title: Sediment flux quantification across the Permian – Triassic boundary of the SE Germanic Basin: implications for climate recovery and sediment routing system analysis
Creators: name:  Ravidà,  Domenico C. G.   
name:  Caracciolo,  Luca 
name:  Heins,  William A. 
name:  Stollhofen,  Harald 
Publisher: name: Deutsche Geologische Gesellschaft - Geologische Vereinigung e.V. (DGGV)
Year: 2021

description: Developing numerical approaches for predicting sediment flux variations is of primary importance for understanding the evolution of ancient sediment routing systems (SRS) and quantifying the role of external forcing controls. However, it is a particularly challenging task often hampered by the lack of solid paleo-climatic, paleo-tectonic and sedimentological constraints. Mass balance-based techniques, the most used in deep-time (&gt;107 yr), suffer the intrinsic uncertainty of the stratigraphic record, determined by the impossibility to quantify hiatuses, unconformities and sediment reworking. To overcome uncertainties, we propose an alternative workflow built on the relationships between sediment flux (Qs), geomorphological, climatic and hydrological parameters expressed via BQART modelling. We test this approach on Middle Permian-Early Triassic terrestrial sequences of the SE Germanic Basin (Franconian Basin), a region that appears relatively well preserved, where more recent tectonic inversions did not significantly alter the original basin configuration. Input variables derive from high detail paleodrainage and paleogeographic reconstructions, integrated plate modelling and structural kinematics, global circulation models and sandstone compositional signatures. Two approaches for area estimates, two climate models and two timescale resolutions are employed to simulate eight different environmental scenarios. Furthermore, we apply the probabilistic Monte Carlo Simulation to cover the probability of different outcomes and quantify the uncertainty of each input variable. All the simulations are in general agreement: Middle Permian sediment flux is steadily around 3.0 Mt yr−1, increases by 31% (4.6 Mt yr−1) in the Late Permian and by nearly 100% (7.4 Mt yr−1) across the Permian-Triassic boundary (PTB). Simulated variations of sediment load mirror changes in facies association interpreted from borehole sequences and defined by: (i) Middle-Late Permian ephemeral deposition in alluvial/fluvial fan settings, (ii) transition from sabkha to meandering depositional settings throughout the Late Permian, and (iii) onset of perennial braided deposition in the Early Triassic. Qs estimates agree with those of modern drainages under analogous environmental conditions, confirming the accuracy of the newly developed analytical workflow. Sedimentological and quantitative provenance analyses untangle the role of climate and tectonism on drainage modifications and sediment flux variations, corresponding to intensified monsoonal precipitation and the establishment of extensional tectonic regime across the PTB. Overall, this study provides new insights into the highly debated evolution of the continental sequences across the Permian-Triassic transition with strong implications for both regional and global paleoenvironmental reconstructions.