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MINES AND MINERALS DIVISION
ONTARIO GEOLOGICAL SURVEY
Open File Report 5702
Study of Curvilinear Structural Features in the Parry Sound Area, Grenville Province, using Landsat Thematic Mapper-Images
by
M.L. Tremblay
1989
This project is part of the five year Canada-Ontario 1985 Mineral Development Agreement (COMDA), a subsidiary agreement to the Economic and Regional Development Agreement (ERDA) signed by the governments of Canada and Ontario
Parts of this publication may be quoted if credit is given. It is recommended that reference to this publication be made in the following form:
Tremblay, M.L.
1989: Study of Curvilinear Structural Features in the Parry Sound Area, Grenville Province, using Landsat Thematic Mapper-Images/ Ontario Geological Survey Open File Report 5702, 28p., 11 figures.
Ministry ofNorthern Development
Ontario and Minesi
Ontario Geological Survey
OPEN FILE REPORT
Open File Reports are made available to the public subject to the following conditions:
This report is unedited. Discrepancies may occur for which the Ontario Geological Survey does not assume liability. Recommendations and statements of opinions expressed are those of the author or authors and are not to be construed as statements of govern ment policy.
This Open File Report is available for viewing at the following locations:
(1) Mines LibraryMinistry of Northern Development and Mines 8th floor, 77 Grenville Street Toronto, Ontario M7A 1W4
(2) The office of the Regional or Resident Geologist in whose district the area covered by this report is located.
Copies of this report may be obtained at the user's expense from a commercial printing house. For the address and instructions to order, contact the appropriate Regional or Resident Geologist's office(s) or the Mines Library. Microfiche copies (42x reduction) of this report are available for |2.00 each plus provincial sales tax at the Mines Library or the Public Information Centre, Ministry of Natural Resources, W-1640, 99 Wellesley Street West, Toronto.
Handwritten notes and sketches may be made from this report. Check with the Mines Library or Regional/Resident Geologist's office whether there is a copy of this report that may be borrowed. A copy of this report is available for Inter-Library Loan.
This report is available for viewing at the following Regional or Resident Geologists' offices:
ALGONQUIN DISTRICT SOUTHEASTERN DISTRICT REGIONAL MINERALS BOX 190, MAIN ST. B.S. 43 OLD TROY ROAD SPECIALIST DORSET, ONTARIO TWEED, ONTARIO BOX 3000, HIGHWAY 28 POA 1EO KOR 370 BANCROFT, ONTARIO
ROL ICO
The right to reproduce this report is reserved by the Ontario Ministry of Northern Development and Mines. Permission for other reproductions must be obtained in writing from the Director, Ontario Geological Survey.
V.G. Milne, Director Ontario Geological Survey
Foreword
New insight into the structural framework of the Grenville Structural Province of the Canadian Shield in Ontario led to a subdivision of the gneissic terrains of the Parry Sound and Muskoka areas into several domains and subdomains which are juxtapositioned against each other along distinct boundary zones.
In a pilot project the author of this report tried to recognize these boundaries on Landsat satellite images and found that this is impossible based on lineament analysis alone. Lineament density and characteristic textures on satellite images, however, appear to correspond with local aeromagnetic patterns, and the author suggests that more refined lineament density maps may very well be used as good reconnaissance mapping tools.
V.G.MilneDirectorOntario Geological Survey
CONTENTS
ABSTRACT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii
ACKNOWLEDGMENTS.............................................xv
INTRODUCTION. . . . . . . . . . . . . . .. . .. ... .. . . . . . . . . . . . . . . . . . . . . . . . . .l
GENERAL GEOLOGY..................... . . . . . . . . ... .. ... . . . . . . . . .2
PREVIOUS WORK. .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . .2
METHODOLOGY... .. ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
RESULTS. . . . . . . . . .. . . . . . . ... . . . ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
DISCUSSION AND CONCLUSION...................................14
REFERENCES..................................................17
FIGURES.....................................................24
ADDITIONAL FIGURES.................................BACK POCKET
vii
List of Figures
Figure 1: Tectonic Domains of the Parry Sound Area, redrawn after
Davidson (1986). The Algonguin Domain is separated
into several subdomains and the Muskoka Domain
comprises the Seguin, the Rosseau and The Moon River
Subdomains. The rectangle indicates the extent of the
study area.
