MINERALOGY AND PETROLOGY OF THE INTRUSIVE COMPLEX OF THE PLINY RANGE, NEW HAMPSHIRE.

Abstract

Field relations, major-element analyses of rocks, and microprobe analyses of minerals from the Pliny Range, N. H. suggest that the rock units represent at least four phases of igneous activity. Both whole-rock and biotite Fe/(Fe plus Mg) ratios reflect the complex magmatic history and imply significant variation in oxidation state of the separate magmas. Other support for a complex history comes from details of amphibole chemistry, the F contents of amphiboles and biotites, and the Mn contents of ilmenites. These and other data preclude a genetic model based on continuous differentiation of single parent magma.