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Abstract How tectonic forcing, expressed as base level change, is encoded in the stratigraphic and geomorphic records of coupled source‐to‐sink systems remains uncertain. Using sedimentological, geochronological and geomorphic approaches, we describe the relationship between transient topographic change and sediment deposition for a low‐storage system forced by rapid rock uplift. We present five new luminescence ages and two terrestrial cosmogenic nuclide paleo‐erosion rates for the late Pleistocene Pagliara fan‐delta complex and we model corresponding base level fall history and erosion of the source catchment located on the Ionian flank of the Peloritani Mountains (NE‐Sicily, Italy). The Pagliara delta complex is part of the broader Messina Gravel‐and‐Sands lithostratigraphic unit that outcrops along the Peloritani coastal belt as extensional basins have been recently inverted by both normal faults and regional uplift at the Messina Straits. The deltas exposed at the mouth of the Pagliara River have constructional tops at ca. 300 m a.s.l. and onlap steeply east‐dipping bedrock at the coast to thickness between ca. 100 and 200 m. Five infrared‐stimulated luminescence (IRSL) ages collected from the delta range in age from ca. 327 to 208 ka and indicate a vertical long‐term sediment accumulation rate as rapid as ca. 2.2 cm/yr during MIS 7. Two cosmogenic¹⁰Be concentrations measured in samples of delta sediment indicate paleo‐erosion rates during MIS 8–7 near or slightly higher than the modern rates of ca. 1 mm/yr. Linear inversion of Pagliara fluvial topography indicates an unsteady base level fall history in phase with eustasy that is superimposed on a longer, tectonically driven trend that doubled in rate from ca. 0.95 to 1.8 mm/yr in the past 150 ky. The combination of footwall uplift rate and eustasy determines the accommodation space history to trap the fan‐deltas at the Peloritani coast in hanging wall basins, which are now inverted, uplifted and exposed hundreds of metres above the sea level. 

Advancements in the quantitative investigation of fluvial topography in tectonically active regions account for the emerging numerical modelling of river profiles and their linear inversions. Applications of a geomorphic approach strive for the reconstruction of long-term tectonic deformation histories by decoding base-level fall signals transiently embedded in the geomorphic record. I present integrated results from river profile inversions and marine terraces analyses, here used to outline the deformation model associated to a debated crustal fault system at the southern termination of the Calabrian Forearc High (Central Mediterranean). The study aims at constraining spatial and temporal variations in geometry, strain partitioning, slip rate, and time-transgressive propagation of the tectonic deformation associated with a fault system. In particular, I systematically analyze river profiles draining the eastern flank of the Peloritani Mts. in northeastern Sicily (southern Italy), a NNE-SSW- trending mountain ridge thought as located at the footwall of an active, ESE-dipping normal fault. I perform the linear inversions of fluvial topography by applying recently available MATLAB scripts, and I carry out the analysis of terraced surfaces by both GIS tools and MATLAB-based software packages. The results I obtain suggest that the eastern flank of the Peloritani Mts. have been deformed according to at least three main stages of uplift accommodated along distinct, ~10–15 km-long en-échelon arranged fault segments. The reconstructed evolution of tectonic deformation unveils time-transgressive, southward propagation since the last ~600 kyr, inset in a general increase, through time, of the regional component of uplift. The results of this study contribute to address the issues of the deformation style and strain partitioning along complex and/or debated fault systems. These results also demonstrate the potential of the geomorphic approach in defining the spatial and temporal tectonic evolutionary model of a region. 

