A tectonic window in south-western Iran.

Abstract

From Dr. E. Lehner :— The peculiar conditions in the Niriz region, and especially at Kuh-i-Dalnashin, afford apparently unassailable evidence of the existence of a nappe of radiolarites and green rocks which was formed in Upper Cretaceous time. From my knowledge of published papers and of unpublished reports by the geologists of the Anglo-Iranian Oil Company I believe that, for the whole disputed zone from Oman to the Mediteranean, no other case of equal merit has been made out in favour of such a nappe. It is therefore desirable that Dr. Gray's conclusions be put to every test. The paper does not explicitly deal with the roots of the composite radiolarite-green igneous nappe. It describes, however, in some detail the stratigraphical succession in the “Late Tertiary Overthrust Zone” and its south-eastern extension at Aghirq. Here the radiolarites are only thinly developed, as intercalations in the sandstones which mark the coming in of the Kirman facies of plant-bearing Jurassic. It would, therefore, seem obvious that the roots of the nappe must be looked for to the south of this zone, either in the Dehbid valley, which is covered by Neogene or Quaternary, or in a region now overridden by the late Tertiary thrusts. Yet in the sections (pl. ix) the Dehbid valley is shown as a gently folded monocline, and the drawing of the thrust zone does not admit the probability of a root zone underneath. Where does Dr. Gray assume the root to be ? The paper tentatively suggests a