A tentative discussion on the principle and method for division of metallogenic units

Abstract：It is emphasized in this paper that, so far as the principle and method for compilation of metallogenic map are concerned, mineralization itself should be more preferentially taken into consideration, though tectonic setting is the basis. Mineralization itself is the first important factor in delineation of a metallogenic unit and its boundary. The authors still use the term metallogenic province here. Nonetheless, different from previous usage, the term metallogenic province here has not only space attribute, but, what is more important, time attribute. The metallogenic province used here means an area where mineral deposits are distributed and formed due to the same or related mineralization in the same or nearly the same epoch and geological settings on a certain tectonic basis. Metallogenic regions (zones), metallogenic potential and prospective regions are thus delineated. A metallogenic region (zone) is an area delineated on the basis of distribution of mineral deposits and favorable geological settings. A metallogenic potential region is delineated on the basis of favorable geological settings with or without known occurrences of mineralization therein. A prospective region is predicted or speculated in consideration of favorable geological settings for mineralization concerned. Following this consideration, the authors suggest a principal framework and steps to divide metallogenic units on the tectonic basis. Metallogenic units in cratonic areas are divided into metallogenic provinces of basement stage, cover stage and post-cratonic stage. Metallogenic units in orogenic areas are divided into metallogenic provinces of early stage, late stage and post-orogenic stage. Metallogenic units of mineralizations related to mafic and ultramafic rocks are delineated according to the fractures, rifts or ophiolite zones concerned. Boundaries of metallogenic units developed in late stages of craton or orogen, especially in post-cratonic or post-orogenic stages, may be discordant with or even traverse tectonic boundaries.The authors have primarily delineated some metallogenic units in consideration of the circumstance of China, for example, the Jiao (Shandong)-Liao (Liaoning) magnesite talc-graphite metallogenic province in the eastern end of the North China Craton, the Yan (Hebei)-Liao (Liaoning) iron-gold metallogenic province in the northern margin of the North China Craton, the West Qinling lead-zinc metallogenic province in the West Qinling Variscan Orogen and the Da Hinggan Ling polymetal-iron metallogenic province in the Da Hinggan Ling Variscan Orogen as well as metallogenic potential and prospective regions therein. This division, in fact, has implied and predicted prospecting areas.