National High Magnetic Field Laboratory, and Department of Earth, Ocean and Atmospheric Sciences, Florida State University, Tallahassee, FL 32310, USA.
Science. 2012 Feb 17;335(6070):818-23. doi: 10.1126/science.1214697. Epub 2012 Jan 26.
Weathering of uplifted continental rocks consumes carbon dioxide and transports cations to the oceans, thereby playing a critical role in controlling both seawater chemistry and climate. However, there are few archives of seawater chemical change that reveal shifts in global tectonic forces connecting Earth ocean-climate processes. We present a 68-million-year record of lithium isotopes in seawater (δ(7)Li(SW)) reconstructed from planktonic foraminifera. From the Paleocene (60 million years ago) to the present, δ(7)Li(SW) rose by 9 per mil (‰), requiring large changes in continental weathering and seafloor reverse weathering that are consistent with increased tectonic uplift, more rapid continental denudation, increasingly incongruent continental weathering (lower chemical weathering intensity), and more rapid CO(2) drawdown. A 5‰ drop in δ(7)Li(SW) across the Cretaceous-Paleogene boundary cannot be produced by an impactor or by Deccan trap volcanism, suggesting large-scale continental denudation.
抬升陆岩石的风化作用消耗二氧化碳并将阳离子运移至海洋，因此在控制海水化学和气候方面起着至关重要的作用。然而，几乎没有关于全球构造力变化的海洋化学变化的记录，这些变化将地球的海洋-气候过程联系在一起。我们从浮游有孔虫中重建了海水锂同位素（δ(7)Li(SW)）的 6800 万年记录。从古新世（6000 万年前）到现在，δ(7)Li(SW)上升了 9 个千分比（‰），这需要大陆风化和海底反向风化发生巨大变化，与构造抬升增加、大陆剥蚀加速、大陆风化越来越不协调（风化强度降低）以及 CO2 快速消耗的情况一致。白垩纪-古近纪界线处 δ(7)Li(SW) 下降 5‰，不可能是由撞击器或德干陷阱火山作用引起的，这表明发生了大规模的大陆剥蚀。
