长江经济带城市旅游科技创新差异的时空格局演变研究

城市旅游科技创新是长江旅游带建设的重要驱动力。以长江经济带130个城市旅游科技专利申请总量作为指标,分析2000—2017年长江经济带城市旅游科技创新差异的时空演变格局特征。发现：（1）总体呈现显著且缓慢上下波动的演变特征,带内城市群旅游科技创新差异大小依次是成渝城市群、长江中游城市群、长三角洲城市群。（2）空间分布形成“核心-边缘”的城市聚散发育格局,旅游科技创新较强的城市聚集于苏锡常都市圈、杭州都市圈、宁波都市圈及带内省会城市。（3）呈现锁定的高水平和低水平俱乐部,活跃的中低水平和中高水平俱乐部, 不同城市旅游科技创新差异类型之间发生转移的概率居多,尤其是2010—2017年期间向上转移类型的数量增加了11个,增加城市主要分布于杭州都市圈、合肥都市圈、武汉都市圈、环鄱阳湖城市群。     

中东欧“地区化”进程的动因分析——以波兰为例

欧洲“地区化”进程分别从20世纪80和90年代在西欧和中东欧开始。西欧国家“地区化”进程受到全球化和欧盟的推动。以波兰为代表的中东欧国家“地区化”进程,除了受全球化推动之外．还受苏联解体后国家内部“民主化”、“现代化”改革需求以及地方政府联合等因素的推动。欧盟通过地区政策的运行对推动中东欧国家“地区化”进程起到积极作用,但该作用不能被过分夸大。     

活动大陆边缘岩浆作用及构造演化——以敦煌地块为例

大陆边缘弧是汇聚板块边界与俯冲有关的岩浆作用产物, 通常记录了造山带弧岩浆作用、造山过程和大陆地壳形成与演化等诸多重要的地质过程。作为中亚造山带中段最南部的构造单元, 敦煌地块为传统定义上具有早前寒武纪变质结晶基底的微陆块, 其后在古生代时期经历了多期次、多阶段的与中亚造山带造山相关的构造热事件并使其发生再活化, 进而产生了一系列广泛的弧岩浆-变质作用事件。然而, 对于该陆块古生代弧岩浆作用机制和地壳构造演化历史缺乏系统的研究。本文综合近十多年来对敦煌地块的诸多最新研究进展, 系统梳理了古生代岩浆岩岩石组合类型、年代格架、地球化学组成以及同时期变质-沉积构造热事件演化特征, 得到以下认识: (1)敦煌地块古生代岩浆作用过程呈现阶段性特征, 即幕式岩浆作用, 构造位置上从东北部逐渐迁移到南部再折返到中部, 大致可划分为五期: ~510Ma、440~410Ma、390~360Ma、~330Ma和280~245Ma, 而变质作用事件主要集中在450~360Ma; (2)古生代岩浆岩类型主要以钙碱性Ⅰ型花岗岩、埃达克质岩石、少量S型花岗岩和高钾花岗岩为主, 且岩石成分从寒武纪低钾拉斑系列逐渐转变为二叠纪高钾、富硅特征; (3)同位素地球化学特征表明, 敦煌地块中-北部寒武纪-泥盆纪发育的与俯冲相关的弧岩浆对新生地壳的生长起了重要贡献, 并伴随古老地壳再造事件; 而南部泥盆纪-石炭纪岩浆作用则以古老地壳物质重熔为主; (4)基于埃达克质岩石的证据, 敦煌地块在古生代时期经历了两次显著的地壳增厚事件, 早期可能是与北山南部石板山地体/弧碰撞以及幔源岩浆底侵有关, 而晚期可能是与俯冲板片后撤或回卷相关, 地壳厚度可达~55km; (5)敦煌地块属于中亚造山带中段最南部一个具有前寒武纪基底的古老微陆块, 后期卷入了古亚洲洋南向俯冲相关的造山事件使其被强烈破坏与改造。该微陆块作为古亚洲洋南部的活动大陆边缘弧, 被与俯冲作用有关的阶段性弧岩浆底侵、部分熔融、增厚地壳和区域性变质作用等机制改造与活化, 产生了阶段性侵位的陆缘弧岩浆作用。这些认识为探究中亚造山带微陆块的起源和造山带的构造演化提供新的约束。

