中国西北地区岩浆铜镍矿床地质特点与找矿潜力

西北地区是中国岩浆铜镍硫化物矿床最为发育的地区,主要有3个重要成矿期,其地质特点、成矿条件、形成标志等存在明显不同.笔者梳理了 目前诸多学者对岩浆铜镍硫化物矿床的研究工作,并结合野外实际,发现大陆裂谷是形成巨型-超大型岩浆铜镍硫化物矿床的构造背景条件,铁质系列的镁铁-超镁铁质岩体才可能形成有经济价值的岩浆铜镍硫化物矿体...     

Flood risk assessment in Quzhou City (China) using a coupled hydrodynamic model and fuzzy comprehensive evaluation (FCE)

Natural Hazards - To evaluate urban flood risk while considering spatial and temporal characteristics, this paper establishes an assessment method based on a coupled hydrodynamic model and a fuzzy...     

Geology, Geochemistry and Minerogenesis of the Shijuligou Zinc–Copper Deposit in Gansu, China

Abstract: The Shijuligou deposit was separated by an arcuate ductile shear zone cross the center of the deposit region, resulting in the difference between the southern and northern ore bodies. The lead (Pb) isotopic data of ores of the Shijuligou copper deposit have averages of 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb in 17.634, 15.444, and 37.312, respectively. It has been shown that ore-forming metals originated from intrusive and extrusive rocks in the upper part of ophiolites. The sulfur isotopic data of pyrite and chalcopyrite in the northern part change from +7.61‰ to +8.09‰ and +4.95‰ to +8.88‰ in the southern part. Isotopes of δ18O in the Shijuligou copper deposit are between +11.1‰ and +18.6‰, with the calculated δ18OH2O at +0.65‰. It is suggested that the mineralized fluid is a mixture of magma fluid, meteorological water, and seawater through circulating and leaching metals from the volcanic rocks. The zircon uranium-lead (U–Pb) dating of gabbro is 457.9±1.2 Ma, and the lower crossing age of the discordant and concordia curves of pyroxene spilite of zircon is 454±15 Ma. It is indicated that the Shijuligou deposit formed in a new ocean crust (ophiolite) of the back-arc basin in the late Ordovician. Mineralization should occur in the intermittence period after strong volcanic activity, and the age should be the late Ordovician. Moreover, the mineralization of ophiolite-hosted massive sulfide deposits in the ancient orogenic belt of the late Ordovician in the northern Qilian Mountains was controlled by the primary fault/fracture, with the forming of a metallogenic hydrothermal system by a mixture of volcanic magma fluid and seawater, which circularly leached the metallogenic metals from the volcanic rocks, resulting in their accumulation. The ore bodies were transformed with morphology and metallogenic elements. Jasperoid is an important sign for prospecting such deposits. There were many island arcs in the continent of China. This study provides evidence for understanding and exploration of ophiolite-hosted massive sulfide deposits in western China, especially in the area of northern Qilian Mountains.     

Simulating and understanding effects of water level fluctuations on thermal regimes in Miyun Reservoir

ABSTRACT

Water temperature dynamics in a reservoir are affected by its bathymetry, climatic conditions and hydrological processes. Miyun Reservoir in China is a large and deep reservoir that experienced a large water level decline in 1999–2004 due to low rainfall and relatively high water supply to Beijing. To study changes of stratification characteristics in Miyun Reservoir from 1998 to 2011, the one-dimensional year-round lake model MINLAKE2010 was modified by adding a new selective withdraw module and a reservoir hydrological model. Simulation results under three scenarios demonstrated that the new MINLAKE2012 model accurately predicted daily water levels and temperature dynamics during the water level fluctuation period. The water level decline led to 7.6 and 3.8°C increases in the maximum and mean bottom temperatures and about 29 days reduction in the stratification days. These simulation results provide an insight into the thermal evolution of Miyun Reservoir during the planned future water filling process.

