山东枣庄杨家堡子铁矿床地质特征及成因探讨

杨家堡子铁矿位于山东省枣庄市峄城区峨山镇,隶属苍峄铁成矿带,矿体赋存于新太古代泰山岩群山草峪组上部的变质岩中。该矿床内圈定磁铁矿体11个,求得铁矿石(333)资源量3 378.2万t,矿床平均品位TFe 33.30%,mFe 22.64%。主矿体为Ⅲ-6矿体,占矿床总资源量的83.69%,其长度1 137 m,最大斜深1 065 m,埋深707~1 369m,形态复杂程度中等,品位变化属均匀类型。含矿岩石为磁铁石英角闪岩。矿石中的主要有用组分为Fe,伴生元素含量较低,均无综合回收利用价值,有害组分S、P的含量均较低,经选矿后可达到炼钢及炼铁要求。矿石结构主要有粒状变晶结构和柱状变晶结构;矿石的构造主要为条带状构造,块状构造的矿石较少,但品位相对较高。矿石自然类型为原生磁铁矿石,工业类型属需选磁性铁矿石。该矿床成因与苍峄铁矿一脉相承,为典型的BIF型铁矿。根据区内以及邻区的见矿情况结合磁异常特征分析,杨家堡子矿区有良好的找矿前景。     

Dating for Jifanggou metamorphic complex in central Jilin and its tectonic implications

Based on the results of four regional geological surveys of 1: 50000 including Shulan County map in Jilin,taking Shulan area as the study area,the authors re-delineated the rock type assemblages,e.g. metamorphic rhyolite,metamorphic tuffaceous breccia lava,sericite-quartz schist and tremolite altered rock,etc.,and the structural contacts between them. With the help of in-situ LA-ICP-MS U-Pb dating for zircons,it is concluded that the zircon crystallization ages of the metamorphic rhyolite,the metamorphic andesitic tuff breccia lava and the tremolite altered rock are 339. 1 ± 1. 3 Ma( n = 27,MSWD = 0. 78),351. 8 ± 1. 7 Ma( n = 21,MSWD = 0.82),and 362.0±1.8 Ma( n = 43,MSWD = 2.2) respectively. The metamorphic complex is actually a set of tectonic melange which comprises the rocks in different types,sources,times,or tectonic settings,and was formed by tectonism.     

沂水县杏山官庄铁矿地质特征

在汞丹山凸起中分布的基性—超基性岩体,其磁铁矿含量高者可构成矿体。利用高精度磁测、钻探等方法开展了沂水县杏山官庄铁矿的普查工作,大致查明了该矿体的规模、形态和产状,认为该矿床具有低品位、工程地质条件简单的特点,综合分析矿床成因属岩浆分异型磁铁矿矿床。     

京九铁路江淮段降水型路基坍塌的地质、降水条件分析

京九铁路是新开辟的连接北京和香港九龙的南北大动脉,1996年9月正式通车。其中江淮段指淮河与长江之间的 306.1 km区段,自河南淮滨站至湖北蕲春站。由于沿线地形复杂,降水强度大,路基坍塌成为安全运行的主要危害。据统计,1997－2007年间,发生各种坍塌灾害455次,毁坏路段总长约53 000 m。运用京九铁路江淮段地质资料、1997－2007年 11 a间所发生的路基坍塌资料和铁路沿线10个气象站雨量实况资料,对京九铁路江淮段地质地岩状况进行了分类,分级处理了不同地质条件下路基坍塌的发生频次和强度,详细分析了路基坍塌发生前24～72 h雨量,得到诱发京九铁路江淮段路基坍塌灾害的地质条件和降水阀值,并对各种不同地质条件下发生路基坍塌的降水阀值及其超过阀值后灾害次数上升情况进行评述,绘制出京九铁路江淮段路基坍塌易发程度等级分区图,提出了相应的处治方法和系统图。可见不利地质条件与强降水共同作用是导致某些路段路基集中坍塌的根本原因。     

东疆地区某氧化铜矿选矿试验研究

对新疆东疆地区某氧化铜矿石进行选别试验,确定该氧化铜矿选别流程为一粗二扫一精：选别的最佳条件为：磨矿细度90％;粗选硫化钠用量2500g／t;BX与丁胺黑药组合使用做捕收剂,用量分别为3500g／t和850g／t;2#油用量106g／t.铜精矿品位25．76％,回收率73.51％.     

