Late Quaternary clay minerals off Middle Vietnam in the western South China Sea: Implications for source analysis and East Asian monsoon evolution

High-resolution clay mineral records combined with oxygen isotopic stratigraphy over the past 450 ka during late Quaternary from Core MD05-2901 off Middle Vietnam in the western South China Sea are re-ported to reconstruct a history of East Asian monsoon evolution. Variations in Illite, chlorite, and kaolinite contents indicate a strong glacial-interglacial cyclicity, while changes in smectite content present a higher frequency cyclicity. The provenance analysis indicates a mixture of individual clay minerals from various sources surrounding the South China Sea. Smectite derived mainly from the Sunda shelf and its major source area of the Indonesian islands. Illite and chlorite originated mainly from the Mekong and Red rivers. Kaolinite was provided mainly by the Pearl River. Spectral analysis of the kaolin-ite/(illite chlorite) ratio displays a strong eccentricity period of 100 ka, implying the ice sheet-forced win-ter monsoon evolution; whereas higher frequency changes in the smectite content show an ice sheet-forced obliquity period of 41 ka, and precession periods of 23 and 19 ka and a semi-precession period of 13 ka as well, implying the tropical-forced summer monsoon evolution. The winter monsoon evolution is generally in coherence with the glacial-interglacial cyclicity, with intensified winter monsoon winds during glacials and weakened winter monsoon winds during interglacials; whereas the summer monsoon evolution provides an almost linear response to the summer insolation of low latitude in the Northern Hemisphere, with strengthened summer monsoon during higher insolation and weakened summer monsoon during lower insolation. The result suggests that the high-latitude ice sheet and low-latitude tropical factor could drive the late Quaternary evolution of East Asian winter and summer monsoons, respectively, implying their diplex and self-contained forcing mechanism.     

辽宁省积雪对自动气象站观测地气温差的影响

利用1971—2016年辽宁省61个气象站气温、地表温度、积雪日数和积雪深度资料,分析了积雪的保温作用及其对地气温差的影响。结果表明：更换自动站前后地表温度观测方式的差异导致地气温差显著增大,地气温差的增大程度受所在区域积雪日数、积雪深度的影响显著。在积雪期较长、积雪较厚的地区,积雪引起反照率增大,使得雪面温度降低,导致雪气温差减小,而雪的保温作用使得地气温差显著增大。因此,更换自动站前地（雪）气温差与积雪日数呈显著负相关,而更换自动站后地气温差与积雪日数呈显著正相关。各台站之间地气温差随积雪深度的变化系数差异较大,为0.045~0.858 ℃?cm^-1,在年平均积雪日数＜40 d、年平均极端积雪深度＜10 cm的区域,积雪的保温作用随积雪深度增大而显著增大;在年平均积雪日数＞40 d、年平均极端积雪深度＞10 cm的区域,10 cm以下的积雪对土壤保温作用随积雪深度增大显著,当积雪深度＞10 cm后,其保温作用随积雪深度增大的幅度明显减小。     

Late Carboniferous porphyry copper mineralization at La Voluntad,Neuquén,Argentina: Constraints from Re–Os molybdenite dating

The La Voluntad porphyry Cu–Mo deposit in Neuquén, Argentina, is one of several poorly known porphyry-type deposits of Paleozoic to Early Jurassic age in the central and southern Andes. Mineralization at La Voluntad is related to a tonalite porphyry from the Chachil Plutonic Complex that intruded metasedimentary units of the Piedra Santa Complex. Five new Re–Os molybdenite ages from four samples representing three different vein types (i.e., quartz–molybdenite, quartz–sericite–molybdenite and quartz–sericite–molybdenite ± chalcopyrite–pyrite) are identical within error and were formed between ~312 to ~316 Ma. Rhenium and Os concentrations range between 34 to 183 ppm and 112 to 599 ppb, respectively. The new Re–Os ages indicate that the main mineralization event at La Voluntad, associated to sericitic alteration, was emplaced during a time span of 1.7 ± 3.2 Ma and that the deposit is Carboniferous in age, not Permian as previously thought. La Voluntad is the oldest porphyry copper deposit so far recognized in the Andes and indicates the presence of an active magmatic arc, with associated porphyry style mineralization, at the proto-Pacific margin of Gondwana during the Early Pennsylvanian.     

