Atlas of Deformational and Metamorphic Rock Fabrics. Questo articolo non è disponibile.Atlas of Deformational and Metamorphic Rock Fabrics

In May 1976 Lucian B. Platt organized a highly successful Penrose Confer­ ence on The Formation of Rock Cleavage at Bryn Mawr College in Penn­ sylvania, U. S. A. The meeting drew together about 70 specialists from both sides of the Atlantic and from Australasia, who contributed discussions on various aspects of rock cleavage and its formation. Even early in the meet­ ing it became clear to the participants that they lacked a common terminol­ ogy, that often the same technical word implied different things to different people and that observables and descriptors were loosely defined. In an at­ tempt to improve communication the present editors contacted about 190 workers after the conference with a view to compiling a set of photographs with captions to illustrate exactly what workers were talking about. As a re­ sult the compilation was published as a limited edition by an inexpensive offset process at the University of Tasmania. The success of that provisional edition of the Atlas of Rock Cleavage and the responses of the readers prompted us to make a more extensive collection of material, contact a wider range of workers and, with the support of Dr. Konrad Springer, to publish the present higher-quality reproduction of the contributors' plates.

I. Introduction.- Glossary of Cleavage Terms.- II. Processes Contributing to Development of Cleavage.- Possible Geometrical Changes.- Possible Material Processes.- Extensions and Examples.- III. Possible Links Between Observables and Processes.- The Structure of the Problem.- Instances Where a Process Can Be Inferred.- Commentary.- Appendix I: A System for Drawing Conclusions from Observables.- IV. The Plates.- Continuous Cleavage.- Section 1 Continuous Cleavage Formed by Coarse, Aligned Grains.- Section 2 Fine Continuous Cleavage in Rocks Composed Largely of Phyllosilicates.- Section 3 Continuous Cleavage in Rocks Composed Largely ofNon-Phyllosilicate Minerals.- Spaced Cleavage.- Section 4 Crenulation Cleavage with Gradational Boundaries.- Section 5 Zonal Crenulation Cleavage with Discrete Boundaries.- Section 6 Crenulations Bounded by Cracks.- Section 7 Disjunctive Cleavage Defined by Simple Cracks.- Section 8 Disjunctive Cleavage Defined by Wiggly Cracks or Seams.- Section 9 Cleavage Defined by Anastomosing Seams.- Section 10 Cleavage Defined by Planar Seams.- Section 11 Cleavage Defined by Wispy Seams.- Section 12 Cleavage Defined by Flame-like Seams.- Section 13 Cleavage Defined by Seams Differentiated Without Dissolution or Disaggregation Aspects.- Section 14 Cleavage Defined by Differentiation on Grounds of Texture or Geometry but not Composition.- Other Topics.- Section 15 Nonplanar Differentiation and Blastesis.- Section 16 Cleavage: Indications of Genesis and Strain.- Section 17 Cleavage and Polyphase Deformation.- Section 18 Cleavage Refraction and Cleavage-fold Relationships.- References.