C - Lublin

USING PETROGRAPHIC AND MAGNETIC METHODS FOR THE SOILS
PARENT MATERIAL ORIGIN INDICATION
Alekseeva V.A.
Data from quartz grain micromorphology were compared with those obtained
from magnetic and heavy mineral analysis for two sections of Pleistocene
sediments in the Upper Oka River Basin (central part of the Russian Plain). The
aim of the study was to compare the particularities of depositional processes and
sediment provenance for the Early-Middle Pleistocene alluvial sediments, two
horizons of the Middle Pleistocene moraines, which are divided by the complex of
fluvial-glacial and lacustrine sediments, and the Late Pleistocene cover loams on
the top surfaces, which are the soil’s parent rocks (Complex analysis …, 1992).
The published heavy mineral data suggests the one primary source from
Scandinavia for two separate moraine layers, thus the difference in the relative
content of material derived from Scandinavian source was noticed (Complex
analysis …, 1992). The increase in content of hornblende, garnet and epidote and
decrease of staurolite, tourmaline, glauconite and siderite content is characteristic
for younger moraine layer and can be explained by the gradual loss of influence of
the underlying, carbonate-rich bedrocks and greater input of Scandinavian material
The data obtained by magnetic measurements show the largest differences between
the pre-glacial alluvial sediments of Early-Middle Pleistocene age and the complex
of glacial sediments of Middle Pleistocene age (Alekseeva, Hounslow, in prep.).
The lowest values of magnetic mineral abundance characterize pre-glacial
sediments and can be explained by fluvial reworking of the carbonate-rich
bedrocks. The glacial sediments contain up to 16 times larger amounts of magnetic
material with the maximum values for the younger moraine layer and cover loams.
Such a difference between the two moraine complexes is probably a reflection of
the greater Fe-oxide content in sediments from the Scandinavian source.
The study of the quartz surface grain micromorphology by scanning electron
microscope (SEM) is a tool for help in differentiating ancient sedimentary
environments and potential transport mechanisms (Krinsley and Doornkamp, 1973;
Higgs, 1979). This methodology assumes that grain shape and surface features
reflect the environmental history of the discrete particles. Abrasion of quartz
produces mechanical surface textures, which are characteristic for specific
environments. Features due to chemical action can also be distinguished by means
of the SEM and a number of criteria are available to separate these mechanical and
chemical textures (Krinsley and Doornkamp, 1973).
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