Part B: Stratigraphic and Magmatic Setting of Mineral Occurrences

Magmatic and stratigraphic settings exert a first order control on the formation of various mineral deposit types. Some sating are rich in mineral wealth while others are barren. Stratigraphic setting is of particular importance where stratif&m or stratabound minerill deposits are concerned x orebodies are commonly restricted to specific stratigraphic intervals. For example. within the area bounded hy the Alsek and Tatshenshini Rivers, Upper Triassic rocks include a stratigraphic interval that is spectacularly endowed with massive &hide copper mineralization. On the other hand. no significant mineral occurrences have yet heen recognized in either the thick and extensive Paleozoic limestones or the widespread Jura-Cretaceous granodioritic bodies. Thus, an understanding of the stmigrnphic and magm;uic setting of mineral occurrences is the first step toward accurate delineation of mineral potential tracts, a primary objective of the Tatshenshini project, as outlined in Part A. Structural and def~rrmational events affecting the distribution of rocks formed within various slratigraphic and magmatic settings are discussed in Part C.