摘要
斜长岩产出可分为两类：层状型和岩体型。前者不形威独立岩体，而为层状基性-超基性杂岩中的斜长岩层。这种杂岩体具韵律性，层状构造发育，造岩矿物成分随层位有规律变化，它是基性岩浆重力结晶分异的产物，时代不限。岩体型斜长岩只产于前寒武纪，呈巨大岩体，多见于地台和地质的边缘，常与环斑花岗岩共生。它在大陆壳的分布虽不广，但其产出的构造位置、侵入的围岩、形成时代、岩性及与之共生岩石和含矿性等都有明显的共性。
The Damiao anorthosite suite occurs in the high-grade Precambrian metamorphie rocks in the axial part of the Inner Mongolia Anticline. It is a monoclinal layered intrusive, with distinguishable layers of anorthosite, monzonite and quartz monzonite from the top to the bottom of the suite. Gradation evidence can be noticed between these layers. Accumulation structure is obvious in anorthosite. In anorthosite feld-spar belongs to antiperthite and plagioclase host is An 44-49, while in the acid rock facies, perthite and plagioclase are present. The suite investigated can be as-signed to andesine type.Both the Damiao anorthosite and the Miyun rapakiwi granite are calc-alkaline in terms of petrochemical characteristics, and the latter exhibits a very close petroche-mical similarity, i.e., high in Al and K, with the acid member in the top layer of the anorthosite suite in Damiao. In view of the close temporal and spatial rela-tionship and the resemblance of rock structure, it is thought that the two suites are resulted from a single parent magma under approximate tectonic environments, and that gravitative fractionation may have played an important role during their evolution.Calculations show that the parent magma of the suites bears obvious resemblance to quartz diorite and quartz monzonite in composition, which is in agreement with the experiments by Green. The Damiao anorthosite suite is characterized by deep source and shallow implacement as evidenced by high-pressure, high-temperature ex-periments, geothermometry, petrochemical features as well as the occurrence of pigeonite.
出处
《地球化学》
CAS
1980年第3期263-277,i002,共16页
Geochimica
