有關(guān)研究報(bào)告指出,，關(guān)于侵蝕的地質(zhì)記錄表明,，在過去500萬年全球沉積速度增加了4倍,。我們值得對這些報(bào)告做了一個全球性的解釋,。人們所提供的解釋包括造山運(yùn)動和全球變冷速度的增加,。
現(xiàn)在，Jane Willenbring 和Friedhelm von Blanckenburg重新分析了原始數(shù)據(jù),，并利用關(guān)于鈹同位素比的海洋記錄,，來獲取過去侵蝕速度和巖石風(fēng)化的一個間接測量結(jié)果。關(guān)于過去1200萬年全球侵蝕速度的增加或風(fēng)化材料的突增他們都沒有發(fā)現(xiàn)明確證據(jù),。他們提出,，新生代全球變冷一定有其他原因，而的確出現(xiàn)的造山運(yùn)動對全球侵蝕或風(fēng)化通量幾乎沒有影響,。 （生物谷Bioon.com）
生物谷推薦原文出處：
Nature doi:10.1038/nature09044
Long-term stability of global erosion rates and weathering during late-Cenozoic cooling
Jane K. Willenbring1 & Friedhelm von Blanckenburg1
1 Deutsches GeoForschungsZentrum GFZ, Section 3.4: Earth Surface Geochemistry, Telegrafenberg, D-14473 Potsdam, Germany
Over geologic timescales, CO2 is emitted from the Earth’s interior and is removed from the atmosphere by silicate rock weathering and organic carbon burial. This balance is thought to have stabilized greenhouse conditions within a range that ensured habitable conditions1. Changes in this balance have been attributed to changes in topographic relief, where varying rates of continental rock weathering and erosion1, 2 are superimposed on fluctuations in organic carbon burial3. Geological strata provide an indirect yet imperfectly preserved record of this change through changing rates of sedimentation1, 2, 4. Widespread observations of a recent (0–5-Myr) fourfold increase in global sedimentation rates require a global mechanism to explain them4, 5, 6. Accelerated uplift and global cooling have been given as possible causes2, 4, 6, 7, but because of the links between rates of erosion and the correlated rate of weathering8, 9, an increase in the drawdown of CO2 that is predicted to follow may be the cause of global climate change instead2. However, globally, rates of uplift cannot increase everywhere in the way that apparent sedimentation rates do4, 10. Moreover, proxy records of past atmospheric CO2 provide no evidence for this large reduction in recent CO2 concentrations11, 12. Here we question whether this increase in global weathering and erosion actually occurred and whether the apparent increase in the sedimentation rate is due to observational biases in the sedimentary record13. As evidence, we recast the ocean dissolved 10Be/9Be isotope system as a weathering proxy spanning the past ~12?Myr (ref. 14). This proxy indicates stable weathering fluxes during the late-Cenozoic era. The sum of these observations shows neither clear evidence for increased erosion nor clear evidence for a pulse in weathered material to the ocean. We conclude that processes different from an increase in denudation caused Cenozoic global cooling, and that global cooling had no profound effect on spatially and temporally averaged weathering rates.
