1. Petrology of late proterozoic
volcanics of the ridge Pai-Khoi
Кaneva Tatyana
Institute of Geology of the Komi Science Center
of the Ural Branch of the Russian Academy of Sciences
2. The aim of my scientific work is petrological description and
indetification of geodynamic conditions of volcanic rocks
formation of the ridge Pai-Khoi. Also it is supposed to compare
and to find relationship between
late proterozoic volcanites of
Pai-Khoi and the ridge Ochenyrd.
3. The following problems were set:
detailed petrological and mineralogical characteristics;
characteristics of the material composition of rocks;
comparison of paleodynamic conditions of volcanic formation
Morozov suite in Pai-Khoi and ridge Ochenyrd rocks.
The following methods are used:
optical microscopy of petrographic samples;
the electron microscope analysis of minerals;
silicate analysis;
geochemical analysis (ICP-MS).
4. Geological map sheets doneogenovyh formations R-41-XX, XXI,
Amderminsk area, JSC "Polyargeo" 1:200 000.
Schematic geological map of the Upper
Proterozoic sediments of Amderminsk (by V.V.
Tereshko). Note: Amderminsk suite - 17;
Morozov suite - 12; Sokolninsk suite - 15
(Timonin et al, 2004).
The Riphean - Vendian
volcanic complex forms a
synclinal structure of the
nucleus Amderminsk anticline
on the territory of the Pai-
Khoi and is its base.
5. Morozov formation of Late Riphean age
(RF3mr) in the northeastern part of the range
of Pai -Khoi is represented by various
volcanic rocks:
volcaniclastic;
effusive.
6. Trachybasalt and lithocrystalloclastic tuffs trachybasalt
composition are predominant, lower classes make up the suite.
Trachybasalt serialnoporfirovoy structure
and amygdaloidal texture
Structure of tuffs trachybasaltic lithocrystalloclastic psephites- psammitic ,
clastic texture
7. In the upper section they are replaced by trachyandesite basalt and
trachyandesites having fragmentary outputs.
Trachyandesites with pilotaxitic structure
microfluidics and texture
8. Lithocrystalloclastic tuffs
rhyodacite composition confined
to the upper suites and spread p.
Yudesyadyaha
Structure of rhyodacite tuffs
lithocrystalloclastic psammitic , clastic texture
9. Variation diagram of AFM [(Na2O + K2O)-FeO *-MgO] Morozov suite rocks (RF3mr) and ridge Ochenyrd (RF3bd). Border
tholeiitic and calc-alkaline series on H. Kuno. Note: Morozov suite (RF3mr): 1 - trachybasalt; 2 - trachyandesite; 3 -
trachyandesites; 4 - rhyodacites; 5, 6 - volcanics ridge Ochenyrd.
10. Diagram Lutz K2O-TiO2 rocks Morozov suite (RF3mr) and ridge
Ochenyrd (RF3bd). Note: 1-island arc basalts; spreading zone: 2-
oceanic rifts, 3-continental rifts.
Charts Lutz and Miyashiro,
built on rock-forming
elements, figurative points
breeds tend to island arc
basalts.
Miyashiro diagram Na2O/K2O- (Na2O + K2O): 1 - back-arc spreading zone; 2 -
island-education. Note to all the diagrams: Morozov suite (RF3mr): 1 -
trachybasalt; 2 - trachyandesite; 3 - trachyandesites; 4 - rhyodacites; 5, 6 -
volcanics ridge Ochenyrd.
11. Discriminatory chart Th-Hf/3-Ta D. Wood basalts: A - N-type
MORB; B - E-type MORB and intraplate tholeiites; C - intraplate
alkali basalts; D - basalt volcanic arcs (Wood, 1980). Note: 1 -
trachybasalt and 2 - trachyandesite Morozov suite (RF3mr).
The diagrams constructed from rare
earth elements, in terms of
compositions of volcanics Morozov
suite are located in the fields of
basalt volcanic arcs.
Discriminatory chart Y-Cr: VAB - basalt volcanic arcs;
WPB - intraplate basalts; MORB - MOR basalts (Pearce, 1982).
Note: 1 - trachybasalt and 2 - trachyandesite Morozov suite (RF3mr.
12. Conclusion
Thus, comparing geodynamic rocks in Morozov
formation in the north-eastern part of the ridge
Pai-Khoi and ridge Ochenyrd we assume that the
volcanic rocks have formed in a single
suprasubduction setting, but in different parts of
a complex island arc system.
