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The idea for the present Spilite Volume was born during the Spilite Symposium at the XXIIIrd session of the International Geological Con gress in Prague, 1968. At that time, only a restricted number of petro logists working on spilites was present and, therefore, the group assem bled agreed that a Symposium Volume should also include recent papers by many other spilite specialists. At the same time it was agreed that the papers presented at the Symposium should be returned to the authors for changes and additions. This procedure of upgrading and amending the papers has continued until this year (1973) for various technical and editorial reasons. The information presented here is, therefore, up-to date. To those familiar with the spilite problem it is obvious that the time had come for a review of its state. Also, the existing litera ture had become so voluminous that a monographic review was necessary. Following a modern trend, the authorship for this review was spread among specialists with variable experience. For readers not necessarily familiar with the spilite problem, a brief summary is presented here. A short historical note is followed first by the observations, then by the interpretations, finally by some of the major features of scientific logic as they pertain to the problem of the primary or secondary origin of some of the rocks termed spilites and keratophyres.
Vols. 1-108 include Proceedings of the society (separately paged, beginning with v. 30)
The problem of time-and strata-bound formation of ore deposits has during the past decade become one of the most debated topics in cur rent international discussion. Due to the amazing results of modern mineral exploration and world-wide geophysical research, the mutual relationship between the complex geological history pf a crustal seg ment and the development of distinct metallogenic provinces (ore belts) has received much interest. Reviewing the earth's history in this light one can now recognize metallogenic epochs even of global range which document the existence of world-wide time-bound ore enrich ments. The knowledge of these metallogenetic processes has been growing step by step for several decades. It began with simple observations and sceptic interpretations, which at first threw heretical spot lights on to the edifices of the prevailing theories on granitic differentiation as the favoured source of ore deposits. It was obvious that the new ideas at first referred to ore enrichments in sedimentary sequences, nowadays summarized under the term strata-bound, and mainly interpreted as stratiform or sedimentary ore deposits. Moreover, the modern term "strata-bound" also includes ore mineralizations which are bound to distinct units of layered (intrusive or extrusive) igneous complexes as a general descriptive term without genetical restriction! Albert Maucher is one of the representatives of the initial era who discussed these genetical questions critically in the decade before the 2nd World War.