Morpho tectonic units of the Zagros Orogenic Belt, NE Iraq: a modern analogue for subduction accretion processes

The Zagros Mountain Belt extends over more than 1800 km through Iraq and southern Iran in front of the Zagros Mountain chain. It forms the boundary between the Iranian Plateau and the Mesopotamian and Gulf basins (Fig. 1). It can be subdivided geomorphologically into: the High Zagros Belt and the Zagros Simply Folded Belt separated by the High Zagros Fault (Berberian and King, 1981; Falcon, 1974; Stockline, 1968). From a tectonic point of view, however, five zones along the length of the Zagros Orogenic Belt can be distinguished (e.g. Stocklin, 1974, 1986; Falcon, 1974; Sten, 1985; Berberian, 1995): the Zagros Imbricate Zone, the Simply Folded Zone, the Zagros Foredeep, the Mesopotamian Foreland Basin and the Arabian foreland. However, the most common subdivision of the Zagros Orogenic Belt is the five structural zones parallel to NW-SE trend through the belt; from the NE to the SW they are: the Urumieh-Dokhtar Magmatic Arc, the Sanandaj-Sirjan Metamorphic Zone, the High Zagros Zone (Imbricate or Crush zone), the Zagros Simply Folded Belt and the Mesopotamian Foreland Basin (Fig. 2). The High Zagros Zone is referred to by Jassim et al. (2006) as the Penjween-Walash Sub-zone. Towards the SW the Main Zagros Thrust separates the Sanandaj-Sirjan and Imbricate Zones (Berberian, 1995; Agard et al., 2005) and constitutes the suture between Arabian and Iranian plates. The Imbricate Zone represents the innermost part of the Arabian deformed margin, featuring radiolarian chert-bearing accretionary terrane and the Upper and Lower Allochthonous Thrust Sheets over the NE Arabian margin. The aim of this paper is to describe the characteristic morphological features of the Penjween-Walash Subzone and to discuss the tectonic implications of this subzone.