Collapse of dome cup ends under external hydrostatic pressure

An experimental investigation was carried out in which four dome cup ends were tested to failure under external hydrostatic pressure. The collapse pressures of the dome cup ends were compared with that of a conventional dome cap end. The investigation revealed that the dome cup ends were structurally more efficient than the conventional dome cap ends. All the vessels were made from the same batch of glass fibre matting and associated material.     

Fishery biology of jumbo flying squid Dosidicus gigas off Costa Rica Dome

The jumbo flying squid(Dosidicus gigas) population was surveyed with the help of Chinese squid jigging vessels off the Costa Rica Dome(4°–11°N, 90°–100°W) in 2009 and 2010. The daily catch of D. gigas in the two survey cruises ranged from 0 to 5.5 t and was mostly obtained from the areas bounded by 6°–9°N and 91°–94°W and by 6°30′–7°30′N and 96°–97°W. The sea surface temperature in the areas yielding the most catch ranged from 27.5 to 29℃. The sex ratio of the total catch was 3.75:1(female: male). The mantle length of the squid ranged from 211 to 355 mm(male) and from 204 to 429 mm(female) with an average of 297.9 and 306.7 mm, respectively. In the relationship of the mantle length(mm) and body weight(g) of the squid, there was no significant difference between sexes. The female and male were at a similar maturity, and most individuals are maturing or have matured with a few females being spent. The size(mantle length) and age at the first sexual maturity were 297 mm and 195 d in females, and less than 211 mm and 130 d in males, respectively. Most of the sampled stomachs(70.6%) had no food remains. The major preys of the squids were fish, cephalopods and crustaceans, with the most abundant Myctophum orientale and D. gigas. The preys in more than 65% of the non-empty sampled stomachs evidenced the cannibalism of D. gigas. The results improved current understanding of the fishery biology of D. gigas off the Costa Rica Dome, which may facilitate the assessment and management of relative fishery resources.     

丽江2.4米望远镜的圆顶侧窗自动化控制系统

丽江2.4 m望远镜的圆顶采用方位随动和滑动式天窗的超半球结构,起初为改善因圆顶和望远镜终端电子设备引起的内外大气湍流,设计了大面积的多组机械式侧窗。但由于高平台手动操作危险、缓慢、不精确且易损坏,为实现侧窗稳定的多组自动控制,开发了基于STM32板的嵌入式圆顶侧窗自动控制系统,利用WiFi模块、串口模块和手柄实现侧窗的远程和多通道控制。同时结合气象数据、圆顶位置信息等使系统能根据气象阈值进行预警、自动开合,并尽量减小风对望远镜振动的影响。侧窗控制系统的设计可满足上层系统集成的需要。该系统稳定可靠,能满足侧窗的自主运行与人为控制。     

南极内陆考察沿线GPS高精度定位点测量结果分析

中山站至 Dome- A考察是中国承担的“国际横穿南极科学考察”( ITASE)计划的一部分。考察沿线布设有 GPS高精度定位点 ,通过两期观测数据的计算可知 ,考察沿线的冰川整体上以8- 2 4 m/a的速度向西北方向 (兰伯特冰川盆地方向 )流动 ,而且 ,越接近冰盖边缘 ,运动速度越快 ,最快达到 1 0 0 m/a。同时 ,由于冰川的流动 ,引起了 GPS点垂直方向 0 .2 - 1 m的沉降量     

EPMA and PIXE dating of monazite in granulites from Stary Gierałtów, NE Bohemian Massif, Poland

Chemical Th–U–total Pb (CHIME) dating of monazite by electron probe microanalyzer (EPMA) and proton microprobe (PIXE) was carried out on felsic granulites from Stary Gierałtów, Poland, which represent part of the Orlica-Śnieżnik Dome in the NE Bohemian Massif. Analyzed monazite is characterized by mosaic zoning rather than simple core-to-rim growth, and strontium contents of up to 750ppm. An isochron age of 347 ± 13Ma represents timing of amphibolite-facies metamorphism, in agreement with previously published estimates.     

南极中山站-Dome A断面表层雪稳定同位素空间分布及环境影响因素分析

中山站-Dome A断面是表层雪稳定同位素组成分析的理想区域,沿线进行δ18O、δD和d的空间分布及环境影响因素研究对反映东南极地区的气候变化和物质来源具有关键意义。因而,本文基于线性回归及相关性分析方法,详细探究了断面上多种环境因素与表层雪稳定同位素分布的空间关系。结果表明,温度和地理因素与同位素比值之间有显著相关关系,且海拔是地理因素中的主要影响因素,随海拔上升表层雪的δ18O呈线性下降趋势。另外,通过断面上δ-T斜率与南极其他断面对比,发现斜率可能具有冰盖近岸和内陆地区较低的区域性特征,而造成这一现象的原因是水汽源区的改变和低温条件下水汽过饱和时的同位素动力分馏。最后,d的空间分布在沿海区域和内陆区域也有不同,推测主控因素分别是水汽源区条件和温度。     

The role of viscous heating in Barrovian metamorphism of collisional orogens: thermomechanical models and application to the Lepontine Dome in the Central Alps

