CALC-ALKALINE MAGMA GENESIS: THE PAN-AFRICAN CONTRIBUTION TO CRUSTAL GROWTH?

Abstract

Voluminous granitic crust with associated calc-alkaline volcanics of Pan-African age (960–520 Ma) is recorded from the Arabian–Nubian Shield. Magma generation is considered against the background of controversy concerning marginal versus intracraton tectonics during earlier Precambrian times. That Pan-African tectonics and crustal growth should be regarded as transitional between Archaean and modern styles is doubtful in view of the decreasing decay rate of terrestrial heat production during the Earth's history.