Timing of UHP exhumation and rock fabric development in gneiss domes containing the world's youngest eclogite Facies rocks,southeastern Papua New Guinea

The youngest known ultrahigh‐pressure (UHP) rocks in the world occur in the Woodlark Rift of southeastern Papua New Guinea. Since their crystallization in the Late Miocene to Early Pliocene, these eclogite facies rocks have been rapidly exhumed from mantle depths to the surface and today they remain in the still‐active geodynamic setting that caused this exhumation. For this reason, the rocks provide an excellent opportunity to study rates and processes of (U)HP exhumation. We present New Rb–Sr results from 12 rock samples from eclogite‐bearing gneiss domes in the D'Entrecasteaux Islands, and use those results to examine the time lag between (U)HP metamorphism and later ductile thinning, penetrative fabric development and accompanying metamorphic retrogression at amphibolite facies conditions during their exhumation. A Rb–Sr age for a sample of mafic eclogite (with no preserved coesite) from the core zone of the Mailolo gneiss dome (Fergusson Island) provides a new estimate of the timing of HP metamorphism (5.6 ± 1.6 Ma). The strongly deformed quartzofeldspathic and granitic gneisses (90–95% by volume) that enclose variably retrogressed relict blocks of mafic eclogite (5–10% by volume) yield Rb–Sr isochron ages from 4.4 to 2.4 Ma. For the UHP‐bearing gneisses of Mailolo dome, previously published U–Pb ages on zircon and our Rb–Sr isochron ages are consistent with a mean time lag of 2.2 ± 1.5 Ma (~95% c.i.) for passage of the rock between eclogite and amphibolite facies conditions. New thermobarometric data indicate that the main syn‐exhumational foliation developed at amphibolite facies conditions of 630–665 °C and 12.1–14.4 kbar. These pressure estimates indicate that the lower crust of the Woodlark Rift was unusually thick (>40 km) at the time of the amphibolite facies overprint, possibly as a result of accumulation and underplating of UHP‐derived material from below. Our data imply a minimum unroofing rate of 10 ± 7 mm year^?1 (~95% c.i.) for the (U)HP body from minimum HP depths (73 ± 7 km) to lower crustal depths. This minimum unroofing rate reinforces previous inferences that the exhumation from the mantle to the surface of the gneiss domes in the D'Entrecasteaux Islands took place at plate tectonic rates. On the basis of previous structural studies and the new thermobarometry, we attribute the high (cm year^?1) exhumation to diapiric ascent of the partially molten terrane from mantle depths, with a secondary contribution from pure shear thinning of the terrane after its arrival in the crust.     

Copper‐gold mineralisation in New Guinea: Tectonics,lineaments, thermochronology and structure

In New Guinea, the upper crust is rich in Late Miocene and Pliocene copper‐gold deposits, yet the host intrusives are mainly in the New Guinea Fold Belt and are of mantle origin and not directly subduction‐related. Structural, thermochronological and geodynamic analyses of the Grasberg, Porgera, Ok Tedi and Frieda River deposits show that the richest deposits occur along the eastern edge of the intersections between long‐lived crustal transfers perpendicular to strike and strike‐parallel crustal extensional faults that were strongly inverted during Late Miocene ‐ Pliocene orogenesis. The deposits are all associated with north‐northeast‐trending transfers, parallel to the aeromagnetic grain in basement, across which the continent‐ocean suture shows >50 km horizontal separation, as identified by the southern limit of the central New Guinea ophiolites. In the fold belt, the transfers coincide with the termination of regional anticlines or uplifts that are 150–200 km long and 30–60 km wide. Balanced sections reveal that the southern limit of these regional anticlines is commonly fault‐bound and coincides with major facies and thickness changes, indicating long‐lived, crustal extensional faults that were inverted. Fission track and ⁴⁰Ar/³⁹Ar cooling ages show that mineralisation occurred during inversion of these faults and, hence, correlates with propagation of orogenesis from northeast to southwest. It is proposed that the pre‐compression New Guinea margin comprised step‐like promontories and embayments delineated by long‐lived crustal fracture zones, as on Australia's North West Shelf. During Late Miocene ‐ Pliocene compression the crust was thickened, accompanying melting of the underlying mantle, and the crustal fracture zones were reactivated as transfers. Where the transfers intersected crustal extensional faults that were being inverted, local zones of dilation occurred, allowing emplacement of mantle magmas and associated mineralisation. When the deformation propagated southwards, so did the crustal thickening and the reactivation of major faults, allowing emplacement of younger magmas and mineralisation.     

