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Detailed Reference Information |
Jouanne, F., Ménard, G. and Darmendrail, X. (1995). Present-day vertical displacements in the north-western and southern Jura Mountains: Data from leveling comparisons. Tectonics 14: doi: 10.1029/94TC03336. issn: 0278-7407. |
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Two high-precision leveling networks were successively surveyed in France, the NGF, measured during the 1886--1907 period, and the IGN69, measured from 1965 to 1979. The accuracy of these levelings (standard deviation of 1.8 mm/√km to 3.8 mm/√km) allows us to compute the vertical displacements of the benchmarks between two different eras. The results indicate the occurrence of discrete zones of uplift and subsidence: (1) a regional uplift (up to 1.4 mm/yr) of the Subalpine Massifs; (2) an important uplift of the internal Jura (up to 2 mm/yr); (3) a relative subsidence of the southern part of the Jura (0.8 mm/yr); and (4) a relative subsidence of the Bresse Basin with respect to the external Jura. Comparing the spatial distribution of zones of uplift and their respective vertical displacement rates with a regional structural cross section leads to the conclusion that present-day uplift of the Belledonne and Bornes Massifs and of the internal parts of the Jura Mountains, can be explained by crustal shortening along a major basement-involving thrust fault. This fault ramps up under the Bornes Massif from a depth of 12 km to 7 km, turns into a flat under the Molasse Basin, ramps up to the top of the basement at the north-eastern margin of the internal Jura Mountains, and reaches the surface in the external Jura. The Sal¿ve ramp-anticline is carried by a bifurcation of this thrust. Horizontal displacement rates of 6 mm/yr at the Bornes ramp, 2 mm/yr at the Sal¿ve ramp, and 4 mm/yr at the internal Jura ramp have been determined by inversion of profiles of uplift rates. Whether this basement-involving thrust fault was already active during the Miocene main folding phase of the Jura Mountains or whether it was activated only during Pliocene-Pleistocene times is subject to debate. ¿ American Geophysical Union 1995 |
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Abstract |
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Keywords
Geodesy and Gravity, Control surveys, Geodesy and Gravity, Crustal movements—intraplate, Tectonophysics, Continental neotectonics, Information Related to Geographic Region, Europe |
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Publisher
American Geophysical Union 2000 Florida Avenue N.W. Washington, D.C. 20009-1277 USA 1-202-462-6900 1-202-328-0566 service@agu.org |
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