Mineral Deposits and Diastrophism

Abstract

This is a brief essay on the geology of mineral deposits, in which the writer emphasizes the necessity of geotectonic and magmagenetic studies in dealing with genetical problems of mineral deposits. Such studies are important not only in the purely scientific investigation but also in the practical researches of mineral deposits. But for the fundamental knowledge of regional geology comprising the tectonic and magmatic history with which the formation, enrichment, and structural behavior of the deposits in the region are closely connected, no perfect researches of mineral resources nor solving the fundamental problems concerning them can be undertaken in a vast, unexplored area, though some mineralogical or structural problems of limited kind or of local ones may be solved by general or empirical knowledge of ore deposits.
The present states of mineral deposits is the resultant of all geological processes to which they have been subjected from the time of their formation to the present, and the degree of enrichment, primary or subsequent, and structural behaviors of the mineral deposits are so closely related to them that no student of mineral deposits can lose sight of them both in fundamental and practical investigations. From this point of view, the writer presents a classification of mineral deposits, bearing much weight on the tectonic and magma-genetic processes that lead to their formation and enrichment.
The writer also pays attention to the general association, of certain types of mineral deposits and those of geological formation, and presents some interpretation of it, besed chiefly on geotectonics.
Lastly, some reference is made to the problem of ore-contamination that seems very probable in the light of recent geotectonic theories and data of lead isotopes in ore materials. It may be certain that ore materials, within the reach of our observation and utilization, have concentrated mainly in the upper earth's crust through the recurrence of diastrophism (crustal movements and igneous activity), and it is presumed that the great majority (or at least appreciable part) of them have been circulating within the upper earth's crust in the course of crustal development since the earliest geological time, though certain amounts of iron, titanium, chromium, etc., might have been supplied from depths by basic or ultrabasic magmas of abyssal generation.