摘要
一、侵入杂岩岩石、矿物特征(一)杂岩的阶段划分 这个燕山晚期杂岩体,主要侵入于山东某铁矿区奥陶纪地层,少数与寒武系和石炭-二叠系呈侵入接触关系。经各方面调查研究,它具多阶段侵入活动特点,根据穿插关系主要可分五个期次。岩石类型及产出地点见下表(表1)。
The Yenshanian magmatic complex consists of a series of poly-staged intrusions.The igneous rocks of each stage have their own characteristics in petrology,mineralogy and petrochemistry,and a certain regularity in the evolution of magma from its early to its late stage has revealed.The rock bodies related to the iron deposits show strong differentiation,assimilation and late stage metasomatism.The rocks are chiefly intermediate in composition and are characterized by a high content of CaO,Fe_(2)O_(3)+FeO+MgO,alkalies,especially Na_(2)O,and also high ratio of Fe_(2)O_(3)/FeO.Through the study,the author has noticed that different mineral-pairs occur in regular intergrowth of different genetic significance as follows:orthopyroxene and clinopyroxene;orthopyroxene and hornblende;clinopyroxene and hornblende;plagioclase and orthoclase.The corresponding crystal axes and planes of the pair minerals that constitute the intergrowth are near to,but not parallel to each other as usually supposed,and their optical elements posses feature of directed arrangement.In the contact metasomatic iron ore deposits of this region,there occurs a strong alkaline metasomatism of the intrusive which reveals a remarkable alteration zonation.The physicochemical properties of minerals of the same group in various zones are different,for instance,there arc certain differences in mineral variety and physicochemical properties for such mineral groups as garnet,pyroxene,phlogopite,chlorite,etc.
作者
董振信
Dong Zhenxin(Laboratory of Shandong Bureau of Geology)
出处
《地质学报》
1978年第2期81-94,169,共15页
Acta Geologica Sinica
