River linear inversion to assess drainage base-level fall history in North-western Apennines and implications on the Alessandria Basin tectonic activity

Drainage network systems are responsive elements to recent active tectonics from among all the topographic features. In geodynamically active areas, fluvial landscapes can record different processes through the formation and current presence of features related to spatial-temporal variation in base-level fall and vertical incision of stream channels. This study focuses on the tectonic evolution of the Alessandria Basin, a synorogenic tectonic basin located at the junction between the Alps and the Apennines, that experienced progressive subsidence during the overthrusting of the Monferrato Thrust Front (the westernmost outer arc of the Apennine belt) onto the Po Foreland Basin. Even though several studies have assessed the Neogene tectonic evolution at a regional scale, rates and timing of the Quaternary activity are still poorly understood in terms of both Alps/Apennines uplift and activity of the compressive front of the Monferrato Arc. In this paper, we applied the method of the river profile linear inversions to reconstruct the base-level fall history of 6 catchments that drain into the Alessandria Basin. We used nine 10Be-derived basin-average denudation rates to constrain the erodibility parameter needed to infer base-level fall rates from χ-transformed river profiles. The results describe the tectonic history of the area in the last ∼5 Ma, documenting increases in base-level fall rate with an initial peak between 3 and 2.5 Ma, and a second between 2 and 1.5 Ma. While the first peak is coeval with the uplift phase that involved most of the northern-central Apennine, the second one suggests an acceleration in subsidence of the Alessandria Basin concurrently with the uplift of the Monferrato Thrust Front

Variable Quaternary Uplift Along the Southern Margin of the Central Anatolian Plateau Inferred From Modeling Marine Terrace Sequences

The southern margin of the Central Anatolian Plateau (CAP) records a strong uplift phase after the early Middle Pleistocene, which has been related to the slab break‐off of the subducting Arabian plate beneath the Anatolian microplate. During the last 450 kyr the area underwent an uplift phase at a mean rate of ~3.2 m/kyr, as suggested by Middle Pleistocene marine sediments exposed at ~1,500 m above sea level. These values are significantly higher than the 1.0–1.5 m/kyr estimated since the Late Pleistocene, suggesting temporal variations in uplift rate. To estimate changes in uplift rate during the Pleistocene we studied the marine terraces along the CAP southern margin, mapping the remnants of the platforms and their associated deposits in the field, and used the TerraceM software to identify the position and elevation of associated shoreline angles. We used shoreline angles and the timing of Quaternary marine sedimentation as constrains for a Landscape Evolution Model that simulates wave erosion of an uplifting coast. We applied random optimization algorithms and minimization statistics to find the input parameters that better reproduce the morphology of CAP marine terraces. The best‐fitting uplift rate history suggests a significative increase from 1.9 to 3.5 m/kyr between 500 and 200 kyr, followed by an abrupt decrease to 1.4 m/kyr until the present. Our results agree with slab break‐off models, which suggest a strong uplift pulse during slab rupture followed by a smoother decrease.Key Points: The marine terrace evolution modeling allowed the reconstruction of the Quaternary uplift trend. The uplift trend describes a bell‐shaped path in the last 500 kyr, with a peak in uplift rates at MIS7 (3.4–3.8 m/kyr). Results are in agreement with numerical models that relate strong uplift pulses to slab break‐off.MIUR‐Italy Dipartimenti di EccellenzaMillennium Scientific Initiative (ICM)DEUTSCHES GEOFORSCHUNGSZENTRUM POTSDAM Blended DEA

Variable Quaternary Uplift Along the Southern Margin of the Central Anatolian Plateau Inferred From Modeling Marine Terrace Sequences

The southern margin of the Central Anatolian Plateau (CAP) records a strong uplift phase after the early Middle Pleistocene, which has been related to the slab break‐off of the subducting Arabian plate beneath the Anatolian microplate. During the last 450 kyr the area underwent an uplift phase at a mean rate of ~3.2 m/kyr, as suggested by Middle Pleistocene marine sediments exposed at ~1,500 m above sea level. These values are significantly higher than the 1.0–1.5 m/kyr estimated since the Late Pleistocene, suggesting temporal variations in uplift rate. To estimate changes in uplift rate during the Pleistocene we studied the marine terraces along the CAP southern margin, mapping the remnants of the platforms and their associated deposits in the field, and used the TerraceM software to identify the position and elevation of associated shoreline angles. We used shoreline angles and the timing of Quaternary marine sedimentation as constrains for a Landscape Evolution Model that simulates wave erosion of an uplifting coast. We applied random optimization algorithms and minimization statistics to find the input parameters that better reproduce the morphology of CAP marine terraces. The best‐fitting uplift rate history suggests a significative increase from 1.9 to 3.5 m/kyr between 500 and 200 kyr, followed by an abrupt decrease to 1.4 m/kyr until the present. Our results agree with slab break‐off models, which suggest a strong uplift pulse during slab rupture followed by a smoother decrease