Thermal models for Barrovian metamorphism driven by doubling the thickness of the radiogenic crust typically meet difficulty in accounting for the observed peak metamorphic temperature conditions. This difficulty suggests that there is an additional component in the thermal budget of many collisional orogens. Theoretical and geological considerations suggest that viscous heating is a cumulative process that may explain the heat deficit in collision orogens. The results of 2D numerical modelling of continental collision involving subduction of the lithospheric mantle demonstrate that geologically plausible stresses and strain rates may result in orogen‐scale viscous heat production of 0.1 to >1 μW m^?3, which is comparable to or even exceeds bulk radiogenic heat production within the crust. Thermally induced buoyancy is responsible for crustal upwelling in large domes with metamorphic temperatures up to 200 °C higher than regional background temperatures. Heat is mostly generated within the uppermost mantle, because of large stresses in the highly viscous rocks deforming there. This thermal energy may be transferred to the overlying crust either in the form of enhanced heat flow, or through magmatism that brings heat into the crust advectively. The amplitude of orogenic heating varies with time, with both the amplitude and time‐span depending strongly on the coupling between heat production, viscosity and collision strain rate. It is argued that geologically relevant figures are applicable to metamorphic domes such as the Lepontine Dome in the Central Alps. We conclude that deformation‐generated viscous dissipation is an important heat source during collisional orogeny and that high metamorphic temperatures as in Barrovian type metamorphism are inherent to deforming crustal regions.     

Transient analysis for fluid injection into a dome reservoir

A dome-shaped layer can be selected as a storage site for fluid injection. In this study, we develop a mathematical model for simulating transient head distribution in a heterogeneous and anisotropic dome-shaped layer due to a constant-head injection in a fully penetrating well. In the model, a form of step change is adopted to approximate the upper and lower boundaries of the dome and then the layer is split into two regions. The Laplace-domain solution of the model is developed using the Laplace transform and method of separation of variables. The transient injection rate at wellbore can then be obtained based on Darcy’s law and Bromwich integral method. The predicted head contours from the head solution show significant vertical flow components near the location of step change in the dome reservoir. The results of sensitivity analysis indicate that the hydraulic conductivity is the most sensitive parameter and the specific storage is the least sensitive one to the injection rate after a short period of injection time. In addition, the injection rate for a dome reservoir is also very sensitive to the change of the height for the reservoir near the injection well (first region) at a very early injection time. In contrast, the injection rate is more sensitive to the change of the height of the second region than that of the first region at late time. This analytical solution may be used as a primary tool to assess the capacity of fluid injection to various dome reservoirs.     

Ages of internal granitoids in the Southern Cross region,Yilgarn Craton,Western Australia,and their crustal evolution and tectonic implications

Southern Cross, where gold deposits are sited in narrow greenstone belts surrounding granitoid domes, was one of the earliest gold mining centres in Western Australia. SHRIMP U–Pb zircon and Pb‐isotope studies of the largest granitoid dome, the Ghooli Dome (80 × 40 km), provide important constraints on the crustal evolution and structural history of the central part of the Archaean Yilgarn Craton, Western Australia, which includes Southern Cross. The north‐northwest‐south‐southeast‐oriented ovoid Ghooli Dome has a broadly concentric foliation that is subhorizontal or gently dipping in its central parts and subvertical along its margins. Foliated granitoids in the dome are dated at ca 2724 ± 5 and 2688 ± 3 Ma using the SHRIMP U–Pb zircon and Pb–Pb isochron methods, respectively. These new data, together with the published SHRIMP U–Pb zircon age of 2691 ± 7 Ma at another locality, 20 km from the centre of the Koolyanobbing Shear Zone, suggest that the Ghooli Dome was emplaced at ca 2.72–2.69 Ga. Because the Ghooli Dome and the other domes, which are enveloped by narrow greenstone belts, are cut by the >650 km‐long and 6–15 km‐wide Koolyanobbing Shear Zone, the ca 2.69 Ga age is interpreted as the maximum age of the last major movement on this structure. The pre‐2.69 Ga history, if any, of the shear zone remains unknown. The shear zone is intruded by an undeformed porphyritic granitoid which has a SHRIMP U–Pb zircon age of 2656 ± 4 Ma. This age is, thus, the minimum age of major movement along this shear zone. Post‐gold mineralisation pegmatitic‐leucogranite from the Nevoria gold mine has a SHRIMP U–Pb zircon age of 2634 ± 4 Ma, with xenocrystic zircon cores of ca 2893 ± 6 Ma, constraining the minimum age of gold mineralisation there to ca 2.63 Ga. The ca 2.72–2.69 Ga granitoids also contain ca 2.98 and 2.78 Ga xenocrystic zircon cores, suggesting an extensive crustal prehistory for their source. Whereas there is a general temporal relationship between the periods of older (ca 3.0 Ga) and younger (ca 2.80 and 2.73 Ga) volcanism and the older (2.98, 2.78 and 2.72–2.69 Ga) granitoid intrusions, there is no known volcanism temporally associated with the 2.65–2.63 Ga granitoid intrusions in the Yilgarn Craton. Other heat sources and/or tectonic processes, required for the generation of these intrusions, are interpreted to be related to a lithospheric delamination event related to continental collision.     

东南极洛多姆冰帽粒雪晶粒的生长

对东南极洛多姆冰帽16个地点粒雪晶粒平均面积的详细研究表明,表层数米内晶粒的迅速生长在低积累区较为显著,随积累率增大逐渐减弱,原因可能是随积累率增大粒雪在近表层停留时间变短。晶粒平均面积随深度及年代的变化都可以较好地用线性关系近似表示。由于采样地点间积累率的巨大差别,积累率对晶粒平均面积深度关系影响较大。随积累率增加,晶粒平均面积的增加速率随深度明显减小。晶粒生长速率随温度的关系在-17℃左右开始和Gow(1975)的关系偏离,反映出晶粒生长过程的自扩散激活能可能和温度有关,其值随温度升高而增大。