Statistical approach on mixed carbonate-siliciclastic sediments of the NE Brazilian outer shelf
Abstract
The northeastern Brazilian continental shelf has a mixed carbonate-siliciclastic sedimentation system. This study applied statistical analysis on superficial sediments to access the conditions and controls of sedimentary distribution and processes along the outer shelf depositional environment. The total of 123 grabbed sediment samples were analyzed as mean grain size, standard deviation, skewness, and kurtosis. The outer shelf presented mean grain size ranging from very coarse sand to very fine sand. Standard deviation ranges from moderately sorted to very poorly sorted. Skewness ranges from strongly fine-skewed to strongly coarse-skewed. Kurtosis intervals range from very platykurtic to very leptokurtic. The bivariant analysis revealed correlations between the statistical parameters and sedimentary facies in three environments: outside the Açu reef (OAR), Açu inter-reef (AIR,) and in the Açu Incised Valley (AIV). The coarse sediments are poorly selected, showed positively skewed essentially, and had the lowest kurtosis values in bioclastic coarse sand of the OAR area related to, whereas medium to fine sands are siliciclastic and bioclastic, moderately sorted, positively skewed, and showed the highest values of kurtosis in the AIR and AIV. The kurtosis and skewness parameters evidenced the distinction between the three zones on the outer shelf. The results revealed the relationship of hydrodynamic regimes and shelf sedimentation with the in situ carbonate production and trapped relict siliciclastics.
- Publication:
-
Geo-Marine Letters
- Pub Date:
- December 2020
- DOI:
- 10.1007/s00367-019-00625-8
- Bibcode:
- 2020GML....40.1001D