Results from the 40Ar/39Ar incrementally heated analyses are given in Figures F2, F3, F4, and F5 and in Tables T3 and T4. Complete data tables with additional data are provided (see "OSU-191" and "OSU-185" in the "Supplemental Materials" contents list).
Figure F2 shows the age spectra for all Site 1149 samples listed in Table T3. The age spectra for Sample 185-1149A-1H-2, 55–56 cm, after a first step with broad ages ranging from ~0 to 2.28 Ma shows a progressive increase in ages from ~1.0 Ma to a final segment with a broad age range between ~1.02 and 3.4 Ma. The weighted plateau age is 1.15 ± 0.20 Ma, and the total fusion age is 1.12 ± 0.28 Ma.
The sample below (Sample 185-1149A-2H-1, 54–55 cm) exhibits a significantly younger age pattern, characterized by a broad age range in the first step (0–0.92 Ma) followed by a steady series of segments with ages between 0.28 and 0.36 Ma. The weighted plateau age is 0.28 ± 0.04 Ma, and the total fusion age is 0.31 ± 0.06 Ma.
Sample 185-1149A-3H-2, 43–44 cm, exhibits older ages than Sample 2H-1, 54–55 cm, and broad age ranges in all the steps (ranging from 0.42 to 0.81 Ma). The weighted plateau age is 0.44 ± 0.08 Ma, and the total fusion age is 0.502 ± 0.13 Ma.
Sample 185-1149A-3H-4, 55–56 cm, after a first step with age 0.0 ± 0.0 Ma, shows a series of segments with a progressive increase in ages from 0.43 to 0.76 Ma. The weighted plateau age is 0.71 ± 0.07 Ma, and the total fusion age is 0.69 ± 0.12 Ma.
Sample 185-1149A-4H-1, 89–90 cm, is characterized by a narrow younger age range first step followed by a steady series of segments with ages between 0.6 and 1 Ma. The weighted plateau age is 0.76 ± 0.08 Ma, and the total fusion age is 0.85 ± 0.10 Ma.
Sample 185-1149A-4H-3, 96–97 cm, is characterized by a broad range of older ages in the first step followed by a steady series of segments with ages between 0.65 and 1.05 Ma. The weighted plateau age is 0.89 ± 0.10 Ma, and the total fusion age is 0.96 ± 0.10 Ma.
Sample 185-1149A-6H-1, 98–99 cm, is characterized by a series of steady segments with narrow age ranges between 1.5 and 1.80 Ma. The weighted plateau age is 1.58 ± 0.06 Ma, and the total fusion age is 2.03 ± 0.07 Ma.
Sample 185-1149A-7H-7, 49–50 cm, is characterized by a first step with broad age range (0–5 Ma) followed by a steady series of narrower age segments ranging from ~2.5 to 3.0 Ma. The weighted plateau age is 2.68 ± 0.03 Ma, and the total fusion age is 3.11 ± 0.17 Ma.
Sample 185-1149A-8H-6, 147–148 cm, is characterized by a first step with ages ranging from ~2.45 to 3.75 Ma followed by a series of narrow steps with ages ranging from 2.9 to 3.1 Ma. The last step has broad ages ranging between 1.5 and 4.25 Ma. The weighted plateau age is 3.03 ± 0.04 Ma, and the total fusion age is 3.08 ± 0.12 Ma.
Sample 185-1149A-10H-5, 80–81 cm, exhibits a series of stepping narrow segments with increasing ages. The weighted plateau age is 5.41 ± 0.31 Ma, and the total fusion age is 5.56 ± 0.12 Ma.
Sample 185-1149A-12H-6, 79–80 cm, exhibits a first segment with a broad range in ages (5.75–7.25 Ma) followed by a series of steady segments with ages ranging between 6.25 and 6.50 Ma. The last segment exhibits an older and broader range of ages between 8.4 and 10.5 Ma. The weighted plateau age is 6.30 ± 0.06 Ma, and the total fusion age is 6.58 ± 0.09 Ma.
Sample 185-1149A-13H-3, 115–116 cm, exhibits a first step with a broad age range (5.75–6.75 Ma) followed by a steady series of segments with a narrow age range between 6.75 and 7 Ma. The last two segments exhibit broader age ranges between 6 and 7.5 Ma, and 7.5 and 9.0 Ma. The weighted plateau age is 6.92 ± 0.05 Ma, and the total fusion age is 7.02 ± 0.06 Ma.
