Subsidence and uplift by slab-related mantle dynamics: a driving mechanism for the Late Cretaceous and Cenozoic evolution of continental SE Asia?

Abstract

Continental SE Asia is the site of an extensive Cretaceous-Paleocene regional unconformity that extends from Indochina to Java, covering an area of c. 5 600 000 km 2 . The unconformity has previously been related to microcontinental collision at the Java margin that halted subduction of Tethyan oceanic lithosphere in the Late Cretaceous. However, given the disparity in size between the accreted continental fragments and area of the unconformity, together with lack of evidence for requisite crustal shortening and thickening, the unconformity is unlikely to have resulted from collisional tectonics alone. Instead, mapping of the spatial extent of the mid-Late Cretaceous subduction zone and the Cretaceous-Paleocene unconformity suggests that the unconformity could be a consequence of subduction-driven mantle processes. Cessation of subduction, descent of a northward dipping slab into the mantle, and consequent uplift and denudation of a sediment-filled Late Jurassic and Early Cretaceous dynamic topographic low help explain the extent and timing of the unconformity. Sediments started to accumulate above the unconformity from the Middle Eocene when subduction recommenced beneath Sundaland.

A record of continental collision and regional sediment flux for the Cretaceous and Palaeogene core of SE Asia: implications for early Cenozoic palaeogeography

“…Except in West Sulawesi and Sumba there was no subduction beneath the Sundaland region from about 80 Ma until 45 Ma. The paucity of sedimentary rocks of Late Cretaceous to Palaeocene age indicates regional uplift (Hall & Morley 2004;Hall et al 2009) during this time and has been interpreted by Clements et al (2011) as a response to changing dynamic topography, driven initially by subduction, and later by collision and subsequent slab breakoff. Clements et al (2011) suggested that during Jurassic and Early Cretaceous subduction there was a dynamic topographic low centred on Sundaland.…”

“…The paucity of sedimentary rocks of Late Cretaceous to Palaeocene age indicates regional uplift (Hall & Morley 2004;Hall et al 2009) during this time and has been interpreted by Clements et al (2011) as a response to changing dynamic topography, driven initially by subduction, and later by collision and subsequent slab breakoff. Clements et al (2011) suggested that during Jurassic and Early Cretaceous subduction there was a dynamic topographic low centred on Sundaland. When subduction ceased in the Late Cretaceous the dynamic topography was reversed and the entire region became emergent although without great elevation (as a consequence of a long-wavelength uplift) and detritus, eroded from exposed Sundaland, was transported to the continental margins.…”

“…There are thick, laterally extensive sedimentary sequences of Jurassic and Early Cretaceous age exposed over large areas of Indochina and the Malay Peninsula referred to as the Khorat Group and lateral equivalents (Racey 2009). It is unclear how far south these, and equivalent sequences, extended prior to regional uplift in the Late Cretaceous and development of the SE Asia Regional Unconformity (Clements et al 2011), but it is probable that some of these rocks were extended well south into Sundaland, and were reworked into Cenozoic sediments.…”

“…Smyth et al 2007;Hall 2009) during the Early and early Late Cretaceous halted subduction beneath Sundaland (e.g. Hall 2009;Clements et al 2011). From the Late Cretaceous to c. 45 Ma the margin was inactive Hall 2009) and much of the Sundaland region was emergent (Clements et al 2011).…”

“…Hall 2009;Clements et al 2011). From the Late Cretaceous to c. 45 Ma the margin was inactive Hall 2009) and much of the Sundaland region was emergent (Clements et al 2011). As a consequence of this regional elevation there are almost no sedimentary rocks of Late Cretaceous-Early Palaeogene age in the region.…”