Download Updating the 1/50.000 geological maps of IGME with remote

Updating the 1/50.000 geological maps of IGME with Remote Sensing
data, Marine Geology data, GPS measurements and GIS techniques.
The case of KEA Island
Konstantinos G. Nikolakopoulos*a, Panagiotis I. Tsombosa Dimitrios Mitropoulosa, Alexandra
Zervakoua, Bernhard Grasemannb, Christoph Iglsederb, Konstantin Petrakakisb, Monica Müllerb, A.
Hugh N. Riceb, Klaus Voitb, Andras Zámolyib and Erich Draganitsc
a
Institute of Geology & Mineral Exploration (IGME), Olympic Village Entrance C,
13677 Acharnae, Greece, [email protected]
b
University of Vienna, Department of Geodynamics & Sedimentology, Vienna, Austria,
c
University of Technology, Institute for Engineering Geology, Vienna, Austria,
ABSTRACT
In this study the combined use of field mapping and measurements, remote sensing data analysis and GIS techniques for
the geological mapping of KEA Island at a 1/50.000 scale, is presented. The geological formations, geotectonic units and
the tectonic structure were recognized in situ and mapped. Interpretation of high resolution satellite images (Quickbird)
and medium resolution satellite images (Landsat 7 ETM and ASTER) has been carried out in order to detect the linear or
not structures of the study area. The in situ mapping was enhanced with data from the digital processing of the satellite
data. Marine geology data such as bathymetric data and seismic profiles were also taken into account. All the analogical
and digital data were imported in a geodata base specially designed for geological data. After the necessary topological
control and corrections the data were unified and processed in order to create the final layout at 1/50.000 scale.
Keywords: KEA Island, geological mapping, satellite images, GIS
1. INTRODUCTION
The basic cartographic scale for geological mapping at the Institute of Geological and Mineral Exploration of Greece
(IGME) is 1:50,000; at this scale, the whole country has been covered, by 325 map sheets (Figure 1). Field work for
these maps was undertaken during the last six decades, by both Greek and other geologists. As a result of this procedure,
there are still significant problems regarding the standardisation of geological terms (lithostratigraphic and structural
names) and about where the stratigraphic and tectonic boundaries lie within Greece.
In many regions, it has been noted that adjacent geological maps show marked inconsistencies at their boundaries. These
have arisen because the different geologists, working at different times, have interpreted their mapping with different
geological and geotectonic models. A particular problem is that the currently used model for the geotectonic zones of
Greece was developed after 1970.
The Institute of Geological and Mineral Exploration of Greece (I.G.M.E), acting within the framework of CSF 2000–
2006 (Community Support Framework 2000-2006, Operational Program Competitiveness, Priority axis 7: Energy and
Sustainable Development, Measure 7.3: Exploitation of natural recourses and support in meeting environmental
commitments, Action 7.3.1) has been implementing a project called “Collection, codification and documentation of
geothematic information for urban and suburban areas in Greece - pilot applications”. The sixth sub-project has been
concerned with updating fifty 1:50,000 geological map sheets, using GIS and remote sensing techniques. The geological
map sheet, Kea Island, has been included in the updating project and a new geological map is being produced by IGME,
in collaboration with the University of Vienna.
Remote Sensing for Environmental Monitoring, GIS Applications, and Geology IX, edited by Ulrich Michel, Daniel L. Civco,
Proc. of SPIE Vol. 7478, 74780O · © 2009 SPIE · CCC code: 0277-786X/09/$18 · doi: 10.1117/12.830268
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2. GEOLOGY OF THE ISLAND
Field work on Kea, updating the previous 1972-73 work (Figure 2), has shown that two major geotectonic units are
present on the island. An autochthonous low metamorphic grade footwall and an overlying fault zone, seen as numerous
minor klippen, formed during top-to-SSW extension. No hangingwall has been unequivocally identified.
Fig. 1. The Greek territory is covered by 325 geological maps at 1/50.000 scale. With red color some of the geological
maps that are being updated. With blue color the KEA map sheet.
The metamorphic footwall, which dominates the island, with a tectonic thickness of >380 m, has two major units:
•
Marbles, 0.1-30m thick, medium to very finely crystalline, mostly monomineralic, thin laminated, of a whitish,
bluish or grey colour, often intensely folded and boudinaged on both small- and large-scales. This is a calcite (ultra)mylonite. Thin quartzofeldspathic layers may occur within the marbles.
•
Chloritic schists with lithologically lensoid variations in quartz, carbonate, epidote, actinolite, biotite and talc. These
schists predominate, except along the eastern and southern margins of the island, where marbles are very common.
