剪切带中的金矿化作用：一种三阶段矿床成因模型

通过对大量含金石英脉的剪切带的研究,我们提出一种石英脉型的三阶段成矿模型。这些阶段表明:随着剪切带的演化,金含量逐渐增加,这三个阶段为:形成“不可见”金的早期阶段,形成细粒金的中期阶段和形成金粒的第三阶段。早期阶段是一种广义的剪切带发展阶段,由两个分阶段组成,该阶段的特点是形成了一种构造糜棱岩,这种构造带就成了后来的热液活动的通道,在岩石形变和热液活动的双重作用下,这种构造中的岩石经历了一种矿化作用,但还决定于原岩的成分。矿化作用的强度向着这种构造的中心方向逐渐增加,而构造活动中心位置正是发生强烈硅化和硫化物化的场所。在第一分阶段中金位于磁黄铁矿的晶格中(金含量高达30ppm)磁黄铁矿呈浸染状分布于整个构造带之中。在第二分阶段,在构造中心处的黄铁矿—白铁矿不够稳定,从其中析出的金便进入局部富含铁的硫化物晶格中:如黄铁矿、毒砂(其中金的百分重量比高达1.6wt％)和辉铁锑矿。在中间阶段中(该阶段也由两个连续的分阶段组成),在这些剪切带中产生了一些连续的裂缝,在其中形成了一些乳白色石英的石英脉和透镜体。由于后继的构造活动。这些石英脉又会碎裂,形成石英微粒,为金矿化提供了“容器”。本文中所说的含金石英脉就是这一阶段特有的产物。其特点是由于早期阶段的含金硫化物不稳定而产生了可见的自然金。一般说来,这种金颗粒非常细(只有几个微米)而且不含银。在一些脆弱的区域里,在早期的或者中期阶段形成的构造中可以出现第三阶段即第五个分阶段。它相当于一个裂隙发育阶段,在这个阶段中形成了网状石英脉或是石英和碳酸盐脉,引起早期阶段含金矿化物中矿物的重新运移。这种重新运移作用形成了粒状的金,其大小有几个毫米,而且富含银(即银金矿)。     

Grounded or submerged bulk carrier: the potential for leaching of coal trace elements to seawater

This study investigates the potential for leaching of coal trace elements to seawater from a grounded bulk carrier. The coal type and ecological scenario was based on the grounding of the "Shen Neng" (April 2010) at Douglas Shoal located within the Great Barrier Reef (Queensland, Australia). The area is of high ecological value and the Queensland Water Quality Guidelines (2009) provided threshold limits to interpret potential impacts. Coal contains many trace elements that are of major and moderate concern to human health and the environment although many of these concerns are only realised when coal is combusted. However, "unburnt" coal contains trace elements that may be leached to natural waterways and few studies have investigated the potential ecological impact of such an occurrence. For example, coal maritime transport has increased by almost 35% over the last five reported years (Jaffrennou et al., 2007) and as a result there is an increased inherent risk of bulk carrier accidents. Upon grounding or becoming submerged, coal within a bulk carrier may become saturated with seawater and potentially leach trace elements to the environment and impact on water quality and ecological resilience. The worst case scenario is the breakup of a bulk carrier and dispersal of cargo to the seafloor.     

Survival and movements of Magellanic penguins rehabilitated from oil fouling along the coast of South America, 2000-2010

Oil pollution is a significant conservation concern. We examined data from six institutions along the coast of South America: Emergency Relief Team of the International Fund for Animal Welfare, Fundación Mundo Marino, Centro de Recupera??o de Animais Marinhos, Natura Patagonia, Associa??o R3 Animal, and Mar del Plata Aquarium and data from resightings in Argentina, Brazil, Chile and Falkland/Malvinas Islands. From 2000 to 2010, 2183 oiled Magellanic penguins were rehabilitated as part of the routine activities of these institutions or during emergency responses to eight oil spills in which they were involved; all rehabilitated penguins were flipper banded and released. Since their release, 41 penguins were resighted until 31 December 2011. The results demonstrate that, when combined with other prevention strategies, the rehabilitation of Magellanic penguins is a strategy that contributes to the mitigation of adverse effects of oil spills and chronic pollution to the species.