DATA MANAGEMENT AND MAP PRODUCTION IN THE GEOLOGICAL MAPPING PROJECTS IN MOZAMBIQUE

Transcription

1 GTK Consortium Geological Surveys in Mozambique , edited by Yrjö Pekkala, Tapio Lehto & Hannu Mäkitie Geological Survey of Finland, Special Paper 48, 23 33, 2008 DATA MANAGEMENT AND MAP PRODUCTION IN THE GEOLOGICAL MAPPING PROJECTS IN MOZAMBIQUE by Tiainen, M., Rantala, O., Kahra, A. & Kuosmanen, E Data management and map production in the geological mapping projects in Mozambique. Geological Survey of Finland, Special Paper 48, 23 33, 11 figures. This paper briefly describes the data flow in the geological mapping projects LOT 2 and LOT 3 in Mozambique, including a short description of the data sets, data management and databases developed and map production in different phases of the project. Both the final digital and paper printed products are described. The products comprised geological and mineral deposit maps as print-ready files, paper prints and GIS map database, mineral deposit database, field observation databases and tables of the results of laboratory studies. All data (250 GB) have been delivered to the Client (Direcção Nacional de Geologia, Moçambique; DNG) on an external disk with an integrated DVD for presentation of the products. Key words (GeoRef Thesaurus, AGI ): geologic maps, bedrock, data management, cartography, data bases, Mozambique. Geological Survey of Finland, P.O. Box 96, FIN Espoo, Finland markku.tiainen@gtk.fi INTRODUCTION Two geological mapping projects (LOT 2 and LOT 3) covered north-western, central and southern Mozambique (see Fig. 1). The projects comprised the re-interpretation of existing geological data, collection of new data and compilation of new geological maps of the project areas. The activities carried out during the project were subdivided into three main phases: 1) Data gathering and preparation of the data; 2) Geological review and compilation of the map data; and 3) Verification and final digital products. Most of the project activities, such as map production and data management, were overlapping and continued throughout the project. The main tasks and products of different phases are described in a data flow chart (Fig. 2). The core of the whole process has been the digital map library (DML) that was continuously updated by new data during the project. The final version of the DML was ready at the end of the project at the same time as the final products were completed and handed over to the Client (Direcção Nacional de Geologia, Moçambique; DNG). Map production and data management of LOT 2 and LOT 3 projects were coordinated by GTK. Practical work was conducted in three organizations, GTK, ITC and GEUS. ITC was in charge of the processing of remote sensing data and the topo- 23

2 graphical base data of LOT 2. Topographical base data of LOT 3 area were prepared by GEUS. The data bases and final geological maps were prepared by GTK. Details of the databases, maps and map production process are described in the Final Technical Reports of LOT 2 and LOT 3 projects. MAP PRODUCTION PROCESS Map production procedure included the design of databases, preparation, digitization, scanning and storage of data as well as processing and interpretation of data and finally map preparation and printing of geological maps. Several versions of preliminary maps have been prepared for fieldwork and evaluation purposes. The total number of final geological and mineral deposits map products, including English and Portuguese versions, was 144 map sheets, and the total number of printed maps delivered to the client during the project was about 700 prints. The map production team has continually worked in close co-operation with the mapping geologists. Fig. 1. The mapping area of the GTK Consortium (LOT 2, LOT 3 and LOT 2/3 extension), with an index of the geological map sheets published at the scale 1:

3 All digital geological data have been compiled as seamless GIS data from which the printed maps were prepared as square degree sheets, with the standard layout and legend. The final maps include 19 one square degree sheets, 19 double sheets at the scale 1: and 20 map sheets at the scale 1: (Figs 1 & 3). Fig. 2. Flow chart of the data. The preparation and compilation of new products are in grey boxes and the results of the compilation processes are in yellow boxes. 25

4 Fig. 3. Detailed geological maps, 20 map sheets in total, including 6 double sheets, were produced at the 1: scale from Fingoè, Cuchamano and Manica areas. PRELIMINARY MAP PRODUCTS Preliminary maps were based on the compilation of existing geological data, aerial photograph interpretation and on the new interpretation of satellite ima-ges as well as airborne magnetic and radiometric surveys. The most important source data comprised the following data sets: 1) Geological data: 1:1 million scale geological map of Mozambique (scanned); Hunting Team geological maps at the scale 1: (digitised); Geological maps of the map series Cartgeologica de Mozambique na escala 1: from the 1950s and 1960s (scanned); 2) Satellite images comprising Landsat ETM 7 imagery and ASTER VNIR scenes; 3) Shuttle Radar Topography Mission (STRM) elevation data; 3) Aerial photographs from selected areas; 4) Airborne geophysical data of Fugro; 5) Mineral resource data from reports; and 6) Topographic paper maps at the scale 1: (scanned). Several combinations of different data sets have been prepared to visualise geological features and to support geological interpretation of the mapping areas. The preliminary geological maps were prepared for fieldwork before the field seasons. Details of the geological interpretation procedure are described in the paper by Schetselaar et al. of this volume. 26

