December 2, 2011
Geologic relationships of granitoid bodies in NW Turkey
This summer, I conducted fieldwork in NW Turkey and collected samples from granite
plutons in order to better understand their tectonic evolution. I prepared for this work by
collecting maps of my field area from Google Earth and Google Maps. These consisted mainly
of road maps. I also used a paper geologic map.
I would now like to create more useful and conclusive maps of my field area that can be
used in my thesis. These maps will effectively display the geology of my field area as well as
sample locations. I would also like to obtain DEMs of my field area to help interpret the
relationship between faults and granite plutons in my field area.
It will be very helpful to have all of this information stored in a usable GIS that I can
manipulate as needed. I will also be able to create maps from the DEM that can be used to
analyze that interaction between faults and the granite plutons in the region.
Turkey is the amalgamation of numerous continental fragments that were sutured
together by the opening and closing of Tethyan Oceans. Currently, Turkey is undergoing
compressional tectonics in the east, strike-slip tectonics across the entire northern portion of the
continent, and extensional tectonics in the west. As the African plate collides with the Eurasian
plate, the Arabia platform collides with Anatolia in the west. A free lateral boundary in the west
allows for strike-slip tectonics to occur and for Turkey to escape laterally southwestward via the
North Anatolian Shear Zone. The retreat of the Hellenic Arc is believed to be caused by slab-
roll back that results in extension in western Turkey.
Northwest Turkey is a complex region that contains geologic evidence of the suturing of
continental fragments followed by the current N-S extension and SW strike-slip movements.
There are multiple granite bodies in this region that were exhumed during the current
extensional regime. During my field season, I focused on collecting samples from three plutons
including the Kozak, Eybek, and Kestanbolu.
The object of this project is to create a useable GIS that will be used to analyze the
geologic relationships of granitoid bodies in northwest Turkey. Data will also be used to analyze
the relationships of samples collected this past summer. The final products will be a geologic
map of my field area, a road map with granite outcrops, contours and sample locations, and a
hillshade and aspect map with granite outcrops and faults to help analyze the topography of the
2. Data Collection
ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) Global
DEM v.2 data was obtained from NASA
ctangle). This ASTER GDEM is a product of METI and NASA. ASTER data was sent to me via
e-mail Mark Helper because a NASA account is needed to download data from this website. I
needed two tiles to cover my field area and they are N39E026 and N39E027. This data is 30m
resolution and is in a zipped folder that contains metadata and a GeoTiff.
An online geologic map of Turkey with high resolution was hard to find. I scanned a
paper version of a geologic map with my field area and saved it as a .jpeg that could be opened
An online file containing an accurate and complete set of roads in Turkey was hard to
find. During fieldwork, I found that Google Maps was very accurate with roads in my field area.
Therefore, I used a screen shot of Google Maps for roads of my field area for this GIS. I was
also able to find precise latitude and longitude coordinates for points on my screen shot that
could be used to georeference my roads screen shot.
During field work, sample locations were recorded as waypoints on a handheld GPS
unit. These latitudes and longitudes were exported as an excel file that could be imported into
Before any processing any data with ArcGIS, I first created a folder for my project on an
external drive. This folder contained the two unzipped ASTER files, the scanned geologic map,
screen shot of roads from Google Maps, and the excel table of my sample locations. I also,
created a geodatabase for the geologic map I would be digitizing titled “NWTurkey”. Also, I
created a folder titled ‘MyData’ to save anything I modified such as the ASTER files. I opened a
black ArcMap document and connected it to this project folder I created. I initially set the data
frame coordinate system to GCS_WGS1984 (Figure 3.1).
The spatial reference of the data frame was set to GCS_WGS1984.