Well placement optimization subject to realistic field development constraints

This work considers the well placement problem in reservoir management and field development optimization. In particular, it emphasizes embedding realistic and practical constraints into a mathematical optimization formulation. Such constraints are a prerequisite for the wider use of mathematical optimization techniques in well placement problems, since constraints are a way to incorporate reservoir engineering knowledge into the problem formulation. There are important design limitations that are used by the field development team when treating the well placement problem, and these limitations need to be articulated and eventually formalized within the problem before conducting the search for optimal well placements. In addition, these design limitations may be explicit or implicit. In this work, various design limitations pertaining to well locations have been developed in close collaboration with a field operator on the Norwegian Continental Shelf. Moreover, this work focuses on developing constraint-handling capability to enforce these various considerations during optimization. In particular, the Particle Swarm Optimization (PSO) algorithm is applied to optimize for the well locations, and various practical well placement constraints are incorporated into the PSO algorithm using two different constraint-handling techniques: a decoder procedure and the penalty method. The decoder procedure maps the feasible search space onto a cube and has the advantage of not requiring parameter tuning. The penalty method converts the constrained optimization problem into an unconstrained one by introducing an additional term, which is called a penalty function, to the objective function. In contrast to the penalty method, only feasible solutions are evaluated in the decoder method. Through numerical simulations, a comparison between the penalty method and the decoder technique is performed for two cases. We show that the decoder technique can easily be implemented for the well placement problem, and furthermore, that it performs better than the penalty method in most of the cases.     

闪电产生氮氧化物对青藏高原臭氧低谷形成的影响

为了进一步了解青藏高原闪电的产生氮氧化物（LNO_x）经由光化学反应对O₃浓度变化及夏季O₃低谷形成的可能影响,本文利用2005~2013年由OMI卫星得到的对流层NO₂垂直浓度柱（NO₂ VCD）、O₃总浓度柱（TOC）和O₃廓线以及星载光学瞬变探测器OTD和闪电成像仪LIS获取的总闪电数资料,对青藏高原和同纬度长江中下游地区的TOC和NO₂ VCD月均值时空分布特征、闪电与NO₂ VCD的相关性和O₃的垂直分布特征及其与LNO_x的关系进行了对比分析。结果表明,青藏高原的O₃低谷主要出现在夏季和秋季,其TOC值比同纬度长江中下游地区低约10~15 DU（Dobson unit）。青藏高原NO₂VCD总体较小,表现为夏高冬低的分布特征。青藏高原夏季O₃浓度受南亚高压的影响总体呈减小趋势,但因强雷暴天气导致对流层中上部LNO_x浓度升高,并随强上升气流向对流层顶输送,同时通过光化学反应使O₃浓度增加,缩小了青藏高原和同纬度地区的O₃浓度差,减缓了O₃总浓度的下降,抑制了夏季O₃低谷的进一步深化。     

内蒙古阿拉善北部雅干构造带白山组火山岩年龄、地球化学特征及其对区域构造演化的约束

阿拉善北部雅干地区古生代火山岩发育,研究其形成时代和地质特征,对探讨中亚造山带中段南缘北山弧盆系的演化具有重要的意义。对雅干地区原划奥陶系火山岩进行了同位素年代学与地球化学研究,获得流纹岩LA-ICP-MS锆石U-Pb年龄为298.4±1.5Ma,时代为早二叠世初期,结合岩石组合特征和区域对比,将其重新厘定为上石炭统—下二叠统白山组。该套火山岩富SiO2、高K2O、低TiO2,属于钙碱性系列; 相对富集Rb、Pb、K等大离子亲石元素,明显亏损Ta、Nb、P、Ti等高场强元素; 呈现为轻稀土元素相对富集、重稀土元素相对亏损的的右倾特征,具有较明显的负Eu异常,显示出陆缘弧火山岩的地球化学特征。上述证据表明,雅干地区白山组火山岩形成于古亚洲洋向明水-旱山地块北缘俯冲的陆缘弧构造环境。     

