Towards the inversion of tectonic signals from deep-marine archives:Competing tectonic signal propagation from across the Alps into the marine sink

从深海档案中反演构造信号：从阿尔卑斯山到海洋汇的竞争构造信号传播

• 批准号: 427212285
• 负责人: Professorin Dr. Anne Bernhardt
• 金额: --
• 依托单位: Institut für Geologische Wissenschaften
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/427212285?language=en
• 关键词: Towards; inversion; tectonic; signals; deep

The sedimentary fill of peri-orogenic basins is a product of the interplay between tectonics, climate, sediment transport, and transient storage processes. In turn, sediment archives are often used to reconstruct past tectonic activity and mountain building over various time scales. However, our ability to quantitatively assess how changes in tectonic exhumation influence terrestrial erosion and sediment budgets, and how and at what rate these signals propagate through sediment-routing systems into the marine archives is severely limited. Moreover, these signals may be modified, dampened or even destroyed along their travel paths. Hence, we need to quantify the travel times of tectonic signals into the stratigraphic record and the imprint of these signals on the resulting stratigraphy. This is important to interpret sedimentary archives correctly and to ultimately invert these archives to the upland control factors that shaped these sedimentary successions. A key area to investigate such signals is the Northern Alpine Foreland Basin due to the large amount of available data in the Alpine source area and its foreland. Three major tectonic exhumation and uplift events occur during the late Oligocene to middle Miocene in the Alps: the exhumation of Penninic units in the Lepontine Dome and the Tauern Window, and the uplift of paleosurfaces in the Northern Calcareous Alps. Each of these tectonic events is characterized with a unique sediment-provenance signature that allows us to estimate how and at what rate these tectonic signals propagate into Late Oligocene to Miocene sediments and how they are manifested in the sedimentary sink. The sedimentary successions in the Upper Austrian Molasse Basin were investigated using a large 3D seismic-reflection cube (3300 km2). We recently established a new biostratigraphic and chemostratigraphic framework based on foraminifers, nanofossils and ∂13C. We sampled sediment core and outcrop for heavy mineral extraction. Moreover, we calculated spatially averaged sedimentation rates using the new geochronologic control and sediment volumes. We propose to analyze the sediment archives for the unique tectonic exhumation and uplift signatures using heavy mineral-assemblage analyses and apatite thermochronology (U-Pb, AFT, AHe), apatite geochemistry, and Nd and Sm isotopic composition of apatite and mudstone. We will determine lag times between the individual exhumation and uplift events in the Alps and the arrival of its sedimentary response in the basin. Our results will quantify sediment volumes exported to the Upper Austrian Molasse and determine travel time and mode of distinct tectonic exhumation and uplift signals into the adjacent sediment archives. The quantification of the travel times and the expression of these tectonic signals in the deep-marine stratigraphic record are crucial in our strive to correctly interpret sediment archives and to ultimately be able to invert these records into their upland forcings.

造山带边缘盆地的沉积充填是构造、气候、沉积物搬运和瞬时储存过程相互作用的产物。反过来，沉积物档案往往被用来重建过去的构造活动和山区建设在不同的时间尺度。然而，我们的能力，定量评估如何在构造折返的变化影响陆地侵蚀和沉积物的预算，以及如何以及以何种速度传播这些信号通过沉积物路由系统进入海洋档案是严重有限的。此外，这些信号可能沿其传播路径被修改、衰减或甚至被沿着破坏。因此，我们需要量化构造信号进入地层记录的传播时间以及这些信号在所产生的地层上的印记。这对于正确解释沉积档案并最终将这些档案转化为塑造这些沉积序列的高地控制因素非常重要。研究此类信号的一个关键区域是北方阿尔卑斯前陆盆地，因为在阿尔卑斯源区及其前陆有大量可用数据。渐新世晚期至中新世中期，阿尔卑斯山发生了三次主要的构造折返和隆升事件：Lepontine穹丘和Tauern窗的Penninic单元的折返，以及北方石灰质阿尔卑斯山古地表的隆升。这些构造事件的特点是一个独特的沉积物来源的签名，使我们能够估计这些构造信号如何传播到晚渐新世到中新世沉积物，以及它们是如何表现在沉积汇。使用大型三维地震反射立方体（3300平方公里）对上奥地利Molasse盆地的沉积序列进行了研究。我们最近建立了一个新的生物地层和化学地层框架的基础上有孔虫，纳米化石和13 C。我们对沉积物岩心和露头进行取样，以提取重矿物。此外，我们使用新的地质年代学控制和沉积量计算空间平均沉积速率。我们建议使用重矿物组合分析和磷灰石热年代学（U-Pb，AFT，AHe），磷灰石地球化学，以及磷灰石和泥岩的Nd和Sm同位素组成来分析沉积物档案中独特的构造折返和隆升签名。我们将确定在阿尔卑斯山的个别折返和隆起事件之间的滞后时间，并在盆地中的沉积反应的到来。我们的研究结果将量化输出到上奥地利磨拉石的沉积物量，并确定不同的构造折返和隆起信号进入相邻沉积物档案的旅行时间和模式。在深海地层记录中，旅行时间的量化和这些构造信号的表达对于我们正确解释沉积物档案并最终能够将这些记录转化为高地作用力至关重要。