【摘要】 <正> 汉诺坝碱性玄武岩富含歪长石巨晶体。迄今为止,尚未有关于该类歪长石结构研究方面的报导。本文以汉诺坝三个工作区不同产状碱性玄武岩中歪长石巨晶体为研尧对象,以X光单晶照相为主,辅以X光粉末法、光学显微镜、透射电镜等方法,着重研究它们的结构特更多还原

【Abstract】 The paper is concerned with the anorthoclase megacrysts collected from Damaping Volcanic Cone, Zhangjiawan Lava Sheet and Taoyaowan Pipe in Hannuoba Basalt, which are all alkali basalt. The study is focused on the complex structures of the anorthoclase megacrysts and was carried out mainly by means of single-crystal diffraction in addition to the powder X-ray diffraction, chemical analysis and optical study. The anorthoclase megacrysts from Damaping are characterized by their simpler structures. Only albite law or pericline law twinning can be found on the single diffraction patterns. The same patterns of anorthoclase megacrysts from Taoyapwan Pipe are characterized by bond satellite diffractions, which are caused by density modulation structures.The direction of its wave transmition is nearly parallel to the normal of (10 0 1) and the length is about 100. Several kinds of complex structure diffractions including coherent decomposition (cryptoperthite) and long-Period albite twinning (transverse modulation structure)were found on the patterns of the anorthoclase megacrysts from Zhangjiawan Lava Sheet. The period of the transverse modulation is 17 to 18b.An anorthoclase crystal structure has been determined. The least-squares refinment led to a final discrepancy index R=0.072. The bond lengths of T-O tetrahedron indicate that the structure is almost topochemically monoclinic symmetry.更多还原