Monsoonal activity and paleoclimate evolution in the NW-Pacific over the past 4 Ma

北太平洋通过北太平洋环流内冰川调节的热输送、经纬温度交换的调节以及驱动全球风系统，构成了全球气候演变的关键因素。西边界流、黑潮是水运的关键，亚洲季风和西风急流是气团运输调节太平洋气候的关键。近400万年的太平洋气候演化包括中更新世暖期（MPWP）、北半球冰期（NHG）开始、中更新世过渡期（MPT）和中布鲁内斯事件。在赤道带和东太平洋，气候演化研究较好，而在受黑潮和亚洲风系统强度强烈影响的西北-菲律宾海，长期古气候记录仍然缺失。在U1437地点钻探的沉积物岩心提供了超过4 Ma的连续和准确的年代记录，在之前的项目中，我们获得了大量数据，尽管时间分辨率在1到3 Ma之间仍然非常不令人满意。我们的研究覆盖了过去1 Ma的海洋表面温度重建的分子代用物（TEX86, UK ' 37），并首次在太平洋使用植物蜡质分子示踪剂研究亚洲尘流。现有记录的时间分辨率不允许重建mwp、NHG和MPT的关键气候阶段。为此目的，必须研究150个额外的样本，以补充现有的分辨率为10至20 ka的数据集，该数据集将涵盖40 ka轨道节律频带。对太平洋地区与尘埃有关的蜡质研究的独特研究需要扩展，以改进对源区域和风轨迹的识别，这可能通过脂质的复合特定同位素分析来促进。结合脂质结构组成和xrf扫描获得的微量元素流入的连续记录，可以进行物源研究和4 Ma以上的风系统重建。我们将讨论亚洲季风风系统和西风急流作为太平洋主要沙尘运输媒介之间的区别。在过去1 Ma的时间里，我们假设ITCZ存在纬向波动，U1437站点以西风系统为主，但基于单一地点的研究很难证明这一点。对于邻近的ODP 1208和DSDP 296站点，我们将研究选择的高风强度区间的样本，以获得纬向风转移的区域格局。U1437站点现有初步数据集的完成将有助于填补过去4ma西太平洋古气候重建的巨大空白。

The North Pacific constitutes a critical element in global climate evolution via glaciation-modulated heat transport within the North Pacific Gyre, regulation of latitudinal and meridional temperature exchange and by driving global wind systems. The western boundary current, the Kuroshio is crucial in water transport, the Asian Monsoons and westerly Jetstream are essential for air mass transport regulating Pacific climate. The last 4 Ma (Million yeasrs) of Pacific climate evolution with the Mid Pleistocene Warm Period (MPWP), the onset of Northern Hemisphere Glaciation (NHG), the Mid-Pleistocene Transition (MPT) and the Mid-Brunhes Event include dramatic phases of climate reorganization. In the equatorial belt and the Eastern Pacific, the climate evolution is studied well, whereas in the NW-Philippine Sea, which is strongly influenced by the Kuroshio and the strength of Asian wind systems, a long-term paleoclimate record is still missing. Sediment cores drilled at site U1437 provide a continuous and well dated record over 4 Ma, for which in previous projects we generated a substantial amount of data though the temporal resolution remains very unsatisfactorily between 1 and 3 Ma. Our studies covering the past 1 Ma were based on molecular proxies (TEX86, UK‘37) for sea surface temperature reconstruction and for the first time in the Pacific on molecular tracers for Asian dust influx using plant wax lipids. The temporal resolution of the existing record does not permit a reconstruction of the critical climate phases of the MPWP, the NHG, and the MPT. For this purpose, 150 additional samples have to be studied to complement the existing data set at a resolution of 10 to 20 ka, which will cover the 40 ka frequency band of orbital rhythmicity. The unique study on dust-associated wax lipid study in the Pacific requires an extension for improved recognition of source regions and wind trajectories that may be facilitated by compound specific isotope analysis of lipids. In combination with structural composition of lipids and continuous records of trace element influx achieved by XRF-Scanning, provenance studies and wind system reconstruction over 4 Ma can be achieved. We will address the emerging topic of discrimination between Asian monsoonal wind systems and the Westerly Jetstream as major dust transport agents in the Pacific. For the past 1 Ma we postulate a latitudinal fluctuation in the ITCZ and the dominant westerly wind system at site U1437, which based on the study of a single location is difficult to prove. For selected neighboring sites ODP 1208 and DSDP 296, where excellent chronologies are available, we will study samples from selected high wind intensity intervals to obtain a regional pattern of latitudinal wind shifts.A completion of the existing preliminary data set at site U1437 will facilitate and close a large gap in West Pacific paleoclimate reconstruction for teh past 4 Ma.