     

Corrigendum: Geological setting and origin of fuchsite‐bearing rocks near Menzies,Western Australia

Quartz‐andalusite‐fuchsite rocks in an Archaean greenstone belt at Menzies, Western Australia, are described in their geological setting. They are shown to have developed from intense metasomatism of layered rocks of komatiitic composition. Ratios of the immobile components Al₂O₃, TiO₂, Cr, V and Zr are consistent, despite wide variations in their absolute values, and compare closely with those of an underlying komatiite suite. Marked depletion of Ca, Na, Mg and Fe has led to a strongly peraluminous composition and enhanced Cr values. Silicification and introduction of K has also occurred. Most of the metasomatism took place before peak metamorphism, and the mineral assemblage is now dominated by andalusite, fuchsite, and recrystallized quartz. Schlieren or vein‐like segregations rich in andalusite, chromite, rutile and minor sulphides and tourmaline are interpreted as the original fluid pathways, where concentration of immobiles was achieved through solution of mobile components, and volume loss. They have been termed residual veins. Metasomatism is believed to have taken place by synvolcanic processes analogous to those operating in modern hot spring systems. The rocks were severely modified by metamorphism and tectonism. The fuchsitic rocks at Menzies are compared to similar rocks in other areas.     

Tectonothermal evolution of the gneiss complex at Salur in the Eastern Ghats Grnaulite Belt of India

Textural relations, thermobarometry and petrogenetic grid considerations in the syn-tectonic granitoid massif and the enveloping metasedimentary gneisses at Salur are consistent with a counter-clockwise P–T –t path for the rocks. The low-P/high-T prograde sector is documented by the pre- to syn-D₁ cordierite±orthopyroxene±garnet±spinel–bearing metatexite leucosomes in metapelites. Heating and loading of the rocks (syn- to post-D₁) resulted in the formation of garnet+orthopyroxene± cordierite-bearing diatexites, and decomposition of cordierite in metatexite leucosomes to orthopyroxene+sillimanite+biotite+quartz symplectites. Near-peak temperature, 850 °C at 8.0 kbar, was reached syn- to post-D₂. Post-peak cooling resulted in the stabilization of coronal grossular and anorthite+calcite symplectites at the expense of scapolite+wollastonite+calcite assemblages in calc-silicate gneisses, and the resetting of cation exchange temperatures at 700–750 °C. Near-isothermal decompression at c. 700–750 °C is manifested by the decomposition of garnet porphyroblasts in the granitoid gneisses to plagioclase+orthopyroxene/ilmenite/biotite two-phase coronas and restabilization of cordierite at garnet margins in metapelites. Subsequent low-P, near-isobaric cooling led to the overprinting of granulite facies assemblages by muscovite+calcite assemblages, and further resetting of cation exchange thermometers to lower temperatures c. 600 °C. The tectonothermal evolution of the Salur gneiss complex vis-a-vis the Eastern Ghats Belt is therefore consistent with high degrees of lower crustal melting, followed by prograde heating of the cover rocks due to magma invasion synchronous with crustal compression, and finally thermal relaxation over a protracted period punctuated by tectonic/erosional denudation of the thickened crust.     

