,为沿推覆构造充填交代所形成.     

K–Ar geochronology of the temporal change of eruptive style in the eastern Izu peninsula, central Japan

Abstract   A recent K–Ar study elucidated that eruptive style in the eastern Izu peninsula changed from polygenetic to monogenetic volcano at 0.3–0.2 Ma. To narrow down the time of change, we determined 10 K–Ar ages on Togasayama Andesite of Amagi volcano, the youngest polygenetic volcano in the area, and Togasayama Monogenetic Volcano, one of the oldest monogenetic volcanoes in the area, which overlies a part of the Togasayama Andesite. Dating results showed that the Togasayama Andesite effused at least from 0.34 to 0.20 Ma, whereas the Togasayama Monogenetic Volcano erupted at 0.26–0.29 Ma, suggesting that the northern part of the Togasayama Andesite effused after the eruption of the Togasayama Monogenetic Volcano. Considering previous data, it is therefore inferred that change of eruptive style in the eastern Izu area occurred during the period 0.29–0.20 Ma, with considerable overlap of both polygenetic and monogenetic volcanism.     

中国东部中新生代构造格局和岩浆岩带的形成与演化

在研究印支期秦岭-大别-苏鲁造山带的形成与地幔差速环流的基础上，系统综合了中国东部中新生代的基底构造对断裂构造的控制，深层构造对隆凹与断陷盆地的制约，伸展构造在陆内及陆缘外的表现，岩浆岩带的时空分布及展布特点等规律，依据中国东部中新生代构造格局与岩浆岩带在时空分布上的宽阔性、方向性、迁移性、分带性，特别是深层构造对浅层断裂构造、伸展构造的制约，以及岩浆岩带、隆起与盆地等自西向东迁移特点，提出其形成机制可能与强大地幔东向差速环流有关。     

Genesis of Kanggur Gold Deposit in Eastern Tianshan Orogenic Belt, NW China: Fluid Inclusion and Oxygen and Hydrogen Isotope Constraints

Abstract. Primary fluid inclusions in quartz and carbonates from the Kanggur gold deposit are dominated by aqueous inclusions, with subsidiary CO₂-H₂O inclusions that have a constant range in CO₂ content (10–20 vol %). Microthermometric results indicate that total homogenization temperatures have a wide but similar range for both aqueous inclusions (120 to 310C) and CO₂-H₂O inclusions (140 to 340C). Estimates of fluid salinity for CO₂-H₂O inclusions are quite restricted (5.9∼10.3 equiv. wt% NaCl), whereas aqueous inclusions show much wider salinity ranging from 2.2 to 15.6 equivalent wt %NaCl.
The 6D values of fluid inclusions in carbonates vary from -45 to -61 %, in well accord with the published δD values of fluid inclusions in quartz (-46 to -66 %). Most of the δ¹⁸O and δD values of the ore-forming fluids can be achieved by exchanged meteoric water after isotopic equilibration with wall rock by fluid/rock interaction at a low water/rock ratio. However, the exchanged meteoric water alone cannot explain the full range of δ¹⁸O and δD values, magmatic and/or meta-morphic water should also be involved. The wide salinity in aqueous inclusions may also result from mixing of meteoric water and magmatic and/or metamorphic water.     

Mise en évidence d'un nouveau front de chevauchement dans l'Atlas tunisien oriental de Tunisie par sismique réflexion. Contexte structural régional et rôle du Trias salifère

Structural interpretations of newly acquired seismic lines in northeastern Tunisia allow us to highlight a new thrust front for the Atlasic range of Tunisia, in contrast to the previously Zaghouan fault thrust Dorsale zone. This new thrust front takes place on weakness tectonic zones, materialized by inherited faults anchored on the pre-Triassic basement. This front seems to be a paleogeographic trend controlling structural style and basin fill with a synsedimentary activity. The front is expressed by reverse faults, thrust faults, back thrusting, and decollement structures. To cite this article: S. Khomsi et al., C. R. Geoscience 336 (2004).     