黄土高边坡稳定性影响因素分析 ——以宝鸡峡引水工程为例

黄土高边坡稳定性受多种因素影响,对高边坡稳定性影响因素进行敏感性分析非常必要。通过建立合理的计算模型,采用灰色关联度法,对影响宝鸡峡引水工程黄土高边坡稳定性的主要因素进行了分析。结果表明,土体的内摩擦角和黏聚力对其稳定性影响最大;采用正交实验分析可知,除土体的内摩擦角、黏聚力和坡高外,地震作用对黄土高边坡稳定性的影响也较大。以上分析表明,抗剪强度指标是影响黄土高边坡稳定的主要敏感性因素,提出了在黄土高边坡稳定性分析时应尽量使抗剪强度指标的选取准确、合理,同时也应考虑边坡高度和地震的影响,进而为黄土高边坡类的工程设计和运行管理提供重要参考。     

河北灵寿县变质岩区大理岩系赋水规律分析

河北灵寿县山丘区是太行山前典型的严重缺水地区。在该区广泛分布的片岩、片麻岩等变质岩的富水性一般较差。对变质岩区大理岩系地下水赋存规律的分析可以更好地指导和帮助当地群众解决长期面临的缺水问题。分析结果表明:该区主要存在三种大理岩含水岩组类型和两种蓄水构造类型;地下水水化学类型为Ca-HCO3型水,水质符合国家饮用水标准。     

超基性岩红土风化壳中镍的表生富集规律及矿化结构研究 ——以印尼苏拉威西岛Kolonodale矿区为例

文章选取印尼苏拉威西岛Kolonodale红土型镍矿区为研究区,对201个浅井剖面共采取3 161件风化壳样品,进行了w(Ni)值的测试,以揭示超基性岩红土风化壳中Ni的表生富集规律及矿化结构特征。研究结果表明,在平面上,矿区内风化壳的w(Ni)平均值的高低与地形地貌关系密切。斜坡带、坡脚堆积带的风化壳为含镍高值区,其w(Ni)值为0.8%~1.8%;山顶平台区、山脊的风化壳为含镍低值区,其w(Ni)值为0.7%~1.4%。在垂向上,风化产物的w(Ni)值的高低与取样深度及样品属性密切相关。w(Ni)值随着红土带→腐岩带→基岩带的变化出现低值(0.85%~1.55%)→高值(1.15%~4.75%)→低值(≤0.55%)的波动变化规律。矿层的产状(分布、深度、厚度)与风化壳产状之间表现出明显的正相关关系。矿区内的低品位矿层〔1.5%≤w(Ni)≤2.0%〕和高品位矿层〔w(Ni)≥2.0%〕单独或组合发育,产出"正常型双层矿化"、"倒置型双层矿化"、"低品位单层矿化"、"高品位单层矿化"和"叠层矿化"等5种矿化结构类型。综合分析认为,富镁及中等程度蛇纹石化的超基性岩母岩、热带雨林气候环境是矿区内发育富镍红土风化壳的首要条件。吸附、离子交换以及次生沉淀等3种成矿作用的共同发育,导致了红土风化壳中Ni表生矿化的连续性、矿石类型的多样性及特高品位矿石的形成。矿床中矿化结构类型的多样化是区域构造背景、地形地貌、构造发育、水文条件等诸多因素耦合作用的结果。文章指出,在今后的红土型镍矿床的找矿勘查过程中,需要综合考虑各类内、外生控矿因素对矿床发育的影响,总结矿区尺度的矿化结构规律,可有效地指导矿床勘查工作。     

Origin and geodynamic environments of the metamorphic sole rocks from the İzmir–Ankara–Erzincan suture zone (Tokat,northern Turkey)

