摘要:
大洋沉积物中的微玻璃陨石和火山玻璃是两类性质截然不同的微玻璃体,前者SiO2含量十分稳定,MgO含量比较高,Na2O和MnO含量都很低,并具有Os、Ir等重要地外元素丰度特征。另外,还具有特殊的表面结构以及一定的形成年代。后者的SiO2含量不稳定,MgO含量很低,Na2O和MgO含量比较高,不具有Os、Ir等地外元素丰度特征。因此,不可将它们混为一谈。
Abstract:
In the oceanic sediments generally contained two kinds of glassy grains(the size less than a millimeter), i. e. the microtektites which are extraterrestrial material, and seafloor volcanic glass which are terrestrial material. Because both of them are very different in properties, should not lump together. The tektite distributed widely all over the world is still attended by geologists, meteorists and space scientists, an important research object in various sciences. The microtektites distributed widely in Atlantic, Indian Ocean and Pacific are also same material because they have same physical, chemical properties, surface feature and formed age, which they were divided into different strewn fields. Important characteristics in chemical composition of microtektites are that their contents of SiO2 are stable,contents of MgO are higher, and contents of Na2O and MnO are very low. In addition, also microtektites contained Os, Ir, etc. important trace elements, which are suggested that originate from extraterrestrial. Different microtektites in each strewn fields have variety physical properties, surface feature and formed age. The basaltic glasses in ocean floor are volcanic products in the affirmative. Their properties in colour, type, structure, etc. suggest that they had passed ejected and melted process. Important characteristics in chemical composition of basaltic glasses are that their contents of MgO are very low,contents of Na2O, K2O and MnO are all higher, which simlar to chemical composition of volcanic glasses on the continent. The "bomb-shaped glass" different from microtektites and basaltic glasses. They are mainly composed of SiO2 in chemical composition(contents of SiO2 90%), contents of other oxides are all low. The results of neutron activation analysis indicate that they contained only a few of trace elements(Fe, Co, Au, etc.) none coutain Os, Ir, et. cparticular trace elements. Therefore, they are not extraterrestrial material, and perhaps they are products ejected by volcano from ocean bottom.
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