Broad search for unstable resonant orbits in the planar circular restricted three-body problem

Unstable resonant orbits in the circular restricted three-body problem have increasingly been used for trajectory design using optimization and invariant manifold techniques. In this study, several methods for computing these unstable resonant orbits are explored including grid searches, flyby maps, and continuation. Families of orbits are computed focusing on orbits with multiple loops near the secondary in the Jupiter–Europa system, and their characteristics are explored. Different parameters such as period and stability are examined for each set of resonant orbits, and the continuation of several specific orbits is explored in more detail.     

Heave compensation system of lifting pipeline for deep-sea mining based on combined action of vibration absorber and accumulator

ABSTRACT

A heave compensation system combined with a vibration absorber and accumulator is proposed, with regard to the requirement for poly-metallic nodule mining systems at an ocean depth of 6,000?m in China. The principle of the compensation system was analyzed, its main parameters were designed, and its mathematical model was established. The system performance was simulated and analyzed in MATLAB, and the frequency domain characteristics and compensation rate of the system with different volume accumulators, and with or without vibration absorbers, were compared. A simulation test of the compensation system was conducted. The proposed compensation system had a better compensation effect for a random wave interference under level-6 sea conditions, and the compensation rate being more than 72% with optimal system parameters.     

Origin of a metamorphosed lithic clast in CM chondrite Grove Mountains 021536

Abstract– A metamorphosed lithic clast was discovered in the CM chondrite Grove Mountains 021536, which was collected in the Antarctica by the Chinese Antarctic Research Exploration team. The lithic clast is composed mainly of Fe‐rich olivine (Fo₆₂) with minor diopside (Fs_9.7–11.1Wo_48.3–51.6), plagioclase (An_43–46.5), nepheline, merrillite, Al‐rich chromite (21.8 wt% Al₂O₃; 4.43 wt% TiO₂), and pentlandite. Δ¹⁷O values of olivine in the lithic clast vary from ?3.9‰ to ?0.8‰. Mineral compositions and oxygen isotopic compositions of olivine suggest that the lithic clast has an exotic source different from the CM chondrite parent body. The clast could be derived from strong thermal metamorphism of pre‐existing chondrule that has experienced low‐temperature anhydrous alteration. The lithic clast is similar in mineral assemblage and chemistry to a few clasts observed in oxidized CV3 chondrites (Mokoia and Yamato‐86009) and might have been derived from the interior of the primitive CV asteroid. The apparent lack of hydration in the lithic clast indicates that the clast accreted into the CM chondrite after hydration of the CM components.     

The Analysis of Three Dimensional FEM for Interaction of the Gravity-arch Dam and Complex Ground at Geheyan,Qingjiang River

This paper introduces the analysis of three dimensional finite element method for the gravity-arch dam building on the complex ground. The foundation rock of dip and strain-slip, three faults, two weak intercalations and etc. arc considered in this calculation model. Water static pressure, gravity of dam, uplift, temperature stress and so on are computed, including three dimensional osmotic and temperature fields in the foundation. The range of calculation model is about 1400×900×600m2 . There are 1845 elements of all kinds, 3280 nodes in the network of finite element. The superlax iterative method is used to solve, and three dimensional perspective and software of after treatment are applied in analyses. The dimension of this computation is large, various results of treating complex problems are reasonable. The important basis has applied to designing unit. The computation is important practical significance for Geheyan Dam which is being built.