Origin of the magnetite boundary in the Peninsular Ranges batholith, southern California, U.S.A., and Baja California, Mexico

Abstract

In the Peninsular Ranges of southern California, U.S.A., and Baja California, Mexico, the Cretaceous granitic rocks to the southwest, nearly all of which contain magnetite, adjoin Cretaceous granitic rocks to the northeast, nearly all of which are magnetite-free, along a narrow northwest-trending zone called the "magnetite boundary" A few granitic plutons that straddle this boundary grade from magnetite-bearing (early) to magnetite-free (late).

To investigate the factors that cause variations in magnetite content traverses across representative plutons were examined for variation in whole-rock and mineral chemistry, iron-oxidation state, ammonium in biotite, and non-carbonate carbon in the rock... In order to continue, download full text in PDF.