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doi:10.2204/iodp.proc.324.205.2014 ResultsHole U1346AHysteresis curves were measured on 11 samples from Hole U1346A. Hysteresis parameters are listed in Table T1, and two examples of hysteresis loops are plotted on Figure F1. Mr/Ms ratios range from 0.190 to 0.401, and Hcr/Hc ratios range from 1.33 to 1.68. On a Day plot, these parameters place the samples just below the mixing single-domain (SD)–multidomain (MD) curve from Dunlop (2002) close to the values corresponding to ~20% MD or less (Fig. F2). Hole U1347AHysteresis curves were measured on 67 samples from Hole U1347A (including the samples studied in Carvallo and Camps, 2013). Hysteresis parameters are listed in Table T2, and examples of hysteresis loops are plotted on Figure F3. Two main behaviors can be identified. Most samples are pseudosingle-domain (PSD)-like, with Mr/Ms ratios between 0.096 and 0.350 and Hcr/Hc ratios between 1.30 and 5.00 (Fig. F3A). Among these samples, some seem to contain a small higher coercivity component (Fig. F3B). The other samples are characterized by Mr/Ms ratios close to 0.500, which is characteristic of SD magnetic carriers (Fig. F3C). On a Day plot, these parameters place most of the samples just below the mixing SD–MD curve from Dunlop (2002) close to the values corresponding to ~20% MD or less, but a few samples contain as much as 70% MD grains (Fig. F2). Hole U1350AHysteresis parameters were measured on 64 samples from Hole U1350A (including the samples studied in Carvallo and Camps, 2013). Hysteresis parameters are listed in Table T3, and examples of hysteresis loops are plotted on Figure F4. Of the samples from this hole, 65% have Mr/Ms ratios between 0.100 and 0.250, which is fairly low; coercivities mostly lower than 10 mT; and Hcr/Hc ratios between 1.30 and 1.80 (Fig. F4A). Toward the bottom of the hole, samples have higher Mr/Ms ratios (Fig. F4B), ranging between 0.250 and 0.380, which seems to indicate a more SD behavior. In general, these parameters plot just below the SD–MD mixing line on the Day plot, with a composition between 20% and 50% MD grains (Fig. F2). |
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