Abstract

The Kuh-e Dalneshin area lay close to the northern margin of the Arabian continent during Mesozoic and Palaeogene times. Recent mapping has shown that, except perhaps in the late Cretaceous, it was inactive until it collided with Central Iran in the Miocene: the collision, represented by a Neogene mélange zone in the NE, resulted in the Zagros orogeny, and is expressed in the shelf sediments by folding, parallel faulting and a possible arcuate sinistral shear.

In the late Cretaceous, a localized deepening of the shelf dates from the Cenomanian. A narrow trough in the W subsided to abyssal depths in the Turonian. Following a period of faulting, a more wide spread subsidence affected the shelf in the Coniacian and Santonian: autochthonous cherts and associated sediments accumulated. Basaltic volcanics were erupted in the NE part of this basin, and Permian to Cenomanian neritic exotic blocks were derived presumably from an uplift at the shelf edge. The rocks from the outer edge of this basin slid westwards over their autochthonous counterparts, probably in the Campanian, accompanied by further gliding of masses of earlier Mesozoic cherts, which had previously been emplaced on the continental margin. A sheet of mantle peridotite, partly serpentinized and enclosing neritic and metamorphic exotics, in turn slid into the basin. Shelf sedimentation was renewed in the late Campanian or Maestrichtian, but the transgression did not reach the area until the Eocene.

The derivation and emplacement of the allochthonous rocks in the late Cretaceous are still imperfectly understood: alternative models are discussed, one involving gliding from an aborted spreading ridge along the continental margin, the other more conventionally based on subduction processes. A preference is expressed for the former.

First Page Preview

First page PDF preview
You do not currently have access to this article.