Climate change transformation: A definition and typology to guide decision making in urban environments

Climate change presents a threat to the sustainability of cities and their societies, and must be adequately addressed. Urban environments (cities) are responsible for the creation of a significant amount of greenhouse gas emissions which are the source of climate change. Cities have been increasingly the focus of action to address climate change, yet emissions are not significantly reducing. Additionally, there a lack of integration between adaptation and mitigation. This prevents responses adequate to limit global warming to 1.5^OC, and to be well adapted to anticipated changes. This paper critically analyses existing definitions and typologies of climate change actions. A definition of ‘climate change transformation’ is proposed which includes the integration of adaptation and mitigation goals to enable a new regime in which global warming is limited to 1.5^OC. A new three-part typology: ‘coping, malaction and transformation,’ is presented for categorising climate change actions by the extent to which they integrate adaptation and mitigation, and define a new regime. The typology is accompanied by illustrations to demonstrate the relationship between adaptation and mitigation. The definition, typology and illustration serve to guide effective climate change decision making, and provides principles to guide application in urban environments.     

Petrology,Geochemistry, and Fluid Inclusion Microthermometry of Sphalerite from the Laloki and Federal Flag Strata‐Bound Massive Sulfide Deposits,Papua New Guinea: Implications for Gold Mineralization

The Laloki and Federal Flag deposits are two of the many (over 45) polymetallic massive sulfide deposits that occur in the Astrolabe Mineral Field, Papua New Guinea. New data of the mineralogical compositions, mineral textures, and fluid inclusion studies on sphalerite from Laloki and Federal Flag deposits were investigated to clarify physiochemical conditions of the mineralization at both deposits. The two deposits are located about 2 km apart and they are stratigraphically hosted by siliceous to carbonaceous claystone and rare gray chert of Paleocene–Eocene age. Massive sulfide ore and host rock samples were collected from each deposit for mineralogical, geochemical, and fluid inclusion studies. Mineralization at the Laloki deposit consists of early‐stage massive sulfide mineralization (sphalerite‐barite, chalcopyrite, and pyrite–marcasite) and late‐stage brecciation and remobilization of early‐stage massive sulfides that was accompanied by late‐stage sphalerite mineralization. Occurrence of native gold blebs in early‐stage massive pyrite–marcasite‐chalcopyrite ore with the association of pyrrhotite‐hematite and abundant planktonic foraminifera remnants was due to reduction of hydrothermal fluids by the reaction with organic‐rich sediments and seawater mixing. Precipitation of fine‐grained gold blebs in late‐stage Fe‐rich sphalerite resulted from low temperature and higher salinity ore fluids in sulfur reducing conditions. In contrast, the massive sulfide ores from the Federal Flag deposit contain Fe‐rich sphalerite and subordinate sulfarsenides. Native gold blebs occur as inclusions in Fe‐rich sphalerite, along sphalerite grain boundaries, and in the siliceous‐hematitic matrix. Such occurrences of native gold suggest that gold was initially precipitated from high‐temperature, moderate to highly reduced, low‐sulfur ore fluids. Concentrations of Au and Ag from both Laloki and Federal Flag deposits were within the range (<10 ppm Au and <100 ppm Ag) of massive sulfides at a mid‐ocean ridge setting rather than typical arc‐type massive sulfides. The complex relationship between FeS contents in sphalerite and gold grades of both deposits is probably due to the initial deposition of gold on the seafloor that may have been controlled by factors such as Au complexes, pH, and fO₂ in combination with temperature and sulfur fugacity.     