Figure 2: Tectonic domains indicated by the analysis of Harris et
al. (in press). -MR: Moon River Subdomain, R: Rosseau
Subdomain, S: Seguin Subdomain, PS: Parry Sound Domain,
B: Britt Domain.
Figure 3: Thematic Mapper (TM) band location in the
electromagnetic spectrum.
Figure 4: Curvilinear features of the Parry Sound area.
Figure 5: Comparison between various lineament patterns, L, N,
and S variables and function D. Case "A" represents a
low lineament density zone. In case "B", the hexagonal
cell covers longer lineaments, which is reflected by
the higher D value. In case C, the spacing S
decreases. Finally, pattern D causes N alone to change
value. Function D was the only value to record all the
changes from A to D.
Figure 6: Shear zone geometry redrawn after Ramsay (1980), over
which is superposed a rhombic grid. The hexagon in the
unsheared portion has a lower lineament density than
ix
within the shear zone, as indicated by the parameters
N, L, and S.
Figure 7: Interpreted domain boundaries from Figure 4.
Figure 8: Lineament density contour map of the northern part of
Figure 4.
Figure 9: Correlation between the geology and selected lineament
density contours.
Figure 10: Aeromagnetic map redrawn from GSC (1965).
Figure 11: Correlation between the geology and selected
aeromagnetic contours. Comparison with Figure 8 shows
similar shapes and positions of the contours in the two
maps .
xi
ABSTRACT
Curvilinear structural features of the Parry Sound area were
analyzed at 1:100 000 scale. The Parry Sound Domain was found to
be clearly visible on TM-images. The boundaries of the various
domains were classified into three categories: 1-lineament belts,
typical of the Parry Sound Shear Zone, 2- zones of truncations of
lineaments, more common in the southern part of the area of
investigation, and 3- gradual, which characterizes the eastern
boundary of the Parry Sound Domain. A quantitative analysis of
the lineaments were performed in the northern portion of the map.
Lineament density was evaluated using the function D*(L)(N)7S,
where L* cumulative lineament length, N* number of lineaments,
and S* average lineament spacing. A contoured lineament density
map was generated. Moderately good correlation with geological
data and aeromagnetic data suggests .that a more refined density
map could assist geological mapping.
xiii
ACKNOWLEDGMENTS
I want to thank the Ontario Centre for Remote Sensing for the use
of their material and equipment. I am particularly indebted
toward Dr. Vern Singhroy, and Frank Kenny, who provided
stimulating discussions and support throughout the project. I
thank them warmly. Discussions with Giovanni Diprisco
(geologist, Ontario Geological Survey) were greatly appreciated,
and David Kresz (geologist, Ontario Geological Survey) who
reviewed the first draft of the manuscript. Patricia Taylor
drafted several figures included in this report. Finally I wish
to thank Norm Trowell (geologist, Ontario Geological Survey) for
useful comments.
xv
STUDY OF CURVILINEAR, STRUCTURAL FEATURES IN THE PARRY SOUND AREA, GRENVILLE PROVINCE,
USING LANDSAT THEMATIC MAPPER-IMAGES
by
M.L. Tremblay
l Geologist, Precambrian Geology Section, Ontario Geological Survey, Toronto.
Manuscript approved for publication by V.G. Milne, Director, Ontario Geological Survey, March, 1989.
This report is published with the permission of V.G. Milne, Director, Ontario Geological Survey, Toronto.
x vi i
INTRODUCTION
The Parry Sound Domain forms part of the Central Gneiss Belt
in the Grenville Province. It is located to the east of the Town
of Parry Sound on Georgian Bay. Detailed mapping of the Parry
Sound area was undertaken in 1986 to 1988 by the Ontario
Geological Survey (Bright 1986, McRoberts and Tremblay 1987 /
McRoberts, Macfie and Hammar 1988) in order to improve the
geological database for this domain of predominantly mafic to
intermediate rocks.