The P-T-d development at the basement-cover boundary in the north-eastern Tauern Window (Eastern Alps): Alpine continental collision

Abstract At the basement-cover boundary of the north-eastern Tauern Window (Eastern Alps), the following Alpine P-T-d development has been reconstructed on the basis of macro- and micro-structures as well as preferred crystallographic orientations, mineral parageneses and compositions.
During increasing P-T conditions in the greenschist facies a first period of deformation produced imbrication of the basement gneisses and cover sediments, and then monoclinal folds up to the kilometre scale. Tectonic transport was continuously top-to-the-ENE. A second period of deformation began at about peak P-T conditions of 9 kbar and c. 540–560°C in the south, and about 7–9 kbar and 490–500° C in the north; this continued locally to lower temperature. During the second period, transport was continuously top-to-the-SE. Crystallographic orientations of white mica and plagioclase give particularly useful information on the kinematic framework. In addition, data on the ductile behaviour of dolomite and plagioclase can be inferred. At c. 7–9 kbar, dolomite recrystallization starts at 450–480° C, and the beginning of plagioclase recrystallization coincides with the oligoclase boundary.
In general, the Alpine geodynamic history of the basement-cover boundary may be related to continental collision processes between a northerly plate (European or Briançonnais) and a southerly (Adriatic) one. The first deformation period possibly reflects subduction of the gneiss-sediment boundary toward the WSW, to a depth of 31–32 km. The second period may be a result of obduction toward the NW, followed by late-stage uplift. Most of the basement domes of the eastern Tauern Window appear as a result of the final stage of the first deformation, formed prior to the peak of metamorphism, possibly partly influenced by the final collision between the northern and the southern continents.     

北半球冬季110°—120°E垂直经向环流的年际变化及其与中国东部同期降水的关系

利用NCEP／NCAR再分析月平均风场资料和中国东部120个站的降水资料,分析了1951--2010年北半球冬季110°-120°E经向环流的气候特征,定义了北半球冬季110°-120°E低纬Hadley环流和中高纬气流强度指数,并分析了其强度的长期变化趋势以及对中国东部同期降水的影响。结果表明：（1）北半球冬季110°-120°E经向环流主要包括低纬Hadley环流和中高纬度从高层到低层较-致的偏北下沉气流。（2）北半球冬季110°-120°EHadley环流和中高纬气流强度有明显的年际和年代际变化,二者在长期变化趋势上表现-致,即在1990年以前呈约20a的振荡周期,且波动更大,而在1990年以后呈约10a的振荡周期,波动相对较小。（3）北半球冬季110°-120°E经向环流强度指数对中国东部同期降水的年际变率具有较高的解释率,二者在统计上呈显著的负相关关系。北半球冬季110°-120°EHadley环流强度和中国东部同期降水相关程度大值区集中在江南、华南及江淮地区,中高纬气流强度和中国东部同期降水相关程度大值区集中在西北、江淮及江南地区。（4）东亚地区冬季经向环流异常的显著差异主要表现在中高纬度反向的异常气流和中低纬度反向异常环流圈的变化。强（弱）经向风年,北半球中高纬度从高层到低层为异常的偏北（南）气流,中低纬度对流层存在顺时针（逆时针）方向闭合的异常经向环流,对应中国东部降水显著减少（增多）。     

Convolutional neural networks applied to semantic segmentation of landslide scars

The frequent occurrence of extreme weather events has rendered numerous landslides to a global natural disaster issue. It is crucial to rapidly and accurately determine the boundaries of landslides for geohazards evaluation and emergency response. Therefore, the Skip Connection DeepLab neural network (SCDnn), a deep learning model based on 770 optical remote sensing images of landslide, is proposed to improve the accuracy of landslide boundary detection. The SCDnn model is optimized for the over-segmentation issue which occurs in conventional deep learning models when there is a significant degree of similarity between topographical geomorphic features. SCDnn exhibits notable improvements in landslide feature extraction and semantic segmentation by combining an enhanced Atrous Spatial Pyramid Convolutional Block (ASPC) with a coding structure that reduces model complexity. The experimental results demonstrate that SCDnn can identify landslide boundaries in 119 images with MIoU values between 0.8 and 0.9; while 52 images with MIoU values exceeding 0.9, which exceeds the identification accuracy of existing techniques. This work can offer a novel technique for the automatic extensive identification of landslide boundaries in remote sensing images in addition to establishing the groundwork for future investigations and applications in related domains.