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1.
Continental margins are the transitional zone between continents and oceans. The tectonic deformation of crust in continental margins is very complex. This paper deals with the complex crust tectonics of continental margins in terms of the basic principle that elastic waves travel through semi-infinlte medium and the wave theory of crust. The continental margin off the North American coasts of the Atlantic used to be the active Pacifictype margin. At present, the crust movement in this margin tends to be stable; therefore it becomes the Atlantic type.  相似文献   

2.
The southeast coastal Zhejiang, Fujian, Guangdong provinces and Taiwan in China comprised an important area in ancient Asia where the Yenshanian continental margin magmatic arc well developed in the late Mesozoic time. It is believed that the oceanic trench and subduction zone are situated on the east side of the Central Range in Taiwan. It seems unlikely that the so-called Hercynian-Indosinian ancient island arc folded system would have occurred in this region.  相似文献   

3.
4.
TECTONIC FRAMEWORK OF THE CONTINENTAL BASEMENT OF SOUTHEAST CHINA   总被引:8,自引:0,他引:8  
The chronology and tectonic evolution model of the continental basement in southeast China margin is an important debatable geological subject. The Cathaysia is shown in this paper to be in accordance with many geological facts and also with the age data obtained by multi-dating method. Its age has been determined to range from 900 to 2000 Ma. The age of the unconformity plane in the Cathaysia is 1400 Ma. The collision and suture between the Jiangnan oldland and the Cathaysia took place during the early Jinning Period. Toward Jiangxi, Hunan, Guangdong and Guangxi, these two continents gradually opened to form a residual oceanic basin. The sedimentation centre of the basin continuously migrated southwestward from the Jinning through the Caledonian Period, and finally closed in the Guangxi Movement and Dongwu Movement. The drift-rotation of the Cathaysia after the Jinning Period has been inferred.  相似文献   

5.
The Shangxi Group is the local name in southern Anhui Province and it is believed to be the equivalence of the well-known Banxi Group in Hunan Province, southern China. So the area occupied by the Shangxi Group was regarded as a part of the "Jiangnan old land" of Presinian till it was challenged by the present authors years ago. After we postulated that there may be some strata of Palaeozoic Era in Shangxi Group, some microfossils and then macrofossils of Palaeozoic were found in some part of it. The macrof os-sils, Lingula sp. , Conulariid and the microfossils indicate that most units of the Shangxi Group are Palaeozoic strata. Based on the discovery of these fossils and the recognition of the tectonic-setting of the different tectono-petrologic units in the Shangxi Group, three different stratigraphic sequences (island-arc volcanics, back-arc sediments and the cover of passive margin of Yangtze Continental Plate) are established and the tectonic evolution of them is postulated in the present paper. Al  相似文献   

6.
Dramatic water stage rise and channel aggradation in the middle and lower reaches of the Changjiang (Yangtze) River have been recognized by previous studies. A further analysis of the data from geological, geomorphological, and paleohydrological surveys suggests that these changes might have resulted from sea-level rise since the Lateglacial period. So a mathematical model has been developed here, which reconstructs the processes of water-stage rise and channel aggradation of the Changjiang River as responses to sea-level rise since 12,100 a B.P.  相似文献   

7.
Yupeng Guo  Yan Zhao  Han Gao  Na Gao  Gen Li 《大学化学》2020,35(5):217-222
The online teaching of chemistry and society course has been successfully carried out by using national high-quality online open course as the course resource and Superstar Learning Platform for online teaching. The practice shows that online teaching based on the combination of China University MOOC, and Superstar Learning Platform has been well received by students, who are generally easy to accept and highly motivated to participate. This practice shows good teaching effect.  相似文献   

8.
根据1999-2002年公开的专利,评述了这几年间免处理CTP版材研制开发的内容:1)水处理型;2)附加型;3)形态变化性;4)相变化型.免处理版材被认为是今后CTP版材,尤其是热敏CTP版材发展的方向.但免处理版材若想在实际中推广应用,还有许多问题需待研究解决.  相似文献   

9.
In the light of the plate tectonics the outline of paleogeography, sedimentary properties and facies patterns in the depositional processes of the Wutong Formation at the Lower Yangtze area are discussed. The argument that the Wutong Formation contains not only terrestrial sediments but also marine-terrestrial transitional or marine sediments is expounded to cover the development, evolution and paleoclimate of the Wutong depositional regions.  相似文献   

10.
Based on the characteristics of stratigraphy sedimentary system and paleotectonics, Xizang (Tibet) Tethys can be classified into nine sedimentary basins. The sedimentary and development characteristics of each basin nicely reveal the plate tectonic framework of Xizang (Tibet). The studies show that the Bangong Lake-Dengen fracture zone is intraplate transform boundary, the active continental margin of the Yarlung Zangbo River is of the nature of "range-arc" boundary, not trench-arc-back-arc basin system.  相似文献   