Figure F3 shows the K/Ca variations for all samples; data are listed in Table T3. For most of the samples, there is a good correlation between the K/Ca ratio and the age spectra plots (Figs. F2, F3). Samples 185-1149A-1H-2, 55–56 cm; 2H-1, 54–55 cm; 3H-2, 43–44 cm; 3H-4, 55–56 cm; 4H-1, 89–90 cm; and 4H-3, 96–97 cm, display apparent maximum K/Ca ratio values in the lower temperatures and a monotonic decrease thereafter. Most of the remaining Leg 185 samples have higher K/Ca ratios at the mid-temperature steps (i.e., 700°–825°C) with a lower ratio at the lower and higher temperature steps. The K/Ca ratio values largely overlap in Samples 185-1149A-2H-1, 54–55 cm, and 3H-2, 43–44 cm, which have decreasing values at higher temperatures (i.e., 0.873–0.119 and 0.843–0.021, respectively), and for sample 12H-6, 79–80 cm, with higher ratios at 825°C. Overlapping values are also observed in Samples 185-1149A-4H-1, 89–90 cm, and 4H-3, 96–97 cm, with higher ratios at the lower temperature steps (1.466 and 1.405, respectively) decreasing with higher temperatures to 0.058 and 0.071, respectively. Overlapping values of K/Ca ratios in Samples 185-1149A-3H-4, 55–56 cm; 6H-1, 98–99 cm; and 7H-7, 49–50 cm, show highest K/Ca ratios (i.e., 2.992, 2.804, and 2.894, respectively) at different temperature steps, and lower ratios are observed at the higher temperature steps. Samples 185-1149A-8H-6, 147–148 cm, and 10H-5, 80–81 cm, have overlapping K/Ca ratios with the highest values (i.e., 4.267 and 4.971, respectively) at the 900° and 800°C temperature steps, and lowest values at the higher temperature steps. K/Ca ratios in Samples 185-1149A-1H-2, 55–56 cm, and 13H-3, 115–116 cm, show no overlap with other samples. Sample 185-1149A-1H-2, 55–56 cm, exhibits a monotonic decrease in K/Ca ratio with the overall lowest values of all samples (i.e., 0.261–0.056).
Figure F4 shows the age spectra for all Site 1179 samples, and data are listed in Table T4. The age spectra for Sample 191-1179B-2H-2, 59–60 cm, exhibits three steps of decreasing age ranging between 0 and 0.35 Ma, and two last steps of increasing ages with the last step showing a broad age range (0–1.2 Ma). The weighted plateau age is 0.06 ± 0.04 Ma and the total fusion age is 0.10 ± 0.70 Ma.
Sample 191-1179B-2H-4, 85–86 cm, has two first steps with broad range in ages (i.e., 0.1–1.25 Ma), followed by a steady set of steps with narrower age range between 0.25 and 0.40 Ma, and a last step with broad age spectrum ranging from 0 to 1.75 Ma. The weighted plateau age is 0.36 ± 0.09 Ma, and the total fusion age is 0.99 ± 0.18 Ma.
Sample 191-1179B-4H-6, 18–19 cm, exhibits a series of steady segments of narrow age spectra ranging between 1 and 1.25 Ma, and two last steps with ages ranging between 1.25 and 1.75 Ma, and 1.25 and 3.75 Ma, respectively. The weighted plateau age is 1.03 ± 0.04 Ma, and the total fusion age is 1.09 ± 0.04 Ma.
Sample 191-1179B-5H-1, 31–2 cm, exhibits a similar pattern of the age spectra to the last sample but with slightly older ages. The first step shows a broader range in ages between 0.75 and 1.25 Ma, followed by a series of steady segments with narrower age range (1–1.25 Ma), and the two last steps with an older and broader range in ages (i.e., 2.75–3.25 Ma). The weighted plateau age is 1.14 ± 0.04 Ma, and the total fusion age is 1.39 ± 0.06 Ma.
Sample 191-1179C-5H-6, 68–69 cm, exhibits a first step with broader age range between 1.40 and 2.50 Ma, followed by two segments with narrower range in ages (i.e., 1.75–2.25 Ma). The fourth segment of the age spectra exhibits a sudden decrease on the age range of the sample (i.e., 0.75–1.25 Ma) followed by the two last steps older ages. The weighted plateau age is 2.03 ± 0.16 Ma, and the total fusion age is 1.88 ± 0.14 Ma.
Samples 191-1179C-15H-6, 106–107 cm, and 16H-4, 45–46 cm, exhibit a similar pattern in their age spectra, characterized by a narrow range in ages in all steps. Both samples have broader range in ages in the first step (i.e., 4–4.25 Ma and 4.25–5.25 Ma, respectively) followed by a series of steady segments with very narrow range in ages and ending with one or two segments with relatively broader range in ages (i.e., 5–5.30 Ma and 5.25–6.25 Ma, respectively). The weighted plateau age for Sample 191-1179C-15H-6, 106–107 cm, is 5.39 ± 0.07 Ma, and the total fusion age is 5.32 ± 0.07 Ma. The weighted plateau age for Sample 191-1179C-16H-4, 45–46 cm, is 5.59 ± 0.09 Ma, and the total fusion age is 5.56 ± 0.09 Ma.
Figure F5 shows the K/Ca variations for all samples, and data are listed in Table T4. For most of the samples, there is a good correlation between the K/Ca ratios and the age spectra plots (Figs. F4, F5). Only in Sample 191-1179C-15H-6, 106–107 cm, is the correlation not clear. Samples 191-1179B-2H-2, 59–60 cm; 4H-6, 18–19 cm; 5H-1, 131–132 cm; and 191-1179C-5H-6, 68–69 cm, display apparent maximum K/Ca ratio values in the lower temperatures and a monotonic decrease thereafter. The remaining samples show higher K/Ca ratio values at the 700°–800°C temperature steps. Overlapping values are observed in Samples 191-1179B-2H-2, 59–60 cm; 4H-6, 18–19 cm; and 191-1179C-5H-6, 68–69 cm, with maximum K/Ca ratio values of 3.042, 3.345, and 3.015, respectively. Sample 191-1179C-15H-6, 106–107 cm, exhibits the highest K/Ca ratio observed in samples from both Sites 1149 and 1179, with maximum ratio values of 25.438 and minimum values of 1.143. Sample 191-1179B-2H-4, 85–86 cm, shows very low K/Ca ratio values between 0.563 and 0.003.