Figure 10. Comparison and correlation of tephra zones, magma compositions, and inferred biostratigraphic and radiometric ages of tephra layers and volcaniclastic deposits in eastern Tyrrhenian Site 650 and central Tyrrhenian Site 974. Core recovery and nannoplankton zones of Site 650 are from Kastens, Mascle, et al. (1990), of Site 974 are from Shipboard Scientific Party (1996). Biostratigraphic and paleomagnetic ages at Site 650 are from Channell et al. (1990) and Kastens, Mascle, et al. (1990). Site 650 tephra zones and glass-shard compositions are from Calanchi et al. (1994) and McCoy and Cornell (1990). Note the dominance of high-K calc-alkaline (HKCA) compositions in tephra zones 1a (>3 Ma to 0.8 Ma) and 1b (0.8 Ma to 0.2 Ma), contrasting tephra compositions at eastern Tyrrhenian Site 650 (HKCA + LKCA) and central Tyrrhenian Site 974 (HKCA + LKCA + HKSH) in tephra zones 1a and 1b, and the dominance of alkaline (ALK) magma compositions in tephra zone 2 (0.20 to 0.075 Ma) and tephra zone 3 (0.075 Ma to the present).

Figure 10. Comparison and correlation of tephra zones, magma compositions, and inferred biostratigraphic and radiometric ages of tephra layers and volcaniclastic deposits in eastern Tyrrhenian Site 650 and central Tyrrhenian Site 974. Core recovery and nannoplankton zones of Site 650 are from Kastens, Mascle, et al. (1990), of Site 974 are from Shipboard Scientific Party (1996). Biostratigraphic and paleomagnetic ages at Site 650 are from Channell et al. (1990) and Kastens, Mascle, et al. (1990). Site 650 tephra zones and glass-shard compositions are from Calanchi et al. (1994) and McCoy and Cornell (1990). Note the dominance of high-K calc-alkaline (HKCA) compositions in tephra zones 1a (>3 Ma to 0.8 Ma) and 1b (0.8 Ma to 0.2 Ma), contrasting tephra compositions at eastern Tyrrhenian Site 650 (HKCA + LKCA) and central Tyrrhenian Site 974 (HKCA + LKCA + HKSH) in tephra zones 1a and 1b, and the dominance of alkaline (ALK) magma compositions in tephra zone 2 (0.20 to 0.075 Ma) and tephra zone 3 (0.075 Ma to the present).