苏州城市化进程与城市气候变化关系研究

利用1970—2007年苏州城市及近郊县(市)气象站观测资料,结合Landsat 5卫星反演资料,统计分析城市化进程,对苏州区域气候变化的影响。分析结果表明:从1990s中后期开始,随着经济发展,苏州城市建设速度明显加快,城市化进程对苏州气候影响明显,城、郊气温均有明显的上升趋势,相对湿度呈现下降趋势,降水量整体上呈现上升的趋势,日照时数有明显的下降的趋势;苏州城市热岛效应显现、城市霾出现、太湖蓝藻爆发、极端气候事件增多,也与快速的城市化进程有着一定的关系。     

滇西吉义独蛇绿混杂岩的岩石地球化学特征、成因和构造环境探讨

滇西吉义独蛇绿混杂岩位于金沙江缝合带的南端,岩石组合出露较齐全,包括堆晶橄榄岩、堆晶辉石岩、堆晶辉长岩以及玄武岩等,它们呈构造岩片的形式产出并与外来岩块组成蛇绿混杂岩.堆晶橄榄岩和辉石岩具低Al_2O_3,低TiO_2,而高Mg~#值(Mg~#=0.88～0.92),富集Cr和Ni,稀土总量偏低(∑REE=14.82×10~(-6)～27.75×10~(-6)),倒"U"型的稀土元素分布特征.堆晶辉长岩和玄武岩的Mg~#值较低,分别为0.70～0.79和0.51～0.66,具拉斑系列的演化趋势.玄武岩可以细分为2组:第一组玄武岩以平坦型稀土配分模式,低Mg~#(Mg~#=0.44～0.46),低稀土总量(∑REE=52.29×10~(-6)～60.26×10~(-6))为特征;第二组玄武岩则为LREE弱富集型的稀土配分模式,其Mg~#较高(Mg~#=0.54～0.68),稀土总量也较高(∑REE=62.13×10~(-6)～101.87×10~(-6)).在原始地幔标准化的微量元素配分图解中,两组玄武岩均相对富集大离子亲石元素而亏损Nb、Ta和Ti,与岛弧岩浆岩类似,明显不同于N-MORB.岩石的Sr-Nd同位素组成较为均一和稳定,堆晶橄榄岩和辉石岩的(~(87)Sr/~(86)Sr)_i=0.7051～0.7056,5_(Nd)(t)=2.8～4.1,玄武岩的(~(87)Sr/~(86)Sr)_i=0.7050～0.7056,ε_(Nd)(t)=5.1～5.8,且显示出原始地幔的同位素组成特征,暗示这些岩石为同源岩浆分异演化而成的岩浆产物.岩浆演化的主要方式为分离结晶作用,受地壳混染不明显.岩浆结晶形成岩石的顺序为:堆晶橄榄岩→堆晶辉石岩→堆晶辉长岩→玄武岩2组→玄武岩1组.岩石地球化学特征表明,吉义独蛇绿岩的形成与俯冲作用有关,且形成于金沙江洋内俯冲的消减环境.     

Geochemical characteristics of the oceanic island-type volcanic rocks in the Chiang Mai zone,northern Thailand

The oceanic island volcanic rocks in the Chiang Mai zone, northern Thailand, are usually covered by Lower Carboniferous and Upper Permian shallow-water carbonate rocks, with the Hawaii rocks and potash trachybasalt being the main rock types. The alkaline series is dominant with sub-alkaline series occurring in few cases. The geochemical characteristics are described as follows: the major chemical compositions are characterized by high TiO₂, high P₂O₅ and medium K₂O; the rare-earth elements are characterized by right-inclined strong LREE-enrichment patterns; the trace element patterns are of the upward-bulging K-Ti enrichment type; multi-component plots falling within the fields of oceanic island basalts and alkali basalts, belonging to the oceanic island-type volcanic rocks, which are similar to the equivalents in Deqin and Gengma (the Changning-Menglian zone) of Yunnan Province, China.     