11.
The South China Sea is the westernmost marginal sea in the west Pacific Ocean. On thebasis of the analyses of sedimentary components, biofossils, oxygen-carbon isotopes and theirdatings in four seafloor cores which were collected from the deep sea plain to continentalslope in the northern South China Sea, the environmental variations were basically similarto other tropical ocean areas, and their cycle changes in about the ages of 40 ka and 20 kawere more apparent since the late Pleistocene. During the warm climates, the depositionrate on the continental slope was about 2.6 times as rapid as on the deep sea plain margin.The seafloor in the deep sea plain was below the CaCO_3 compensation depth. During thecold periods, however, the deposition rate on the deep sea plain margin was slightly quickerthan on the continental slope due to the sea level reduction on a larger scale and moresupply of the terrigenous clastics.  相似文献   

12.
This study presents a scheme for delimiting the meiyu period in the Lower Changjiang (Yangtze) region. This scheme was applied to the Clear and Rain Records of Nanjing, Suzhou and Hangzhou to reconstruct the 1723-1800 meiyu climate series. The beginning and ending dates, length, precipitation, and the intensity grades of meiyu were determined. The years of early, heavy, light, and empty meiyu were also given. Statistical analyses of the 18th century meiyu series indicate the existence of the quasi-periodicities of 2-3, 4-5, and 9 years. Many basic characteristics of the modern meiyu also existed in the 18th century. Some characteristics of the Northwest Pacific Subtropical High in the 18th century in typical meiyu years were inferred from the historical meiyu series.  相似文献   

13.
The study of terranes has already become an important subject in research of the Circum-Pacific continental margin. This paper discusses proper understanding of the terrane conception and identifies existence of the Nadanhada terrane according to its difference from the neighbouring massifs in terms of evolutionary history, tectonic background, and deformation features, and to the fault-contact relation between them; analyzes the paleogeographic position variation of the Nadanhada terrane during the Triassic to late Jurassic and the period when the terrane was attached to the ancient continental marging; finally discusses the consequential effects of theterrane accretion from the observed tectonic events after terrane collage.  相似文献   

14.
小叶桉油的分析   总被引:1,自引:0,他引:1  
杨泽东  杨泽榆 《分析化学》1989,17(7):577-581
  相似文献   

15.
样品经硝酸分解,有硫酸钡共沉淀分离铅后,锡在硫酸氯化钠底液中,在峰电位-0.52V处产生良好的还原波,能直接测定电解锰电解锰用阳极板中锡。回收率为98.0%-101.6%,相对标准偏差0.91%-2.98%,方法简便,快速,准确、优于容量法,已应用于工业分析。  相似文献   

16.
《高分子学报》1998,(4):494-497
重氮树脂与十二烷基硫酸钠相互作用研究罗杨磊曹维孝(北京大学化学与分子工程学院北京100871)关键词重氮树脂,十二烷基硫酸钠,负性PS版随着化学与生命科学领域的发展,大分子与小分子在溶液的相互作用越来越受到关注.表面活性剂因其具有自组装能力,...  相似文献   

17.
分析了目前国内发布的光谱标样的不均匀性,提出了要强调要调不均匀性的概念。为了能检出光谱标样的不均匀性,应该重新设计光谱标样的均匀性检验方案,同时应明确定义不均匀性的概念。  相似文献   

18.
The influence that 1,3-butyleneglycol incorporated as polar cosolvent in the aqueous phase determine on the O/ W micromulsion region of the classical system water/ sodium dodecyl sulfate/ pentanol/ heptane, has been studied. Phase diagrams corresponding to aqueous phases made of water/ butyleneglycol in ratios 907sol; 10 and 75/ 25 are compared with the typical system with water.The resulting increase on the OAV microemulsion region for the systems including the glycol, provides a security margin to prepare such compositions with respect to the narrow channel of solubility described for the conventional system. Although the presence of butyleneglycol lead to a shift in the optimal ratio between the aqueous phase and SDS from the 85/ 15 described for the typical system to higher proportions in surfactant, the simplicity of preparation of such O/W microemulsions could compensate the higher amount of SDS required  相似文献   

19.
Populus tomentosa is one special species of poplar growing in North China. Mesophyllprotoplasts were isolated from the axenic shoots and cultured in the modified KM8p liquidmedium. Protoplast-derived cells started to divide after 7 days of culture. The frequencyof cell division reached about 20% in 10 days. The yellowish green calli grew compact andnodular after the hormone concentration of medium was adjusted. Shoot formation occurredwhen the protoplast--derived calli were transferred onto MS medium containing zeatin andIAA or NAA. The shoots rooted readily on 1/2 MS hormone--free medium.  相似文献   

20.
阳图PS版和阴图PS版,分别属光分解和光交联型。阳图PS版在我国已广泛应用,而阴图PS版处起步阶段。由取代二苯胺重氮树脂制备的阴图PS版热稳定性好,贮存期长。  相似文献   

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