ARTICLE IN PRESS
Computers & Geosciences 30 (2004) 785–789
Short note
StratDraw: automatic generation of stratigraphic sections from tabulated field data$ Monika Hoelzel* Department of Geological Sciences, University of Vienna, Althanstr. 14, 1090 Vienna, Austria Received 10 April 2003; received in revised form 27 April 2004; accepted 1 May 2004
1. Introduction The interpretation of stratigraphic and sedimentologic field work is based on geological maps, cross sections and (litho)stratigraphic columns. The investigation of sedimentary rocks is a very important aspect of geology, as they host most petroleum and gas reservoirs as well as most aquifers. The most simple and common way to visualize sedimentologic field data is a lithostratigraphic column, which enables quick presentation of vertical variation of the sediment and the documentation of lateral trends by the correlation of different sections. One of the most useful techniques in the presentation of clastic rocks is to indicate the grain size of individual beds by their horizontal width in the lithologic column according to the grain size, the wider the column, the coarser the components (Miall, 1984; Tucker, 1988). Another presentation technique of lithologic variation in sediments is to indicate the erodibility of different beds by the horizontal width in the lithostratigraphic column (Krumbein and Sloss, 1963). The construction of detailed stratigraphic cross sections and the conversion of the measured field data into graphical columns is rather time consuming and therefore a couple of software packages offer a computerized solution. However, most of these programs for drawing lithostratigraphic columns (e.g. ‘‘PRIZMt’’ from Landmark GeoGraphixs,1 ‘‘DBSond’’ from Geo&Soft Interna-
tional,2 ‘‘Log View’’ or ‘‘WellCAD’’ from Rockware Inc.s,3 ‘‘Winbohr’’ from IDAT4) are software packages, which have an immense overload of other functions, mostly designed for hydrocarbon exploration companies and therefore they are very expensive. This work presents a simple, but efficient freeware written in Visual Basic (VB 6.0) for the translation of field measurements into their graphical representa‘tion in the form of lithostratigraphic columns in combination with the widely used graphic software package CorelDRAWt.5 StratDraw uses tables containing thickness and grain size (or erodibility) field data of sediments to automatically create lithostratigraphic columns. This paper gives an introduction to the program and shows its effectiveness with an example of a lithostratigraphic section from Spiti (NW-Himalaya, India). The program and test datasets can be downloaded from the download-area of the homepage of the Department of Geological Sciences, Vienna6 and/or via anonymous FTP from the website of the International Association of Mathematical Geology.7
2. Program description The simple principle of StratDraw is the continuous stacking of rectangles with their scaled length derived 2
$
Code available from server at http://www.iamg.org/CGEditor/index.htm *Tel.: +43-1-4277-534-35; fax: +43-1-4277-9534. E-mail address:
[email protected] (M. Hoelzel). 1 http://www.geographix.com/products/default.htm. 0098-3004/$ - see front matter r 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.cageo.2004.05.004
http://www.geoandsoft.com/english/dbsex02.htm. http://www.rockware.com/. 4 http://www.idat.de/jsfr/index dj.html. 5 http://www.corel.com. 6 http://www.univie.ac.at/Geologie/downloads/htm. 7 http://www.iamg.org. 3
ARTICLE IN PRESS M. Hoelzel / Computers & Geosciences 30 (2004) 785–789
786 Grain
Grain Size
Size
DIN 4022
Classes
(mm)
Gravel
63 – 2.0
Lithology
Conglomerate Breccia
Index
17, 18
Sand coarse
2.0 – 0.63
medium
0.63 – 0.20
fine
0.20 – 0.063
Silt
Clay
0.063 – 0.002
< 0.002
Sand Sandstone Arenite
13, 14, 15 10, 11, 12 7, 8, 9
Silt Siltstone Clay Mudstone
(3), 4, 5
1, 2, (3)
Fig. 1. Recommended indices for grain size classes after DIN 4022.