Editor D. Koutsoyiannis Associate editor M. Acreman     

昆仑古特提斯构造转换与镍钴锰锂关键矿产成矿作用研究

【研究目的】 特提斯构造域研究愈来愈显示为原特提斯、古特提斯和新特提斯三分的特点,其中古特提斯洋的形成演化及其成矿作用的研究较为薄弱。【研究方法】 本文根据东昆仑夏日哈木早泥盆世超大型镍钴硫化物矿床、帕米尔玛尔坎苏晚石炭世大型火山源沉积型富锰矿和西昆仑大红柳滩晚三叠世大型伟晶岩型锂铍矿床发现事实,将它们成矿的构造地质背景演化作为主线关联起来研究,提出它们分别代表了古特提斯裂解、大洋扩张和闭合后碰撞构造转换结果的认识。【研究结果】 认为与古亚洲洋同期的原特提斯洋于志留纪末碰撞闭合后,在冈瓦纳大陆北缘由于地幔柱作用改造的软流圈发生部分熔融而裂解,形成了以夏日哈木与裂解背景幔源镁铁—超镁铁岩有关的超大型岩浆镍钴硫化物矿床;随着进一步扩张,在早石炭世形成了古特提斯成熟大洋,由于大洋中脊喷发提供的成矿物质,在晚石炭纪随着大洋快速扩张向消减的转换,洋底碳酸盐岩沉积中形成了玛尔坎苏大型富菱锰矿矿床;古特提斯洋闭合后于中三叠世进入碰撞造山阶段,于晚三叠世后碰撞阶段地壳重熔形成的S型花岗岩高温热液流体,并造就了大红柳滩大型伟晶岩型锂铍矿床。早晚古生代之交是古特提斯洋裂解的开始,此时秦祁昆洋为代表的原特提斯主洋已经闭合,作为原特提斯洋弧后盆地的古亚洲洋尽管尚未闭合,但夏日哈木镍钴矿床则是原特提斯造山后陆壳再次裂解的产物,并非形成于原特提斯洋岛弧或后碰撞的环境;锰是亲石元素,岩浆作用中不富集,而在外生沉积作用中富集,说明古特提斯早石炭世新生洋壳是富锰的,淋滤出的锰离子在晚石炭世相对宁静洋底深处碱性环境中形成沉积型碳酸锰矿,代表了较为强烈的岩浆作用阶段向相对宁静的沉积环境的转换;大红柳滩S型花岗岩基及其大规模伟晶岩型锂铍矿的产出,则反映了强烈的碰撞造山作用导致的地壳重熔的地球动力学背景,应是古特提斯洋缝合造山后或后碰撞伸展的环境。【结论】 就已有的成矿事实,东昆仑康西瓦—阿尼玛卿古特提斯缝合带与南部巴颜喀拉的西金乌兰—金沙江和羌塘的龙木错—双湖古特提斯缝合带相比,更富有地质意义。     

面向市级和县级海洋防灾减灾的综合管理系统设计和应用

文章基于市级和县级海洋防灾减灾工作需求,以GIS技术为支撑,开发海洋防灾减灾综合管理系统;详述该系统的监测监控、预报产品集成、海洋灾害综合风险防范服务、风暴潮综合研判、风暴潮漫滩漫堤三维模拟和海洋环境突发事件应急服务6个子系统的设计和应用,以期促进相关工作的开展。     

