Key Laboratory of Surficial Geochemistry, Ministry of Education, School of Earth Sciences and Engineering, Nanjing University, Nanjing, 210026, China.
Sci Rep. 2017 May 24;7(1):2382. doi: 10.1038/s41598-017-02400-0.
Previous studies of the late Cenozoic erosion rate have yielded different views-long-term stable rates or a significant increase at climate transitions-leading to uncertainty concerning the hypothesized global erosion rate controlled by either tectonic uplift or climatic changes. Here, we present a seven-million-year hornblende mineral record along the Lingtai section of the Chinese Loess Plateau. By examining the spatial distribution of hornblende minerals in seven desert basins, which are potential loess source areas, we constructed a ratio of hornblende versus total heavy minerals to reflect past changes in physical/chemical weathering strength. Our results demonstrate that the ratio has generally increased since 7 Ma, with three significant shifts recorded at 2.6 Ma, 1.4 Ma and 0.5 Ma linked to the onset, continuation and expansion of the Northern Hemisphere glaciation, respectively. Given that chemical weathering during the diagenetic history produces a trend of smoothly increasing hornblende migrating upwards, the three shifts at these boundaries can be interpreted as changes in the bedrock erosion rate on the northern Tibetan Plateau, which may be related to tectonic uplift events and incision of the Yellow River. Evidence presented here supports the idea of coupling between climate change, tectonic uplift and regional erosion.
先前有关新生代晚期侵蚀速率的研究得出了不同的观点——长期稳定的速率或气候转变时的显著增加——这导致了假设的全球侵蚀速率是由构造抬升还是气候变化控制的不确定性。在这里，我们展示了沿中国黄土高原灵台剖面的长达 700 万年的角闪石矿物记录。通过检查七个沙漠盆地（潜在的黄土源区）中角闪石矿物的空间分布，我们构建了角闪石与总重矿物的比值，以反映过去物理/化学风化强度的变化。我们的结果表明，自 700 万年前以来，该比值普遍增加，在 260 万年前、140 万年前和 50 万年前分别出现了三个显著的转变，分别与北半球冰期的开始、持续和扩展有关。鉴于成岩历史期间的化学风化产生了角闪石向上逐渐增加的趋势，在这些边界处的三个转变可以解释为青藏高原北部基岩侵蚀速率的变化，这可能与构造抬升事件和黄河的侵蚀有关。这里提出的证据支持气候变化、构造抬升和区域侵蚀之间的耦合观点。