We explore time series of magnetic susceptibility (χ) and anhysteretic remanent magnetization (ARM) in settings of rapid sediment accumulation rate (SAR) with the goals of partitioning exogenic forcings from autogenic processes and to better understand how these magnetic signals are encoded in sedimentary archives. Environmental signals of periodic external forcings commonly operate at Milankovitch frequencies, but in rapid SAR settings autogenic processes including channel avulsions and delta lobe switching both shred high-frequency external forcings, or even impart their own quasi-periodic signals. We measure χ using both a hand-held KT-10 magnetic susceptibility meter and a lab-based Kappabridge KLY-3s, and ARM in the < 2 mm size fraction using a GSD-5 alternating-field and a 2G superconducting magnetometers, with all results mass normalized to SI units. We focus on 40 samples collected at 25 cm intervals from 10 m of propagating foresets in a Gilbert delta of the Provo stage of Lake Bonneville at High Creek, Utah. A luminescence-based age model in this delta establishes a mean SAR of 8 cm/yr and terrestrial cosmogenic nuclide concentrations of both delta sediment and alluvium in the source indicates modern and paleoerosion rates (E) ranging from ~60-100 m/Myr (0.006-0.01 cm/yr). Periodicities of 18 and 33 yrs in the rock magnetic time series are greater than twice the compensation time for these foresets where peaks in χ and ARM are positively correlated with fine-grained matrix. We interpret a positive correlation between E and χ as driven by stripping of soil-mantled hillslopes that harbor greater concentrations of magnetic minerals than the underlying bedrock. The encoding of the environmental signal, here interpreted as autogenic cascading of sediment on foreset surfaces, is primarily set by the SAR and depositional processes, which are decoupled from E. Nevertheless, the strength of the magnetic signal in our sedimentary archive varies with E which can be more widely explored as a E-proxy when locally calibrated. These results offer insight into how to isolate the impact of quasi-periodic tectonic forcings on stratigraphic archives at sub-Milankovitch frequencies, where autogenic processes dominate depositional processes but which also encode critical human-dimension natural hazard information. 

Rapid sediment accumulation rates (SAR) in a fan delta situated on the rapidly uplifting footwall of the Taormina normal fault in NE Sicily preserves a rare record of earthquakes and base level change for a tightly coupled source to sink system. We use this sedimentary archive to reconstruct the kinematics and slip history of the fault and further an understanding of how tectonic forcing across various scales are encoded in stratigraphy. A revised luminescence-based age model indicates that ~82 m of the Pagliara fan-delta foreset facies was deposited in ~11 ka at a mean SAR of ~0.74 cm/yr during MIS 7. Syn-depositional terrestrial cosmogenic nuclide (TCN) determined paleoerosion rates of 0.91±0.12 mm/yr and 1.31 ±0.61 mm/yr are similar to published modern erosion rates for the Pagliara basin of 0.97 ±0.11 mm/yr. At the stratigraphic scale, a time series of magnetic susceptibility (c) sampled at 1 m intervals in the foresets displays four ~2,800 yr / 20 m-thick cycles of growing c, bounded by sharp decreases that do not coincide with changes in sediment texture. The c of the low-grade metamorphic bedrock in the source is 20-100 times weaker than the c of rubified soils mantling the hillslopes, which is comparable to the c of the delta sediments. We propose that large, bedrock-cored landslides quasi-periodically deliver weak c sediment to the delta that dilutes a c signal otherwise dominated by the stripping of soil-mantled hillslopes. We propose that centennial-scale recurrence interval earthquakes are most capable at triggering a basin-scale landslide only after channel incision has increased relief of hillslopes to the threshold condition, which requires millennia to achieve. At the landscape scale of delta geometry and location, the Pagliara delta accumulated in a hanging wall basin that has since been inverted. We reconstruct the history of base level fall for the delta from an inversion of fluvial topography and apportion that record to its rock uplift, delta deposition, and eustatic components. We show that footwall uplift has been unsteady over the past 600 ka ranging from -1 to 3 mm/yr. The integration of our stratigraphic- and landscape scale observations furthers our understanding of the natural hazards related to normal fault earthquakes and their impact on sediment dynamics in this steep, active tectonic setting. 

