As a common and important geological structure,cleavage was recognized and studied by geologists over a century ago.In recent years,geologists have achieved significant progress on cleavage study.However,the term of cleavage is still not well-defined,and the use of cleavage in the literature is very confusing.In addition,there are still some ill-defined and even incorrect terms about cleavage structure in use(such as breaking cleavage,flow cleavage,and shear cleavage),causing confusion and misunderstanding in beginners learning cleavage structure.Cleavage is a tectonic process that involves not only tectonic deformation but also low-grade metamorphism.Therefore,the study of cleavage can help us understand the metamorphism and deformation processes of region rocks,especially the analysis of the relationship between bedding and cleavage,which plays a critical role in guiding field mapping and structural reconstruction.Based on the latest textbooks and research literature,combining the author's teaching practice of structural geology and the problems and teaching difficulties in students'cleavage study,this paper updated and improved the teaching content of cleavage.In future teaching practice,we should emphasize the metamorphic conditions of cleavage formation,clarify confusing concepts,and apply the relationship between bedding and cleavage in field tectonic geological mapping and tectonic restoration.
cleavagemetamorphism and deformationfoldstructural analysis
李玮、王美聪、姜大志、罗金海、冀文斌
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西北大学 地质学系,大陆动力学国家重点实验室,陕西 西安 710069
Department of Earth Sciences,Western University,London ON N6A 5B7,Canada