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The presence of a single Otoceras species (O.boreale), morphologically very variable, at the base of the Nekuchan Formation in Verkhoyansk, we believe, is to be obvious. Some morphological evidence leaves no doubt that two described morphs of O. boreale are s strictly corresponding sexual dimorphic pair. It is very likely that Kummel‘s idea that Canadian. O. concavum Tozer is an invalid species is truthful, considering the range of variability seen in larger Siberian and Himalayan Otoceras fauna. Just above the upper Tatarian Imtachan Formation, the six stages of ammonoid succession can be recognized within the lower part of the Nekuchan Formation in the Setorym River Section:(a) Otoceras boreale;(b) Otoceras boreale-Tompophiceras pascoei; (c) Otoceras boreale-Tompophiceras pascoei-Aldanoceras;(d)Tompophiceras pascoei-Otoceras boreale-Aldanoceras;(e) Tompophiceras morpheous-T.pascoei-Aldanoceras;(f) Tompophiceras more pheous-T.pascoei-Wordieoceras domokhotovi-Ophiceras transitorium;(g)Tompophiceras morpheous-T.pascoei, corresponding to the Otoceras boreale and Tompophiceras morpheous zones. In spite of the domination of Otocerataceae or Xenodiscaceae in both oif these zones and the presence of some Permian type conodonts in the lower part of the Otoceras boreale Zone, they seem to be early Induan in age on the basis of the following arguments:(1) in contrast to the underlying regressive type sediments of the Upper Tatarian Imtachan Formation, both the Otoceras boreale and the Tompophiceras morpheous zones of the lowermost part of the Nekuchan Formation correspond to the single transgressive cycle;(2)typical early Induan ammonoids (Ophiceras and Wordieoceras) have been recognized in the Tompophiceras morpheous zone; (3) all described ammonoid succession stages (a-g) are characterized by very gradual changes and therefore correspond to the different parts of the single zone or to the different zones of the same stage, but not to the different systems (Permian and Triassic);(4)elsewhere in the Boreal realm (Arctic Canada), the conodont index species for the base of the Triassic, Hindeodus parvus, has been reported from the Otoceras boreale Zone. A new scheme of the phylogeny for the Otocerataceae and its Induan-Olenekian offspring (Araxceratidae-Otoceratidae-Vavilovitidae n.fam.-Proptychitidae-Arctoceratidae) and Xenodiscaceae is offered.  相似文献   
2.
我们通常所说的中亚,是指原苏联亚洲部分的中亚细亚地区,即现在的哈萨克斯坦、乌兹别克斯坦、塔吉克斯坦、吉尔吉斯斯坦和土库曼斯坦。这五个国家总面积400余万平方千米,总人口约5500万人。在西方的地理概念中,阿富汗也属中亚国家。中亚深处亚洲腹地,位于扼守亚欧大陆的十字路口,从北向南可进入盛产石油的中东地区;从南向北可进入俄罗斯的高加索、西伯利亚地区;  相似文献   
3.
北方海航道是联系亚、欧、美三大洲潜在的最短航线,在北极地区和西伯利亚地区资源开发中具有重要的运输价值;北方海航道是连接大西洋和太平洋的重要军事通道,是战略导弹核潜艇的隐藏区,在军事侦察方面有重要价值。  相似文献   
4.
《海洋世界》2007,(4):8-16
在地球冷暖交替的变化中,欧洲如同跳跳板的最远一角,暖得最快也冷得最快;如果全球持续变暖,全世界都将变得温暖异常,包括西伯利亚地区,而欧洲会变成北半球的寒极,取代今天西伯利亚的地位,这种趋势说到底就是格陵兰和北冰洋的海洋持续融化的结果。[编者按]  相似文献   
5.
The map of reflecting horizon A, plotted on the basis of regional geophysical materials, yields information about the bottom topography of sedimentary cover of the West-Siberian Basin within Nadym-Taz interfluve. Through morphotectonic analysis about this surface, the authors are able to understand the distribution characteristics of the main topographic irregularities, with the block structure of the lower cover floors and underlying complexes as the focus. The largest irregularities are caused by the presence of three regional altitude steps, which show a regional tendency of basement being submerged in the north-north-east direction. Within these irregularities, the authors have distinguished some regions, which can be divided, based on the characteristics of morphostructural distribution, into two groups, i.e., areal (Nadym, Tol‘ka, Urengoy) and belt (Tarko-Sale, Russko-Chasel‘ka and Messoyakha). The first ones represent quasihomogeneous blocks, whose surfaces are complicated by irregular low-amplitude elevations and troughs and low-gradient zones with gradient values being up to 0.03, or they submerge stepwise, with the leveled areas being separated by zones with high gradients (0.07-0.15). The morphostructure ofthe other group of regions is characterized by the en-echelon distribution of contrastingly positive and negative elements with high values of slope gradients (higher than 0.1-0.2).  相似文献   
6.
10层陆面过程模式及其Offline独立试验   总被引:4,自引:0,他引:4  
利用西伯利亚地区的一个试验点资料和1998年中国淮河流域试验(HUBEX)的加密观测资料,对一个新发展的陆面过程模式进行了模拟检验。西伯利亚地区的单点试验表明,不同时间间隔的边界强迫对地表吸收的净短波辐射和释放的潜热影响较大。淮河流域的模拟结果表明,模式能够较好地模拟出我国夏季半湿润地区陆面特征量的变化趋势。由于模式模拟的地温偏低、净短波辐射偏小。所以模拟的感热和潜热值偏小。对该模式在淮河流域的植被、土壤等参数的合理选取可能会提高模式的模拟效果。  相似文献   
7.
Reflection of stratospheric planetary waves and its impact on tropospheric cold weather over Asia during January 2008 were investigated by applying two dimensional Eliassen-Palm (EP) flux and three-dimensional Plumb wave activity fluxes.The planetary wave propagation can clearly be seen in the longitude-height and latitude-height sections of the Plumb wave activity flux and EP flux,respectively,when the stratospheric basic state is partially reflective.Primarily,a wave packet emanating from Baffin Island/coast of Labrador propagated eastward,equatorward and was reflected over Central Eurasia and parts of China,which in turn triggered the advection of cold wind from the northern part of the boreal forest regions and Siberia to the subtropics.The wide region of Central Eurasia and China experienced extreme cold weather during the second ten days of January 2008,whereas the extraordinary persistence of the event might have occurred due to an anomalous blocking high in the Urals-Siberia region.  相似文献   
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