Reduced continental weathering and marine calcification linked to late Neogene decline in atmospheric CO2
Reduced continental weathering and marine calcification linked to late Neogene decline in atmospheric CO2
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DOI：
10.1038/s41561-019-0450-3
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发表时间：
2019-10
影响因子：
18.3
通讯作者：
Weimin Si;Y. Rosenthal
中科院分区：
文献类型：
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作者：
Weimin Si;Y. Rosenthal
在过去的1500万年里，全球平均方解石补偿深度加深了几百米。这种加深以前被解释为反映了增加的碱度供应海洋驱动的增强大陆风化由于喜马拉雅造山运动在晚第三纪时期。在这里，我们研究质量积累率的主要海洋钙化组，并表明，全球积累的远洋碳酸盐已减少，从晚中新世时代到晚更新世时代，即使CaCO3保存有所改善，这表明减少风化碱度输入到海洋，从而反对喜马拉雅隆起假说的预期。相反，在相对较浅的网站，溶解没有采取收费的相对贡献的球石和浮游有孔虫的远洋碳酸盐的变化，表明球石生产在真光层减少伴随着减少风化碱度输入注册的下降远洋碳酸盐积累。我们的工作突出了一种机制，即除了深海溶解，海洋钙化的变化起作用，以调节碳酸盐补偿，以减少风化与晚第三纪冷却和大气二氧化碳分压下降。
The globally averaged calcite compensation depth has deepened by several hundred metres in the past 15 Myr. This deepening has previously been interpreted to reflect increased alkalinity supply to the ocean driven by enhanced continental weathering due to the Himalayan orogeny during the late Neogene period. Here we examine mass accumulation rates of the main marine calcifying groups and show that global accumulation of pelagic carbonates has decreased from the late Miocene epoch to the late Pleistocene epoch even though CaCO3preservation has improved, suggesting a decrease in weathering alkalinity input to the ocean, thus opposing expectations from the Himalayan uplift hypothesis. Instead, changes in relative contributions of coccoliths and planktonic foraminifera to the pelagic carbonates in relative shallow sites, where dissolution has not taken its toll, suggest that coccolith production in the euphotic zone decreased concomitantly with the reduction in weathering alkalinity inputs as registered by the decline in pelagic carbonate accumulation. Our work highlights a mechanism whereby, in addition to deep-sea dissolution, changes in marine calcification acted to modulate carbonate compensation in response to reduced weathering linked to the late Neogene cooling and decline in atmospheric partial pressure of carbon dioxide.