滇西古特提斯俯冲-碰撞过程的岩浆作用记录

三叠纪岩浆作用广泛发育于澜沧江南带,锆石U-Pb年代学结果及岩石组合特征显示:(1)该区残留有少量的早三叠世火山岩(约248Ma),主要为一套薄层的以安山岩为主的火山岩;(2)中三叠世以大规模的酸性岩浆作用为主,部分地段的中部夹有少量的玄武岩,其中晚期的流纹岩与该区出露巨大的临沧花岗岩基主体具有一致的形成时代(约230Ma);(3)晚三叠世则以基性火山岩为主,夹少量流纹岩为特征的"双峰式"火山岩组合。元素地球化学特征表明,早三叠世火山岩具有典型的岛弧火山岩的特征,暗示其很可能形成于俯冲的构造环境;中三叠世晚期的流纹岩与临沧花岗岩基主体具有非常相似的地球化学特征,结合其流纹岩具有A型花岗岩属性,表明该区中三叠世火成岩形成于碰撞后的构造背景;而晚三叠世基性火山岩虽然在地球化学特征上显示出与岛弧火山岩相似的高铝和Nb-Ta的亏损,但其中部分火山岩具有高镁和板内玄武岩的微量元素比值特征,说明这些火山岩可能形成于碰撞后裂谷(post-collisional rifting)环境。结合区域上前人的研究资料,我们认为西南三江地区古特提斯主洋盆的俯冲闭合可能直到早三叠世晚期才完成,其后的陆-陆/弧碰撞作用可能发生在中三叠世早期,中三叠世中晚期该区进入碰撞后演化阶段,晚三叠世开始处于碰撞后的裂谷阶段,古特提斯在该区的演化最终结束于三叠纪末。     

云南普朗复式岩体地质地球化学特征及成因

根据接触关系和岩石特征将普朗复式岩体划分为3个阶段的侵入岩,由早至晚分别为石英闪长玢岩、石英二长斑岩、花岗闪长斑岩,锆石U-Pb年代学研究揭示侵入岩形成于221～206Ma之间,形成于印支期。岩石地球化学特征表明,岩石富硅、高铝、低碱且相对富钠,由早至晚岩石向富硅、富碱、高钾、低铝、低钙镁的方向演化。Cs、Rb、K、Ba、Sr等大离子亲石元素（LIL）在岩石中明显富集,Y、Hf、Zr、Ti、Nb、Ta等较不活泼的高场强元素（HFS）则在岩石中相对亏损,岩石显示负的Nb异常和高的正Pb异常,表明岩浆起源于上地幔或下地壳,且地壳物质参与了岩浆作用过程。结合Nd同位素测试结果,认为不同阶段的侵入岩为同源岩浆演化和侵入作用的结果。通过构造环境图解判别,斑岩体形成于主动大陆边缘的火山弧构造环境,是洋壳沿甘孜-理塘海沟向西俯冲的产物     

Subaqueous density flow processes and deposits of an island volcano landslide (Stromboli Island, Italy)

Stromboli is a 3000 m high island volcano, rising to 900 m above sea-level. It is the most active volcano of the Aeolian Archipelago in the Tyrrhenian Sea (Italy). Major, large volume (1 km³) sector collapses, four occurring in the last 13 kyr, have played an important role in shaping the north-western flank (Sciara del Fuoco) of the volcano, potentially generating a high-risk tsunami hazard for the Aeolian Islands and the Italian coast. However, smaller volume, partial collapses of the Sciara del Fuoco have been shown to be more frequent tsunami-generating events. One such event occurred on 30 December 2002, when a partial collapse of the north-western flank of the island took place. The resulting landslide generated 10 m high tsunami waves that impacted the island. Multibeam bathymetry, side-scan sonar imaging and visual observations reveal that the landslide deposited 25 to 30 × 10⁶ m³ of sediment on the submerged slope offshore from the Sciara del Fuoco. Two contiguous main deposit facies are recognized: (i) a chaotic, coarse-grained (metre-sized to centimetre-sized clasts) deposit; and (ii) a sand deposit containing a lower, cross-bedded sand layer and an upper structureless pebbly sand bed capped by sea floor ripple bedforms. The sand facies develops adjacent to and partially overlying the coarse deposits. Characteristics of the deposits suggest that they were derived from cohesionless, sandy matrix density flows. Flow rheology and dynamics led to the segregation of the density flow into sand-rich and clast-rich regions. A range of density flow transitions, both in space and in time, caused principally by particle concentration and grain-size partitioning within cohesionless parent flows was identified in the deposits of this relatively small-scale submarine landslide event.     

