RECENT CRUSTAL UPLIFT OF PRECAMBRIAN CRATONS: KEY PATTERNS AND POSSIBLE MECHANISMS
E.V. Artyushkov1, S.P. Korikovsky2, H.-J. Massonne3, P.A. Chekhovich1,4
1O.Yu. Schmidt Institute of Physics of the Earth, Russian Academy of Sciences, ul. Bol’shaya Gruzinskaya 10, Moscow, 123995, Russia
2Institute of Geology of Ore Deposits, Petrography, Mineralogy and Geochemistry, Russian Academy of Sciences, Staromonetnyi per. 35, Moscow, 119017, Russia
3Universität Stuttgart, Institut für Mineralogie und Kristallchemie, Azenbergstr. 18, 70174, Stuttgart, Deutschland
4Moscow State University, Earth Science Museum, Leninskie Gory 1, Moscow, 119991, Russia
Keywords: Докембрийские кратоны, новейшие поднятия коры, механизмы поднятий коры, метаморфизм, Precambrian cratons, post-Miocene crustal uplift, mechanisms of crustal uplift, metamorphism
Abstract
Precambrian cratons cover about 70 % of the total continental area. According to a large volume of geomorphological, geological, paleontological, and other data for the Pliocene and Pleistocene, these cratons have experienced a crustal uplift from 100-200 m to 1000-1500 m, commonly called the recent or Neotectonic uplift. Compression of the Precambrian crust terminated half a billion years ago or earlier, and its uplift could not have been produced by this mechanism. According to the main models of dynamic topography in the mantle, the distribution of displacements at the surface is quite different from that of the Neotectonic movements. According to seismic data, there is no magmatic underplating beneath most of the Precambrian cratons. In most of cratonic areas, the mantle lithosphere is very thick, which makes its recent delamination unlikely. Asthenospheric replacement of the lower part of the mantle lithosphere beneath the Precambrian cratons might have produced only a minor part of their Neotectonic uplifts. Since the above mechanisms cannot explain this phenomenon, the rock expansion in the crustal layer is supposed to be the main cause of the recent uplift of Precambrian cratons. This is supported by the strong lateral nonuniformity of the uplift, which indicates that expansion of rocks took place at a shallow depth. Expansion might have occurred in crustal rocks that emerged from the lower crust into the middle crust with lower pressure and temperature after the denudation of a thick layer of surface rocks. In the dry state, these rocks can remain metastable for a long time. However, rapid metamorphism accompanied by expansion of rocks can be caused by infiltration of hydrous fluids from the mantle. Analysis of phase diagrams for common crustal rocks demonstrates that this mechanism can explain the recent crustal uplift of Precambrian cratons.
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