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

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.

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).

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.

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.

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

In the upper section they are replaced by trachyandesite basalt and

trachyandesites having fragmentary outputs.

Trachyandesites with pilotaxitic structure

microfluidics and texture

Lithocrystalloclastic tuffs

rhyodacite composition confined

to the upper suites and spread p.

Yudesyadyaha

Structure of rhyodacite tuffs

lithocrystalloclastic psammitic , clastic texture

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.

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.

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.

Charts Lutz and Miyashiro,

built on rock-forming

elements, figurative points

breeds tend to island arc

basalts.

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).

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.

The diagrams constructed from rare

earth elements, in terms of

compositions of volcanics Morozov

suite are located in the fields of

basalt volcanic arcs.

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.

Thank you for your attention!