from the grain size/competence and their height based on the layer thickness. In CorelDRAWt, rectangles are defined by two absolute coordinate points in the lower left (x1 =y1 ) and in the upper right corner (x2 =y2 ). The difference between these absolute coordinates is the grain size (x2 x1 ) and the thickness of the layer (y2 y1 ). The data input works with simple tables, produced in any text or table editor. Each row of the table represents one stratum, where the first column defines the thickness (usually in cm) and the second the grain size/competence. These values of grain size/competence must be predefined by fixed index numbers (see Fig. 1). The table must then be converted into a text, where the comma (,) is used implicitly as tabulator separator (see Table 1). The file is then saved as a text file (.txt), which can be read by the program. Before drawing the section, colors may be assigned to any grain size and/or lithology. The color palette is composed of RGB-colors, which means that there are 256 (24-bit) colors. Because VB 6.0 only accepts RGBcolors (Monadjemi, 1999), the palette is not as varied as the CorelDRAW palettes, which includes CMYK and RGB). Fill patterns instead of the colors provided by the program can only be inserted afterwards (e.g. USGS fill patterns available as Encapsulated Post Script (.eps) files8).
8
http://geopubs.wr.usgs.gov/open-file/of99-430/, http://geopubs.wr.usgs.gov/open-file/of99-430/of99-430 patternchart.pdf, http://structure.harvard.edu/Bplesch/map%20patterns/.
Table 1 Input data (in cm) of example section, tabulated (2 columns on left) and in text format (right column). Decimal symbol can be a point as well as a comma Tabulated data Thickness
Width
Data converted to text
198.4 65.3 122.4 73.5 122.4 65.3 195.9 155.1 65.3 236.7 175.5 236.7 163.3 114.3 138.8 134.7 146.9 179.6 159.2 195.9 32.7 85.7 187.8 114.3 191.8 191.8 151.0 175.5 404.1 220.4 608.2 285.7 334.7 261.2 326.5 273.5 296 298 126.5 77.6 367.3 114.3 126.5 138.8 126.5 285.7 208.2 273.5 257.1 187.8 285.7 400.0 114.3 93.9
7 4 7 4 6 4 6 5.5 4 5.5 5.5 5.5 5.5 0.5 5.5 6 7 6 20 13 4 7 9 5.5 6 9 7 1 4 6 4 13 6 6 6 8 13 12 8 1 8 1 8 6 8 5.5 5.5 6 4 5 4 2.5 4 2.5
198.4,7 65.3,4 122.4,7 73.5,4 122.4,6 65.3,4 195.9,6 155.1,5.5 65.3,4 236.7,5.5 175.5,5.5 236.7,5.5 163.3,5.5 114.3,0.5 138.8,5.5 134.7,6 146.9,7 179.6,6 159.2,20 195.9,13 32.7,4 85.7,7 187.8,9 114.3,5.5 191.8,6 191.8,9 151.0,7 175.5,1 404.1,4 220.4,6 608.2,4 285.7,13 334.7,6 261.2,6 326.5,6 273.5,8 296,13 298,12 126.5,8 77.6,1 367.3,8 114.3,1 126.5,8 138.8,6 126.5,8 285.7,5.5 208.2,5.5 273.5,6 257.1,4 187.8,5 285.7,4 400.0,2.5 114.3,4 93.9,2.5
ARTICLE IN PRESS M. Hoelzel / Computers & Geosciences 30 (2004) 785–789 Table 1 (continued)
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3. System requirements
Tabulated data Thickness
Width
Data converted to text
106.1 289.8 310.2 555.1 53.1 224.5 49.0 379.6 183.7 179.6 69.4 98.0 69.4 93.9 73.5 65.3 98.0 163.3 191.8 65.3 57.1 69.4 85.7 146.9 106.1 106.1 69.4 65.3 65.3 69.4 146.9 155.1 244.9
1 2.5 6 2.5 4 2.5 3.5 2.5 16 2.5 3.5 2.5 3.5 2.5 4 4 13 2.5 5 2.5 12 1 5 3.5 2 2 3.5 2 3.5 3.5 4 4 17
106.1,1 289.8,2.5 310.2,6 555.1,2.5 53.1,4 224.5,2.5 49.0,3.5 379.6,2.5 183.7,16 179.6,2.5 69.4,3.5 98.0,2.5 69.4,3.5 93.9,2.5 73.5,4 65.3,4 98.0,13 163.3,2.5 191.8,5 65.3,2.5 57.1,12 69.4,1 85.7,5 146.9,3.5 106.1,2 106.1,2 69.4,3.5 65.3,2 65.3,3.5 69.4,3.5 146.9,4 155.1,4 244.9,17
Additionally, the scale of the section can be modified before the drawing process is started. Every parameter can be re-scaled independently and the units of scale are measured in centimeters. In addition, there are other features to optimize the drawing, such as a second bar (‘‘Litho Bar’’) on the left for remarks or numbering, and an invisible bar (‘‘Optical Bar’’) in the middle. The corners on the right can be created rounded off, in relation to the thickness of the layer. This graphic optimization feature cannot be found in other programs. After the stratigraphic column is created, it can be saved and further processed as a standard CorelDRAW file (e.g. changing the shape, size and color or fill patterns of the generated rectangles). Graded bedding also can be drawn by hand by converting the rectangles into curves.
