Rejuvenation of Appalachian topography caused by subsidence-induced differential erosion
Rejuvenation of Appalachian topography caused by subsidence-induced differential erosion
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DOI：
10.1038/ngeo2187
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发表时间：
2014-07
影响因子：
18.3
通讯作者：
Lijun Liu
中科院分区：
文献类型：
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作者：
Lijun Liu
在古老的造山带，如美国东部的阿巴拉契亚山脉，高点和低点之间的差异-地形起伏-可以在创造山脉的构造力量变得不活跃之后很久继续增加。气候强迫和地幔引起的动力隆升，可以驱动地形的形成，但在阿巴拉契亚山脉缺乏明确的证据。在这里，我用一个数值模拟的动态地形在北美，结合重建的沉积历史，从墨西哥湾，显示复兴的阿巴拉契亚山脉的地形起伏自古近纪时期可能是由地幔引起的动态沉降与下沉的俯冲Farallon板。具体而言，我表明，模式的大陆侵蚀和沉积物沉积中心在墨西哥湾的东迁移密切遵循轨迹预测的动态沉降。此外，墨西哥湾和大西洋西部的快速沉积物沉积脉冲与中新世阿巴拉契亚山脉的侵蚀增强有关，这是由大陆的动态倾斜造成的。该模型预测，这种沉降引起的差异侵蚀造成阿巴拉契亚地形的弯曲均衡调整，导致400米的救济和超过200米的海拔高度的发展。我认为，动力引起的大陆倾斜可能提供了一种机制，在古造山带的地形复兴。
In ancient orogens, such as the Appalachian Mountains in the eastern United States, the difference between the high and low points—topographic relief—can continue to increase long after the tectonic forces that created the range have become inactive. Climatic forcing and mantle-induced dynamic uplift,could drive formation of relief, but clear evidence is lacking in the Appalachian Mountains. Here I use a numerical simulation of dynamic topography in North America, combined with reconstructions of the sedimentation history from the Gulf of Mexico, to show that rejuvenation of topographic relief in the Appalachian Mountains since the Palaeogene period could have been caused by mantle-induced dynamic subsidence associated with sinking of the subducted Farallon slab. Specifically, I show that patterns of continental erosion and the eastward migration of sediment deposition centres in the Gulf of Mexico closely follow the locus of predicted dynamic subsidence. Furthermore, pulses of rapid sediment deposition in the Gulf of Mexico and western Atlantic correlate with enhanced erosion in the Appalachian Mountains during the Miocene epoch, caused by dynamic tilting of the continent. The model predicts that such subsidence-induced differential erosion caused flexural-isostatic adjustments of Appalachian topography that led to the development of 400 m of relief and more than 200 m of elevation. I propose that dynamically induced continental tilting may provide a mechanism for topographic rejuvenation in ancient orogens.