新疆北部晚古生代大规模岩浆成矿的地球动力学背景和战略找矿远景

新疆北部石炭-二叠纪存在大规模岩浆成矿作用,但对成矿地球动力学机制缺乏系统认识。在前人工作和我们近年来工作的基础上,文中扼要总结了我们新的初步认识,旨在为深化研究奠定思想基础。文中指出新疆北部泥盆-石炭纪岩浆活动和成矿作用是板块构造的直接产物。石炭纪的板块消减及有关的岩浆作用可能一直持续到三叠纪。地幔柱岩浆作用的起始时间不详,可能在晚石炭世,但集中表现在二叠纪。两种岩浆构造体系在时间上的叠加和空间上的并存造就了成矿作用的集中爆发以及成矿类型上的时空变化。与之有关的成矿作用和相应的成矿类型主要有：赋存于晚泥盆世-早石炭世海相火山岩中的磁铁矿床（有火山岩浆喷溢成因的可能,但更具有夕卡岩型铁矿的特征）、泥盆纪末到早三叠世与中酸性侵入岩有关的斑岩型（夕卡岩型）铜（钼）矿床以及早二叠世与镁铁超镁铁质侵入岩有关的岩浆铜镍硫化物矿床。后者与南疆塔里木盆地已知溢流玄武岩在时代上（（280±5）Ma）的一致性意味着包括该溢流玄武岩的基性大火成岩省可能分布很广泛,波及北疆的相当地域。如这一推论能够证实,那么与之有成因联系的钒钛磁铁矿和铜镍硫化物矿化点/矿床的分布就不应只局限于已知造山带,应该分布更广。这里造山带的“成矿专属性”很有可能只是构造暴露而已。这一思路有助于我们研究新疆北部晚古生代岩浆成矿作用以及与岩浆作用有关的成矿作用,并对寻找同类矿床有战略指导意义。     

对等网络遥感影像瓦片资源遗传选择算法

对等网络技术的快速发展,为遥感影像数据的高效共享开辟了新的途径。对等节点终端间互相进行数据传输的方式,有效地降低了数据共享对服务器的依赖程度,极大地提高了数据分发传输的效率。由于对等网络中各终端可能存储不同区域的影像数据,因此当需要共享某个影像数据时,选择从哪些终端传输哪些瓦片以提高传输效率,是一个需要解决的重要问题。本文研究对等终端间瓦片数据集的高效共享途径,提出了一种基于遗传算法的瓦片资源选择方法,可以有效地解决对等网瓦片资源选择问题。     

东昆仑夏日哈木铜镍矿区发现早古生代榴辉岩:锆石U-Pb定年证据

<正>1研究目的(Objective)东昆仑夏日哈木超大型岩浆铜镍硫化物矿床所在矿区出露5个镁铁-超镁铁质岩体(编号为Ⅰ、Ⅱ、Ⅲ、Ⅳ、Ⅴ)(图1a),围岩均为金水口群变质岩系。夏日哈木120万吨Ni金属仅赋存于Ⅰ号岩体内,该岩体走向NEE(约60°),长约2.0 km,宽约1.4km,地表出露长1.6 km,宽0.5 km,面积约为0.9km2,岩性主要为橄榄岩、辉石岩和辉长岩。Ⅱ岩体由4个小岩体组成(图1),仅在北部辉石岩中见少量     

东天山香山中镁铁-超镁铁质岩体岩石学与矿物学特征:对成岩成矿过程的约束

香山中镁铁-超镁铁岩体产出于新疆东天山地区的黄山—镜儿泉镁铁-超镁铁岩带。主要的岩石类型为二辉橄榄岩、(含长)单辉橄榄岩、橄榄辉石岩及角闪辉长岩。矿物学特征显示,岩体造岩矿物的结晶顺序为铬尖晶石→橄榄石→斜方辉石→单斜辉石→斜长石→角闪石。电子探针分析显示,同一侵入期次中各岩相具有良好的过渡渐变关系,钻孔剖面上橄榄石含量与颗粒大小、单斜辉石的成分有随深度连续变化的特征,铬尖晶石则具有良好的Cr→Fe3+、Ti的演化趋势,由此反映岩体的形成主要受结晶分异作用的控制;含长单辉橄榄岩中橄榄石和单斜辉石成分的突然变化显示岩浆结晶过程中受到了地壳物质阶段性的混染;模拟计算表明,橄榄石分离结晶伴随着硫化物的熔离;钻孔ZK3693深度为295~325 m,含长单辉橄榄岩中橄榄石、斜长石、单颗粒单斜辉石成分突然性的变化指示在区间内有新鲜的基性程度更高的岩浆注入,而此区间内矿石的Cu、Ni品位明显高于区间外同一岩相岩体,说明新鲜岩浆的注入是香山中岩体硫化物富集的重要原因。