5 GEOLOGICAL MAPPING, MAP PRODUCTION AND NEW GEOLOGICAL MAPS The purpose of the geological field work, carried out in Mozambique during , was to check the preliminary geological interpretations and also to resolve the problems that arose during the compilation of preliminary geological maps and to collect samples for laboratory studies. A considerable amount of new geological information was produced, including over geological field observations, photographs, 350 XRF analyses, 200 microprobe analyses, 38 age determinations and 785 petrophysical determinations. New geological interpretations have also been made during the geological mapping process. All observation data have been stored in MS Access databases and MS Excel spreadsheet tables and delivered to the Client/DNG. The first and most labour-intensive part of map production process was the preparation of all required data layers. Geological polygon data, based on remote sensing interpretations and new geological observations in the field, were compiled by mapping geologists in co-operation with the GIS geologist. Topographical data were compiled from several sources, partly digitized from topographical paper maps and satellite images. A significant part of the road data were collected by GPS during the field work. Hydro data, such as rivers and lakes, were partly taken from landuse data received through the DNG and partly digitized from topographical base maps and satellite images. The ArcGIS compatible geological map database includes the following layers: Lithostratigraphical polygons with label points; Structural lines; Observation points; Tectonic measurements; Sampling points; Dating points; and Mineral deposits. Topographical data layers comprised: A digital elevation model based on Shuttle Radar Topography Mission (SRTM); A simplified topographical base map, including lakes, rivers, roads, railroads, powerlines, contour lines, international boundary, towns, villages, highpoints and mountains. Map layout and symbology was planned in cooperation with the Client and Consulting engineer (Fig. 4). The legend of the geological maps includes a short description of the geological units, arranged in stratigraphical and age order. Geological profiles were compiled onto four map sheets to explain the geological structure of the most important sections. A digital elevation model was used as one layer in the geological maps to visualize the topography of the map area. Index map and declination information were included on each map layout. The final geological maps include five geological layers: lithological/lithostratigraphical polygons; dykes and structural lines as polylines; tectonic measurements, dating results and mineral deposit information as points. The final printed map products of LOT 2 and LOT 3 projects comprise five sets of maps: geological maps at the scale 1: with legend in English and Portuguese, geological maps at the scale 1: with legend in English and Portuguese; and mineral deposit and potential maps with the legend in English. The new digital geological and mineral deposit data were prepared as a seamless ArcGIS map database from which the computer printed paper maps and print-ready PDF files were prepared at the end of the project. The geology of the project area was explained in four Map Explanation reports, each comprising an average of 450 pages. DATABASES During the project, databases were prepared for geological maps, mineral deposits, field observations and laboratory studies. The geological mapping data have also been stored in ESRI Geodatabase format and the results of laboratory studies in MS Excel tables. Mineral deposit data have been stored in an MS Access database. Digital photographs of the field observation sites and rock samples are stored in an Imatch [photo/digital image] database. The information collected on outcrops and in the analysis of samples has been arranged as MS Access databases and MS Excel tables: Observation forms, scanned as PDF files; Geological observation databases in MS Access format; 27

6 Fig. 4. An example of the layout of a geological map (Sheet 1633 Tete). Geological observation databases in ESRI Geodatabase format; Tectonic measurements and descriptions of the observed outcrops as MS Access databases; Digital photographs of outcrops and samples in an image database; Petrophysical measurements in MS Excel tables; Chemical analysis in MS Excel tables; Petrographical thin section studies in MS Excel tables; and Age determinations in MS Excel tables. The MS Access databases and Geodatabase have been linked to geological maps through ESRI Arc- GIS/ArcMap using the observation number as a key. Consequently, the field photographs and results of laboratory studies can be viewed together with the field observations shown on the geological map. MINERAL DEPOSIT DATABASE The inventory of known mineral deposits and occurrences uses ArcGIS and MS Access as the main programmes for the storage, retrieval, manipulation and display of geo-information. The MS Access structure of the mineral data base is illustrated in Figure 5. The compiled data are ready for incorporation into the Mineral Information System (MIS), which has been developed in conjunction with the Documentation Centre. The initial format (structure, mineral names with abbreviations) for the mineral deposit databank, obtained from the Council for Geoscience (CGS), Pretoria, South Africa, was incorporated into the ArcGIS project format. The data, dealing with approximately 90 mineral deposits, was reformatted into ArcGIS shape files in order to facilitate matching with other georeferenced data when producing mineral deposit maps. The forms were designed for the collection of mineral resources data, and they were used both in the library and in the field. Data from the field forms were transferred into the database, often already in field (Fig. 6). Complementary data were extracted from both dig- 28

7 ital and analog DNG reports, published sources and from the Internet (such as company press releases and annual reports). In addition, the GTK Consortium has compiled a new database of 520 mineral deposits and occurrences, including stone, aggregate, gravel and sand quarries. These data cover the entire LOT 2, LOT 3 and Extension Contract areas. During the compilation it was found that the old location of several mineral deposits and showings in different data- Fig. 5. Structure of the database used in the LOT 2 and LOT 3 mineral occurrence inventory. Fig. 6. An example of data capture for the mineral database: attributes for deposit information. 29

