International Journal of Earth Sciences ( IF 2.3 ) Pub Date : 2020-11-27 , DOI: 10.1007/s00531-020-01953-2 Maria Laura Gomez Dacal , Magdalena Scheck-Wenderoth , Eugenio Aragón , Judith Bott , Mauro Cacace , Claudia Tocho
The North Patagonian Massif (NPM) area in Argentina includes a plateau of 1200 m a.s.l. (meters above sea level) average height, which is 500–700 m higher than its surrounding areas. The plateau shows no evidence of internal deformation, while the surrounding basins have been deformed during Cenozoic orogenic events. Previous works suggested that the plateau formation was caused by a lithospheric uplift event during the Paleogene. However, the causative processes responsible for the plateau origin and its current state remain speculative. To address some of these questions, we carried out 3D lithospheric-scale steady-state and transient thermal simulations of the NPM and its surroundings, as based on an existing 3D geological model of the area. Our results are indicative of a thicker and warmer lithosphere below the NPM plateau compared with its surroundings, suggesting that the plateau is still isostatically buoyant and thus explaining its present-day elevation. The transient thermal simulations agree with a heating event in the mantle during the Paleogene as the causative process leading to lithospheric uplift in the region and indicate that the thermo-mechanical effects of such an event would still be influencing the plateau evolution today. Although the elevation related to the heating would not be enough to reach the present plateau topography, we discuss other mechanisms, also connected with the mantle heating, that may have caused the observed relief. Lithosphere cooling in the plateau is ongoing, being delayed by the presence of a thick crust enriched in radiogenic minerals as compared to its sides, resulting in a thermal configuration that has yet to reach thermodynamic equilibrium.
中文翻译:
揭示北巴塔哥尼亚地块高原(阿根廷)的岩石圈尺度热场及其与该地区地形演变的关系
阿根廷的北巴塔哥尼亚地块(NPM)地区包括一个平均高度为1200 m asl(高于海平面的米)的高原,比其周围地区高出500-700 m。高原没有内部变形的迹象,而新生代造山过程中周围的盆地已经变形。先前的工作表明高原形成是由古近纪期间的岩石圈隆升事件引起的。但是,造成高原起源及其当前状态的原因过程仍然是推测性的。为了解决其中的一些问题,我们基于该地区现有的3D地质模型,对NPM及其周围环境进行了3D岩石圈规模的稳态和瞬态热模拟。我们的结果表明,与周围环境相比,NPM高原以下的岩石圈更厚,更暖,这表明高原仍是等静浮力的,因此可以解释其目前的海拔高度。瞬态热模拟与古近纪期间地幔中的加热事件相吻合,这是导致该地区岩石圈隆升的成因过程,并表明这种事件的热机械效应仍将影响当今的高原演化。尽管与加热有关的海拔高度不足以达到目前的高原地形,但我们讨论了也与地幔加热有关的其他机制,这些机制可能导致观测到的起伏。高原岩石圈正在冷却,