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21.
地温变化在气候反馈效应中起着重要作用, 理解地温及其与影响因素之间的时空关系对预测全球温度变化至关重要。利用1998 - 2017年石羊河流域的逐日常规气象观测资料, 采用小波分析结合BP(Back Propagation)神经网络构建了石羊河流域夏季地温预报模型, 结果表明: 日平均地温预测效果在不同站点均为最佳, 其中预测值和观测值的相关系数均大于0.87, 3 ℃以内的预测概率均大于84%。其中, 民勤地区地温预测效果最好, 预测值和观测值的相关系数达到0.91, 3 ℃以内的预测概率达到86%。日最高地温的预测值与观测值的相关系数高于0.8, 但误差平方和、 标准差较大。永昌地区日最高地温的模拟效果最好, 3 ℃以内的预测概率达到83%。日最低地温的预测与观测值的平均相关系数高于0.66, 3 ℃以内的预报概率高于83%, 但预测值略低。其中, 武威地区日最低地温的预测效果最好, 预测值与观测值的相关系数为0.72, 3 ℃以内的预测概率达到94%。研究成果可为有效弥补干旱、 半干旱区地温观测资料缺失和探讨其与局地气候的关系提供一些参考。  相似文献   
22.
Wan  Bo  Wu  Fuyuan  Chen  Ling  Zhao  Liang  Liang  Xiaofeng  Xiao  Wenjiao  Zhu  Rixiang 《中国科学:地球科学(英文版)》2019,62(12):2005-2016
Numerous continents have rifted and drifted away from Gondwana to repeatedly open ocean basins over the past-500 millionyears.These Gondwana-derived continents drifted towards and collided with components of the Eurasian continent to successively close the preexisting oceans between the two.Plate tectonics satisfactorily describes the continental drift from Gondwana to Eurasia but does not define the geodynamic mechanism of continuously rifting to collisions of continents in the Tethy an Realm.After reappraisal of geological records of the rift,collision and subduction initiation from the surface and various geophysical observations from depth,we propose that Eurasia-directed subducting oceanic slabs would have driven Tethyan system in the Phanerozoic.The Eurasia-directed subduction would have dragged the passive Gondwana margin to rift and drift northwards,giving birth to new oceans since the Paleozoic.The closure of preexisting oceans between the Gondwana-derived continents and Eurasia led to continental collisions,which would have induced the initiation of oceanic subduction in the Tethyan Realm.Multiple episodic switches between collision-subduction-rift repeatedly led to the separation of continental fragments from Gondwana and dragged them to drift towards Eurasia.The final disappearance of Neo-Tethy s would have induced collision of the Gondwana-derived continents with the Eurasian continent,giving rise to the Cenozoic Alpine-Zagros-Himalayan collisional system.Therefore,the Eurasia-directed oceanic subduction would have acted as a 'one-way train' that successively transferred the ruptured Gondwana continental fragments in the south,into the terminal in the north.In this regard,the engine of this "Tethyan one-way train" is the negative buoyancy of subducting oceanic slabs.  相似文献   
23.
Any knowledge about Archaean to Palaeoproterozoic magmatic and metamorphic events in North Korea has the potential to make a significant difference to our understanding of the early tectonic configuration and evolution of East Asia. This zircon U–Pb dating and Hf isotopic study documents multiple Neoarchaean to Palaeoproterozoic tectonothermal events from the meta-igneous complex in the Machollyong ‘Group’ of the Rangnim Massif. Two tonalitic-trondjemitic gneiss samples record a crystallization age of meta-igneous protoliths at ca. 2.56 Ga and multiple migmatization and metamorphism from 2.52 to 1.85 Ga. A meta-dolerite sample yields a magmatic emplacement age of ca. 1.83 Ga. In situ zircon Hf isotopic data indicate that most zircons from the gneiss samples have εHf(t) values from –16.9 to + 3.1 and crustal model ages from 2.84 to 3.73 Ga, whereas magmatic zircons from the meta-dolerite dike record εHf(t) values from –5.2 to + 5.2 and model ages of 2.05–2.44 Ga. The first-recognized Neoarchaean tonalitic-trondjemitic migmatite complex in the Rangnim Massif, together with previously identified tonalitic-trondhjemitic-granodioritic (TTG) rocks in the Rimjingang Belt and the coeval counterparts in western Gyeonggi massif, represents the oldest crustal nuclei in the Korean Peninsula. The multiple tectonothermal events in this study present reliable evidence not only for attesting to consanguinity of the basement between the Korean Peninsula and the North China Craton but also for defining the influence scope of the late Palaeoproterozoic orogeny in the Korean Peninsula.  相似文献   
24.
