Abstract

The author’s study, carried out in different parts of four continents, has revealed that large deposits of endogenic ores are usually located in the vicinity of, or above the intersection of, deep-seated fractures, fracture zones or zones of weakness that belong to four sets, N-S, E-W, NW, and NE, or to some of these four sets.

Not all of these major fracture sets are equally developed in the surface or subsurface portion of the individual areas; some of them commonly play a dominant role and some are not developed or not recognized.

The endogenic ore deposits of a distinct type and age which on a global scale are concentrated along a recent or former trench-type plate boundary exhibit, on o more detailed scale, a space relationship to intersections of some of the four major sets of deep-seated fractures. If the course of the respective plote boundary is sufficiently straight, one of the sets of deep-seated fractures usually strikes parallel to it.

The deep-seated fractures which control the distribution of large deposits of endogenic ores usually have a tendency to be spaced equidistantly.

If in a region, a relation of endogenic ore deposits to the intersection of distinct deep-seated fractures is recognized, the symmetry in regional distribution of ore deposits may effectively help in deriving probable positions of further deep-seated fractures which have not yet been proved by other methods. The ages of the ore deposits have to be considered within these studies.

Different criteria of a geological, geomorphological, and geophysical nature assist in plotting positions of empirical fracture trajectories and constructing their nets. Examples are given from the author’s investigations in parts of Western and Central Europe, North America, continental Central America, northern South America, Japan, and Madagascar.

Repetition of the four principal sets of deep-seated fractures which control the distribution of the largest endogenic concentrations of ores in different parts of the world, as well as other criteria, suggest that the main ore-controlling, deep-seated fractures reflect a pattern of basement fractures which may be considerably regular. Other significant criteria are the alignment of large ore deposits along directions intersecting areas of different geological character, passing from ancient ocean areas into ancient continents, and concentration of large deposits along the landward projection of some significant fracture zones of recent oceanic areas.