Contrasting structural styles of gold deposits in the Leonora Domain: evidence for early gold deposition,Eastern Goldfields,Western Australia

The Leonora Domain contains seven significant gold deposits that display markedly different structural styles. Deposits such as Gwalia, Tower Hill and Harbour Lights are characterised by strongly folded and boudinaged veins. In contrast, the Tarmoola/King of the Hills deposit comprises gold lodes that have not experienced ductile conditions. The complex geometry of many of the deposits here has led to multiple interpretations for the timing and nature of gold deposition. The Leonora Domain, located along the margin of the Raeside Batholith 250 km north of Kalgoorlie, is dominated by a strong extensional fabric that wraps around the edge of the batholith and formed during D₁ extension and exhumation of the granite body. In all localities the extensional fabric (S_1b) is overprinted by upright folds and shears produced by the onset of east–west compression (D₂ event) and sinistral transpression (D₃ event). Subsequent east-northeast?west-southwest D₄ shortening produced abundant dextral shears that overprinted and reactivated the D₃ structures. Late orogenic collapse during the D₅ event produced abundant steep planar normal faults.

New structural observations presented here provide evidence that deposits such as Gwalia, Tower Hill and Harbour Lights formed at a very early stage of D₁ extension, prior to the main exhumation event (D_1b). In contrast, gold lodes at Tarmoola/King of the Hills are related to sinistral-reverse shears that developed in the deformed carapace of a large granite body during strong east–west compression (D₃ event). The lodes have formed as a result of strong competency contrast between the granite and the surrounding ultramafic rocks and are more typical of gold deposits elsewhere in the Eastern Goldfields. The spatial distribution of the major early deposits in the Leonora Domain indicates that the first-order control on gold distribution is the major shear along the contact of the Raeside Batholith. The regular spacing of the deposits around the Raeside Batholith likely reflects the rheology and thickness of the extending sequence. Gwalia, Tower Hill and Harbour Lights deposits are located at an apparent bulge in the eastern side of the Raeside Batholith, which may have originally been the highest part of the batholith and, with the onset of extension, may have focused structures and rising hydrothermal fluids into this area.     

一种仿金刚石膜的研究

针对客户声称的表面覆金刚石膜（DF）的合成立方氧化锆进行常规宝石学检测,结果发现,样品为覆膜合成立方氧化锆,但样品表面的覆膜层硬度低、光滑平整,与多晶金刚石膜的粒状结构及单晶金月1石膜表面定向排列的突起等特征均不相同。为了确定表面覆膜层的成分,采用小角X射线衍射仪、X射线光电子能谱仪和红外光谱仪对样品表面的覆膜层进行了物相分析、化学成分分析及谱学测试。X射线衍射分析表明样品表面的覆膜层属于非晶物相;X射线光电子能谱分析表明样品的膜层主要化学成分为C,F。结合薄膜材料资料分析,初步确定其表面覆膜层可能属于非晶氟化碳（a—C：F）膜;红外光谱分析结果显示样品表面的膜层所导致的1068cm-1处的特征峰,进一步验证了X射线衍射分析结论。综合结果表明,该样品表面的覆膜层为非晶氟化碳（a—C：F）膜,是一种仿金刚石膜。     

基于MapGIS组件二次开发MT成果数据的查询及应用

为了方便快捷地利用大地电磁测深来研究深部地壳和上地幔岩石圈层的信息,这里以首次建立的大地电磁测深成果MicrosoftSQLSever数据库为基础,结合VisualBasic语言与MapGIS组件二次开发技术,实现了大地电磁测深成果的空间数据和属性数据信息的查询等功能,其可为不同研究区的岩石圈壳幔电性结构特征的研究提供便捷的技术支持。同时以长江中下游重要成矿区带为例,利用大地电磁测深成果数据的查询功能,开展了岩石圈电性结构的初步研究,并取得了一定的应用效果。     

内蒙古东升庙一带花岗质岩体锆石年代学及其构造意义

研究区位于华北地块北缘西段,是解析中亚造山带构造演化的关键部位。本文在野外地质调查基础上,应用TIMS锆EU—Ph测年法对东升庙一带主要花岗-闪长质侵入岩体进行分析,完善了原有工作成果。证实了该区存在太古代结晶基底（（2619±18）Ma、（2563±1）Ma）,并于古元古代中晚期（2．0Ga）经历了一次强烈的碰撞造山运动,造成了闪长质与花岗质岩浆侵位,以及1．9Ga的变质事件。而后又经历了中元古代伸展裂解、石炭纪中晚期洋壳俯冲（（304±3．4）Ma、（320．5±2．9）Ma）和二叠纪～三叠纪碰撞拼合（（227．6±4）Ma、（246±2．5）Ma）3个重要的构造事件阶段,并伴有大规模岩浆侵入。     

湘江岳阳段沉积物重金属污染特征及其初步生态风险评估

分析了湘江岳阳段表层沉积物样品中10种典型重金属元素(Cd、Cu、Pb、Zn、Cr、Tl、V、Mn、Co和Ni)的含量水平和分布规律,并采用地累积指数法和潜在生态风险指数法,初步评价了沉积物中重金属污染状况和潜在生态风险。研究结果表明:(1)湘江岳阳段沉积物中重金属Cd、Zn、Mn和Cu等污染较为严重,其含量范围分别为8.56～19.4 mg/kg、250～367 mg/kg、1489～2258 mg/kg和40.5～64.7 mg/kg;(2)研究区域中多种重金属潜在生态风险指数(RI)为369～698,表明研究区域沉积物重金属污染导致的潜在生态风险高,且主要风险污染物为Cd和Tl;(3)湘江岳阳段沉积物呈现出以Cd为主的多种重金属复合污染特征。     

铁（氢）氧化物悬液中磷酸盐的吸附-解吸特性研究

铁（氢）氧化物对P的吸持和释放在一定程度上决定着P的生物有效性和水体富营养化。以两种环境中常见晶质铁氧化物（针铁矿和赤铁矿）为对照,采用X射线衍射（XRD）、透射电镜（TEM）、热重分析（TGA）和孔径分析以及动力学和吸附-解吸热力学平衡等技术方法,研究了弱晶质水铁矿对P吸附-解吸特性,并探讨了相关机制。实验表明,三种矿物对P的吸附分为起始的快速反应和随后的慢速反应,它们均符合准一级动力学过程,反应中OH释放明显滞后于P吸附,P吸附经历了从外围到内囤配位、单齿到多齿配位过渡的过程,与晶质氧化铁比,水铁矿吸附容量和OH释放量更大、慢速吸附反应更快、存在缓慢扩散反应阶段,吸附容量依次是：水铁矿（436μmol／m^2）〉针铁矿（262μmol／m^2）〉赤铁矿（228μmol／m^2）,针铁矿和赤铁矿吸附P符合L（Langmuir）模型,而水铁矿更符合F（Fremldlictl）模型。中性盐介质（KCl）中在最大吸附量时P的解吸率依次为：水铁矿（85％）〈针铁矿（10％）〈赤铁矿（125％）,柠檬酸通过配体解吸和诱导溶解两种机制促进P的解吸,最大吸附量时解吸率依次是：针铁矿（25％）〈水铁矿（32％）〈赤铁矿（50％）。