The intent of this study was to analyze the curvilinear,
structural bedrock features visible on remote sensing images and
determine if the domain boundaries of the Parry Sound Domain
(Davidson 1984, Davidson and Grant 1986) could be identified from
the lineament distribution. This could help in the selection of
future mapping sites. A secondary goal of the study was to
develop a quantitative technique enabling the objective analysis
of curvilinear, structural features, and to compare the results
with more subjective visual analysis. This project involved the
collaboration of Dr. V. Singhroy and F. Kenny from the Ontario
Center for Remote Sensing, who provided technical equipment and
support.
GENERAL GEOLOGY
The rocks of the Parry Sound Domain are Middle Proterozoic
in age. They are interpreted to overlie the Britt and the Kiosk
Domains to the west and east respectively (Figure 1) and the
Rosseau Subdomain to the southeast (Davidson 1984). The Parry
Sound Domain is in turn overlain by the Moon River and the Seguin
Subdomains to the southeast. According to this interpretation,
zones of intensely deformed rocks, such as the Parry Sound Shear
Zone, form the boundaries between the various domains and
subdomains. Granulite facies metamorphic grade typical of the
rocks of the interior Parry Sound Domain is locally retrogressed
to Upper and mid-amphibolite facies, particularly within the
shear zones and along the boundaries of the Parry Sound Domain.
Brittle faults associated with the Ottawa-Bonnechere Graben (Kay
1942, Kumarapeli 1976) trend east to northeast with little
displacement observed along them (Culshaw et al. 1988).
PREVIOUS WORK
Harris et al. (in press) investigated the curvilinear
features of the Grenville Province of both Quebec and Ontario, at
a scale of 1:250 000. They demonstrated that the curvilinear
features were clearly visible on Landsat and Seasat images. They
also found that, when analyzed visually, the lineaments could
locally be correlated with known geological features such as
tectonic domain boundaries, shear zones, and folds.
Their interpreted tectonic domain boundaries for the Parry
Sound area (Figure 2) differ slightly from Davidson's (1984)
framework. The Seguin Subdomain does not appear to have well
defined boundaries, although they still place the Subdomain
limits close to Davidson's. The northern boundary of the Parry
Sound Domain is positioned further to the south, and do not
identify the Amhic Subdomain. However, they place a small domain
unrecognized by Davidson (1986) north of the Seguin Subdomain.
Visual interpretation may yield equivocal results, and
lineament literature abounds in warnings against the subjective
nature of lineament maps (Burns and Brown 1978, Parsons and
Yearly 1986). This has stimulated research to measure the
reliability and reproducibility of such maps (Burns and Brown
1978, Huntington and Raiche 1978, Koopmans 1986, Parsons and
Yearly 1986). From this work, it is obvious that a high degree
of variability may exist between different lineament maps of the
same region, depending on technical factors such as the time of
scene acquisition, bands used and resolution, and human factors
such as interpretation criteria, experience and fatigue of the
interpreter.
In order to perform a more objective analysis of lineament
maps, it is becoming common to reduce the importance given to one
given lineament, and instead emphasize lineament families.
Lineament density is an increasingly used parameter in map
analysis (McGuire and Gallagher 1976, Sawatzky and Raines 1978,
Abel-Rahman et al. 1978, Fitz and Thiessen 1986), although
reservations have been recently expressed by Parsons and Yearly
(1986). The author agrees that absolute density is an unreliable
parameter, but thinks that relative density remains to be tested
in geological applications.
In the literature, studies of straight lineaments are
favored over curvilinear features, probably due to the interest
of the mineral industry combined with the relative geometric
simplicity. As a result, the quantitative study of curvilinear
features is scarcely found in the literature (Peterson 1974).
The methods used in these quantitative studies were not very
successful. The method used in this study was first described by
Tremblay (1988) .
