摘要
用弗氏台及透射电子显微镜（ＴＥＭ），对唐巴勒超基性岩体中碎斑状纯橄岩及糜棱岩化斜辉橄榄岩内主要造岩矿物──镁橄榄石的组构与超微构造进行了研究，两种手段所获结果基本一致。它们的位错组态各具特色；碎斑状纯橄岩内的幔成镁橄榄石表现出位错列特征，根据单根位错及位错列得出的布氏矢量为α［１００］，滑移系为（０１０）［１００］。在糜棱岩化斜辉橄榄岩内的幔成镁橄榄石表现出典型的多层结构，而且滑移方向明显，测定的速线方向为［２１１］，进一步还形成了许多出溶物。它们的位错密度、应力或活动性表现出前者小于后者，根据中粗粗幔成镁橄榄石及细粒重结晶或微粒变晶壳成镁橄榄石的组构特征分析它们的滑移系，前者为（０１０）［１００］，后者为（０１０）［００１］。再结合它们的赋存部位及其形成机理分析，北部与南部，深部与浅部或幔成与壳成矿物的组构或组态特征存在差异是理所当然的。这些特征之研究，对于分析铬铁矿等矿产的成矿与找矿具有一定的地质意义。
By means of the Fedorov stage and transmission electron microscope (TEM), the fabric and ultramicrostructure of forsterite, the main rock-forming mineral of both murbrukdunite and mylonitized saxonite in the Tangbale ultrabasic rockbody, has been studied in the paper and the results gained in two ways are same. Their configurations of dislocation are respectively different. In mubruk dunite, the mantle-formed forsterite represents characteristics of the dislocation array that the Burger vector (b) is a (100) and its slip system is (010) (100).In mylonitized saxonite, the mantle-formed forsterite shows a typical multilayed structure and an obviously slip direction, the trace direction is (211) , and a number of exsolved materials further generated out. It is noted that the density, stress and activeties of dislocation of the former forsterite is smaller than that of the later forsterite; and Burger vector (b)of the former shows (010) (100) and that of the later shows (010) (100), according to analysing for their slip system and fabric features of the medium-coarse grained, mantle-formed forsterite and the fine grained recrystal lized or microgranular blastic, crust-formed forsterite. In addition, combined with the analysis for their occurrence and mechanism, it is apparent that the features of fabric or configuration of minerals from the northern or southern, abyssal or hypabyssal, mantle-or crust-formed, are different. These features certainly have the geological significance in analysing and researching for mineralization and exploration of chromite.
出处
《西北地质科学》
1994年第1期1-10,共10页
Northwest Geoscience
关键词
唐巴勒
超基性岩
橄榄石
超微结构
地幔岩
Tangbale,ultrabasic rock,olivine,fabric,ultramicrostructure
