The Burakovka layered pluton of basic and mafic rocks is the largest intrusive
massif in the Baltic Province composed of Si- and Mg-rich boninite-like rocks. The pluton consists
of two individual bodies, each having its own internal structure, and contacting each other in their
apical parts, known as the Aganozero and Shalozero-Burakovka bodies. Both bodies have a similar
rock sequence including five differentiated zones (upward): mafic rocks, pyroxenite, gabbro norite,
pigeonite gabbro norite, and magnetite gabbro diorite (the latter found only in the Shalozero-Burakovka
Body). Being generally similar to each other, these bodies differ notably in the styles of
their cumulate stratigraphy and, to a lesser extent, in composition.
The pluton is distinguished by the presence of markers - singular interlayers of high-temperature
mafic cumulates emplaced in the sequence of lower-T formations. Their origin is
believed to have been associated with the intrusion of fresh magma portions into the crystallizing
magma chambers. The same mechanism is believed to have been responsible for a macrorhythmic
pattern found in the southeastern portion of the Shalozero-Burakovka intrusive body.
Using chemical and mineralogical data, it is shown that the bodies discussed were derived
from similar high-Si and high-Mg magmas, except that the Aganozero Body was emplaced 50
million years later than the Shalozero-Burakovka intrusion: the former was dated (Sm-Nd isochron)
2372
22 Ma ( e Nd=-3.22
0.13 ), and the latter, 2433
28 Ma
( e Nd=-3.14
0.14 ). It is concluded
that the Burakovka Pluton was a long-lived magma center which developed above a local mantle
plume, the origin of which had been associated with the activity of a megaplume which had been
responsible for the existence of the Baltic province throughout a period of 200 million years.