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.

中文翻译：

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巴西东北外陆架混合碳酸盐-硅质碎屑沉积物的统计方法

巴西东北部大陆架具有碳酸盐-硅质碎屑混合沉积体系。本研究对表层沉积物进行统计分析，以了解沿外陆架沉积环境的沉积分布和过程的条件和控制。对总共 123 个抓取的沉积物样品进行了平均粒度、标准偏差、偏度和峰度分析。外架呈现平均粒度，从非常粗的沙子到非常细的沙子。标准偏差范围从中等排序到非常差排序。偏度范围从强烈的精细偏斜到强烈的粗偏斜。峰度区间的范围从非常 platykurtic 到非常 leptokurtic。双变量分析揭示了三种环境中统计参数与沉积相之间的相关性：Açu 礁 (OAR) 外、Açu 礁间 (AIR) 和 Açu 切割谷 (AIV)。粗沉积物选择不佳，基本呈正偏斜，OAR 区生物碎屑粗砂的峰度值最低，而中至细砂为硅质碎屑和生物碎屑，分选中等，正偏斜，峰度值最高。 AIR 和 AIV 中的峰度。峰度和偏度参数证明了外陆架上三个区域之间的区别。结果揭示了水动力状况和陆架沉积与原位碳酸盐生产和圈闭的残余硅质碎屑的关系。并且在 OAR 区域的生物碎屑粗砂中具有最低的峰度值，而中至细砂是硅质碎屑和生物碎屑，中等分选，正偏斜，在 AIR 和 AIV 中显示出最高的峰度值。峰度和偏度参数证明了外陆架上三个区域之间的区别。结果揭示了水动力状况和陆架沉积与原位碳酸盐生产和圈闭的残余硅质碎屑的关系。并且在 OAR 区域的生物碎屑粗砂中具有最低的峰度值，而中至细砂是硅质碎屑和生物碎屑，中等分选，正偏斜，在 AIR 和 AIV 中显示出最高的峰度值。峰度和偏度参数证明了外陆架上三个区域之间的区别。结果揭示了水动力状况和陆架沉积与原位碳酸盐生产和圈闭的残余硅质碎屑的关系。