RT Journal Article
T1 Pulsating continents on Venus: An explanation for crustal plateaus andtessera terrains
A1 Romeo Briones, Ignacio
A1 Turcotte, Donald L. (Donald Lawson)
AB We propose that tessera terrains on Venus represent continental crust that does not participate in theperiodic recycling of the lithosphere through global subduction events.We have studied the force balance onthe boundary of a continental area that survives a global subduction event using an analytical model. In theproposed model, the ratio between the crustal and lithospheric mantle thicknesses controls the forcebalance. If the crust thickness is less than ∼2/5 of the lithospheric mantle thickness, the continental area willbe compressed, but if the crustal thickness is higher than ∼2/5 of the lithospheric mantle thickness, thecontinental area will spread out and collapse. Consequently, if the lithospheric mantle beneath a continentalregion is delaminated during a global subduction event, the continent will collapse generating tessera inliersdominated by extensional tectonics. But if a significant portion of lithospheric mantle remains, then thecontinental area will be compressed generating a plateau by crustal shortening. The observed plateau heightscan be explained by this model, a ≈2 km height plateau can be generated by a lithospheric mantle thicknessof 40 km while a ≈4 km height plateau can be generated by a 90 km thick lithospheric mantle. We havemodelled this crustal thickening of a continental area by tectonic contraction using a thin viscous sheetapproach with a Newtonian viscosity for the crust. The force from a hot mantle elevated during a globalsubduction event is enough to build up a plateau by compression in ∼50 Ma using a viscosity for thecontinental crust of η=1021 Pa s and ∼200 Ma for η=5·1021 Pa s. During this compressional stage concentricfold and thrust belts are generated in the plateau-continent, erasing any impact craters that were present.The subsequent stabilization of a new crust and lithosphere in the surrounding mantle changes the forcebalance allowing a moderate gravitational collapse of the plateau-continent accommodated by radialgrabens. The pulsating continent model links for the first time the generation of crustal plateaus and theorigin of the volcanic plains predicting the observed equivalent effective crater density for both terrains.
PB Elsevier Science B.V., Amsterdam
SN 0012-821X
YR 2008
FD 2008
LK https://hdl.handle.net/20.500.14352/49710
UL https://hdl.handle.net/20.500.14352/49710
LA eng
DS Docta Complutense
RD 6 abr 2025