by Michael Studinger, Lamont-Doherty Earth Observatory

Figure 1: The Lake Vostok basin is only a small (50 km wide) tectonic feature within the overall setting of a several hundred km wide continental collision zone between the Gamburtsev Subglacial Mountains and the Dome C region (Studinger et al., 2003b). By constructing a variety of kinematic and flexural models for the deformation of the crust and then comparing the predicted and observed Bouguer gravity, we conclude that the tectonic boundary along Lake Vostok is most likely the consequence of the overthrusting of a pre-existing passive continental margin by thick thrust sheets. The Lake Vostok basin was probably formed by minor extensional reactivation of the basal thrust faults and the collapse of the overlying sedimentary units. In other words, Lake Vostok is not a rift. The gravity modeling is consistent with the relatively thin crust east of Lake Vostok imaged from teleseismic receiver function analysis and Werner deconvolution estimates for the depth to magnetic basement across the entire region. For details see Studinger et al. (2003a and b).

Tectonic Control of Subglacial Lakes - Why does it matter?

For details see Bell et al., (2006).

MODIS Image of Subglacial LakesThe morphology of surface lakes strongly influences their ecology and limnology. This morphology is a result of both the geologic processes that produce topographic basins and the regional climatic and local hydrologic processes that control water depth and sediment infilling. Although basin forming processes range from glacial scour to meteorite impacts, the deepest, oldest surface lakes are tectonically controlled and contain diverse exotic ecosystems (see Table 1 below). Subglacial lakes are also thought to be ancient systems that may contain exotic biota. Two newly defined subglacial lakes (Bell et al., 2006) are aligned parallel to Lake Vostok (see figure on the right). Other data shows that they are distinguished by distinct gravity lows, flat ice surface slopes and have estimated water depths of at least 900 m. Surface elevation data indicates that large deep subglacial lakes have a profound influence on the regional ice sheet topography and probably ice sheet flow. The sub-rectangular morphology of the Sovetskaya and 90°E lakes and their position along the western edge of this foreland basin indicate these features may be similarly fault controlled. The tectonic fabric of this foreland basin or pre-existing structures (Studinger et al., 2003b) provides the template for the elongate fault-bounded topographic depressions necessary to form this province of large, deep subglacial lakes. The tectonically controlled depth of these lakes should provide consistent water depths through changing climatic conditions over the past 10–35 Ma. Unlike the shallow lakes in West Antarctica and beneath Dome Concordia, these deep subglacial lakes remained stable environments through many glacial cycles since their origin 10–35 Ma enabling the development of novel ecosystems.

Table 1: Water Depth of Tectonically Controlled Lakes
Surface Lakes
Subglacial Lakes
Lake Tahoe, USA (501 m) Lake Vostok, Antarctica (>900 m)
Lake Issyk-kul, Kyrgyzstan (668 m) 90ºE Lake, Antarctica (~900 m)
Lake Tanganyika, Africa (1479 m) Sovetskaya Lake, Antarctica (deep)
Lake Malawi, Africa (706 m) -
Lake Baikal, Siberia (1637 m) -

Publications related to the Tectonic Control on Subglacial Lakes in Antarctica:

Bell, R.E., Studinger M., Fahnestock, M.A., and Shuman, C.A., Tectonically controlled subglacial lakes on the flanks of the Gamburtsev Subglacial Mountains, East Antarctica, Geophys. Res. Lett., 33, L02504, doi:10.1029/2005GL025207, 2006.

Studinger, M., Karner,G.D,  Bell, R.E., Levin, V., Tikku, A.A., Raymond, C.A., Geophysical Models for the Tectonic Framework of the Lake Vostok Region, East Antarctica, Earth Planet Sci. Lett., 216, 663-677, doi:10.1016/S0012-821X(03)00548-X, 2003.

Studinger, M., R.E. Bell, G.D. Karner, A.A. Tikku, J.W. Holt, D.L. Morse, T.G. Richter, S.D. Kempf, M.E. Peters, D.D. Blankenship, R.E. Sweeney, and V.L. Rystrom. Ice cover, landscape setting, and geological framework of Lake Vostok, East Antarctica, Earth Planet. Sci. Lett., 205(3-4), 195-210, doi:10.1016/S0012-821X(02)01041-5, 2003.