Petrogenesis of Lamproites

Abstract

The development of realistic hypotheses for the petrogenesis of potassic rocks has been hindered, until recently, by the tendency of petrologists to consider all leucite-bearing K-rich rocks as being related. Sufficient geological, geochemical, and mineralogical evidence (see Chapter 2) has now accumulated to show that this assumption is not correct, and that at least three distinct clans of potassic rocks exist. These diverse magmas cannot be derived from the same source or be related to each other by processes such as fractional crystallization or assimilation. Consequently, many of the older petrogenetic hypotheses, summarized and discussed by Turner and Verhoogen (1960) and Gupta and Yagi (1980), have no relevance to the genesis of the lamproite clan as defined in this work. In particular the hypotheses of Holmes (1950) and Marinelli and Mittempherger (1966), involving reaction of granitic rocks with carbonatite or limestone, respectively, must be regarded as irrelevant to lamproite genesis.

For Nature is a perpetuall circulatory worker, generating fluids out of solids, and solids out of fluids, fixed things out of volatile, and volatile out of fixed, subtile out of gross and gross out of subtile. Some things to ascend and make the upper terrestriall juices.

Isaac Newton (675)