Origin of Basins Jammed in the Tethyan Realm; Lessons from Immature Stages

Pubellier, Manuel ¹
(1)Geology, CNRS, Paris, France.

In the western Tethys realm (Iran-Turkey) the oceanic domain existing prior to the shortening was not as developed as it was in the East. Models reconstructing the basins and margins invoke shearing in the midst of the Neotethys crust and shortening of marginal basins. However the mechanisms, timing and duration of the jumps of lithospheric boundaries where deformation is accommodated are difficult describe.

In order to illustrate the rapid shifts in deformation zone, we explore the mechanisms of present-day opening and closure of basins in SE Asia. There, opening of basins is confined in the Tertiary and the closure of the basins started in the Neogene, thus allowing geophysical and geological observations of immature stages of basin closure. The different stages all controlled by the consequence of a long lasting subduction which firstly creates marginal basins floored with oceanic crust, and later closes these basins when the subduction is perturbed. The processes of shortening are all illustrated in SE Asia, from the subduction blocking to reversal, subduction of the back arc basin, transfer to the opposite margin and subduction of the entire basin. These examples display progressively more advanced phases of collision tectonics with characteristic structural, metamorphic, and magmatic features, prior to the impending Australia-Eurasia continental collision in the future.

Based on the experience on the evolution of recent basin collapses with very rapid shifts from extensional to compressional regimes, from obduction of ophiolite and mountain building to extensional collapse, it is suspected that tectonic events which are invoked in the Middle East region or other areas may actually be more complex and actually integrate a series of independent short-lived events.

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