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1.
童银洪  卢传亮  刘永 《科技咨询导报》2013,(32):241-243,246
采用“平板珍珠”研究方法,将白云岩平板插入和固定在马氏珠母贝Pinctadamartcnsij(Dunkcr)的内表面,获得不同阶段的平板珍珠、采用扫描电子显徽镜观察在平板珍珠形成过程中沉积序列,旨在阐明海水珍珠的形成机理。为开发新型珠核材料提供理论指导。  相似文献   
2.
  总被引:11,自引:0,他引:11  
This paper summarizes the lithogeochemical features of composite lavas, dikes and plutons composed of early Cretaceous associated basic-acidic igneous rocks from the coastal area of Zhejiang-Fujian. On the basis of the studies on Nd, Sr, Pb isotopic signatures and geochemical characteristics of large ion lithophile elements (L1LE) , light rare earth elements (LREE) and high field strong elements ( HFSE) of these contemporary basic-acidic igneous rocks, it is considered that the source enrichment caused by the subduction of Pacific plate and contamination of crustal rocks and melts during ascending process may lead to the formation of basaltic magmas with a high LILE concentration. These late Mesozoic composite basic-acidic igneous rocks are the products of the interactions between crust and mantle in active continental margin.  相似文献   
3.
结合野外产状,通过对塔子山新生代玄武岩及其地幔捕虏体在显微镜下进行详细系统的岩相学研究,得到玄武岩为块状构造,斑状结构,大斑晶矿物主要是橄榄石、辉石;基质呈玻晶交织结构或间粒-间隐结构,主要是长柱状长石、双锥状六边形橄榄石、辉石、少量副矿物和玻璃质。玄武岩携带的尖晶石二辉橄榄岩捕虏体,以镶嵌不等粒状结构为主,主要由橄榄石、单斜辉石、斜方辉石和少量尖晶石组成。  相似文献   
4.
太平洋板块边界和内部均发育大量火山,是研究地球火山的天然实验场。综述了太平洋火山特征与深部成因机制,表明研究人员对地球不同环境下的火山(包括大洋中脊、俯冲带岛弧、板内地幔柱等)进行了系统性研究,分别构建了减压熔融、俯冲板片脱水与富水地幔楔熔融、地幔柱高温熔融的经典模式。但目前学界对于板内非地幔柱型火山的深部岩浆起源以及浅部喷发通道等重要科学问题仍缺乏清晰的认识。未来需要采用创新观测手段,开展多学科交叉研究以取得突破。  相似文献   
5.
    
《科学通报(英文版)》1994,39(13):1106-1106
  相似文献   
6.
构造了一个求解最小函数依赖集Fmin的计算机算法.该算法将求解Fmin的逻辑推理过程包装在一个C 函数之中,通过运行与此函数相配套的程序,可以快速、准确地获得与所给函数依赖集F等价的Fmin从而使求解Fmin的过程方便、快捷.  相似文献   
7.
  总被引:2,自引:0,他引:2  
The Yulinshan accumulations of volcanic rocks and interbedded weathered mantles provide a unique chance for studying the processes and environment of the formation of the planation surface in central Tibetan Plateau. Geochemical,40Ar/39Ar and K/Ar geochronologic investigations of the weathered mantles and high-potassium volcanic rocks reveal that the volcano-weathered mantle accumulations formed under arid or semi-arid subtropic environment in 30–24 Ma. The sole planation surface of the Qiangtang region finally formed in about 20 Ma.  相似文献   
8.
以西南印度洋脊为例,从地形地貌、地幔性质与岩浆作用等方面分析了该超慢速扩张脊地质特征,并分别对西南印度洋洋脊西段、中段、东端热液活动及多金属硫化物成矿特征进行总结。结果表明:西南印度洋脊中间隆起段热液活动可能主要受深部岩浆热源控制,而东西两侧脊段热液活动可能主要受构造或基底岩石类型控制;地幔性质、岩浆作用与热液活动等方面仍是超慢速扩张洋脊今后研究的主要方向。  相似文献   
9.
  总被引:16,自引:0,他引:16  
Much attention has been paid in the last two decades to the physical and chemical processes as well as temporal-spatial variations of the lithospheric mantle beneath the North China Craton. In order to provide insights into the geodynamics of this variation, it is necessary to thoroughly study the state and structure of the lithospheric crust and mantle of the North China Craton and its adjacent regions as an integrated unit. Based on the velocity structure of the crust and upper mantle constrained from seismological studies, this paper presents various available geophysical results regarding the lithosphere thickness, the nature of crust-mantle boundary, the upper mantle structure and deformation characteristics as well as their tectonic features and evolution systematics. Combined with the obtained data from petrology and geochemistry, a mantle flow model is proposed for the tectonic evolution of the North China Craton during the Mesozoic-Cenozoic. We suggest that subduction of the Pacific plate made the mantle underneath the eastern Asian continent unstable and able to flow faster. Such a regional mantle flow system would cause an elevation of melt/fluid content in the upper mantle of the North China Craton and the lithospheric softening, which, subsequently resulted in destruction of the North China Craton in different ways of delamination and thermal erosion in Yanshan, Taihang Mountains and the Tan-Lu Fault zone. Multiple lines of evidence recorded in the crust of the North China Craton, such as the amalgamation of the Archean eastern and western blocks, the subduction of Paleo-oceanic crust and Paleo-continental residue, indicate that the Earth in the Paleoproterozoic had already evolved into the plate tectonic system similar to the present plate tectonics.  相似文献   
10.
  总被引:3,自引:0,他引:3  
Sulfide fluid incluision study on mantle xenoliths of Hannouba has been carried out by EPMA analysis. It is indicated that the Ni/Fe ratios of metal sulfides in sulfide-melt inclusions from Hannuoba seem to be related to host rocks. These data of lherzolite (pentlandite) are obviously higher than those of olivine pyroxenite (mainly pentlandite, partly pyrrhotine). The LRM analysis shows that sulfur (H2S + SO2) occupies larger proportion in gas composition of CO2 fluid inclusions, generally more than mol 20%. This may be related to sulfide inclusions which are frequently found.  相似文献   
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