长江口—杭州湾及其邻近海域沉积动力环境及物源分析   总被引:2,自引:0,他引:2  
长江口—杭州湾及其邻近海域的物质输运与生态环境受海域沉积动力特征和物质来源影响。本文利用长江口—杭州湾及其邻近海域沉积物的粒度、铂族元素、稀土元素等分析资料,采用Pejrup M等提出的三角图分类法对长江口—杭州湾及其邻近海域沉积动力环境进行详细分析,将研究区分为8个沉积环境分区:二个强动力河口现代沉积区,二个近岸水团交汇作用区,一个陆架水团锋面区,二个残留沉积区,一个冷涡旋的现代沉积区。对比分析了各沉积动力环境区的粒度特征及其水动力条件,揭示各种水动力条件下的沉积特征,以及各种沉积环境的物源输入特征,为长江、黄河与东海间的物质输运和交换等的研究提供基础资料,有助于我们进一步理解物源、搬运介质、沉积条件等因素对海岸—陆架沉积体系的影响,为河口沉积学和生物地球化学等方面研究提供有用信息。  相似文献   
25.
本文收集、整理、研究了70年代以来的高温高压下岩石的Vp,Vs,Vp/Vs,Vp各向异性等实验资料后得出:(1)低压下岩石Vp的急剧变化是由岩石中裂纹与孔隙等引起的;(2)温度升高可增大由岩石组构引起的Vp各向异性的变化率;(3)同种岩石在不同的大地构造环境中具有不同的波速值与变化规律;(4)Vp在高地温区随温度先降低而后升高,其原因是由矿物相变造成的,与地壳中低速带的性质相当。文章最后讨论了实测波速转换为岩石类型时实验研究岩石波速的意义。  相似文献   
26.
27.
1 Introduction Mesozoic volcano-intrusive rocks are widely distributed in the Da Hinggan Range of northeastern China, and are considered as one of the most spectacular geological sights in eastern Asia. Recently, studies on granites with high εNd(t) values and Phanerozoic crustal growth in the Centra Asian Orogenic Belt have greatly promoted fundamental research into the geology of this area (Jahn et al., 2000, 2001, 2004; Wu et al., 2000, 2002, 2003). However, work on the eruption time,…  相似文献   
28.
Located in the middle segment of the Trans-North China Orogen, the Fuping Complex is considered as a critical area in understanding the evolution history of the North China Craton (NCC). The complex is composed of various high-grade and multiply deformed rocks, including gray gneiss, basic granulite, amphibolite, fine-grained gneiss and marble, metamorphosed to upper amphibolite or granulite facies. It can be divided into four rock units: the Fuping TTG gneisses, Longquanguan augen gneisses, Wanzi supracrustals, and Nanying granitic gneisses. U-Pb age and Hf isotope compositions of about 200 detrital zircons from the Wanzi supracrustals of the Fuping Complex have been analyzed. The data on metamorphic zircon rims give ages of 1.82-1.84 Ga, corresponding to the final amalgamation event of the NCC, whereas the data for igneous zircon cores yield two age populations at -2.10 and -2.51 Ga, with some inherited ages scattering between 2.5 and 2.9 Ga. These results suggest that the Wanzi supracrustals were derived from the Fuping TTG gneisses (-2.5 Ga) and the Nanying granitic gneisses (2.0-2.1 Ga) and deposited between 2.10 and 1.84 Ga. All zircons with -2.51 Ga age have positive initial εHf values from +1.4 to +10.9, suggesting an important crustal growth event at -2.5 Ga through the addition of juvenile materials from the mantle. The Hf isotope data for the detrital zircons further imply that the 2.8 Ga rocks are important components in the lower crust, which is consistent with a suggestion from Nd isotope data for the Eastern Block. The zircons of 2.10 Ga population have initial εHf values of-4.9 to +6.1, interpreted as mixing of crustal re-melt with minor juvenile material contribution at 2.1 Ga. These results are distinct from that for the Western Block, supporting that the Fuping Complex was emplaced in a tectonic active environment at the western margin of the Eastern Block.  相似文献   
29.
Wang  Kaiyong  Wang  Fuyuan 《地理学报(英文版)》2020,30(8):1341-1362
Journal of Geographical Sciences - There is a lack of basic theory and method to examine the effect of administrative division (AD) adjustment on the regional development. Based on the theory and...  相似文献   
30.
旨在研究受人类经济活动影响的植被资源及其动态变化趋势的程度,采用基于归一化植被指数的像素二分模型,利用2002—2010年(武汉市每年8月)的卫星遥感数据,对武汉地区6年间的植被覆盖变化进行监测分析。结果表明,植被覆盖度变化与武汉GDP增长率有着紧密联系:2002—2007年,武汉经济较缓慢上升,植被覆盖度基本维持在55%左右;而2007—2008年武汉GDP总值增长率高达26.06%,但随之而来的是植被覆盖度由高峰期的61.68%下降到49.18%,是历年来的最低水准; 2008—2010年经济发展放缓,植被指数有小幅度回升。人类经济活动是影响植被资源的重要因素。  相似文献   
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