Sierra Nevada uplift

geologic controversy - Rise of the Sierra Nevada

The Sierra Nevada range of eastern California is one the most famous ranges in the world, but the timing and processes that led to its elevated topography is a major question mark. Christopher Henry (2009) summarizes this controversy and explains that most researchers once considered Sierran uplift to have mostly occurred during the last 10 million years, but more recent studies argue for much earlier uplift in the Mesozoic. The issue is related to the proposed “Nevadoplano” of DeCelles (2004), who argued that the present day Great Basin region (mostly Nevada) was a high plateau during the Mesozoic, much like the modern day Altiplano of the central Andes. The Sierra Nevada region would have formed the flank of this great plateau. Mulch et al. (2006) and Cassel et al. (2009) supports an early rise model with stable isotope evidence that suggest the Sierra Nevada was near its current elevation by at least the Eocene and Oligocene. Major batholithic volcanism also occurred at this time and is consistent with thickened crust. In contrast, Ducea and Saleeby (1996) propose the Sierra Nevada was uplifted in the late Cenozoic following the removal of a dense eclogitic root; citing thermobarometry of mantle xenoliths. Both sides seem to have support look for more work to be done on this issue.

Figure 1 of Henry (2009) showing modern day topography overlain by flow direction of ancient rivers.

Sources

Henry, C. D., 2009, Uplift of the Sierra Nevada, California, Geology,

Cassel, E.J., Graham, S.A., and Chamberlain, C.P., 2009, Cenozoic tectonic and topographic evolution of the northern Sierra Nevada, California, through stable isotope paleoaltimetry in volcanic glass: Geology, v. 37, p. 547–550.   

DeCelles, P.G., 2004, Late Jurassic to Eocene evolution of the Cordilleran thrust belt and foreland basin system, western U.S: American Journal of Science, v. 304, p. 105–168, doi: 10.2475/ ajs.304.2.105.

Ducea, M.N., and Saleeby, J.B., 1996, Buoyancy sources for a large, unrooted mountain range, the Sierra Nevada, California: Evidence from xenolith thermobarometry: Journal of Geo- physical Research, v. 101, p. 8229–8244, doi: 10.1029/95JB03452.

Mulch, A., Graham, S.A., and Chamberlain, C.P., 2006, Hydrogen isotopes in Eocene river gravels and paleoelevation of the Sierra Nevada: Science, v. 313, p. 87–89.