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| Titel |
Large scale field measurements of stylolites: stylolite lateral extent and roughness |
| VerfasserIn |
Leehee Laronne Ben-Itzhak, Amir Sagy, Einat Aharonov |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250049253
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| Zusammenfassung |
| Stylolites are rough surfaces formed by localized dissolution, mostly in carbonates and
sandstones. They reflect important diagenetic processes in sedimentary basins, such as local
mass transfer, compaction, and porosity reduction. Understanding how, where and
when they form can improve prediction of their occurrence and their effect on flow,
and thus has appreciable geological and economical implications. In spite of their
importance, fundamental issues concerning their structure and evolution are still
debated.
Our field study was conducted on the “Blanche” cliff of the Ein El-Assad Formation
(Lower Cretaceous) exposed in Northern Israel. The Blanche here is a ~50m-thick
biomicritic limestone, with very low porosity. It consists of well-developed bedding-parallel
stylolites that can be traced through the entire outcrop (>1km), and most likely continue
beyond the exposure. Such a tracing length for stylolites is remarkable, and is observed for
the first time. It has implications for understanding scales of permeability units and their
structural continuity.
We measured stylolite roughness in-situ using Ground-based LIDAR at 3-mm resolution.
A single scan provides millions of points that may be interpolated to generate a topographic
map or hundreds of profiles. Thus, the technique allows a statistical approach when
calculating roughness. Our measured surfaces range in size from 0.9X0.4 m2 to 9.3X2.8 m2.
Previous studies showed already that stylolite roughness is fractal over several orders of
magnitude (Karcz and Scholz, 2003; Renard et al., 2004; Schmittbuhl et al., 2004; Ebner et
al., 2009). However these previous measurements were performed at scales smaller than
0.3m. Here we report measurements of stylolite surface roughness at a scale larger than
ever measured before (10-2-101m), allowing observation of both the previously
reported fractal roughness and of a previously unobserved upper limit for fractal
behavior above ~0.1m. Surface growth models of stylolites (Ebner et al., 2009;
Koehn et al. 2009) suggest that this newly recognized upper limit may be used as a
measure of the amount of dissolution along the stylolites. These growth models and
their agreement with observations also support a physical model in which stylolites
develop from existing surfaces rather than propagate in-plain as has been previously
suggested for other case studies (e.g., Fletcher and Pollard, 1981; Raynaud and
Carrio-Schaffhauser, 1992). The modeling aspects are presented in a companion
talk.
References
Ebner, M., Koehn, D., Toussaint, R., Renard, F. and Schmittbuhl, J., 2009. Stress
sensitivity of stylolite morphology. Earth and Planetary Science Letters, 277,
394-398.
Fletcher, R.C., and D.D. Pollard, 1981. Anti-Crack Model for Pressure Solution
Surfaces, Geology, 9 (9), 419-424.
Karcz, Z. and Scholz, C.H., 2003. The fractal geometry of some stylolites from
the Calcare Massiccio Formation, Italy. Journal of Structural Geology, vol. 25,
p. 1301-1316.
Koehn, F., Renard, R., Toussaint, R. and Passchier, C.W., 2007. Growth of
stylolite teeth patterns depending on normal stress and finite compaction. Earth
and Planetary Science Letters, 257, 582–595.
Raynaud, S., and E. Carrioschaffhauser, 1992. Rock Matrix Structures in a Zone
Influenced by a Stylolite, Journal of Structural Geology, 14 (8-9), 973-980.
Renard, F., Schmittbuhl, J., Gratier, J.P., Meakin, P. and Merino, E., 2004.
Three-dimensional roughness of stylolites in limestones. Journal of Geophysical
Research, vol. 109, B03209, doi:10.1029/2003JB00255.
Schmittbuhl, J., Renard, F., Gratier, J.P. and Toussaint, R., 2004. Roughness
of stylolites: implications of 3D high resolution topography measurements.
Physical Review Letters, 93 (238501). doi:10.1103/PhysRevLett.93.238501. |
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