Evidence for multiphase folding of the central Indian Ocean lithosphere

Abstract

Long-wavelength (100-300 km) folding in the central Indian Ocean associated with the diffuse plate boundary separating the Indian, Australian, and Capricorn plates is Earth's most convincing example of organized large-scale lithospheric deformation. To test the timing and mechanics of this deformation as implied by plate-kinematic and deformation models, we present a new analysis of the seismic stratigraphy of the Bengal Fan sediments. This shows that the folding of the oceanic lithosphere was multiphase, with major events in the Miocene (8.0-7.5 Ma), Pliocene (5.0-4.0 Ma) and Pleistocene (0.8 Ma). The Miocene phase was the most intense and involved deformation of an area south of 1°S, whereas in the Pliocene the activity shifted northward. In the final phase (Pleistocene) the activity was focused in the equatorial region. No evidence was found Krishna et al. 2 for deformation prior to 8.0-7.5 Ma. The spatial extent of the Pleistocene folding event overlaps the Pliocene and/or Miocene folding events and coincides with both the area of most active faulting and the zone of greatest historical seismicity. The seismic data show that the timing of reverse faulting, and thus more significant shortening of the lithosphere, generally coincided with the phases of folding, but there are examples of folding of the oceanic lithosphere without associated reverse faulting.

Spectral analysis of the gravity and elevation along the western Africa–Eurasia plate tectonic limit: Continental versus oceanic lithospheric folding signals

“…Cloetingh et al, 1999Cloetingh et al, , 2002Stephenson and Cloetingh, 1991;Lambeck, 1983;McAdoo and Sandwell, 1985;Ziegler et al, 1995;Bonnet et al, 2000;Gerbault, 2000;Krishna et al, 2001) to put forward a process of deformation through buckling of the entire lithosphere (known as lithospheric folding). These have been found within intraplate settings, both in continental lithosphere (Brittany, Iberia, Artic Canada, Central Asia, Alps, and Pannonian Basin) and in oceanic lithosphere (Indian Ocean).…”

Folding and necking across the scales: a review of theoretical and experimental results and their applications

“…(35). Cloetingh and Burov (2011) compiled wavelengths of folded lithosphere, including crustal, mantle and whole lithosphere folding, for 17 regions worldwide, including Central Asia (Burov et al, 1993), central Australia (Lambeck, 1983b), the north-east European platform (Bourgeois et al, 2007), the Tibet/Himalayan syntaxes belt (Shin et al, 2015) and the Indian oceanic lithosphere (McAdoo and Sandwell, 1985;Krishna et al, 2001), and showed that all fold wavelengths are between 40 and 700 km. Not surprisingly, wavelengths for crustal folding are the smallest and wavelengths for whole lithosphere folding are the largest.…”

Untitled

“…Throughout the Neogene, the Bengal Basin underwent significant multiphase deformation that resulted in the folding of the plate between the Ninetyeast Ridge and the 85°E Ridge (Krishna et al, 2001). In addition to the Miocene and Eocene unconformities (Curray et al, 2003), site survey data revealed two additional regional unconformities.…”