Description
Summary:To analyze the mineralogical composition of sediments we freeze-dried and milled 19 samples for X-ray diffractometry (XRD) using a PHILIPS PW1820 goniometer (40 kV, 40 mA, from 3 to 100°, step-rate 0.05°, Co ka radiation). Data processing was performed using the free software MacDiff 4.0.7. To avoid influence of opal and organic matter in the samples (Voigt, 2009), we used the ratio of the peak area intensities of each mineral to the sum of the peak area intensities of all detected minerals, and used this value to estimate percentages.