TITLE:
Ripple Tectonics—When Subduction Is Interrupted
AUTHORS:
Zvi Ben-Avraham, Gerald Schubert, Emanuele Lodolo, Uri Schattner
KEYWORDS:
Plate Tectonics, Subduction-Collision Transition, Miocene-Pliocene Transition
JOURNAL NAME:
Positioning,
Vol.11 No.3,
July
1,
2020
ABSTRACT: Subduction plays a fundamental role
in plate tectonics and is a significant factor in modifying the structure and topography
of the Earth. It is driven by convection forces that change over a >100 Myr time
scale. However, when an oceanic plateau approaches, it plugs the subduction, and
causes slab necking and tearing. This abrupt change may trigger a series of geodynamic
(tectonic, volcanic) and sedimentary responses recorded across the convergence boundary
and its surrounding regions by synchronous structural modifications. We suggest
that a large enough triggering event may lead to a ripple tectonic effect that propagates
outwards while speeding up the yielding of localized stress states that otherwise
would not reach their threshold. The ripple effect facilitates tectonic, volcanic,
and structural events worldwide that are seemingly unrelated. When the world’s largest
oceanic plateau, Ontong Java Plateau (OJP), choked the Pacific-Australian convergence
zone at ~6 Myr ago, it induced kinematic modifications throughout the Pacific region
and along its plate margins. Other, seemingly unrelated, short-lived modifications
were recorded worldwide during that time window. These modifications changed the
rotation of the entire Pacific plate, which occupies ~20% of the Earth’s surface.
In addition, the Scotia Sea spreading stopped, global volcanism increased, the Strait
of Gibraltar closed, and the Mediterranean Sea dried up and induced the Messinian
salinity crisis. In this paper, we attribute these and many other synchronous events
to a new “ripple tectonics” mechanism. We suggest that the OJPincipient collision
triggered the Miocene-Pliocene transition. Similarly, we suggest that innovative
GPS-based studies conducted today may seek the connectivity between tectonic, seismic,
and volcanic events worldwide.