Age datums, and abundance of Discoaster brouweri and Coccolithus pelagicus in ODP Site 180-1115 sediments

The relative abundance of warm-water Discoaster brouweri vs. cool-water Coccolithus pelagicus provides a useful proxy for interpreting Pliocene surface water temperature trends at Ocean Drilling Program Site 1115 (Solomon Sea). Surface waters were mostly warm during the early Pliocene with a slightly cooler interval centered on 4.5 Ma. A more pronounced cool interval occurred at ~3.2 Ma. The early and mid-Pliocene cool periods may reflect Antarctic glacial growth. A mid-Pliocene warm interval occurred from ~3.1 to 2.8 Ma. Temperature began to decline beginning ~2.7 Ma, marking the onset of Northern Hemisphere glaciation. This long-term decline in surface water temperature is interrupted by a brief warming event at ~2.3 Ma.暖水种布劳尔盘星藻（Discoaster brouweri）与冷水种大洋颗石藻（Coccolithus pelagicus）的相对丰度，是解译所罗门海海洋钻探计划（Ocean Drilling Program）1115站位上新世表层海水温度变化趋势的有效代用指标（proxy）。上新世早期表层海水整体偏暖，存在一个以4.5 Ma为中心的小幅降温时段。约3.2 Ma时出现更为显著的冷期。上新世早中期的冷期或可反映南极冰盖的生长。上新世中期暖期出现于约3.1 Ma至2.8 Ma期间。约2.7 Ma起海水温度开始持续下降，标志着北半球冰期的启动。这场长期的表层海水降温过程，被约2.3 Ma的一次短期升温事件打断。