Reference : Delta and deep basin Jurassic deposits from Iran: relationship between magnetic susce...
Scientific congresses and symposiums : Paper published in a book
Physical, chemical, mathematical & earth Sciences : Earth sciences & physical geography
Delta and deep basin Jurassic deposits from Iran: relationship between magnetic susceptibility and facies
Sardar Abadi, Mehrdad mailto [Université de Liège - ULg > > > Form. doct. sc. (géologie - Bologne)]
Da Silva, Anne-Christine mailto [Université de Liège - ULg > Département de géologie > Pétrologie sédimentaire >]
Zamanzadeh [> >]
Abstract 4eme Congrès Français de Stratigraphie, Strati2010, Paris, France, 30 Augustus – 2 September
from 30-08-2010 to 02-09-2010
4eme Congrès Français de Stratigraphie, Strati2010, Paris, France, 30 Augustus – 2 September
[en] Kashafrud Formation ; Kopeh Dagh basin ; Iran ; Sedimentology ; Magnetic susceptibility
[en] This study concerns, the Kashafrud Formation from Kopet Dagh Basin in its type section, which corresponds to the first Jurassic sedimentary cycle in Iran,. Sedimentary studies were carried out to propose a paleoenvironmental model of the sedimentary succession. Furthermore, magnetic susceptibility (MS) measurements were performed and compared with sedimentological evolution. The MS curve evolution is related to the abundance of magnetic minerals, which itself is related to lithogenic supplies which could be related mostly to sea level and climatic changes. Theoretically, a regression will lead to a more important proportion of landmass exposed and so to an increase of detritic minerals in the sedimentary system and so to an increasing MS. A transgression will decrease MS (Ellwood et al., 2000).
Palaeoenvironments of this Jurassic succession from base to top are: flood dominated delta, deep basin deposits, silisiclastic and mixed silisiclastic and carbonate shoreface deposits.
Comparison between facies evolution and MS curve shows that the facies which are deposited in delta and shoreface zones have low MS values; on the contrary basinal deposits are presenting high MS values. The facies deposited in mixed silisiclastic and carbonate shoreface have lowest MS values. So it appears that the deeper basinal deposits have the highest MS values and the shallower deltaic and shorelines facies have the lowest MS values, in opposition with theoretical background. This could be related to water agitation and sedimentation rate during deposition. In the deltaic and shoreface environments, a high water agitation could prevent the detritic particles to settle and a high sedimentary rate could dilute the magnetic minerals (see Da Silva et al., 2009). It actually seams that the carbonate production in the upper parts of the studied interval has led to a dramatic decrease in MS values. This study clearly shows the significant role of MS in environmental analysis, and the importance of a strong sedimentological background.

Ellwood, B.B., Crick, R.E., El Hassani, A., Benoist, S.L. & Young, R.H., 2000. Magnetosusceptibility event and cyclostratigraphy method applied to marine rocks: detrital input versus carbonate productivity. Geology, 28: 1135-1138.

Da Silva, A.-C., Mabille, C. & Boulvain, F., 2009. Influence of sedimentary setting on the use of magnetic susceptibility: examples from the Devonian of Belgium. Sedimentology, 56: 1292-1306.

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