4. ArcGIS Data Processing
To process the ASTER data I dragged my two unzipped geotiff files from ArcCatalog into
ArcMap. These files were automatically projected in my document. In order to see the
elevation in documents I had to change the symbology of the layers (Figure 4.1). The
symbology tab is located under properties when you right click on the ASTER layers in the
Table of Contents (TOC). Symbology was changed to stretched with standard deviations of
Screen shot of ArcMap and 2
ASTER data. Notice the line
in the middle separating the
Because there are two ASTER datasets, the elevation scales are different for each file
and there appears to be a line between the two sets (Figure 4.1). Therefore, I used to the
Mosaic tool to create a new raster with the two datasets combined (Figure 4.2). The ‘mosaic to
new raster’ tool is located in Arctoolbox under data management tools, then raster, and then
Screen shot of ArcMap and
one ASTER raster after
using the mosaic tool
I loaded the geologic map into my ArcMap document by dragging the scanned map I
save as a .jpeg from ArcCatalog into my document. To georeference the map (Figure 4.3), I
turned on the georeference toolbar and also opened the link table. I used the ‘add control points’
tool to add six points to intersecting latitude and longitude lines on the geologic map in my field
area. I then changed the X Map and Y Map locations in the link table to the corresponding
latitude and longitude points on the map. I rectified the image, saved it in the ‘My_Data’ folder,
and opened the new georeferenced raster in ArcMap. In ArcCatalog, I defined the coordinate
system of the image to GCS_WGS1984, the same as the data frame.
Georeferencing the geologic
map by adding six control
point in ArcMap.
The screen shot of my field area that I took from Google Maps was loaded into ArcMap.
By right clicking on a point in Google Maps and choosing ‘What’s Here?’, Google Maps will give
the latitude and longitude of that location (Figure 4.4). In ArcMap, I georeferenced my roads
screen shot by adding four points. In the link table, I changed the X Map and Y Map locations to
precise latitude and longitude coordinates obtained from Google Maps (Figure 4.5). I then
rectified the image, saved it in the ‘MyData’ folder, changed the coordinate system of the image
to GCS_WGS1984 in ArcCatalog, and then loaded the newly georeferenced image into my
Using Google Maps ‘What’s Here?’
tool to determine precise latitude
and longitude of map points.
Georeferencing roads image in
ArcMap with latitudes and
longitudes obtained from Google
The ASTER, geologic map, and roads datasets exceed the extent of my area of interest
so, I needed to clip them. I added a polygon that encompassed my field area titled ‘Map_Area’
to my geodatabse (Figure 4.6). I then used the clipping tool located in ArcToolbox under ‘Spatial
Analyst’, then ‘Extraction’, and then ‘Extraction by Mask’ to clip the ASTER, geologic map and
roads rasters to my Map_Area polygon (Figure 4.7). These newly clipped rasters were
automatically added to ArcMap and saved in the ‘MyData’ folder. I now have ASTER data, a
geologic map, and a roads image that only cover my area of interest.
Screen shot of Map_Area
polygon overlaying the
Clipped ASTER data to
To convert my geologic and roads maps from
raster files to shapefiles, I had to digitize each raster. In
my NWTurkey geodatabase I created a new feature line
class named ‘roads’ and gave it the same coordinate
system as the dataframe: GCS_WGS1984. I also
created a new feature dataset titled ‘Geology’. Within
this dataset I created a new feature line class titled
‘structures’, a new feature point class titled ‘cities’, and a
new feature line class titled ‘contacts’. The ‘structures’
feature class has the domain of fault types which
contains the codes of faults and sutures. The ‘contacts’ Construction of code values for the Units
domain of the contacts feature class .
feature class has the Domain Name of ‘Units’ that
contains the coded values of the following unit names unit names: volcanics, ophiolitic mélange,
undifferentiated metamorphic rocks, amphibolite, schist, granite, metagranite, marble,
carbonates, sediments, and continental clastics (Figure 4.8). I can now edit these feature
classes and digitize by geologic map (Figure 4.9).
Newly created feature
datasets and feature classes
for digitizing the geologic
map and roads image.
To digitize the geologic map, I only
displayed the geologic map layer and turned on
the editor for the geologic map and contacts
feature class. I then traced all contact lines in
my research area while periodically saving my
edits (Figure 4.10). I then repeated the same
process to digitize faults and cities. I then built
a topology for my contact lines (Figure 4.11) and Figure 4.10.
Construction of code values for the Units
fixed all errors until there were no more. I then domain of the contacts feature class.
made the contact lines into polygons
representing all the rock types in my geologic map. I could then assign the unit name attributes
to each rock type and then change the symbology for each rock unit. I also assigned the fault
type attributes to each of my faults or sutures and adjusted the symbology (Figure 4.12). I then
labeled the cities, converted them to annotation and adjusted and edited their names.
Screen shot of ArcMap with
Topology rules (above) and
generated topology (right).
The pink lines and boxes
were errors I had to correct.
Screen shot of contact lines
converted to polygons.
