Tsukanov1, S.G. Skolotnev2
Shirshov Institute of Oceanology RAS. Moscow, 117997
2 Geological institute RAS, Moscow, 109017.
The chemical composition of minerals and ultramaphic and maphic
rocks from peridotite massiff of Poputnaya Mountin and from
blocks in serpentinite melanges in northern part of Valagin
Ridge was studied. It was assigned to two ophiolites complexes.
One of them is a fragment of ancient oceanic crust, which
was a basement for Achayvayam-Valagin paleoarc. It is represented
by tholeiite basalts, pelagic sedimentary deposits and gabbroids
from melange. The tholeiite basalts and gabbroids are similar
to N-tipe MORB by petrogrochemical composition. Pelagic sediments
are represented by red and braun chert which have santonian-campanian
age by microfauna radiolariya. The second ophiolite complex
is represented by highly depleted supra-subduction peridotites
massiff of Poputnaya Mountin. According to the composition
of mine minerals these peridotites are joined in four groups.
Rocks from different groups are irregulary interbedded into
massiff of Poputnaya Mountin. These groups are separated
by composition of spinels and ortopiroxen. Some of them lie
in the field of abisal oceanic peridotites. The others -
in the field of supra-subduction garzburgites and dunites,
some rocks have intermediate compositions.