Topography and Gravity Reveal Denser Cratonic Lithospheric Mantle Than Previously Thought

Yaoyi Wang, Lijun Liu, Quan Zhou

Research output: Contribution to journalLetterpeer-review

Abstract

The density structure of the cratonic lithospheric mantle (CLM) remains debated. We suggest that one important reason for which many geodynamic studies favor neutrally buoyant CLM is that they adopted separate reference frames when estimating the isostatic effects of continental and oceanic lithosphere, while instead a globally consistent one should be used. This reflects a misconception that continental crust perfectly balances the surrounding oceanic lithosphere. Using a unified global reference frame with recent constraints on crustal properties and residual topography, we show that assuming neutrally buoyant CLM leads to prominent negative residual topography (∼−1.3 km) and positive residual gravity (∼354 mGal) within cratons relative to oceans, neither of which can be explained by the effects of the convecting mantle. This requires the CLM, especially that with thick keels, to be less compositionally buoyant and denser than previously thought, a conclusion supporting recent observations on CLM deformation.

Original languageEnglish (US)
Article numbere2021GL096844
JournalGeophysical Research Letters
Volume49
Issue number1
DOIs
StatePublished - Jan 16 2022

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)

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