新型自动气象站故障判断及处理办法

摘要：通过对新型自动气象站在运行过程中常见故障的分析,结合新型自动气象站的功能结构,总结故障发生的现象、原因和维修方法,供同行借鉴参考。     

波力发电方案的工程性探讨

本文从工程角度出发，分析了波力发电的困难，从而指出，在目前技术水平下，一个现实性的波力发电装置必需具备的条件，并结合原理性，分析了值得重视的二类波力发电装置。进而推介了一种工程性较强的柱式波力发电系统。     

Climatic influence upon early to mid‐Holocene fire regimes within temperate woodlands: a multi‐proxy reconstruction from the New Forest,southern England

A combined pollen, charcoal and climatic record is presented from Cranes Moor, southern England, covering the period c. 10 500–5850 cal a BP. It is shown that the occurrence of burning is closely related to natural processes, including prevailing climatic conditions and vegetation composition. These burning events are often linked to an increase in the summer moisture deficit, implying that the timing of burning events is linked to periods of warmer/drier climate during the Holocene Thermal Maximum (c. 11 000–5000 cal a BP). These events play an important role in the vegetation composition and succession around the site. The nature of the burning recorded at the site shows strong similarities with other records from northern Europe. This study throws caution on suggestions that fire in the Holocene record from areas such as the British Isles is linked only to human activity, and enhances the possibility that natural fire incidence played an important role in natural woodland structure dynamics.     

新疆于田阿什库勒火山群若干新的野外地质证据

位于青藏高原北缘的新疆于田阿什库勒火山群地区是中国大陆现代火山和地震活动最活跃的构造区之一,是研究青藏高原演化的重要窗口,但由于地处高海拔(4700~5600m.a.s.l.)无人区,研究程度还很低,甚至还不曾开展过系统详细的野外地质调查。本文报道最近在这一地区的一次野外考察结果,在前人鲜为涉足的阿什库勒盆地北部发现了苏贝稀1号、苏贝稀2号和托甫热三个火山口,并且在前人有争议的盆地南部高台山地区找到确凿的证据,重新认定高台山火山的存在。我们还在高台山和椅子山火山之间考察了前人未曾报道的小黑沟火山。由小黑沟流向乌鲁克库勒湖的火山熔岩流动和冷却过程中形成的熔岩冢等火山地质景观在严酷的荒漠环境中迄今仍然保存完好,表明小黑山火山很可能是一座全新世的火山,是本次考察到的最年轻的火山。     

巴布亚新几内亚铜金矿床成矿时代及成矿控制因素

巴布亚新几内亚是在澳大利亚板块与太平洋板块斜向和快速汇聚的边界带内演化的,是世界上构造运动最复杂的区带之一,其地球动力学演化涉及俯冲与火山岛弧（岩浆弧）形成、弧陆碰撞与造山、俯冲陆壳折返-岩浆侵入-成矿作用等地质作用。地质年代学研究指出,巴布亚新几内亚主岛（新几内亚岛）的地球动力学次序是：①引起抬升和折返的碰撞作用;②折返期间或稍后的侵入作用;③侵入岩体系晚期的成矿事件。在地球动力学次序中,巴布亚新几内亚铜金成矿时代主要集中在25～0Ma之间,其中几个世界级矿床更为年轻,成矿年龄只有6-0Ma。笔者按成矿时代将巴布亚新几内亚铜金成矿作用分为第一高潮（23～12Ma）、第二高潮（7-1Ma）和第三高潮（现在进行时）（0．5-0Ma）。巴布亚新几内亚铜金成矿受大地构造、侵入杂岩体、特定赋矿地层、转换构造、背斜、各种断裂、破火山或火山管道等控制。     

城市给排水管道检测新技术

随着城市年龄的增加和地下管道的老化,我国各大城市给排水管道爆裂事故频发,给城镇居民的正常生活带来了严重干扰。武汉暴雨后,“到武汉来看海”一时成网络流行语,这更使江城排水系统的尴尬显露无疑,造成社会影响是不言而喻的。本技术在软硬件方面进行大胆创新,关键技术在于：将传统管道摄像系统和GIS技术、物联网技术巧妙的结合在一起,实现数字管道的思维,开发出三套适用于给排水管道检测的功能软件,适应于用户要求。设备技术出于国内一流,还具有环保节能的特点,可以提高经济效益。