Biotic and geochemical evidence for a global latitudinal shift in ocean biogeochemistry and export productivity during the late Pliocene
Biotic and geochemical evidence for a global latitudinal shift in ocean biogeochemistry and export productivity during the late Pliocene
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DOI：
10.1016/j.epsl.2011.05.046
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发表时间：
2011-08
影响因子：
5.3
通讯作者：
C. Bolton;K. Lawrence;S. Gibbs;P. Wilson;T. Herbert
中科院分区：
文献类型：
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作者：
C. Bolton;K. Lawrence;S. Gibbs;P. Wilson;T. Herbert
在上新世晚期（~ 3至2.5 Ma），来自世界各地的蛋白石和C37烯酮积累的海洋记录显示，高纬度地区的长期变化值较低，低纬度和中纬度地区的较高值。这些变化与北方半球冰川作用的加剧大致一致，并暗示了出口生产力的变化，对上新世大气二氧化碳浓度有潜在的影响。然而，对全球生产力纬度变化的解释需要进行测试，因为记录的地点与地点之间的比较可能存在不确定性，而这些不确定性可能会受到与生产、出口和保存相关的高度非线性过程的影响。在这里，我们评估推断上新世纬向生产力转变的解释，提出新的记录C37烯酮积累大洋钻探计划（ODP）网站982在北大西洋和生物组合（钙质nannoplankton）从这个网站和ODP网站846在热带太平洋东部。我们的研究结果证实了C37烯酮积累的解释，在这些网站的总出口生产力的代理，表明大规模的生产力下降，在高纬度和热带网站的增加记录强劲。我们的结论是，加强北方半球冰川在上新世晚期与海洋地球化学的深刻重组。
During the late Pliocene (~ 3 to 2.5 Ma), oceanic records of opal and C37alkenone accumulation from around the world show a secular shift towards lower values in the high latitudes and higher values in the low and mid latitudes. These shifts are broadly coincident with the intensification of northern hemisphere glaciation and are suggestive of changes in export productivity, with potential implications for Pliocene atmospheric carbon dioxide concentrations. The interpretation of a global latitudinal shift in productivity, however, requires testing because of the potential uncertainties associated with site to site comparisons of records that can be influenced by highly nonlinear processes associated with production, export, and preservation. Here, we assess the inferred Pliocene latitudinal productivity shift interpretation by presenting new records of C37alkenone accumulation from Ocean Drilling Program (ODP) Site 982 in the North Atlantic and biotic assemblages (calcareous nannoplankton) from this site and ODP Site 846 in the eastern tropical Pacific. Our results corroborate the interpretation of C37alkenone accumulation as a proxy for gross export productivity at these sites, indicating that large-scale productivity decreases at high latitudes and increases at tropical sites are recorded robustly. We conclude that the intensification of northern hemisphere glaciation during the late Pliocene was associated with a profound reorganisation of ocean biogeochemistry.