Modelling the spatial and temporal distribution of rainfall: a case study in the wet and dry tropics of North East Australia

Rainfall regimes with strong spatial and temporal variation are characteristic of many coastal regions of north and eastern Australia. In coastal regions of north eastern Australia, regimes vary considerably over short distances. This occurs because of changes in local topography, including the height and orientation of mountain ranges and the direction of the coastline with respect to the prevailing moist south east air stream. Northern Australia experiences a tropical monsoon climate with rainfall occurring predominantly during the summer months. Areas with a closer proximity to the coast typically experience the heavier rainfalls. While networks of rainfall gauges have been established and continuous records are available for most of these stations from the 1890s, their low distribution density relative to the complexity of rainfall pattern they are required to represent means that there remains a poor understanding of the spatial and temporal distribution of rainfall in the wet tropics. An enhanced knowledge of rainfall distribution in both space and time has the potential to deliver significant economic and environmental benefits to managers of natural resources. This paper reports on the application of a technique for estimating mean annual and mean monthly rainfall across the Herbert River catchment of north east Australia's dry and wet tropics. The technique utilises thin plate smoothing splines to incorporate both location and elevation into estimates of rainfall distribution. We demonstrate that the method can be applied successfully at the meso scale and within the domain of routinely available data. As such, the method has broad relevance for decision making.     

REE and (э)Nd of clay fractions in sediments from the eastern Pacific Ocean: Evidence for clay sources

Clay fractions in the non-calcareous surface sediments from the eastern Pacific were analyzed for clay minerals, REE and 143Nd/144Nd. Montmorillonite/illite ratio (M/I ratio), total REE contents ((REE), LREE/HREE ratio and cerium anomaly (бCe) may effectively indicate the genesis of clay minerals. Clay fractions with M/I ratio >1, бCe (0.85, (REE (400 μg/g, LREE/HREE ratio (4, and REE patterns similar to those of pelagic sediments are terrigenous and autogenetic mixed clay fractions and contain more autogenetic montmorillonite. Clay fractions with M/I ratio <1, бCe=0.86 to 1.5, ΣREE=200 to 350 μg/g, LREE/HREE ratio (6 and REE distribution patterns similar to that of China loess are identified as terrigenous clay fraction. The 143Nd/144Nd ratios or (э)Nd values of clay fractions inherit the features of terrigenous sources of clay minerals. Clay fractions are divided into 4 types according to (э)Nd values. Terrigenous clay minerals of type I with the (э)Nd values of -8 to -6 originate mainly from North American fluvial deposits. Those of type II with the (э)Nd values of -9 to -7 are mainly from the East Asia and North American fluvial deposits. Those of type III with (э)Nd values of -6 to -3 could come from the central and eastern Pacific volcanic islands. Those of type IV with (э)Nd values of -13 to -12 may be from East Asia eolian. The terrigenous and autogenetic mixed clay fractions show patchy distributions, indicating that there are volcanic or hot-spot activities in the eastern Pacific plate, while the terrigenous clay fractions cover a large part of the study area, proving that the terrigenous clay minerals are dominant in the eastern Pacific.     

福建沿海土壤地球化学分类及基准值研究

利用多目标区域地球化学调查成果,探讨了福建沿海土壤地球化学分类的方法,提出了分类命名方案和诊断标准,将研究区土壤按SiO₂含量划分为铁铝土、硅铝土、铝硅土、硅土4个大类,其中硅铝土又分为一般硅铝土、铁质硅铝土、钾质硅铝土、硫铁质硅铝土4个亚类,铝硅土分为一般铝硅土和钾质铝硅土2个亚类;提出了在各种统计量中,中值比较客观地反映元素含量背景,适合作为基准值;给出了研究区各类土壤的分布图和52种元素及pH的基准值,分析了其成因和农业利用情况。     

福建省水氡观测资料变化规律与质量分析

本文对福建省水氡观测资料变化规律进行分析,并试图利用相对均方差、拟合噪声水平和相对年变幅等三项指标,对福建省8个水氡点的观测资料质量进行初步探索。