METHODOLOGY
Cloud free Landsat-5 TM-images of bands 4, 5 and 7 (Figure
3), acquired on October 25, 1986 were projected and enlarged to a
scale of 1:100 000 over a mylar sheet using a Procom-2 projector
to cover the Parry Sound Domain . This study is based on the
assumption that curvilinear features reflect the trend of the
foliation, which is supported by Harris et al.(in press), and by
detailed mapping from McRoberts and Tremblay (1988). Concordant
linear and curvilinear features subparallel to each other through
to represent unit contacts, layering, foliation, ductile shear
zones were traced, while non-concordant straight features
representing brittle structures were not traced. The
curvilinear features in places are not concordant and may
intersect one another. Some of the intersecting features
possibly represent glacial features. However, McRoberts and
Tremblay (1987) and Culshaw et al.(1988) showed that two phases
of migmatization occurred in some parts of the Grenville
Province, thereby generating two gneissic foliations. They may
in places form intersecting curvilinear features visible on
satellite images. Non-concordant curvilinear features therefore
were traced so as to represent the two phases of ductile
deformation.
It was found that previous field knowledge of some part of
the map area influenced lineament recognition in a significant
way. The discrimination between straight lineaments representing
brittle features and curvilinear features was difficult in zones
where no detailed bedrock geology map was available. In such
cases, when there were doubts as to the nature of the lineament,
it was eliminated from the map. This explains why more
lineaments are shown in the better known northern part of the
Parry Sound Domain (Figure 4, pocket), and the density in other
areas may not reflect the true situation.
In the quantitative analysis, three parameters were used to
evaluated the lineament density: "L"-cumulative lineament length,
"N"-number of lineaments, and "S"-average spacing of lineaments.
Because the objective of the study was to determine the position
of tectonic domain boundaries/ it was desirable to find a
technique that could help identify shear zones. From examination
of Ramsay's diagrams (1980), it appears that the morphology of a
shear zone is typified by more closely spaced foliation planes
within the shear zone relative to the unsheared rocks. The
lineament density therefore would be expected to be higher in a
shear zone. In an attempt to enhance lineament density, the
three parameters L, N, and S were used to determine a density
factor, D:
D* (L)(N)7S
The variables L, N, and S can all be used independently to
estimate density. The advantage of using the three parameters
lies in the increased sensitivity to patterns that one variable
alone would not identify (Figure 5). However, it is not possible
to positively identify shear zones using this relation, as thin
rock units may have lineament density highs unrelated to
shearing.
L, N and S were measured for hexagonal cells 2 centimetres
in diameter, measured from the corners (Figure 6), over an
objective rhombic grid with a l centimetre spacing covering the
northern portion of the curvilinear lineament map. "N" and "S"
were measured across a line perpendicular to the trend of the
lineaments within the hexagon and passing through the center of
the cell. Results were then contoured. Lakes were treated as
map boundaries and contours were stopped at their margins.
Hexagonal cells were chosen over other possible cell shapes
because they optimize the area-radius ratio, and can cover an
area completely (Sijmons 1978). The grid spacing, which is half
the cell diameter, provides a greater degree of exactness
(Sijmons 1978) than a spacing equal to the diameter of the cell.
Sijmons (1978) suggests that a smaller cell size along with a
smaller grid spacing ( i.e. 1/4 the cell diameter) should be
used. As all measurements were done by hand, with a mapping
wheel and a ruler, to follow Sijmons' parameters would have
resulted in increasing the error on the measurements and
increasing the time required to perform the analysis by a factor
of 16.
The analysis was first attempted at a scale of 1:50 000.
This scale proved to be impractical, as the background noise due
to areas of swamps, overburden, lakes, settlements and crops
overshadowed the lineaments attributable to foliations. The
results presented here deal only with 1:100 000 scale analysis.
RESULTS
Curvilinear Lineament Map
The identification of domain boundaries on the curvilinear
lineament map was carried on using the same criteria used by
8
Harris et al. (in press): namely, the presence of truncation
relationships and continuous belts of lineaments juxtaposed to
zones of contrasting lineament distribution. An effort was made
to typify the boundaries as simple truncation relationships, or
lineament belts defined by a band composed of several concordant
lineaments bounded on each side by zones of contrasting lineament
distribution.