ABSTRACT

The Late Cretaceous accretionary complex of the ?zmir–Ankara–Erzincan suture zone, near Artova, is composed mainly of peridotites (variably serpentinized), amphibolite, garnet-micaschist, calc-schist, marble, basalt, sandstones, neritic limestones. The metamorphic rocks were interpreted as the metamorphic sole rocks occurring at the base of mantle tectonites, because: (i) amphibolites were observed together with the serpentinized peridotites suggesting their occurrences in the oceanic environment; (ii) foliation in amphibolites and serpentinized peridotites run subparallel to each other; (iii) all these metamorphic rocks and serpentinized peridotites are cross-cut by the unmetamorphosed dolerite dikes with island arc tholeiite-like chemistry. Geochemical characteristics of the amphibolites display enriched mid-ocean ridge basalt (E-MORB)- and ocean island basalt (OIB)-like signatures. The dolerite dikes, on the other hand, yield an island arc tholeiite-like composition. Geothermobarometric investigations of the metamorphic sole rocks suggest that the metamorphic temperature was ~650 ± 30°C and the pressure condition was less than 0.5 GPa. Dating of hornblende grains from amphibolite yielded age values ranging from 139 ± 11 to 157 ± 3.6 Ma (2σ). The oldest weighted average age value is regarded as approximating the timing of the intra-oceanic subduction. These cooling ages were interpreted to be the intra-oceanic subduction/thrusting time of the ?zmir–Ankara–Erzincan oceanic domain.     

Structural and geochronological relationships of metamorphic soles of eastern Mediterrranean ophiolites to surrounding units: indicators of intra‐oceanic subduction and emplacement

This paper is a synthesis of structural and geochronological data from eastern Mediterranean ophiolitic metamorphic rocks and surrounding units to interpret the intra‐oceanic subduction and ophiolite emplacement mechanism.

Metamorphic rocks occur as discontinuous tectonic slices at the base of the ophiolites, generally between the peridotite tectonites and volcanic‐sedimentary units, and locally in fault zones in the overlying peridotites. They consist essentially of amphibolite, and in lesser quantities, micaschist, quartzite, epidotite and marble.

Geological and geochronological data indicate that recrystallization of the metamorphic rocks occurred in the oceanic environment. The contact between the metamorphic rocks and the hanging‐wall is parallel to the foliation of the metamorphic rocks, and is interpreted as the fossil plane of intra‐oceanic subduction. Structural relationships suggest that intra‐oceanic subduction was situated between two lithospheric blocks separated by an oceanic fracture zone. Therefore the Neotethyan ophiolites with metamorphic soles represent the remnants of the overriding oceanic lithosphere's training slices of the metamorphic rocks at the base.

In the Anatolian region, radiometric dating of metamorphic rocks from the Taurus and Izmir‐Ankara‐Erzincan zone ophiolites yield nearly identical ages. Besides, palaeontological and structural data indicate coeval opening and similar oceanic ridge orientation. Consequently it is highly probable that Taurus and Izmir‐Ankara‐Erzincan zone ophiolites represent fragments of the same oceanic lithosphere derived from a single spreading zone. Palaeontological data from underlying volcanic and sedimentary units point out that the opening of the Neotethyan ocean occurred during Late Permian‐Middle Triassic time in the Iranian‐Oman region, during Middle Triassic in Dinaro‐Hellenic area, and finally during Late Triassic in the Anatolian region.

Radiometric dating of the metamorphic rocks exhibit that the intra‐oceanic thrusting occurred during late Lower‐early Late Jurassic for Dinaro‐Hellenic ophiolites, late Lower‐early Late Cretaceous for Anatolian, Iranian and Oman ophiolites well before their obduction on the Gondwanian continent. Neotethyan ophiolites were obducted onto various sections of the Gondwanian continent from late Upper Jurassic to Palaeocene time, Dinaro‐Hellenic ophiolites during late Upper Jurassic‐early Lower Cretaceous onto the Adriatic promontory, Anatolian, Iranian and Oman ophiolites from late Lower Cretaceous to Palaeocene onto the Aegean, Anatolian and Arabic promontories.