|
|||||
|
|
Incipient metamorphism between Ufa and Beloretzk, western fold-and-thrust belt, southern Urals, Russia |
|
| Authors: | I Matenaar U A Glasmacher W Pickel U Giese V N Pazukhin V I Kozlov V N Puchkov L Stroink R Walter |
| Institution: | Geologisches Institut, RWTH Aachen, Wüllnerstrasse 2 D-52056 Aachen, Germany, DE Max Planck Institut für Kernphysik, Postfach 103980 D-69029 Heidelberg, Germany, DE Institut für Geologie, Geochemie und Lagerst?tten des Erd?ls und der Kohle, RWTH Aachen, Lochnerstrasse 4-20 D-52064 Aachen, Germany, DE Institut für Geologische Wissenschaften und Geiseltalmuseum, Martin-Luther-Universit?t Halle-Wittenberg, Domstrasse 5 D-06108 Halle (Saale), Germany, DE Ufimian Geoscience Center, Russian Academy of Sciences, K. Marx street, 450000 Ufa, Russia, RU Institut für Geophysik, Ruhr-Universit?t Bochum, Postfach 102148, D-44721 Bochum, Germany, DE Geologisches Institut, RWTH Aachen, Wüllnerstrasse 2 D-52056 Aachen, Germany, DE |
| Abstract: | The low-temperature thermal history of Paleozoic and Precambrian shales and slates was studied in detail along a NW–SE transect between Ufa and Beloretzk in the western fold-and-thrust belt of the southern Urals, Russia. The aim of the investigations was to compare four thermal parameters, namely illite and chlorite crystallinity, vitrinite reflectance, and Conodont color alteration index (CAI), in order to quantify the finite (i.e. maximum) thermal grade. The transect extends from Devonian to Permian sedimentary units of the pre-Uralian foredeep, crossing Precambrian siliciclastic and carbonate units of the Bashkirian megaanticlinorium into the Paleozoic units of the Ural-Tau antiform. In general, the four methods indicate similar metamorphic grades of the samples. The finite thermal grade ranges from lower diagenesis (Ro=0.9%, CIS-FWHMill001ad=0.770 Δ°2Θ, CIS-FWHMchl002ad=0.447 Δ°2Θ, CAI=1.5) in the pre-Uralian foredeep to epizone (CIS-FWHMill001ad=0.243 Δ°2Θ, CIS-FWHMchl002ad=0.252 Δ°2Θ, CAI=6) in the eastern part of the Bashkirian mega-anticlinorium and the Zilair synclinorium. All parameters show a sudden change in value at thrust boundaries and an increase in metamorphic grade with stratigraphic age within structural units. In comparison, the westernmost Precambrian units of the Ala-Tau-anticlinorium are characterized by thermal grades of lower diagenesis. Magmatic dikes cause a wide variation of the thermal grade in the western part of the Bashkirian megaanticlinorium. Also in areas with an intensive cleavage development (Zilair synclinorium) the finite thermal grade shows a stronger relationship towards the deformation than the stratigraphic position. |
| Keywords: | |
| 本文献已被 SpringerLink 等数据库收录！ | |