structural/textural features of a rock type, its composition
and genesis, he can easily recognize and translate such
Cl into the said rock type. A so to speak read-out of Cl’s
is known to be most reliable in case of generally
classified, or undivided, geological sequences, like
granitoids, gabbroids, effusives, metamorphites, etc.
Using an “image” language, one can read from
sedimentation strata a rock composition and geometry of
crystalline formations, their fabric, relative age and other
particulars, zones of plastic strain and metasomatism
included. In other words, one can create a “lay-out” of a
geological map; moreover, the lay-out of an
aerophotogeological map can be made for any area
overlain by a cover of unconsolidated sediments,
whatever the physiographic conditions of this area are.
Besides, the Cl gives means to construct, when needed,
geological maps for the surfaces of regional
unconformities within the basement, at its various depth
intervals, in the crystalline rocks varying in composition.
An example of a 1/200,000-scale map showing the LPO's
and results of structurai interpretation thereof is given in
Figure 1 (Q-cover thickness up to 50 m). Where the
LPO's strike in a nearly latitudinal direction one can trace
a distinctly pronounced Cl of an anticlinal fold with a
trend close to meridional. The fold is discontinuous
because of longitudinal faults that cut the fold's closure
into three segments resembling a trident. A central
structural high is accompanied in the W and E by narrow
and parallel minor inverted folds, of which the western
one is nearly asymmetric, while the eastern fold is just
cut off along the fault. The anticline has resulted most
likely from vertical movements in the process of magma
intrusion, as one may judge from a series of sills
developed within the anticline. Host rocks responded to
folding by forming medium-size fault blocks, or
mesoblocks, varying in height. In the south, trains of
lakes have enabled a concealed fault, that marks off the
confines of megablocks, to be identified running normal
to the fold's lineation and axes. As it follows from the CI's
geometry, a group of rocks constituting a territory may be
regarded as granitoids and their varieties.
Figure 2 shows another case of reading out, in the same
scale, the lithological/facial mode of the crystalline
formations under the sedimentary cover as thick as 60
m. Plotted in the drawing is an outcrop area of a jaspilite
formation containing iron hornfels (in the middle). The
fabric of the hornfel strata is marked by a nearly parallel
course of LPO's, whereas the hornfel-bearing host rocks
constitute a gneiss complex, displaying their typical Ci in
the form of extended and very slightly undulating LPO'’s
which not infrequently close up at acute angles.
In 1984 a really unexpected result was obtained in the
north of the Fennoscandian Shield (Kola peninsula,
Lovozero area). While examining a 1/500,000-scale
satellite image, it turned out that the Khibiny massif (size
45km x 36km, area 1300 sq.km, relative elevation up to
800 m, absolute elevation range 1,100-1,200 m), which is
subsiding gradually eastwards, and the Lovozero
mountainous terrain (5 km to the west, size 25km x
27.5km, area 680 sq.km) were originally nothing else
than a single intrusion. One may consider the Khibiny
massif of to-day to be a basis, while the Lovozero massif
is understood to be a former apex that slipped off a
previously single construction eastwards. The satellite
image pretty clearly betrays on the Khibiny massifs
surface a space which, as our experience ip
photointerpretation suggests, reminds us of a cut-off that
corresponds by its area to the basement of the Lovozero
massif. Being projected on to the Khibiny mass
hypsometric, landscape and structural contours of the
Lovozero coincide completely with the Khibiny's contours
in plan view. Nor do the massifs differ in their inner
structure. It should be noted that ever since the Very
beginning of research activities in the Khibiny intrusion
area (1840) and Lovozero massif (1887) those two have
been treated by all researchers as two separate alkaline
multiple intrusion bodies which possessed a complex
structure and primary layering.
In a period 1990-1992 that hypothesis was checked by
interpretation aimed to spot an emplacement channel of
the Lovozero massif. Results of interpreting the Archean-
Proterozoic basement rocks at a depth interval of 1,000.
800 m beneath the Lovozero alkaline rock complex are
presented in Figure 3 (a,b). Plotted in Figure 3a are the
LPO's, while their interpretation in terms of lithoiogy and
facies is shown in Figure 3b. Basing then upon the
already available geological map of the Lovozero
massifs surround (1981) overlain by the Lovozero
formations, and looking at the Cl's, we succeeded in
reconstructing the following stratigraphic sequence of the
basement complex: (a) Archean rocks - granites and
gneiss-granites, — (b) granodiorites and . gneiss-
granodiorites, (c) Archean-Proterozoic rocks - gneiss-
diorites and gneiss-gabbro-diorites, (d) inferred iron-ore
formation, (e) gneisses,(f) rocks with their composition
not defined yet. As for the intrusive formations, we
managed to plot (g) granites, (h) intrusive bodies filling
the fauits, (i) dikes and dike-like bodies varying in
composition and age. We also identified those faults that
betrayed unconformity in rocks, in particular (k) thrust
faults, (I) normal faults, and (m) shifts.
We have not revealed, however, any feeder, nor any sign
of it. On the other hand, as it can be perceived from the
Cl's, the rock complex related to a bottom of the
Lovozero strata that slipped off the Khibiny massif can be
described as far from being simple. Some of its parts
appear to be deformed rocks that formed while the
Lovozero strata were sliding off and down. Good
indicators of that are plates of foliation and echelon-like
displacement along the planes of sliding off the massifs
bottom, as well as the thrust-fault crush zones which
attain a thickness of 3 m, as is known from drill log data
of 3 boreholes.
Integrated geological-geophysical surveys that the
“Petersburg Geophysical Expedition” State Enterprise
(PGE) carried out in the area in scrutiny in 1990-1992
were aimed to provide a basis for detail exploration. The
specialists involved in the project pointed out a certain
genetic affinity between the geological sections of the
Khibiny and Lovozero massifs in terms of lithology and
structural/textural features. Thus, a poikilitic nepheline
syenite complex at the bottom section of the Lovozer
strata correlates well with a ristschorrite at an errosion
cut plane of the Khibiny intrusive rock formations. Deep
layers of foyaites, as a differentiated rock complex in the
middie of the Lovozero formations, are similar to the
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International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B7. Vienna 1996