Polygons were assigned unit
names and appropriately
To digitize the roads layer, I only displayed the roads rater and turned on the editor for
the roads feature class (Figure 4.13). I then traced all roads in my area of interest while
periodically saving my edits.
Digitizing roads in editing
I also wanted to be able to display just the granite bodies in some of my maps. To
separate these from the other rock units I used the ‘select by attribute’ option from the ‘selection’
menue. I adjusted the layer to ‘RockUnits’ and the method to ‘create new selections’ I then set
up my query to select the units that were equal to granites (Figure 4.14). This way only the
granite would be highlighted. In the TOC, I right clicked on the ‘rockunits’ layer and chose the
‘exportdata’ option. I set it to export only the selected features and saved this within my
geodatabase as ‘granitebodies’ (Figure 4.14). Now I can display only the granite rock units from
my geologic map to be displayed on other maps I make.
The ‘Select by
(left) used to
select only granite
rock units that
could then be
To add my sample locations I used the ‘Add XY data’ option to upload the Excel table
(Figure 4.15) with my latitude and longitude coordinates. I then adjusted the symbology for the
samples and labeled the features by ‘identity’, the sample names. I then converted the labels to
annotation by right clicking on the data set in the TOC. When the labels were converted, I was
then able to move them independently to more appropriate locations in the document.
(left) of GPS
ArcMap by the
‘Add XY Data’ tool
ASTER Processing continued
To further process my ASTER data I first changed the coordinate system of my data
frame to WGS_1984_UTM_Zone35N. I then created I00m contours of the ASTER data by
using the ‘contour’ tool in ArcToolbox (Figure 4.16). It is located under ‘Spatial Analyst’ tools
and then ‘surface analysis’. I then labeled the contour lines.
produced from the
ASTER data by
using the ‘contour’
I also produced a hillshade and aspect map (Figure 4.17). To create a hillshade and
aspect map I used the ‘hillshade’ and ‘aspect’ tools located in ArcToolbox. These are located
under the ‘Spatial Analyst’ tools and then ‘surface analysis’. My input rasters were the ASTER
data and the output rasters were saved in the ‘My_Data’ folder.
Hillshade map generated
by using the ‘hillshade’
tool located in ArcToolbox
as seen on the left side of
5. Data Calculations
I wanted to be able to compare the surface area of my three plutons. To do this I went
to the properties tab of my ‘sampleplutons’ layer in the TOC. I then added a new field titled
‘Area’. This new field is then available in the attribute table of this data layer. By right-clicking
on the ‘Area” column a ‘calculate geometry’ tool is available. This tool can be used to calculate
the area of the plutons in units of square kilometers (Figure 4.18).
The ‘Select by Attributes’ tool (left) used to select only granite
rock units that could then be exported (right).
Surface Area of Plutons
Pluton Surface Area (km2)
6. Data Presentation
The geologic map (Figure 6.1) displays active faults, suture zones, geological units, and
sample locations of my field area. I can use this map to examine location of samples within the
pluton area as well as the proximity of faults to the granite plutons.
Figure 6.1. Finalized geologic map of field area in northwest Turkey.
The aspect map (Figure 6.2) simultaneously shows the direction and degree of slope for
the terrain of my field area. The faults and sample locations in this area are also included.
Figure 6.2. Aspect map of field area and associated faults. The large island
in the bottom left corner is the Greek island of Lesbos, not associated with the
field area. .
The hillshade map (Figure 6.3) provides a 3D effect of visual relief for my field area.
This is useful to better analyze the location of my granite plutons with respect to active fault in
the area. It is also, useful in analyzing the terrain around faults.
Figure 6.3. Hillshade map of field area with granite bodies and associated
faults. Various lineament patterns can be seen throughout the area. This may
be a result of N-S extension and SW strike-slip motion. The large island in the
bottom left corner is the Greek island of Lesbos, not associated with the field
The contour map (Figure 6.4) displays the topography of the region through contour
lines. This map also, contains the granite plutons and sample locations.
Figure 6.4 . Contour lines of the field area with granite plutons.
Field Map with Granites and Roads
This field map (Figure 6.5) is useful in displaying the roads around the granite plutons in
my sampling area. This map also displays the location of my collected samples with respect to
the roads. Contour lines are also, displayed.
Figure 6.5. Field map of area of interest that includes contour lines, roads,
granite bodies, and locations of samples collected.