Wyniki wyszukiwania - BazTech

Ograniczanie wyników

1 Geology, Geophysics and Environment

1 2012

Znaleziono wyników: 1

Liczba wyników na stronie

Wyniki wyszukiwania

Sortuj według:

Ogranicz wyniki do:

New data on the petrology of metamorphic rocks from the Kuekvun' uplift (North Chukotka area)

Kulyukina N. A., Tikhomirov P. L., Yapaskurt V. O.

Geology, Geophysics and Environment

2012

Vol. 38, no. 4

490--91

Kuekvun' uplift is located within Chaun folded zone of Mesozoic Verkhoyansk--Chukchi foldbelt. Outcropped metamorphic rocks were explored here in 1960-1970s during the geological surveying. On latest geological maps (scale is 1:500,000) metamorphic rocks of Kuekvun' uplift are dated Devonian-Middle Carboniferous (based on palaeontological data). Metamorphic rocks of the Kuekvun' uplift are represented by gneisses and schists formed from Mid-Palaeozoic sedimentary units, composed by fine-grained clastic rocks with minor carbonates. The clastic material contains an admixture from a volcanic source of mafic to intermediate composition. Almost all of the rocks were changed in the amphibolite facies. Two samples of plagiogneisses, which represent both the marginal and the central structural zones of the uplift has been a subject of a detailed study. Metamorphism temperature estimation has been done using garnet-biotite (Perchuk & Lavrent'eva 1983) and garnet-staurolite (Perchuk 1991) geothermometers. The mineral paragenesis and the composition of coexisting garnet, biotite and staurolite indicate the temperature of metamorphism of 560-600°C, and the pressure of 2.5-4 kbar, which corresponds to the depth of 8-12 km. Such conditions imply the relatively high geothermal gradient (nearly 60°C/km), approaching that for periplutonic metamorphic aureoles. Garnets from the marginal and the central zones of the uplift reveal a similar zonation pattern. The only notable difference is the presence of compositionally contrasting Caenrichedrim in garnets from the central zone. Such rims could result from the evolution of the entire metamorphic complex, but they could also be related with local processes, like the crystallization of granitic plutons, which are widespread within the observed area.