He John J Y, Kapp Paul
Department of Geoscience, University of Arizona, Tucson, AZ, 85721, USA.
Nat Commun. 2023 Jul 22;14(1):4433. doi: 10.1038/s41467-023-40147-7.
The sinking of gravitationally unstable lithosphere beneath high-elevation plateaus is proposed to be a key driver of their uplift. Numerical geodynamic models predict that lithosphere removal can lead to transient, dynamic topographic changes that could be preserved in the surface record, particularly in sedimentary deposits of lakes or playas that are subsequently inverted. However, few such examples have been documented. Here we show that the Miocene Bidahochi Basin, which was partially and intermittently filled by the Hopi Paleolake, preserves a record of the quasi-elliptical surface response to a viscous drip of lithosphere >100 km beneath the Colorado Plateau. New detrital zircon U-Pb, Lu-Hf, and trace-element data reveal systematic isotopic, geochemical, temperature and fO transitions in magmatism proximal to the basin. Integration of geophysical, geochemical, and geological evidence supports a spatially and temporally varying record of subsidence and uplift that is consistent with models of progressive dripping beneath plateaus with thick lithosphere. We demonstrate that dynamic topography at the scale of individual lithosphere drips can be recognized on the Colorado Plateau, despite the strength of its lithosphere.
高海拔高原之下重力不稳定岩石圈的下沉被认为是其隆升的关键驱动力。数值地球动力学模型预测,岩石圈移除会导致瞬态、动态的地形变化,这些变化可能会保存在地表记录中,尤其是在随后发生反转的湖泊或干盐湖的沉积矿床中。然而,此类实例鲜有记录。在此我们表明,中新世的比达霍奇盆地曾被霍皮古湖部分且间歇性地填满,它保存了对科罗拉多高原下方超过100千米岩石圈粘性垂滴的准椭圆形地表响应记录。新的碎屑锆石U-Pb、Lu-Hf和微量元素数据揭示了盆地附近岩浆活动中系统的同位素、地球化学、温度和fO转变。地球物理、地球化学和地质证据的整合支持了沉降和隆升在空间和时间上变化的记录,这与厚岩石圈高原下方渐进垂滴模型一致。我们证明,尽管科罗拉多高原岩石圈强度大,但在其之上仍可识别出单个岩石圈垂滴尺度的动态地形。