Discussion

Abstract

Professor K. C. Dunham said that he had had the pleasure of visiting parts of the Hadhramaut with Dr Beydoun, when they had examined ‘basement’ and ‘cover’ rocks on which Dr Beydoun had subsequently published. The scanty radiometric evidence obtained suggest a very late Pre-Cambrian or early Cambrian age for the metamorphism and igneous activity in the ‘basement’. Here it appeared that there was a transition from phyllites to rocks of the amphibolite facies. Large masses of andesite covered the sediments and pre-dated post-tectonic granites. He added that the possibility of publishing the remaining Somaliland maps was being considered. In reply to Professor Dunham, Dr Bichan thanked him for his remarks and welcomed the announcement that consideration was being given to the publication of the remaining Somaliland maps. Although in the Hadhramaut there appeared to be transition from phyllites to rocks of the amphibolite facies, no definite evidence of a similar phenomenon occurred on Socotra. The phyllitic rocks of the Hadibu series of Socotra appeared to be younger than the amphibolite facies rocks which lie both to the west and to the east. A similarity does exist however between Socotra and the Hadramaut in the relation of the volcanic rocks and the granites. It was hoped that radiometric determinations could be carried out on the Socotra rocks in the relatively near future and thus augment the scanty data available from the Gulf of Aden region. Dr Beydoun wished to acknowledge the subsequent field investigations carried out in the former Western