The Parry Sound Shear Zone appears to be the only boundary
in the area of investigation defined by a truly continuous belt
of lineaments (Figure 4 and l, pocket). The width of the zone
varies, but lineaments within it are highly continuous. The zone
undulates gently which suggests that it is folded. The northern
segment of the zone is narrower and gradually becomes only
vaguely defined near the eastern margin of the domain. The
northern-most arc-like boundary of the Parry Sound Domain
boundary drawn in Davidson's map (Figure 1) does not appear to be
part of the Parry Sound Domain in the lineament map. Instead,
the lineaments delineating the arc-like structure appear to be
truncated by the Parry Sound Shear Zone.
The eastern boundary of the Parry Sound Domain is not
defined by either truncation relationships or lineament belts.
Rather, it is represented by a gradual change in lineament
density and orientation. This zone is one of a greater
accumulation of Quaternary sediments (Mollard 1981a, b, c, d)
and, although, the recognition of lineaments is difficult, the
recognized lineament distribution does not suggest the presence
of a high strain zone.
An exception to this along the eastern boundary is the area
corresponding to the Ahmic Subdomain. Here / a westerly closing
fold pattern is clearly visible from the lineament distribution.
This Subdomain boundary appears as a belt of lineaments
truncating Parry Sound Domain structures to the west. As was the
case for the eastern boundary of the Parry Sound Domain, it was
not possible to define the eastern extent of the Ahmic subdomain.
The southern limit of the Parry Sound Domain is complex due
to the juxtaposition of three tectonic subdomains. The
southwestern margin is truncated by lineaments delineating a
large northwest-trending fold, corresponding to the perimeter of
the Moon River Domain. Truncation of the Parry Sound structures
is sharp / although not defined by a belt of lineaments. Instead,
the structure of the Moon River Subdomain is dominated by
concordant continuous lineaments, with some internal variations
suggesting earlier deformation. The boundary is concordant to
the internal lineament pattern of the Moon River Subdomain, and a
zone of higher strain at the margin cannot be identified from the
Landsat TM-imagery. The northerly oriented structures of the Go
Home Subdomain are also clearly truncated by the Moon River
Subdomain.
10
Much like the eastern boundary of the Parry Sound Domain,
the boundary with the Rosseau Subdomain is not defined by a
lineament belt or truncation relationships, but is rather
characterized by a gradual change in lineament patterns. The
Rosseau's interval structures are folded about northeasterly axes
and refolded about northwesterly axes. This interference results
in circular map patterns. The limbs of the earlier northeast-
trending fold set appears to truncate locally short lineaments,
which suggests that the limbs were the site of shearing. Those
limbs and the boundary between the Parry Sound Domain and the
Rosseau Subdomain share the same orientation. The position of
the boundary can be inferred from a very narrow zone of
discontinuous lineaments. The absence of recognized lineaments
adjacent to that zone does not permit the recognition of
truncation relationships. Instead, Parry Sound Domain lineaments
nearest to the boundary appear to share similar orientation.
This boundary is thus classified as gradational.
Davidson et al. (1982) identified a tectonite zone
separating the Parry Sound Domain from the Rosseau Subdomain,
with "...marked truncation of the Parry Sound lithology,
structure and metamorphism" (p.182). This is not recognized on
TM-curvilinear lineament map, and may be explained by the
relative lineament scarcity in the boundary zone.
The western contact of the Rosseau with the Moon River
Subdomain is delineated by a belt of lineaments. The eastern
11
contact with the Seguin Subdomain is defined by truncation
relations of the Rosseau's structures.
The northern extent of the Seguin Subdomain is poorly
defined. The western limit adjacent to the Rosseau Subdomain
appears to branch within the Parry Sound Domain, not curving into
the Seguin northern boundary. Instead, the latter is offset to
the south and is characterized by a wide zone of less continuous
but sub-parallel lineaments. This subdomain is thus similar to
the Parry Sound Domain, with a well defined western margin and a
more diffuse northern limit. This suggests movement was
concentrated along the western portion of the domains.
