Offset on the Main Recent Fault of NW Iran and implications for the late Cenozoic tectonics of the Arabia-Eurasia collision zone

Abstract

Summary We use drainage patterns, geological markers and geomorphological features to determine a right‐lateral offset of ∼50 km, and possibly as much as ∼70 km, on the Main Recent Fault in NW Iran. This fault trends NW–SE and forms the NE border of the Zagros mountains. It accommodates the strike‐slip component of the N–S convergence between Arabia and Eurasia, with the NE–SW shortening component being accommodated in the Zagros Fold Belt. Its ∼50 km strike‐slip offset implies a shortening of ∼50 km in the fold belt and ∼70 km total N–S convergence accommodated in the NW Zagros. This is a substantial fraction of the 85–140 km overall Arabia–Eurasia convergence expected over the last 3–5 Ma. If the Main Recent Fault initiated at that time, as seems likely from geological arguments, it has a horizontal slip rate of at least 10–17 mm yr−1 and should be the source of frequent earthquakes of Ms 6–7, as has been seen in the 20th century and the earlier historical record. The similarity of the offsets and probable ages of the North Anatolian and Main Recent Faults suggests that they have been active as an almost continuous zone of right‐lateral shear on the north edge of the Arabian and Anatolian plates since the early Pliocene.

Collisional model for rapid fore‐arc block rotations, arc curvature, and episodic back‐arc rifting in subduction settings

“…[69] The transition from strike-slip dominated deformation at the western end of the Zagros on the Main Recent Fault (MRF) [e.g., Talebian and Jackson, 2002] to north-south directed shortening [e.g., Jackson et al, 1995] within the Zagros fold and thrust belt east of $47°E further supports our suggestion that central Iran pivots about a nearby pole, near the Arabia/Eurasia collision zone. However, given the sparsity of geological data bearing on the late Cenozoic history of rotation of Iran and timing of tectonic events, we cannot be completely certain that Iran/Arabia collision and the rotation of Iran are products of the collision/subduction induced rotation model we propose in Figure 3.…”

“…Block modeling is done using the method and software developed by McCaffrey [1995McCaffrey [ , 2002. We break the region into two tectonic blocks (Central Iran and Lut blocks) similar to suggestions of previous studies [e.g., Vernant et al, 2004;Reilinger et al, 2006] and using known active faults as block boundaries [e.g., Talebian and Jackson, 2002]. Our block model is of course much simpler than the true tectonic situation is likely to be, largely because the distribution of GPS data does not warrant a more complex model (see also discussion by Reilinger et al [2006], who use a similar block model configuration).…”

Crustal-scale cross-sections across the NW Zagros belt: implications for the Arabian margin reconstruction

“…The northwards convergence of Arabia and Eurasia triggered the formation of the Main Recent Fault (MRF), a large dextral strike-slip fault that re-activated segments of the Main Zagros Fault (Talebian & Jackson, 2002) and cut the previously emplaced Gaveh Rud and Sanandaj-Sirjan basal thrusts (GRT and MZF, respectively). The relatively rectilinear trace of the fault seems to indicate a steep geometry at depth, which is in agreement with the steep limit of the Arabian crust as shown in the balanced cross-section (Fig.…”

Porphyry copper assessment of the Tethys region of western and southern Asia: Chapter V in <i>Global mineral resource assessment</i>

“…Pliocene-Holocene right-lateral strike-slip displacements, principally along the Bitlis-Zagros suture zone where offset over the past 3-5 m.y. is estimated between 50 and 70 km, further document the oblique nature of the continuing collisional process (Talebian and Jackson, 2002).…”

“…Strike-slip displacements are estimated at between 50 and 70 km over the past 3-5 million years (m.y.) (Talebian and Jackson, 2002;Jackson and McKenzie, 1984). This compressional to transpressional regime continues today.…”