Variations in the western Pacific warm pool across the mid-Pleistocene: Evidence from oxygen isotopes and coccoliths in the West Philippine Sea
Variations in the western Pacific warm pool across the mid-Pleistocene: Evidence from oxygen isotopes and coccoliths in the West Philippine Sea
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DOI：
10.1016/j.palaeo.2017.07.008
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发表时间：
2017-10
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通讯作者：
Hanjie Sun;Tiegang Li;Chuanlian Liu;F. Chang;Rongtao Sun;Z. Xiong;Baizheng An
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文献类型：
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作者：
Hanjie Sun;Tiegang Li;Chuanlian Liu;F. Chang;Rongtao Sun;Z. Xiong;Baizheng An
我们提供来自国际海洋全球变化研究计划 (IMAGES) 核心 MD06-3050 的浮游有孔虫氧同位素和深花球丰度数据，这些数据是在西太平洋暖池 (WPWP) 边缘的西菲律宾海收集的。我们的记录揭示了早在 1.5 Ma 黑潮源区上层水结构就发生了显着变化，并一直持续到中更新世气候转变 (MPT)。这些变化通过黑潮源区温跃层（基于浮游有孔虫氧同位素差异）和营养线（基于颗石藻物种 Florisphaera profunda 的相对丰度）的重建得到证实。温跃层/营养层的演化具有三个突出的阶段：1）第一阶段（1.5-1.1 Ma），其特征是浅温跃层的低幅度变化； 2) 第二阶段（1.1–0.8 Ma），其特征是相对较浅的温跃层/营养线的高振幅变化； 3）第三阶段（0.8–0.5 Ma），其特征是深部温跃层/营养线的低幅度变化。结合热带太平洋纬向海面温度梯度，上层海水结构的演变可以与整个MPT的热带气候变化联系起来，包括大气环流的加强和长期类厄尔尼诺状态的逐渐停止。 0.8 Ma之前，WPWP的上层水结构是不对称的，北缘有浅的温跃层/营养线，而WPWP和南海的中心有深的温跃层/营养线。现代WPWP大约是在0.8 Ma左右建立的，从那时起，上层水域结构整体同步变化。将 MD06-3050 核心的 Globigerinoides ruber 测试得出的 δ18O 值与西太平洋其他核心的 δ18O 值进行比较表明，较低的冰期/间冰期 G. MD06-3050 0.8 Ma 之前的 ruberδ18O 值可能与 WPWP 的增强和大气环流模式的变化有关。
We present planktonic foraminifera oxygen isotope andFlorisphaera profundaabundance data from the International Marine Global Change Study Program (IMAGES) Core MD06-3050, which was collected in the West Philippine Sea on the margin of the Western Pacific Warm Pool (WPWP). Our records reveal marked changes in the upper water structure in the Kuroshio source region as early as 1.5 Ma, continuing through the mid-Pleistocene climate transition (MPT). These changes are evidenced by reconstructions of the thermocline (based on planktonic foraminiferal oxygen isotope differences) and the nutricline (based on the relative abundance of the coccolithophore speciesFlorisphaera profunda) in the Kuroshio source region. The evolution of the thermocline/nutricline featured three prominent phases: 1) phase I (1.5–1.1 Ma), which was characterized by low-amplitude variations in a shallow thermocline; 2) phase II (1.1–0.8 Ma), which was characterized by high-amplitude variations in a relatively shallow thermocline/nutricline; and 3) phase III (0.8–0.5 Ma), which was characterized by low-amplitude variations in a deep thermocline/nutricline. Combined with the zonal sea surface temperature gradient in the tropical Pacific, the evolution of the upper water structure can be linked to tropical climatic changes across the MPT, including the intensification of atmospheric circulation and a gradual cessation of the long-term El Niño-like state. The upper water structure of the WPWP was asymmetric before 0.8 Ma, with a shallow thermocline/nutricline along the northern margin and a deep thermocline/nutricline in the center of the WPWP and South China Sea (SCS). The modern WPWP was established by approximately 0.8 Ma, and the upper water structure has changed synchronously as a whole since that time. A comparison of the δ18O values derived fromGlobigerinoides rubertests from the MD06–3050 core with those from other cores in the western Pacific suggests that the lower glacial/interglacialG. ruberδ18O values in MD06-3050 before 0.8 Ma could be related to the enhancement of the WPWP and to changes in atmospheric circulation patterns.