Internal Structures
The northern part of the Parry Sound Domain is characterized
by medium length, northeast-trending lineaments, and short, more
easterly trending lineaments.
Toward the south, it becomes increasingly difficult to
identify concordant lineaments characterizing foliation.
However, it is possible to delineate round and complex fold
structures, two to four kilometres in amplitude, east of the
Whitestone anorthosite. At least two fold generations are
present. In the Moon River and Seguin Subdomain and the Britt
Domain, similar patterns were recognized. In the latter, they
are distributed in northeast-trending bands 10-15 kilometres in
12
width, bounded by lineament belts. These may represent
structures pre-dating shearing along the lineament belts.
One can predict that in the field, the rocks within these
zones would contain structures of different generations, rather
than the more intensely deformed and transposed rocks contained
in the lineament belts. It is usually in those zones that two
sets of lineaments are found to intersect. One set can commonly
be attributed to the fold pattern while the other locally appears
axial planar to it. The trend of the latter set is commonly
concordant to the trend of the lineaments outside the zone of
intersecting lineaments.
Density map
The correlation between the lineament map (Figure 4) and the
contoured density map (Figure 8) is relatively poor. In the
density map, areas of high lineament density may locally parallel
the trend of the foliation but they are more commonly oriented at
an angle apparently unrelated to the structure. Although these
areas are representative of high lineament density on the map,
they cannot be readily used for structural interpretation. The
zones of intersecting lineaments are in part responsible for
intra-domain high density zones. It is suggested that some of
these zones reflect structurally complex, although not
necessarily' sheared rocks.
13
When compared to the geological data (Figure 9), the density
map shows a good correlation with the eastern boundary of the
Parry Sound Domain as shown by Davidson (1984). However, since
this is a gradational margin with respect to the lineament map,
its positioning depends upon the lineament contour interval and
thus its exact location remains arbitrary. In this zone, very
low and high lineament densities are juxtaposed. The northern
boundary of the Parry Sound Domain is well delineated in the east
but absent in the west. The western boundary is marked by zones
of intermittent high lineament density. At the northern and the
western boundaries, the orientations of the high density zones
parallel the trend of the lineaments. However, the presence of
other high density zones, apparently randomly distributed
throughout the Britt Domain, makes the identification of the
domain boundary difficult in the absence of geological data.
A major northeast-trending shear zone within the Britt
Domain recognized by Davidson and Grant (1986) is well delineated
by the 100-contour (Figure 8)as a broad zone containing some high
lineament density areas. This suggests that intra-domain shear
zones could potentially be identified with density maps.
Correlation between the density map and aeromagnetic data
(GSC, 1965a-d) yields more interesting results (Figure 10 and
11). Correlation between lineament density and aeromagnetic
signature commonly corresponds in location and extent. Locally,
high density zones correspond to aeromagnetic highs or lows.
14
This is best shown at the northern and eastern boundary of the
Parry Sound Domain, where complicated patterns are present on
both maps, almost in the same location.
DISCUSSION AND CONCLUSION
The extent of the Parry Sound Domain is defined by several
boundary types, the western margin or the Parry Sound being the
only one to distinctly suggesting a ductile shear zone boundary
Shear Zone. The boundaries with the Seguin and the Moon River
Subdomains are truncation relationships, and no zone of localized
shearing can be identified. The eastern boundary with the Kiosk
Domain and southern boundary with the Rosseau Subdomain are
marked by a gradual change in lineament pattern and distribution,
and do not suggest the presence of intensely sheared rocks.
The types of geological features associated with the various
boundary types remain to be tested in the field. Macfie's
analysis (1988) suggests that, in contrast with the Parry Sound
Shear Zone, the boundary between the Parry Sound Domain and the
Seguin Subdomain is not a clearly defined tectonic zone as shown
by Davidson (1968), but he does not exclude the possibility of a
more easterly located boundary.
