21 ka以来帝汶海区钻孔堆叠记录的古海洋学意义

印尼穿越流是连接西太平洋和印度洋的唯一载体,与东亚季风和ENSO活动密切相关。帝汶海区是印尼穿越流的主要出口之一,该区不同钻孔末次冰期以来的古海洋学记录显示在长时间尺度上变化存在着很高的相似性。为了捕捉出口处印尼穿越流的平均信号,本研究将这些记录进行堆叠,并与其他海区的钻孔记录进行对比,探讨印尼穿越流对东亚季风和ENSO活动的响应。总体上,堆叠记录较为精准地复制了各个钻孔记录的信息。帝汶海区表层海水温度堆叠记录与其他海区钻孔记录对比显示末次冰期至12~6 ka期间帝汶海可能位于暖池范围内,而晚全新世时位于暖池的边缘;温跃层深度、海水温度和盐度堆叠记录揭示自末次冰期以来印尼穿越流温跃层流呈现逐渐强化的趋势。结合现代水文资料和堆叠记录与其他古海洋古气候记录的对比等,本文推测了不同时期ENSO的冷暖期状态以及东亚季风对印尼穿越流的影响方式和过程。

     

Making migration meaningful: Achievements through separation in Mongolia

Mongolia has experienced two decades since the demise of the Soviet Union and has implemented strategies to strengthen its economy and its democratic practices. Transitions from being a nomadic society to a Soviet satellite state and onwards to liberal democracy have greatly impacted family life. The article focuses on changing patterns of mobility in the Mongolian ‘age of the market’ and its effects on population groups. Internal and international migration has continually risen as individuals and families have moved to places of opportunity. Connections are believed to be maintained during periods of absence by migrant family members, as both men and women are culturally permitted to be separate from their families. Migration is understood to contribute to prosperity, and separations contribute to generate growth and hishig (good fortune) for the good of the family. However, such mobility is also a way to escape family patriarchy and conformity, and can contribute to loss, hardship, and uncertainty for family members left behind. Further, mobility provides opportunities and a means to escape the stigma of ‘laziness’ culturally associated with poverty and immobility. Postsocialist separation has inadvertently contributed to the breakdown of the institutions of marriage and family – institutions that were supported by separations in the pastoral economy.     

Triggering transformative change: a development path approach to climate change response in communities

While climate change action plans are becoming more common, it is still unclear whether communities have the capacity, tools, and targets in place to trigger the transformative levels of change required to build fundamentally low-carbon, resilient, healthy communities. Evidence increasingly supports the finding that this transformation is not triggered by climate policy alone, but rather is shaped by a broad array of decisions and practices that are rooted in underlying patterns of development. Even so, these findings have rarely penetrated the domain of practice, which often remains squarely focused on a relatively narrow set of climate-specific policies. This article builds a conceptual framework for understanding the dynamics of community-level development path transformations that may both dramatically reduce GHG emissions and significantly enhance community resilience. This framework illuminates eight critical enablers of innovation on climate change, each of which is illustrated by compelling examples of community-level experimentation on climate change across the province of British Columbia, Canada. It is concluded that community-based climate (or sustainability) policy might be more likely to trigger development path shifts if it employs a longer time horizon, recognition of adaptability and feedbacks, integrated decision making, and systems thinking.     

Stratigraphy and thermoluminescence dating of Late Glacial cover sand in Denmark

In western Jutland deposits with a texture and structure similar to Dutch cover sands have been found. Investigations have been carried out on the lithology and the lithostratigraphic sequences. Pollen analysis is used for biostratigraphic correlation, and ages have been obtained by the radiocarbon method as well as by thermoluminescence techniques using both quartz and eldspar. The five sites are presented separately and the data are integrated into a general stratigraphic outline of the Late Glacial cover-sand sequence in Jutland. During the latest part of the Upper Pleniglacial and the earliest Late Glacial, older cover-sand type was deposited. Locally this sediment was also deposited during the later parts of the Late Glacial. Younger cover-sand type was deposited primarily during the Early Dryas and Late Dryas, but some sand of this type was also laid down during the Allerød and the earliest Holocene. The palaeobotanical records are discontinuous, but plant growth was probably present throughout the Late Glacial; only during the Altered did the deposition of sand decrease long enough to allow a relatively stable vegetational development. The investigation shows that the sequence of events in Jutland is similar to the Dutch record.     

Tetrahedral compression in (Mg,Fe)SiO3 orthopyroxenes

Single-crystal structure determinations at pressure have shown that the structural response of synthetic (Mg_0.6Fe_0.4)SiO₃ orthopyroxene to compression is the same as that previously observed in MgSiO₃ orthoenstatite. At pressure below ～4?GPa there is no significant compression of the SiO₄ tetrahedra, while above ～4?GPa the tetrahedra decrease in volume as a result of Si?O bond shortening. A study of the compressional behaviour of synthetic FeSiO₃ orthoferrosilite also shows the same behaviour below 4?GPa, but studies at higher pressures are precluded due to the transformation of the sample to the higher density C2/c high-clinoferrosilite polymorph. A further single-crystal study to 6?GPa of a Ca²⁺-containing natural orthopyroxene shows that chemical substitution of, primarily, Al³⁺ and Ca²⁺ into the structure of orthopyroxene inhibits the initial rapid compression of the M2?O3 bonds observed in the synthetic samples, and no significant tetrahedral compression is observed in this sample. Raman data collected from synthetic MgSiO₃ orthoenstatite show that there is a change in the rate of change of frequency with pressure, δν/δP, between 3.5 and 6.0?GPa, but no changes in the number of observed bands. These observations indicate a non-symmetry-breaking change in the properties of the orthoenstatite, which is associated with the change in compression mechanism observed using X-ray diffraction techniques at this pressure.     

Age and origin of clayey silt ‚brickearth’︁ in west London,England

The loamy ?brickearth’? deposits overlying coarse cold climate Kempton Park, Lynch Hill and Taplow Gravels of the R. Thames in west London are dated by thermoluminescence and mineralogical comparisons with loesses of three known ages. Although much of the ?brickearth’? resembles loess, it often contains more sand or clay than typical loess, and the mineralogical studies suggest that even the coarse silt (16–63 μm) fraction is rarely similar in composition to any known English loess. The thermoluminescence measurements suggest that most of the ?brickearth’? on the Taplow and Lynch Hill Gravels was deposited in the late Devensian, whereas that on the Park Gravel is mainly Flandrian. It is suggested that the latter is mainly floodloam, whereas the earlier ?brickearth’? is a mixed aeolian sediment derived from various local sources in and close to the Thames Valley.     

A magnetopause in the double-pulsar binary system

Francis Graham-Smith and Maura Ann McLaughlin describe the interactions in the first double-pulsar system, which produce a comet-shaped magnetosphere with remarkable similarities to that surrounding the Earth.     

Oligoprenyl-curcumanes and other new aromatic isoprenoids from the 1.64 billion year old Barney Creek Formation

Carbonaceous dolomites and shales of the 1.64 billion years (Ga) old Barney Creek Formation (BCF), McArthur Basin, northern Australia contain the oldest, clearly indigenous biomarkers. We describe three new series of regularly branched aryl isoprenoids with base ions at m/z 119, 161 and 175. The m/z 119 compounds were identified as a complete series of C₁₅–C₄₀ oligoprenyl-perhydro-ar-curcumenes (oligoprenyl-curcumanes). Their likely biogenic precursors are oligoprenyl-β-curcumenes that occur in a wide range of bacterial phyla.