8 bases was not coherently documented. Therefore, it was necessary to make GPS-controlled field checks on the deposits. Inspection of mineral occurrences proved to be time consuming and often impossible. This was due to the inaccuracy of the reported coordinates (~ one minute, meaning a maximum error of ~ one km) in existing documents and, having been abandoned for over 40 years, a general lack of surface features of most workings. Occasionally, even greater discrepancies of up to 2 to 3 km were found when comparing indicated locations with GPS-verified locations. OBSERVATION DATABASES IN MS ACCESS FORMAT Field observations from LOT 2 and LOT 3 areas have been saved from observation forms into two MS Access databases. The database Final_moza_UTM36S_2006.mdb includes observations from GTK Consortium mapping areas. All these observations have originally been made in the UTM36S coordinate system. Because a part of the GTK Consortium LOT 3 mapping area extends to the UTM37S coordinate system area, 177 observations have also been saved to the database Final_ Moza_UTM37S_2006.mdb. This arrangement will help users to export data to various GIS programmes. Most data have been saved into following tables: description, lithology, metamorphic minerals, observation (main table), ore minerals, sample, structure and tectonics. The structure of these two databases (36S and 37S) is identical. Tables, fields and relations are shown in Figure 7. Fig. 7. Structure of the field observation database. 30

9 Observation database in ESRI Geodatabase format The geodatabase Final_Moza_obs_geodatabase_ 2006.mdb includes basically the same information as the MS Access databases. This database was developed to help users to utilize observation information in an ESRI ArcGIS environment. All information has been converted to one coordinate system (UTM36S). The data have been divided into such entities that are useful in map production (Fig. 8). Fig. 8. Structure of the ESRI ArcGIS observation database. The GTK Consortium [photographic/digital image] database, including digital photographs, has been constructed using the IMatch image database programme ( The software is designed to enable the viewing, editing and organization of a digital image collection. The image files in the [photographic/digital image] database of the Mozambique include metadata in IPTC format and consist of the fields shown in Figure 9. The metadata information includes information collected by the camera (date etc.) and geological information that has been transferred from observation databases. The user interface has been developed to help users to easily browse the digital photographs stored in the database (Fig. 10). By using this application a user can locate images with the help of a keyword list based on rock names or by using the map sheet number or map name. It is also possible to download images. A downloaded image includes metadata information. Photographic/Digital image database Fig. 9. Structure of the [photographic/digital image] database. 31

10 Fig. 10. Web-based user interface for image viewing. FINAL PRODUCTS OF THE PROJECT The products of the project in LOT 2 and LOT 3 area have comprised intermediate maps and reports during different phases and the final products at the end of the project. The main intermediate products of the project, also used as milestones, were: A action plan for the project at the beginning of Phase I; Preliminary geological maps, satellite image maps at the beginning of Phase II and field work plans before the field seasons; Field-checked geological maps at the end of Phase II; Draft final geological maps at the beginning of Phase III. The final phase of the projects included the preparation of final digital products, including printready files of geological maps and map sheet explanations, geological map data as a seamless map covering both LOT 2 and LOT 3 areas in ArcGIS compatible format and a final technical report of the project. Geological maps and map sheet explanations have also been printed as paper copies. The final products of the projects comprise the following Geological and Mineral Resources maps: Geological maps at the scale 1: , including mineral occurrences, paper prints and print-ready files; Mineral Resources Potential maps at the scale 1: , paper prints and print-ready files; Geological maps at the scale 1:50 000, including mineral occurrences, paper prints and print-ready files. The following databases: Digital geological maps and ArcInfo/ArcView compatible GIS database; Databases of field observation data and the results of laboratory studies. And the following documents: Geological map sheet explanations; Final technical report of the project; Integrated DVD of the products of LOT 2 and LOT 3 projects. Digital databases comprise the observation and mineral databases in MS Access, the digital image database in IMatch, the results of laboratory studies in MS Excel tables and geological observations in Esri Geodatabases and MS Access observation databases. 32

11 The final geological maps have been submitted to the Client as paper prints, print-ready PDF files and as a seamless GIS data. The GIS data have also been delivered to the MIS project to be arranged into the digital map database of the DNG. Geological Map Explanations (Vol. 1 4) and the Final Technical Reports of LOT 2 and LOT 3 projects have been delivered to the Client as paper prints and as PDF files. All the final products of the project have been collected in an integrated DVD that can be used to present and search the results, products and data prepared by LOT 2 and LOT 3 projects (Fig. 11). All products and data of the projects were also delivered to the Client on a removable disk that includes 2500 separate files and 250 GB of data in total. Fig.11. Front page of the searchable DVD that contains the products of the LOT 2 and LOT 3 geological mapping projects. ACKNOWLEDGEMENTS We wish to thank Dr. Jouni Vuollo, GTK, for comments that considerably improved the text. 33