It is impossible to evaluate Davidson's (1986) tectonic
framework based on lineament analysis alone. However, the
different domain boundary types suggested in the lineament
15
distribution may reflect various degrees of shearing and/or
recrystallization typical of unique boundary regimes. Shear
zones with predominantly extensional, compressional or strike
slip components are all common in mountain belts and could show
characteristic morphology. Such variations should equally be
expected in Proterozoic terranes.
The density map correlates poorly with the lineament map/
but shows interesting agreement with geological data as the
domain boundary can be delineated. This suggests that a
lineament study as described here could assist geological
mapping, much as do aeromagnetic maps. Because it only retains
the basic lineament information, ideally, the technique used in
the present investigation could provide uniform and consistent
data, independent of the investigator.
The correspondence with local aeromagnetic patterns is a
positive result. One can speculate that aeromagnetic signatures
depend on rock types, which in turn will display characteristic
textures in a Landsat image. One of the factors influencing the
textural variation is the lineament distribution. This may
explain the correlation. Nevertheless, even this limited
association suggests potential applications for more refined
density maps as reconnaissance mapping tools.
Several factors handicap the quantitative analysis. The
distribution of high density zones in the density map appears
16
greatly affected by the presence of swamps, lakes, rivers,
overburden, and cultivated areas. These usually correspond to
zones of low lineament densities, and offset the pattern
attributable to geological factors. One way to compensate for
this problem is to interpolate data in the low density zones
(Frank Kenny, Assistant, Ontario Center for Remote Sensing, 1988,
pers. comm.), or to treat swamps, lakes, etc. as map borders, and
not generate data for these zones. In this map, these zones were
found to be too numerous to apply either of these two solutions,
as the map would have comprised 5Q* interpolated data with the
first solution, or 5(H of holes with the second one.
The zones of intersecting lineaments have been found to make
the recognition of shear zones difficult, as they are also
expressed as high density zones. It is suggested that these
zones be treated differently in the measurement procedure (i.e.
include an intersection factor) in order to enhance concordant
lineament zones.
Another major drawback to the technique is the time
necessary for the analysis. As noted earlier, a smaller cell
size and a smaller grid would yield more exact results. However,
this can hardly be done without the help of an automated image
analysis system capable of performing these particular tasks.
The existence of such a system is unknown to the author. Such
analysis could reveal the true potential of the method.
17
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18
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19
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20
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21
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22
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23
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24
Figure 1: Tectonic Domains of the Parry Sound Area/ redrawn after
Davidson (1986). The Algonquin Domain is separated
into several subdomains and the Muskoka Domain
comprises the Seguin, the Rosseau and The Moon River
Subdomains. The rectangle indicates the extent of the
study area.
25
k* M pissing
ke Simcoe
Figure 2: Tectonic domains indicated by the analysis of Harris et
al. (in press). -MR: Moon River Subdomain, R: Rosseau
Subdomain, S: Seguin Subdomain, PS: Parry Sound Domain,
B: Britt Domain.
26
E(D
o qco
CD o CO
CM o
CM CMd
CD
d
o d
CD qd
•o e
sX) CO
CO
CM
0)x -pc•H
Co.^
4J(QO0iH
T3Cid
.Q^— s
sEH"-*
M0)Q4CU(QZ
O•H J-)(de0)x:E-"
CO
0)M3O*
g*
3 14-PO0)p,(0
0-H-P0)Co*(dgoJ.)-po0).H0)
CM qd
Ec
O)c
0m
>0
27
N-2
L-2 7mm
S-10mm
O-5.4
N and L are constant
N-2
L-3 4mm
S-5mmD-13
B
N and S are constant
N-2
L-3 4mm
S-10
0=6.8
L and S are constant
N-3
L-3 4mm
S-5mmD-20
Figure 5: Comparison between various lineament patterns, L, N,
and S variables and function D. Case "A" represents a
low lineament density zone. In case "B", the hexagonal
cell covers longer lineaments, which is reflected by
the higher D value. In case C, the spacing S
decreases. Finally, pattern D causes N alone to change
value. Function D was the only value to record all the
changes from A to D.