‘We do not want to leave our land’: Pacific ambassadors at the United Nations resist the category of ‘climate refugees’

The issue of the social geographical dimensions of climate change is timely and important. This paper sets out to explore one example of this: how people living in the Pacific who are most at risk of being made landless by climate change are portrayed in policy discourse, and how high-level international representatives of Pacific nations have responded to these portrayals. At the heart of this is contention over the portrayal of Pacific Island peoples as ‘climate refugees’. This paper analyses a number of documents since the 1980s, largely from non-governmental organisations (NGOs) that deploy the identity construct of ‘climate refugees’. Fieldwork undertaken at the United Nations in New York in 2004 also enabled seven interviews with national ambassadors representing Pacific small island states. Interviews revealed how Pacific ambassadors have responded to the category of ‘climate refugees’, and positioned themselves in the discursive field surrounding the climate change debate. A poststructuralist framework, drawing on Foucault’s ideas of discourse and subject categories provided a means to critically scrutinise and better understand how people from Pacific countries are imagined in the wider, global geopolitical arena, but crucially, how leaders from these nations also construct themselves in relation to climate change and its associated impacts.     

北天山东段阿奇山组火山岩的地球化学特征及锆石U-Pb年龄

阿奇山组分布于北天山东段觉罗塔格构造带内部的雅满苏岛弧带中,属于原雅满苏组下部的火山岩部分,而上部火山岩则属于土古土布拉克组。在阿奇山地区,阿奇山组由中-酸性火山岩、火山碎屑岩和火山碎屑沉积岩组成。岩石地球化学特征显示为钙碱性岛弧火山岩系列,火山岩主体具有高Sr、Na₂O、Al₂O₃、SiO₂, 低MgO、Y、Yb,及明显亏损HFSE、Nb、Ta等特征,与经典埃达克岩地球化学特征吻合,Nb、Sr、Sr/Y值显示为俯冲型埃达克岩。地球化学相关图解等表明岩浆同化混染作用弱、经历了辉石、斜长石、钛铁氧化物和磷灰石的分离结晶作用、且部分熔融发生在石榴石稳定域。与东部土屋-雅满苏地区阿奇山组火山岩的对比研究表明,东部地区的火山岩不具埃达克岩特征,说明埃达克岩分布的局限性。锆石U-Pb SHRIMP 谐和年龄为341.7±2.7Ma,与首次在该组中采集的化石资料完全一致,代表了火山岩的形成年龄。与其北部大南湖岛弧带中的小热泉子组、企鹅山组形成年龄（325.1±3.2Ma、322.6±2.0Ma）对比研究暗示,准噶尔板块南缘石炭纪存在构造-岩浆活动随时间由南向北迁移。     

昆明和北京两幢建筑物表面热力效应的观测对比

利用昆明、北京两座城市内建筑物为研究对象, 对其不同朝向外墙壁面、屋顶面表面温度及壁面近旁气温进行了观测, 分析了建筑物外墙壁面表面温度及其近旁气温的垂直分布以及壁面、屋顶对周围大气的热力效应特征, 并对两座城市内建筑物的热力状况进行了比较分析。研究表明:建筑物表面温度受太阳辐射的影响要比近旁气温大得多, 一般说来, 壁面昼间是热源, 夜间是热汇; 受研究对象所在的大区域气候、人类活动等影响, 建筑物外表面的热力效应有许多异同; 建筑物屋顶面与近旁空气间的平均热通量基本为正值, 呈现较强的热源效应, 其热力效应强度与太阳辐射呈现正相关; 城市建筑物的外表面 (壁面、屋顶面) 已成为城市区域内有别于城市地面, 且对城市立体气候的形成具有不可忽视影响的热力作用面。     

应用城市地表能量平衡方案研究城市冠层结构对城市热岛的热力影响

用南京大学区域边界层模式NJU-RBLM, 通过对一组理想试验的模拟, 研究了TEB方案 (town energy balance) 和SVAT方案 (soil－vegetation－atmosphere transfer) 模拟城市热岛现象的差异及本质原因, 发现TEB方案对城市热岛 (UHI) 尤其是夜间UHI模拟效果更优, 这是由于TEB方案具备较强模拟城市储热项的能力形成的。此外, 深入探讨UHI对大气边界层热力结构的影响, 发现UHI现象使城市和郊区的近地层位温廓线在清晨和傍晚都存在明显差异, 同时使城市区域气温全天高于郊区, 且日间城乡温差能达到的高度明显高于夜间。分析人为热源和建筑物冠层对UHI的影响时发现: 人为热源对UHI的影响在夜间强于白天, 而建筑物对白天城市湍能的影响强于人为热源的作用。