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271.
以2015-02-09果敢冲突后大量缅甸难民进入中国云南省这一事件为背景,结合实地调研所做的问卷和访谈,从交往的基础、交往的形式、交往的频度以及影响交往的因素等方面探讨了中缅边民交往状况。结果发现:1)中缅边民交往的基础有历史渊源、地理空间和政策的支持;2)交往的形式和内容有商贸、教育和情感等;3)中缅边民交往的频度和强度非常高;4)影响中缅边民交往的因素有中缅国家间关系、中缅之间边境贸易政策和两国对外开放政策等。  相似文献   
272.
对西秦岭北缘漳县地区上新统韩家沟砾岩的地貌特征、高程分布、沉积特征、构造变形等研究表明:1)该套砾岩分布受西秦岭北缘断层系F2逆冲断层控制,主要由巨砾-中砾砾岩组成,有近源快速磨拉石沉积的特征,代表了上新世以来西秦岭地块沿北缘断层向北逆冲挤出形成的再生前陆磨拉石盆地,指示了西秦岭地块上新世以来的一次强烈的构造隆升。2)这套砾岩出露高程及宏观地貌特征指示了其形成之后又与西秦岭地块一起经历了侵蚀夷平,形成了现今海拔2 600 m 左右统一的夷平面。该夷平面的整体隆升和解体、韩家沟砾岩雅丹地貌形成和发育六级侵蚀阶地或基座阶地的漳河水系形成才真正标志着西秦岭及北缘区域的整体隆升。现今海拔1 800 m 漳河河床与2 600 m 山顶夷平面之间的高差反映了西秦岭及其北缘第四纪以来至少相对隆升了800 m。3)西秦岭北缘漳县韩家沟砾岩下伏的渐新统-中新统红层盆地沉积序列具有伸展断陷盆地充填特征,指示了这个时期西秦岭北缘处于拉张伸展构造状态,也就是说以构造挤压缩短为动力学背景下的青藏高原隆升和构造变形在渐新世-中新世时期尚未扩展至西秦岭北缘区域。尽管该断陷盆地最上部河流相-洪泛相粗碎屑沉积增多和之后地层掀斜及褶皱缩短有可能反映了中新世末或上新世初西秦岭北缘由伸展到挤压的构造转换和构造隆升,但这并不是西秦岭及北缘区域的一次强烈隆升。综上所述,我们认为西秦岭北缘上新统韩家沟砾岩出现标志着西秦岭地块向北强烈逆冲和构造隆升,但西秦岭的这次强烈隆升仅持续到上新统韩家沟砾岩沉积结束,之后西秦岭地块和北部的再生前陆磨拉石盆地一起经历了整体隆升和侵蚀夷平,形成了上新世末或第四纪初的统一夷平面。该山顶夷平面是西秦岭及其北缘区域最后整体强烈隆升的起点。韩家沟砾岩雅丹地貌形成、发育六级侵蚀阶地或基座阶地的漳河水系形成真正指示了西秦岭及北缘区域的整体隆升过程。如果西秦岭及其北缘新生代以来隆升过程在青藏高原东北缘具有代表性,那么就说明青藏高原东北缘真正隆升成为现今青藏高原系统组成部分只是上新世末期或第四纪以来地质事件。  相似文献   
273.
The extent, basal conditions and retreat history of a Loch Lomond Stadial glacier are reconstructed based on detailed geomorphological and sedimentological assessment. We present new evidence from the vicinity of Coire Ardair that supports the former existence of a warm-based, locally-fed valley glacier, with probable cold-based ice on the surrounding plateau. This is broadly consistent with modelled creep-dominated flow in the upper catchment and sliding-dominated flow throughout much of the valley. A dense suite of moraines, primarily formed in ice-marginal environments, records a multi-phase recessional history: (1) active and oscillatory retreat; (2) a prolonged ice stillstand; (3) partial ice stagnation with occasional minor readvances; (4) increased oscillatory retreat with a substantial readvance event; and (5) rapid and uninterrupted retreat. We propose that a Coire Ardair glacier responded to sub-centennial scale climate fluctuations, possibly associated with the periodic delivery of warmer air masses to the region, rather than to a single, prominent shift in climate.  相似文献   
274.
