Quantifying river incision and uplift in the Rhenish Massif by dating of fluvial terraces in the Rhine Valley using the 10Be–26Al burial dating method

通过使用 10Beâ26Al 埋葬测年方法对莱茵河谷河流阶地进行测年，量化莱茵河地块的河流切入和隆起

• 批准号: 525049675
• 负责人: Professor Dr. Ralf Hetzel
• 金额: --
• 依托单位: Institut für Geologie und Paläontologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/525049675?language=en
• 关键词: Quantifying; river; incision; uplift; Rhenish

The Rhenish Massif is a prominent example for a region with well preserved sequences of river terraces. These terraces formed by the incision of the Rhine and its tributaries into the Paleozoic bedrock. The youngest terrace above the narrow and steep Rhine valley – the so-called Younger Main Terrace – constitutes an important geomorphological marker, for which an age of 700-800 ka is assumed based on paleomagnetic data. Using this age and the height of the Younger Main Terrace above the Rhine, a model for river incision and uplift of the Rhenish Massif was developed, which predicts an abrupt increase in the rate of incision and uplift at 700-800 ka. In contrast, an alternative model, which is based on the identification of a larger number of Main Terraces by several hundred drillings and a correlation of the entire terrace sequence of the Rhine with paleoclimate records, indicates an older age of ca. 1.3 Ma for the Younger Main Terrace. This model implies slower and nearly constant rates of uplift and incision in the Rhenish Massif. To better constrain the uplift and incision history and to decide which model is correct, absolute age determinations for the Main Terraces of the Rhine are required. Such age constraints are, however, still missing. To quantify the history of river incision and uplift of the Rhenish Massif, we will date the most important Main Terraces in the plateau valley of the Rhine by applying 10Be–26Al burial dating. This innovative and still rarely used method allows dating fluvial terrace deposits in the age range of 0.4 to 5 Ma, even if the terraces lack a well-preserved surface due to erosion, deposition of younger cover sediments, and/or anthropogenic influence. As confirmed by our preliminary investigations, the terrace sediments of the Rhine are very well suited for this kind of age dating. The planned project will provide the first absolute time constraints for the Main Terraces along the Rhine at seven carefully selected sites. With these age constraints it will be possible to reconstruct the incision history of the Rhine and the tectonic uplift history of the Rhenish Massif in unprecedented detail and to relate the uplift to geodynamic causes. In particular, clarifying the age of the Younger Main Terrace has far-reaching consequences, because in the past several studies were based on the assumption of an age of 700-800 ka. Therefore, the results of this project will not only be relevant for reconstructing the incision and uplift history of the Rhenish Massif, but also for studies on landscape evolution, mass balances, neotectonics, and time-dependent models for the uplift.

对于拥有保存完好的河流阶地序列的地区来说，莱茵地块是一个突出的例子。这些阶地是由莱茵河及其支流切入古生代基岩形成的。狭窄而陡峭的莱茵河流域上方最年轻的阶地--所谓的年轻主阶地--构成了一个重要的地貌标志，根据古地磁数据推测其年龄为700-800ka。利用这一年龄和莱茵河上较年轻的主阶地的高度，建立了莱茵河地块的河流切割和抬升模型，预测在700-800ka之间切割和抬升的速率急剧增加。相反，另一种模型是基于通过数百次钻探识别出更多的主要阶地，并将整个莱茵河阶地序列与古气候记录相关联，表明较年轻的主要阶地的年龄较老，约为1.3 Ma。这一模型意味着莱茵地块的抬升和切割速度较慢且几乎是恒定的。为了更好地约束隆升和切割历史，并确定哪种模型是正确的，莱茵河主要阶地的绝对年龄是必需的。然而，这样的年龄限制仍然缺失。为了量化莱茵河地块的河流切割和抬升历史，我们将利用10Be-26Al测年技术对莱茵河流域高原最重要的主要阶地进行测年。这种创新的方法仍然很少使用，即使由于侵蚀、年轻盖层沉积物的沉积和/或人为影响，阶地缺乏保存完好的表面，也可以对0.4至5 Ma的河流阶地沉积进行测年。我们的初步调查证实，莱茵河的阶地沉积物非常适合于这种年龄测定。计划中的项目将为莱茵河沿岸的七个精心挑选的地点的主要梯田提供第一个绝对时间限制。有了这些年龄限制，就有可能以前所未有的细节重建莱茵河的切割历史和莱茵河地块的构造隆起历史，并将隆起与地球动力学原因联系起来。尤其是，弄清年轻主阶地的年龄具有深远的影响，因为过去的几项研究都是基于700-800ka的年龄假设。因此，该项目的结果不仅对重建莱茵地块的切割和隆升历史具有重要意义，而且对地貌演化、物质平衡、新构造和隆升的时间相关模式的研究也具有重要意义。