-
Date submitted2023-03-30
-
Date accepted2023-09-21
-
Date published2023-10-27
Mineral composition and thermobarometry of metamorphic rocks of Western Ny Friesland, Svalbard
The results of the study of mineral composition and microstructure of representative metapelitic and calcic pelitic schist and amphibole-biotite gneiss, occurring in the northern part of the Western Ny Friesland anticlinorium, are reported. Mineral composition was analyzed with a JSM-6510LA scanning electron microscope with a JED-2200 (JEOL) energy dispersive spectrometer. Metamorphic conditions were assessed with various mineral geothermometers (garnet-biotite, Ti-in-biotite, Ti-in-muscovite, Ti-in-amphibole, garnet-amphibole, amphibole-plagioclase, and chlorite) and geothermobarometers (GASP, GBPQ, GRIPS, GBPQ, phengite, etc.). It has been shown that peak temperature and pressure for rocks of the Paleoproterozoic Atomfjella Series forming the western limb of the anticlinorium are consistent with those for the high-pressure part of the upper amphibolite facies (690-720 °С, 9-12 kbar), and the peak temperature and pressure for rocks of the Mossel Series occurring in the eastern limb and rest on the Atomfjella rock sequence, are consistent with the high-pressure part of the lower amphibolite facies (580-600 °С, 9-11 kbar). In addition to the high-temperature parageneses Ms-Bt-Grt-Pl (±Ky, St), Bt-Grt-Pl-Kfs-Cal (±Scp) and Bt-Hbl-Ep-Grt-Pl, the rocks of the both series display the low-temperature assemblage Ms-Chl-Ep-Ab-Prh-Ttn, which was formed upon transition from greenschist to prehnite-pumpellyite facies (260-370 °С).
-
Date submitted2022-04-06
-
Date accepted2022-06-15
-
Date published2022-07-26
Geological and structural position of the Svetlinsky gold deposit (Southern Urals)
The paper presents the geological and structural position of the large Svetlinsky gold deposit in the Kochkar anticline (Southern Urals), localized in the zone of the Late Paleozoic (D 3 ) deep thrust of the western dip. The study confirms and clarifies the notion of its multiphase and polychronism. The thrust caused bending moments in its wings, subsidence of the lying crust, emergence of a shallow marine basin with rapid accumulation of terrigenous carbonate sediments (C 1 v), and formation of numerous landslide structures. The heating of rocks in the anticline core was accompanied by granitization and dome formation. A small Svetlinsky dome formed in the immediate vicinity of the thrust, creating a thermobaric gradient field (С 2 ). The zone of dome dynamic influence also includes the adjoining thrust area, complicated by a series of sub-vertical thrusts of sub meridional strike and numerous steeply dipping subparallel cracks of the latitudinal strike, synchronously filled with vein quartz and accompanied by hydrothermal metasomatic rock transformations. The formation of the gold deposit occurred during the post-collisional relaxation stage (from P 1 to, probably, the Early Jurassic). The association of gold mineralization with the Svetlinsky dome is indicated by the presence of native gold in Neogene ravine placers in the dome area and marbles of the Svetlinsky deposit, in association with fluorite, F-phlogopite, Cr-muscovite, pink topaz, pure quartz, and native sulphur. The presence of native gold in Neogene ravine placers in the dome area and marbles of the Svetlinsky deposit, in association with fluorite, F-phlogopite, Cr-muscovite, pink topaz, pure quartz, and native sulphur, indicates the association of gold mineralization with the Svetlinsky dome.
-
Date submitted2008-10-24
-
Date accepted2008-12-01
-
Date published2009-12-11
History and prospects for the development of the karelian isthmus facing stone mineral base
- Authors:
- A. Y. Tutakova
The prerequisites for the development of the deposits, the previous studies and the current state of Karelian Isthmus facing stone sources as well as their comparison with those of other regions of Northwestern Federal Districts of Russia are considered. The objects for top-priority geological prospecting are determined.