StratDraw is an independent application that interacts with CorelDRAWt. It can be used with CorelDRAWt versions 10, 11 and 12, based on Microsoft Windows system software. The application of StratDraw requires no special setup or installation process, once downloaded and saved on the PC.
4. Application and example Fig. 2 is an example of a stratigraphic section created with the presented program. The section (Lipak formation, Middle Devonian to Early Carboniferous) from Draganits et al. (2002) is a part of the classical Paleozoic stratigraphy of Spiti (NW-Himalayas), representing the almost continuous succession from the Paleozoic to the Cretaceous of the northern Indian passive continental margin (Stoliczka, 1866). The formation comprises mixed siliciclastics and carbonates grading into mudstones in higher levels. The corresponding input data for the program is shown in Table 1.
5. Conclusions StratDraw is a simple but functional application, which automatically creates lithostratigraphic columns from field data within the widely distributed standard software package CorelDRAWt. The program is written in Visual Basic (VB 6.0) and in contrary to other programs available as freeware. It offers the possibility to visualize a large amount of data in a very short time because of the automation of the drawing process. Every section is reproducible and the automation makes it possible to draw accurate fullscale graphics. In contrast to many other stratigraphic software solutions, this program draws lithostratigraphic columns, where the grain size is indicated by the width of individual beds. For a better graphical presentation, the corners on the right can be drawn rounded off and a second column for remarks can be added on the left. After the drawing process, graphics can be fully edited within CorelDRAWt. For every grain size/competence, default fill colors are available, but they can also be chosen individually. Fill patterns are not included in the automation, but by editing the graphics afterwards it is possible to insert any fill pattern (e.g. CorelDraw bitmaps, USGS-fill patterns, see footnote 8).
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Fig. 2. Stratigraphic section of the Lipak Formation, Spiti, India. Comparison between published log (Draganits et al., 2002), drawn conventionally (left) and computer generated graphics (without colors) in CorelDRAWt (right). Section’s parameters are: scale=700; grainsize=6; no lithology bar; optical bar=0.2.
ARTICLE IN PRESS M. Hoelzel / Computers & Geosciences 30 (2004) 785–789
Acknowledgements This program was developed within a FWF-Project (P-13740) directed by Michael Wagreich, investigating Miocene basin evolution in Austria. I thank Bernhard Grasemann and Erich Draganits for discussion and the improvement of a previous version of the manuscript. Special thank goes to Lukas Plan for some helpful remarks and ideas and to Andreas Neumann for helping understanding VB 6.0.
References Draganits, E., Mawson, R., Talent, J.A., Krystyn, L., 2002. Lithostratigraphy, conodont biostratigraphy and depositional environment of the middle Devonian (Givetian) to
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Early Carboniferous (Tournaisian) Lipak Formation in the Pin Valley of Spiti (NW India). Revista Italiana di Paleontologia e Stratigraphia 108 (1), 7–35. Krumbein, W.C., Sloss, L.L., 1963. Stratigraphy and Sedimentation. Freeman and Company, San Francisco, CA, 660pp. Miall, A.D., 1984. Principles of Sedimentary Basin Analysis. Springer, New York, 490pp. Monadjemi, P., 1999. Visual Basic. Markt und Technik Verlag, Mu¨nchen, 541pp. Stoliczka, F., 1866. Geological section across the Himalayan Mountains, from Wangtu bridge on the River Sutlej to Sungdo on the Indus: with and account of the formations of Spiti, accompanied by a revision of all known fossils from that district. Memoir of the Geological Survey of India 5, 1–173. Tucker, M.E.(Ed.), 1988. Techniques in Sedimentology. Blackwell Scientific Publications, Oxford, 394pp.