28
B
N-3
L-40mmS-6mm
0=20
N-2
L-20mm S-9mm
0=4
Figure 6: Shear zone geometry redrawn after Ramsay (1980), over
which is superposed a rhombic grid. The hexagon in the
unsheared portion has a lower lineament density than
within the shear zone, as indicated by the parameters
N, l, and S.
INTERPRETED DOMAIN BOUNDARIES
OF THE PARRY SOUND AREA
LEGEND
BOUNDARY TYPES
Lineament Belt
Gradual
Selected intra-domaln
truncation relationships
SCALE
1 MOO 000
2 1 O
Figure 4. Curvilinear features of the Parry Sound area 45 00 45 00
80 10' 79 30'
CURVILINEAR FEATURES
OF THE PARRY SOUND AREA
Figure 7. Interpreted domain boundaries from Figure 4. 45*00
LAKE MUSKOKA
GEORGIAN BAY
45 0080"tO' 79 0 30'
4545 45'
80 10' 79 30'Scale
1 : 100 000LEGEND
Os "" —
100 DENSITY CONTOUR LINE
50 DENSITY CONTOUR LINE
(in Kilometres)
Figure 8. Lineament density contour map of the northern part of Figure 4.
;?rkKiosk DomaiimvXv
SoundParry
illlii asn/cesn
Selected lineament density contour lines Intermediate - mafic gneiss
Granitoid gneiss
Granitoid intrusion
Figure 9. Correlation between the geology and selected lineament density contours.
AEROMAGNETIC CONTOUR MAP
1 '*~- '
t f ' i x V \ i ^ ' f ix O i '
' 'S ,'~ l/' ' f O' ,''}i'' ''fl'i/s '
A v v \ v^x /v /A"-*' ' \\'jfrf' //^^'
. !K /A"-.
45 45.1 . 45 45'
80 10'Scale
100 000
LEGEND
O 4IE
500 GAMMA CONTOUR LINE
100 GAMMA CONTOUR LINE
(in Kilometres)
Figure 10. Aeromagnetic map redrawn from GSC (1965).
Geology of the Parry Sound Area
osk Domain
4- 4- 4- 4- 4- 4- 4- 4- 4- 4- 4-
Sound D
-'•77 t -\-xx-V l'^ |xx-- x -y-\'J- |V1 *,'~'T^C^JS ((V^4^iN'SfW,!}rr7 4-4-4-•x;f;^^N'x^'^^^v^^-r- -'VJsv/'V 1^^^'?w - 1 - *r'-Kx '\c7,7*''^viv^7T/; ^^/^'-'^^^'JtitL'sllrtfityfaity 4- 4- * rKp 7 c\^- v v ^~ |xx"~x\t Y-- v- fi ^\-x- - x . y J"'Krjr^^^*'v-v^ V//+ 4- 4-^ /^r/ " N ^ \ ' x ~~ r, -. /- ~- f \ /, ^ ^ \ x - v ' r -f •-'•r- - r - '*- r* - *-"-x' * * ^ i 7• \ 7V " '' ' -v'i ^N; N 'l ! / ^ \/ - x - i- v '"x ' MJvV\^*! .^yjiC.V* ; *' ; 'A 4^ + 4-^-v^^^^^V,'^^^^^/^OVx^^^i^^^^V^/jN^^^^^^•K^rn7.v^'^.--iJiX!-7 ^ + + ^
-' 'o/rr^-^-.v, .?
^^i^^4-4-4- + 4-4- + 4-4-HI
4-4-4-4-4-4-4-4-4-4- 4-4-4-4-4-4-4-4-4-4-H 4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4--I
4-4-4-4-4-4-4-4-4-4-
Selected aeromagnetic contour lines Intermediate - mafic gneiss
Granitoid gneiss
Granitoid intrusion
Figure 11. Correlation between the geology and selected aeromagnetic contours. Comparison with Figure 8 shows similar shapes and positions of the contours in the two maps.