This article considers how licensing law conceives and practices jurisdiction. It examines the limits of attempts to define and exploit jurisdiction in the regulation of social problems connected to alcohol. Using the case study of a prohibition on the sale of spirits in the Scottish town of Motherwell during the First World War, it analyses how ‘vertical’ legal appeals through higher courts intersected with everyday ‘horizontal’ challenges to the jurisdiction of the local licensing magistrates as the ban pushed drinkers and the problems of drunkenness onto neighbouring authorities. Those higher court challenges importantly confirmed the localness of licensing, but they could not guarantee the effectiveness of the magistrates’ policy. By showing the potentially disruptive daily habits of ordinary citizens and urban infrastructure, the article promotes a social and material legal geography of licensing. In conclusion, it calls for a critical examination of the ‘local’ in local government, and the political geographies that result from appeals to space and scale in the division of governance functions.  相似文献   
275.
The South China Sea(SCS) is one of the most productive and accumulative marginal shelves of organic carbon in the world. To expound the transformation and preservation of organic carbon in the Northeast SCS, where abundant oil and gas resources have been reported, compound specific sterols in free(FR), base hydrolytic(BH), and acid hydrolytic(AH) forms were analyzed in surface and columnar sediments in May, 2016. The results showed that the total contents of sterols detected ranged from 0.15 to 3.74 ppm dry weight in the surface sediments, and gradually decreased from 3.41 to0.17 ppm dry weight from surface to deep sediments, in which cholesterol(27~(△5)) was the most abundant component. Sterols mainly existed in the BH form(54.51%-74.20%), followed by the FR form(25.50%-45.49%) and then the AH form(0-3.77%) in turn, in the surface sediments. BH and FR sterols accounted for 0-49.08% and 50.92%-100% in the columnar sediments, while AH sterols were undetectable. The contents of specific sterols indicated that, the primary source of marine organic carbon was about 5 times as much as that from terrestrial input. More and more FR sterols transformed into BH sterols with increasing sedimentary depth, and BH sterols absolutely dominated in sediment depths under 25 cm. The forms of Sterols C27 were maintained at a relative consistence state, but Sterols C28 to C30 degraded gradually during the sedimentation process. It was suggested that the stability of sterols, based on the chemical structures, might be the primary factor controlling their degradation and preservation in deeper sediments. These results would help to understand the organic carbon(OC) transformation in a hydrate formation area in a marginal sea.  相似文献   
276.
Abstract Eocene (Middle) and Cretaceous (Campanian) radiolarian faunas from the basement rocks of the southern part of South Andaman Island in the northeastern Indian Ocean affirm the sedimentological hiatus that encompassed part of the Paleocene to Early Eocene ages in these islands, and its extension northward to Indoburma region and south to the outer islands of the Sunda Arc.  相似文献   
277.
G. R. Shi  L-P. Zwan 《Island Arc》1996,5(4):386-395
Abstract Paleobiogeographically mixed marine faunas have been well recognized from many Permian marine sequences in northeast China. These mixed faunas are normally associated with Monodiexodina fusulinid assemblages. The mixed faunas are characterized by an admixture of both paleo-tropical Cathaysian taxa and cool-temperate elements. In addition, endemic taxa, especially at a specific level, and anti-tropical forms, are also very distinctive.
Previously, the presence of anti-tropical taxa in these mixed faunas has been used to argue that some of the northeast Asian terranes may have originated from northern Gondwana during the Permian, where they may have been m close proximity to Tibet. However, this interpretation is contrasted by the view offered in this paper. It is argued that the anti-tropical distribution of marine taxa is a normal, predictable biogeographical phenomenon that is probably controlled by certain climatic conditions. Permian anti-tropicality seems to have occurred most strongly during the Late Artinskian to Ufimian, probably in association with the presence of distinct mesothermal climatic zones at the time. In the present study we report a mixed mid-Permian marine fauna (fusulinids and brachiopods) from the Dasuangou Formation of the Yanji area in the eastern Jilin Province of northeast China, and discuss its possible origin in the context of Permian paleogeography and the climates of eastern Pangea.  相似文献   
278.
