A Neogene history of mantle convective support beneath Borneo

Abstract

Most, but not all, geodynamic models predict 1-2 km of mantle convective draw-down of the Earth's surface in a region centered on Borneo within southeast Asia. Nevertheless, there is geomorphic, geologic and geophysical evidence which suggests that convective uplift might have played some role in sculpting Bornean physiography. For example, a long wavelength free-air gravity anomaly of +60 mGal centered on Borneo coincides with the distribution of Neogene basaltic magmatism and with the locus of sub-plate slow shear wave velocity anomalies. Global positioning system measurements, an estimate of elastic thickness, and crustal isostatic considerations suggest that regional shortening does not entirely account for kilometer-scale regional elevation. Here, we explore the possible evolution of the Bornean landscape by extracting and modeling an inventory of 90 longitudinal river profiles. Misfit between observed and calculated river profiles is minimized by smoothly varying uplift rate as a function of space and time. Erosional parameters are chosen by assuming that regional uplift postdates Eocene deposition of marine carbonate rocks. The robustness of this calibration is tested against independent geologic observations such as thermochronometric measurements, offshore sedimentary flux calculations, and the history of volcanism. A calculated cumulative uplift history suggests that kilometer-scale Bornean topography grew rapidly during Neogene times. This suggestion is corroborated by an offshore Miocene transition from carbonate to clastic deposition. Co-location of regional uplift and slow shear wave velocity anomalies immediately beneath the lithospheric plate implies that regional uplift could have been at least partly generated and maintained by temperature anomalies within an asthenospheric channel.

Fault Throw and Regional Uplift Histories From Drainage Analysis: Evolution of Southern Italy

“…For the inverse model, a value of λ s ≈ 1 produces a combination of suitable model roughness (a small “model norm”) and low rms misfit for Calabria (Figure 8a), which is similar to the optimal value used in many previous studies (e.g., Conway‐Jones et al., 2019; Roberts et al., 2018; Rudge et al., 2015). Therefore, our uplift analysis will initially consider inverse models with λ s = 1.…”

Adakites without a slab: Remelting of hydrous basalt in the crust and shallow mantle of Borneo to produce the Miocene Sintang Suite and Bau Suite magmatism of West Sarawak

“…This magmatism, or the increased heatflow associated with it, was most probably responsible for causing crustal melting. Roberts et al (2018) suggested that the mantle beneath Borneo is hotter than ambient mantle but a hotspot origin can be discounted for the West Sarawak and Kalimantan Sintang magmatism.…”

“…The lithosphere of Borneo is thinner than adjacent portions of the Sunda Shelf (Roberts et al, 2018) and the extensive Kuching depocentre implies that a broad swathe of crust between the Lupar Line and the Schwaner Mountains experienced substantial crustal thinning from the Cretaceous until the mid-Cenozoic (Eocene-Oligocene) (Fig. 11a).…”

Continental‐Scale Landscape Evolution: A History of North American Topography

“…Topography is the result of complex interactions between the solid Earth and surface processes that operate on multiple spatial and temporal scales (e.g., Anderson & Anderson, 2010;Roberts et al, 2019). Consequently, surface uplift and subsidence histories have been combined with magmatic and tomographic information to estimate temperatures, wavelengths, and timescales of mantle convection (e.g., Gurnis et al, 2000;Lodhia et al, 2018;Roberts et al, 2018;Salles et al, 2017;van Wijk et al, 2010). The results of these studies imply that mantle processes play a significant role in driving the erosional history of a landscape.…”