Presented in this study is the application of the Image Analysis (I.A.) technique as alternative to the traditional mechanical sieving methods for grain size determination (Bonardi & Tosi, 1994a). The application of Image Analysis technique to study the grain size of recent sand sediments has produced analytical data that are comparable to those obtained by conventional methods. Furthermore, the use of the Image Analysis has provided additional morphological parameters such as grain elongation, shape and roundness that can be useful clues to depositional environment reconstruction

Bonardi, Maurizio

Tosi, Luigi

Earth-prints Repository

RECENT SAND SEDIMENTS GRAIN-SIZE DETERMINATION 
BY IMAGE ANALYSIS 
Maurizio Bonardi* and Luigi Tosi* 
* Consiglio Nazionale delle Ricerche, Istituto per 10 Studio della Dinamica delle 
Grandi Masse, San Polo 1364,30125 Venezia (Italy) 
Abstract 
Presented in this study is the application of the Image Analysis (I.A.) 
technique as alternative to the traditional mechanical sieving methods for grain 
size determination (Bonardi & Tosi, 1994a). 
The application of Image Analysis technique to study the grain size of recent 
sand sediments has produced analytical data that are comparable to those 
obtained by conventional methods. 
Furthermore, the use of the Image Analysis has provided additional 
morphological parameters such as grain elongation, shape and roundness that 
can be useful clues to depositional environment reconstruction. 
Introduction 
Image analysis technique has been successfully applied to the study of 
Late-Quaternary sand sediments from the Venetian Lagoon. The technique 
represents a new approach to grain size determination of sand sediments 
(Allen et al., 1981). and provides new and useful parameters for the 
understanding of sediment transportation, sedimentation and environmental 
conditions. 
Materials and methods 
The first 30 meters of subsoil sediments along the littoral bar that separates 
the Venice Lagoon from the open Adriatic Sea are composed mainly of sand, 
clay, silt and peat (Bonardi & Tosi, 1994b). They carry the imprinting of climatic 
fluctuation and sea level variations that the northern Adriatic basin experienced 
during its formation in the Late-Quaternary. 
It is therefore important to be able to recognise all those mineralogical, 
textural and granulometric parameters (Ehrlich et al. 1980), that may contribute 
to a better understanding of the evolutional processes that have affected the 
formation of the lagoon of Venice. 
Image Analysis is defined here as the technique that uses numerical values 
to characterise and classify images and their properties (Joyce-Loebel, 1985). 
An IBAS 2000 KONTRON image analyser was used for this investigation of 
recent sand deposits. 
The conventional sieving method have been emulated by choosing similar 
diameter measurement intervals; while the percentage of grains for each 
interval, has been considered instead of the weight percentage. 
 
