Subduction Zones Classification: Examples from the Southern Border of Eurasia

Doglioni, Carlo ¹
(1)Sapienza University, Roma, Italy.

The southern border of Eurasia was the site either of rifting or subduction zones since Late Paleozoic times. The direction of motion of Eurasia and the separating or converging plates plates was and still is along the NE-SW direction. A number of plates and microplates drifted away from Eurasia and then returned back, colliding with it. The Paleotethys rifting or the Cimmerian subduction followed the same trend that can be followed from the Dinarides to the Indonesia subductions zones, or from the rifts of the Red Sea to the SE-Indian Ridge today. The subduction zones in the world are characterized by the subduction hinge either converging toward, or diverging from the upper plate. These two settings generate a variety of opposite settings which control a systematic distribution of sedimentary basins. For example, the subduction zone where the subduction hinge converges relative to the upper plate, there form: a double-vergent orogen, no backarc basin; high morphological and structural elevation; thickening of the sandwiched lithospheres; two foredeeps with subsidence rate lower than 200m/Ma; the anticlines have a positive uplift (i.e., the anticline uplift is faster than the regional subsidence in the foredeep); the subduction rate is slower than the convergence rate, and their mean direction of subduction is toward E-or NE. The subduction zone where the subduction hinge rather diverges relative to the upper plate, there form: a backarc basin; a single fast subsiding foredeep (> 1000 m/Ma); single vergent accretionary prism; low morphological and structural elevation; thinning of the upper plate; anticlines may have a negative uplift (i.e., the anticline uplift can be slower than the regional subsidence in the foredeep, and is likely subsided and buried by syn- and post-tectonic sediments); the subduction rate is faster than the convergence rate. Along the Alps, Dinarides, Hellenides, Zagros, Makran, Himalayas, Indonesia subduction zones have the subduction hinge migrating toward the upper plate (E-NE-directed subduction zones). The Apennines, Carpathians and Banda arcs have rather the subduction hinge migrating away with respect to the upper plate (W-directed subduction zones). The evolution of subduction zones, their polarity, and the related orogens at the southern border of Eurasia was controlled by the distribution of the inherited lithospheric anisotropies generated by the tethyan rifting, and the variable decoupling at the lithosphere base.

AAPG Search and Discovery Article #90135©2011 AAPG International Conference and Exhibition, Milan, Italy, 23-26 October 2011.