太古宙地层研究中应注意的几个问题

Some important aspects in the study of Archean stratigraphy

太古宙地层与显生宙地层相比,具有很大的复杂性,研究难度大。研究太古宙地层,在学术思路上应以岩石、地层、构造和地质事件综合研究为基础,配合多种新技术新方法特别是同位素年代学定年为依托。另外,要注意解决好如下6个方面的问题:(1)在“单斜”地层中注意研究有无复杂同斜褶皱;(2)正确判定岩石类型及其属性;(3)多次变形叠加如何与区域变质作用相联系的问题;(4)地层定年中应该注意的问题;(5)特殊岩石单位的定名问题;(6)正确区分变质火山-沉积地层层序和构造接触问题。

It is much more complex and difficult to study Archean stratigraphy than Phanerozoic stratigra-phy.In studying Archean stratigraphy,we should make an integrated study of petrology,stratigraphy,structural geology and geological events,and,on that basis,use new techniques,especially those of geochronology.Furthermore,the following aspects should be emphasized:1.make clear whether there are any complex isoclinal folds in nominal'monoclinic strata';2.determine correctly the types of rock and their attributes;3.identify polyphase deformational overprints and how to correlate them with regional metamorphism;4.understand the problems and pitfalls in geochronologic study;5.clarify the nomenclature of the special units of rocks;6.distinguish correctly the metavolcanic or sedimentary sequence and the pos-sible structural contacts between the different units.