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).
The geological structure, structural relations with the underlying complexes, mineral composition, age and origin of sedimentary-volcanogenic and intrusive formations of the Chamberlain valley area (northern part of the Wedel Jarlsberg Land, Svalbard Archipelago) are considered. As a result of the studies, two stages of the Late Precambrian endogenous activity in this area have been identified. For the first time the Vendian ages (593-559 Ma) of intrusive (dolerites) and effusive (basalts, andesites, tuffs) rocks were determined by U-Pb-method (SHRIMP-II) for Svalbard Archipelago. At the same time, the Grenville ages for large bodies of gabbro-diorites, metadolerites bodies (1152-967 Ma), and metagranites (936 Ma) were determined for the first time for this area, which correlates well with the ages of magmatic formations obtained earlier in the southern part of Wedel Jarlsberg Land. A detailed petrographic and petrochemical characterization of all the described objects were compiled and the paleotectonic conditions of their formation were reconstructed. Based on these data, the Chemberlendalen series, which is dated to the Late Vendian, and the Rechurchbreen series, which the authors attribute to the Middle Riphean and correlate with the lower part of the Nordbucht series are distinguished. The data obtained indicate a two-stage Precambrian magmatism in this area of the Svalbard archipelago and, most importantly, provide evidence for the first time ever of endogenous activity on Svalbard in the Vendian time. This fact makes it possible to reconsider in the future the history of the formation of folded basement of the Svalbard archipelago and the nature of the geodynamic conditions in which it was formed.
Identifying complexes of the early Proterozoic age in the composition of crystal foundation is a key task in studying pre-Cambrian formations of the whole of Spitzbergen and its northwestern part in particular. The territory of that region is formed by three deeply metamorphosed complexes that underwent the processes of migmatization and granitization in mid-Rifey and were broken through by granitoids of mid-Rifey and mid-Paleozoic. In their turn, the outbursts of the foundation are overlayed by terrigene rocks of the Devonian graben of Spitzbergen, conglomerates forming a large share among them. In the course of petrographic and chemical studies of such compositions, as well as isotopic characteristics of zircons from the boulders of basal conglomerates of Red Bay (D 1 ) series, the suite of Wolfberget at Cape Conglomeratodden the presence was identified of reddish (meat-red) granites of isotopic age of 1631±19 Mil years, which is comparable to late Karelian processes manifested actively across the archipelago. It is also proven that transformations of these rocks within the range of 380±42 Mil years are well associated with mid-paleozoic events, considerable restructuring of the foundation associated with them. The age range we defined is another proof of manifestation of early pre-Cambrian (late Karelian) processes in the northwestern Spitzbergen.
Findings in the northwest of Spitsbergen of the hypabyssal intrusions of maphic and ultramaphic compositions with the increased content of alkalis and accessory minerals of kimberlite gave base for the more thorough studies of the region of their propagation, determination of laws governing the arrangement in the zone of the deep submeridional breaking zone Breybogen, study of the physical composition, enriched by xenolites of the mantle level: lherzolites and wehrlites. The Late Paleozoic age, which coincides with the age of kimberlite of Arkhangel'sk region and the mineral-petrographical composition of these species testify about the significant similarity to the pyropic subfacies of kimberlitic magmatism.
The new data on geology of Devonian graben and subjacent complexes allow reviewing the evolution of geodynamic processes in this region during Riphean-Paleozoic. It was confirmed that Cambrian – Early Silurian series were formed in the platform environment under conditions of stable dome-like uplifting of the territory, and the subalkaline granitoids (S2-D1) may be classified as anorogenic intrusion. Devonian riftogenesis was a sequel of regeneration of the Riphean paleo- rift in conditions of general spreading. There are distinguished three stages in formation of the graben: pre-graben, orogenic and post-orogenic ones, with description of complexes formed at those stages. Concluding processes of this type are related to formation of fluorite-barite-рolymetallic occurrences and alkaline-ultrabasic dykes (D3) in zones of deep faults. The conclusion is made that the crust block, representing basement of the Barenz-sea plate in the region, has gone through the recurrent intra-plate riftogenesis in the Middle Paleozoic.
A new metallogenic zone was separated out in a central part of the archipelago Spitsbergen by the results of exploration work. It was shown an integral series of ore areas and fields in the limits of this zone, including the ore field Halvdanpiggen. This field integrates several non-uniformly scaled the ore occurrences, which present a great interest in regard to a material composition of the ore. They likewise produce an information for determination of genesis and outlooks of total metallogenic zone. The article contains data on geology, mineralogy and geochemistry of deposits; it is established their genesis, formation membership and time of origination.