Bonardi, M. and Tosi, L., 1995. Recent sand sediments grain-size determination by image analysis. 
In: (Marabini, F. Editor) Italian Contribution to the China-Italy Bilateral Seminar on Marine Geology, 
(4-6 October 1994, Qingdao, China). Istituto di Geologia Marina, CNR, Bologna, Tech. Rep. 40, 10-13.
Results 
The cumulative curve obtained by I.A. for a sample with at least 200 grains 
is reported and compared with the cumulative curve obtained by simulating the 
conventional mechanical sieving (Fig. 1). 
350 
-- f',. ~ 
-- cumulative curve by I.A. 
--- cumulative curve as by 
conventional sieving 
method 
300 250 200 
Diameter (microns) 
\.' 
\.' 
\.\ 
'\. , 
I\, 
\\ 
\\ 
"-
150 
100 
90 
80 
70 
60 ~ 
50 tI) c: 
40 
E 
en 
~ 30 
~ 20 
.~ 
-.....:: 10 
0 
100 50 
Fig.1. Comulative curve of a sand sample obtained by Image Analysis and by 
simulating mechanical sieving. 
The application of the Image Analysis technique to the sedimentological 
study of a core is shown in figure 2 where the granulometric data of samples, 
taken at increasing depth, are represented by convetional cumulative curves. 
100 
Diameter (micron) 
10 
-tI-l.22m 
--D--5.02m 
--7.22m 
--14.22m 
--f:l- 21.72 m 
---24.22m 
Fig.2. Cumulative curves (I.A. data) for sand samples taken at increasing 
depth from a core from the Venetian Littoral. 
Correlation between average mineralogical composition variations (Fig.3) 
and granulometric parameters (Fig.4) obtained by I.A. for sand samples taken 
at increasing depth from a core from Venetian Littoral. 
11 
Bonardi, M. and Tosi, L., 1995. Recent sand sediments grain-size determination by image analysis. 
In: (Marabini, F. Editor) Italian Contribution to the China-Italy Bilateral Seminar on Marine Geology, 
(4-6 October 1994, Qingdao, China). Istituto di Geologia Marina, CNR, Bologna, Tech. Rep. 40, 10-13.
The compositional and granulometric variations . of the sand samples are 
related to climatic and sea level changes (Bonardi & Tosi, 1994c). 
80 
70 
60 
50 
("10) 40 
30 
20 
10 
....... / ... _----.-
--........... /' - .---. .. ..0 .........• / .-.. .. -.. ... 
•• --...--..... . ................. -0- ••••• / 
_/./.o::::::::::O>-<::::::_~ ______ '" 
0··_···_··········· ········.·· ... 0 .................. 0 ........................... 0 ....... ~ 
./ : 
0 
0 5 10 15 20 25 
depth (m) 
..................... Carbonates .. ··· .... 0·· .... - Silicates -.- Mica 
Fig. 3. Mineralogical composition variations with depth 
0.8 
0.75 
0.7 
0.65 
0.6 
0.55 
0.5 
0.45 
0.4 .--.-----~ • 
0.35 
0.3 
0 5 10 15 20 25 
depth (m) 
r -.- Sorting --0- Avg. Elongation -.- Avg. Roundness I 
Fig. 4. Sedimentological parameters variation with depth. 
Conclusions 
Image Analysis tecnique used for sedimentological investigations offers 
several advantages: 
• the granulometric investigation by Image Analysis technique produces 
analytical data that are comparable to those obtained with the traditional 
sieving method. 
• very limited quantity of sample is required for the analysis. 
• the granulometric measurement is fast and not destructive. 
• average grain size measurement is more accurate than the measurent by 
mechanical sieving. 
• the cumulative curve is obtained by interpolation of the diameter values of all 
grains. 
12 
Bonardi, M. and Tosi, L., 1995. Recent sand sediments grain-size determination by image analysis. 
In: (Marabini, F. Editor) Italian Contribution to the China-Italy Bilateral Seminar on Marine Geology, 
(4-6 October 1994, Qingdao, China). Istituto di Geologia Marina, CNR, Bologna, Tech. Rep. 40, 10-13.
• additional morphological parameters such as elongation and roundness are 
provided. 
• it is possible to improve and change the grains classification at any time, by 
changing the diameter intervals with the rielaboration of the data, whereas, 
with the conventional method, the measurements must be repeated every 
time the set of sieves has been changed. 
• the granulometric investigation can be adapted to the different types of 
sedimentological investigation. 
• simultaneous granulometric, chemical, mineralogical and morphological 
analyses of each grain are possible when the image analyser is used on-line 
with modern SEM or EMP. 
Acknowledgements 
Financial support was provided by the research project: Sistema Lagunare 
Veneziano, L.R. 2.5, u.o. 2. 
The autors thank D.A Walker of the Geological Survey of Canada, for the 
review of the manuscript. The assistance of Dr. I. Calliari of the C.U.G.AS. 
laboratory of the University of Padova is gratefully aknowledged. 
References 
ALLEN T., CHAPMAN & HALL (1981): Particle Size Measurement, Ltd,-3rd 
ed. 
BONARDI M. & TOSI L. (1994a): Studio granulometrico mediante Image 
Analysis (I.A) delle sabbie Tardo Quaternarie del Cordone Litoraneo della 
Laguna di Venezia. CNR-ISDGM, Techn. Rep. 18, Venezia. 
BONARDI M. & TOSI L. (1994b): I sedimenti tardo-quaternari del cordone 
Iitoraneo della Laguna di Venezia: Ie sabbie ".CNR-ISDGM, Techn. Rep. 184, 
Venezia. 
BONARDI M. & TOSI L. (1994c): Climatic and sea level fluctuations evidenced 
in the mineralogical composition of Late Quaternary sediments from the 
Venetian Littoral (Italy): Proc. 14th International Sedimentological Congress, 
Recife, Brasile, 1994, p. E5. 
EHRLICH R., BROWN P.J., VARUS J. M. & EPPLER D. T. (1980): Analysis of 
particle morphology data. In: Advanced Particle Morphology, J. K. Beddow and 
T. P. Meloy (eds.) C.R.C. Press, Florida. 101-119. 
FOLK R. L. (1966): A review of grain-size parameters. Sedimentology 6, 73-93. 
JOYCE-LOEBEL (1985): Image Analysis Principles and Practice, Technical 
Handbook, Gateshead, England. 
13 
Bonardi, M. and Tosi, L., 1995. Recent sand sediments grain-size determination by image analysis. 
In: (Marabini, F. Editor) Italian Contribution to the China-Italy Bilateral Seminar on Marine Geology, 
(4-6 October 1994, Qingdao, China). Istituto di Geologia Marina, CNR, Bologna, Tech. Rep. 40, 10-13.


Recent sand sediments grain-size determination by Image Analysis

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Recent sand sediments grain-size determination by Image Analysis

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