Publication Date:
2020-02-24
Description:
In this study, we report an extensive paleomagnetic study (76 sites) carried out in the Alborz Mts. (northern
Iran), with the aim of reconstructing the rotation history and the origin of curvature of this orogenic chain. The
analyzed deposits are the sedimentary successions of the Upper Red Formation (Miocene), Lower Red Formation
(Oligocene) and Eocene clastic units. Paleomagnetic results indicate that the Alborz Mts. can be considered a secondary
arc that originated as a linearmountain belt that progressively acquired its present day curvature through
opposite vertical axis rotations along its strike. The curvature of the arc was entirely acquired after the middlelate
Miocene,which is the age of the youngest investigated sediments (Upper Red Formation). Overall, our paleomagnetic
data indicate that the Alborz Mts. can be considered an orocline.
Our results define, for the first time, the rotational history of the entire Alborz curved mountain belt, and enable
us to reconstruct the paleogeographic and tectonic evolution of northern Iran in the framework of Arabia-Eurasia
continental deformation. The kinematics inferred by the pattern of paleomagnetic rotations is at odds with the
present day kinematics of northern Iran, characterized by the westward extrusion of the South Caspian block,
and by a left lateral shear between Central Iran and the central and western sectors of the Alborz Mts. By integrating
paleomagnetic datawith stratigraphic, thermochronological, structural and GPS information,we propose that
the initiation of South Caspian subduction and the activation of westward extrusion of South Caspian block occurred
diachronously and that the initiation of the present-day kinematics of northern Iran was quite recent
(Lower Pleistocene, b2 Ma).
Description:
Published
Description:
13-28
Description:
1A. Geomagnetismo e Paleomagnetismo
Description:
JCR Journal
Description:
restricted
Keywords:
Paleomagnetism Alborz Iran orocline
;
04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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