(Table 1) Sr isotopes on carbonates at DSDP Hole 62-463@en

Study of 12 carbonate oozes from Deep Sea Drilling Project Hole 463, in the Mid-Pacific Mountains, suggests mean values of 0.70690 ± 0.00029 (2-sigma) and 0.70712 ± 0.00030 (relative to 0.71014 for the NBS 987 Sr isotope standard) as representing the Sr isotope composition of the Barremian and early Aptian seas, respectively. Two additional values of less than 0.7064 are the least radiogenic values known from the Phanerozoic and may be a consequence of the introduction of Sr depleted in the heavy isotope from massive submarine volcanic activity, which followed the initiation of the latest oceanic spreading episode in the Oxfordian.针对中太平洋海山区深海钻探计划（Deep Sea Drilling Project）463孔采集的12份碳酸盐软泥（carbonate oozes）开展的研究显示，两组平均值分别为0.70690±0.00029（2-sigma）和0.70712±0.00030（以NBS 987锶同位素标准（NBS 987 Sr isotope standard）的0.71014为参照），可分别代表巴列姆期（Barremian）与早阿普第期（early Aptian）海水的锶同位素组成。另有两个低于0.7064的数值，为显生宙（Phanerozoic）已知放射成因最弱的锶同位素值，其成因或与牛津纪（Oxfordian）最新洋壳扩张事件启动后发生的大规模海底火山活动所引入的重同位素贫化锶有关。