The Kinloch Hourn fault is the most prominent of a number of suspectedpostglacial faults in the western Scottish Highlands. These faults areinterpreted to have been reactivated by repeated large (M > 6)palaeoseismic events following deglaciation 10,000–13,000 years ago.Based on inferred deflections of drainage courses, previous studies of thefault have estimated 160 ± 40 m cumulative left-lateral displacementalong a 14 km long active segment during postglacial times. Reportedsoft-sediment deformation phenomena imply that activity on the KinlochHourn fault has persisted into the late Holocene, with the most recentmovement having been associated with a magnitude 5.5–6.0 surface-faultingevent between 3500 and 2400 years ago. The marked contrast betweensuch palaeoseismic activity and the present-day seismic quiescence ofwestern Scotland has stimulated this critical reappraisal of the KinlochHourn fault.This paper reassesses the key lines of evidence for postglacial fault activityand palaeoseismicty on the Kinloch Hourn fault, combining the analysis of1:15,000-scale air photos, field-based geomorphic mapping andpalaeoenvironmental investigations. Our reappraisal of inferred drainagedeflections across the fault contends that previous reports of significant(102 m) left-lateral slip on the fault during the Holocene arespurious. Instead, incidences of Holocene channel abandonment along thefault line are non-synchronous and probably reflect non-tectonic drainagechanges. The timing of soft-sediment deformation in the vicinity of the faultis revised to an early Holocene date (8990–8580 calendar years BP), whichis in accord with both the palaeoenvironmental history of the site andconsistent with published ages of earthquake-induced liquefactionphenomena documented elsewhere in western Scotland. An alleged recent(post-2400 radiocarbon years BP) ground rupture on the fault isquestioned in the light of uncertainty about both the nature of the faultedsoil deposit and the late Holocene age attributed to it.The study concludes that there is no convincing evidence for postglacialsurface rupture on the Kinloch Hourn fault and speculates that the casefor significant (101–102 m) postglacial movement on otherfaults in western Scotland may be similarly `unproven'.  相似文献   
279.
中国东北地区夏季旱涝的分析研究   总被引:30,自引:21,他引:30  
孙力  安刚  丁立 《地理科学》2002,22(3):311-316
利用东北三省及内蒙东北部均匀分布的80个测站40年(1961-2000年)夏季(6-8月)月降水资料以及正态化Z指数变换、小波分析和正交旋转主成份分析等方法,对东北地区夏季降水进行了旱涝等级划分,并探讨了旱涝发生的时间演变规律和空间分布特征。结果表明,东北地区夏季不同级别旱涝出现的几率存在着一定的差异,并且旱涝异常还具有明显的年际、年代际和周期性变化以及阶段性和群发性持征,地理分布上,可将东北地区夏季降分为7个旱涝型(或敏感区),各敏感区内旱涝异常具有相对一致的性质。  相似文献   
280.
The relationship between summer rainfall anomalies in northeast China and two types of El Ni?o events is investigated by using observation data and an AGCM. It is shown that, for different types of El Ni?o events, there is different rainfall anomaly pattern in the following summer. In the following year of a typical El Ni?o event, there are remarkable positive rainfall anomalies in the central-western region of northeast China, whereas the pattern of more rainfall in the south end and less rainfall in the north end of northeast China easily appears in an El Ni?o Modoki event. The reason for the distinct differences is that, associated with the different sea surface temperature anomalies (SSTA) along the equatorial Pacific, the large-scale circulation anomalies along east coast of East Asia shift northward in the following summer of El Ni?o Modoki events. Influenced by the anomalous anticyclone in Philippine Sea, southwesterly anomalies over eastern China strengthens summer monsoon and bring more water vapor to Northeast China. Meanwhile, convergence and updraft is strengthened by the anomalous cyclone right in Northeast China in typical El Ni?o events. These moisture and atmospheric circulation conditions are favorable for enhanced precipitation. However, because of the northward shift, the anomalous anticyclone which is in Philippine Sea in typical El Ni?o cases shifts to the south of Japan in Modoki years, and the anomalous cyclone which is in the Northeast China in typical El Ni?o cases shifts to the north of Northeast China, leading to the “dipole pattern” of rainfall anomalies. According to the results of numerical experiments, we further conform that the tropical SSTA in different types of El Ni?o event can give rise to observed rainfall anomaly patterns in Northeast China.  相似文献   
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