The fault-rock zone comprises ultra-mylonitic calcitic marbles and dolostone breccias. The former have a white to light
grey colour whilst the latter are pale buff coloured. In some instances, the dolostone breccia has been ankeritised, giving
it a dark rust colour. These low-angled fault-rocks are common in the northern (Korisia-Chalara) and southern
(Petroussa) parts of the island and also on hill tops in the central-SE part of the island (e.g. Agios Simeon, Kefala).
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3. REMOTE SENSING DATA AND GIS TECHNIQUES
Landsat imagery was successfully used throughout the years for geological structure recognition due to its synoptic view
over large areas, enabling the detection of regional geological features. In particular, lineament analysis of remotely
sensed data, either by visual or automatic interpretation, is a valuable source of information for studying the structural
setting. Although, Landsat satellite TM data has proved useful for regional geological studies [1], its coarse spectral
resolution provoked difficulties to a detailed mapping of geological composition. This obstacle was overpassed with the
launch of Landsat 7 and Terra satellites. Both ASTER instrument and ETM with a spatial resolution (for the Vnir and
panchromatic band respectively) gave a new impulse to the use of satellite data for geological mapping.
Different algorithm has been applied in geological research, especially to detect geological lineaments such as fault,
joints, dykes, and shear zones [2]. Other researchers [3] used Hough transform for automated lineament analysis using
parts of Landsat TM images. The synergistic use of optical and radar data for the detection of active faults was proposed
[4]. Digital Elevation Models were also used for the detection of linear features and the extraction of the topographic
structure [5].
3.1 GIS
The existing geological map [6] was georenferenced to the HGRS 87.All the tectonic lines were digitized and classified
to the following categories (Figure 3): Fault (FL), Possible Fault (PF), Fault and Boundary (FLB), Overthrust (DO),
Possible Overthrust (PO), Thrust Fault (DU), Possible Thrust Fault (PU). The tectonic lines database was enhanced by
the lineament analysis of satellite data and the DEM of the island.
Fig. 2. The previous geological map-sheet of KEA Island.
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3.2 Lineament Analysis
Lineament analysis is one of the most frequently used routines in remote sensing for structural geological study. The
large coverage of Landsat image mosaic and the improved spatial resolution of the panchromatic band allow an analysis
at both regional and local scale. Moreover the zooming facility provided by the GIS software environment enormously
eases the interpretation process and allows an interactive spatial correlation between local and regional structures.
Although some authors propose fully automatic techniques for lineament detection, visual interpretation is still the most
reliable means for geological lineament analysis because human perception can discriminate this from other lineaments
of diverse nature (roads, crop-field boundaries) using contextual information.
A Landsat ETM+ image with a spatial resolution of 15m and an ASTER image with the same spatial resolution (Figure
3) were also georenferenced to the HGRS 87 and used for the detection and mapping of other tectonic features. Different
RGB combinations of the satellite images were also used for the allocation and separation of the different geological
formations. High resolution satellite image (Quickbird) was orthorectified and also used for the geological mapping and
the allocation of the boundaries of the different formations. All these features were implemented in a Mobile Mapper CE
GPS using Arcpad GIS and checked in situ.
4. IN SITU MAPPING
Extended field work, including new geological mapping, GPS measurements and field data collection was undertaken in
September 2007 and April 2008. In Figure 4 the locations of the in situ measurements are presented. Every tectonic line
was checked and verified in the field (Figures 5, 6 and 7). Every formation and all the geological boundaries were
checked during the geological mapping and the changes were recorded digitally using the Arcpad GIS. The accuracy of
the GPS measurements was better than 3m (DGPS mode using EGNOS).
Fig. 3. The tectonic features of KEA Island as digitized from the previous geological map and enhanced from the satellite
images. A Landsat 7 ETM and an ASTER VNIR image were used.
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5. MARINE GEOLOGY DATA
Marine geology data were also used for the understanding of the tectonic status of KEA Island. In Figure 8 the Surficial
Sediment Map of the Aegean Sea Floor of the broader area is presented. In Figure 9 diverse seismic profiles of the sea
floor around the Island of KEA are also presented. The bathymetric model of the broader area can be observed in Figure
10. From the seismic profiles it was extracted that there are two major directions of the faults. The first direction is NNESSW and the second one is NNW-SSE (Figure 8). The existence of the fault zone at the east of KEA Island is also
verified from the bathymetric measurements. As it can be observed in Figure 10 there is a very deep valley at the East of
KEA Island and a smaller valley at the West of the Island. At the east valley the depth reaches -360m while the
respective depth at the west valley is -300m.
Fig. 4. Allocation of the in situ measurements.
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Fig. 5. A fault zone marked with the red arrow.
Fig. 6. A fault zone marked with red dashed line
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Fig. 7. A fault zone marked with red dashed line.
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Fig. 8. Surficial Sediment Map of the Aegean Sea Floor.
Fig. 9. Seismic profiles of the sea floor around KEA Island.
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Fig. 10. Bathymetric map of the broader area.
6. IGME INTEGRATED GEOGRAPHIC DATABASE
IGME has being implementing the project titled “Data digitizing for the Information System of IGME”. The project
comprises the following basic objectives:
•
Digitizing – vectorization of data derived from 265 analogical and 60 digital geological map sheets of scale
1:50.000.
• Data import into an integrated standardized geographic database in the Hellenic Geodetic Reference System
• (EGSA87) called “Hellas GDB50K” (Geological Database 50 K) covering the whole country.
• Database updating and service.
The geographic database is built in GIS Environment with the use of ArcGIS 9x software (ArcInfo version, ESRI). The
used format for editing and data management is ArcGIS Geodatabase, a native data structure for ArcGIS software. It is a
collection of geographic datasets of various types held in a common file system folder, a Microsoft Access database, or a
multi-user relational database (such as Oracle, Microsoft SQL Server, or IBM DB2). All geoinformation is compiled in
feature classes and grouped in thematically organized feature datasets:
•
•
•
•
Feature Dataset “formations”: It contains feature classes (point, linear, polygon
concerning the geological linear objects and formations of the geological map.
Feature Dataset “cross_section: It contains feature classes (point, linear, polygon
concerning the crosses sections of the geological map.
Feature Dataset “lithcolumn”: It contains feature classes (point, linear, polygon
concerning the lithological column of the geological map.
Feature Dataset “legendboxes”: It contains feature classes (point, linear, polygon
concerning the legend boxes of the geological map.
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geometry or annotation)
geometry or annotation)
geometry or annotation)
geometry or annotation)
•
Feature Dataset “legend”: It contains feature classes (point, linear, polygon geometry or annotation) concerning
the legend of the geological map.
Through the integration of the specific geological database additional processes will be carried out
•
•
•
•
Integrate legends (general and detailed) and codification for the entire geographic database.
Local adjustments of point, linear, polygon features in the overlapping area of adjacent map sheets
Domains and subtypes creation, common for the entire geodatabase.
Metadata creation for the geographic database based on ISO standards.
7. THE NEW GEOLOGICAL MAP OF KEA
In the frame of a more general project, concerning the updating and homogenizing in a common geodata base the
1/50.000 geological maps of Greece, the map sheets of KEA Island was revised.
Remote sensing data, GPS measurements, marine geology data and GIS techniques were extensively used in order to
facilitate and make more accurate the geological mapping. All the data are implemented in the IGME integrated
geographic database. The preliminary new geological map is presented in Figure 11.
Fig. 11. The new map-sheet of KEA Island. Preliminary edition.
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REFERENCES
[1]
M.J. Abrams, D.A. Rothery and A. Pontual, “Mapping in the Oman using enhanced Landsat Thematic Mapper
images,’ Tectonophysics, vol 151, pp. 387-401, (1988).
[2]
Cross, A., and Wadge, G., Geological lineaments detection using the Hough transform, IGARSS’88 Proceedings, pp.
1779-1782, (1988).
[3]
Wang J., and Howarth, P. J., Use of the Hough transform in automated lineament detection, IEEE Transaction on
Geoscience and Remote Sensing, Vol. 28, No. 4, pp. 561-566, (1990).
[4]
Parcharidis Issaak, Nikolakopoulos Konstantinos, Serelis Konstantinos & Baskoutas Ioannis, “Synergistic use of
Optical and Radar data for active faults and corresponding displaced landforms detection in Kozani Basin (Greece)”.
Geocarto International, a multi-disciplinary journal of Remote Sensing and GIS, ISSN: 1010-6049, Vol 16 No 3, p.1723 (2001).
[5]
Jenson S. K., and Domingue, J. O., Extracting topographic structure from digital elevation data for geographic
information system analysis, Photogrammetric Engineering and Remote Sensing, Vol. 54, No. 11, pp. 1593-1600,
(1988).
[6]
E. N Davis, KEA ISLAND:Geological Map of Greece1/50.000, Publication: Institute of Geology and Mineral
Exploration (IGME), (1982).
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