Periodic external environmental forcings, typically operating at Milankovitch frequencies, are known to be encoded in sediments and sedimentary rocks, but sub-Milankovitch frequencies are more difficult to recognize, in part because of temporal overlap with autogenic processes. Here we use luminescence geochronology and rock-magnetic and lithostratigraphic-based cyclostratigraphy to investigate sub-Milankovitch periodicity in three high sedimentation rate deltas located in diverse tectonic and climatic settings. The Sciota kame delta in tectonically stable eastern Pennsylvania (USA) was deposited at a rate of ~2.5 cm/yr over ~1 kyrs and has a concentration of magnetic spectral power at ~53 cm, corresponding to a ~22 yr period. Lacking a subaerial fluvial catchment, periodicity in this delta is necessarily restricted to depositional processes or ice-wasting discharge fluctuations. Similarly, the Provo-stage Lake Bonneville High Creek delta (Utah, USA) was deposited at a rate of ~3 cm/yr over ~3 kyrs. It displays meter-scale coarsening-up bedsets interpreted as decadal-scale discharge variations during foreset propagation. Unlike the Sciota kame, the High Creek delta is fed by a subaerial catchment with little storage that supported a small cirque glacier during the LGM. The High Creek delta also aggraded in the subsiding hanging wall of the East Cache Valley fault and experienced at least one syn-depositional earthquake. Lastly, The Pagliara delta (northeast Sicily, Italy) was deposited at a rate of ~3 cm/yr in the rapidly uplifting footwall of a coastal seismogenic normal fault. This delta has a concentration of magnetic susceptibility spectral power at ~60 cm corresponding to a ~20 yr period. A multi-decadal periodicity emerges in all three deltas, despite the variable catchment, climate, and tectonic setting. We interpret this as representing a quasi-periodic, autogenic depositional process possibly related to distributary channel switching. However, differences in the rock-magnetic power spectra and lithostratigraphy of the Pagliara and High Creek deltas respectfully, indicates that sub-Milankovitch external forcings in the catchments, including tectonics, are also encoded in the delta stratigraphy. 

Interactions between deep Earth geodynamics and Earth surface processes are well documented at various scales, but many challenges remain in how inversion of a fluvially incised landscape should be interpreted in terms of long-term geodynamics or how deep Earth dynamics impact natural hazards. Here, we present results from geomorphic stream channel metrics and modeling of long profiles of streams draining the Tyrrhenian (northern) flank of Sicily (Italy), to assess the inferred, rapid, west-to-east horizontal translation of the Calabrian forearc. A detachment-limited stream power model-based determination of landscape response time and knickpoint migration provides an independent prediction for transient base level fall associated with the sweeping forearc over the past ~4 Ma. The model shows that two pulses of time-transgressive, west-to-east propagating base level fall occurred in the drainages of northern Sicily, where parallel north-flowing streams are arranged across the migrating path of the forearc. The long profile analysis indicates that the paired uplift pulses last ~1 Ma and are separated in time by ~1.5 Ma, consistent with the west-to-east passage first of the forearc high, followed by dynamic uplift in its wake due to sub-lithospheric mantle flow, as proposed in other plate boundary settings. The ongoing surficial response to these dynamics is represented by river incision, knickpoint migration, and drainage divide migration. Furthermore, these processes steepened the landscape, leading to an increase in active landsliding and contributing to the natural hazards in this region. 

We analyze sediment texture, rock-magnetic, and depth-rank time series of meso-scale deltas and interpret the results in terms of autogenic depositional processes and exogenic forcings. As an analogue for natural deltas, this study leverages a semi-controlled environment where the deltas prograde rapidly into quarry settling ponds over decadal time spans and have compensation times on the order of ~2.4 months. The distal parts of two deltas were cored with a Geoprobe to a depth of 8.4 m. Recovery ranged from 30% to 70%, that we model as either sediment compaction or missing section (unconformities). The compaction model allows us to generate a complete time series of a decompacted section whereas the unconformity model allows us to consider the impact of significant periods of missing time. The cores were analyzed every 2 cm for magnetic susceptibility as well as grain size, texture, color, pebble content, and organic content, all of which contribute to an overall relative depth and textural ranking. Multi-taper method red-noise modeling of the time series using Astrochron identifies frequencies which rise above a 99% confidence level. The power spectra show a range of peaks, many of which fall below the compensation time and are disregarded. A significant periodicity of 2.6 months emerges in the compaction model. In the unconformity model, a peridocity of 2.6 months and also longer periodicities of 3.5 and 6 months emerge. These seasonal-scale periodicities are similar to those in regional precipitation data (4.4, 3.1, and 2.6 months) and suggest that exogenic forcing, in this case from precipitation that impacts both discharge in the source and water depth of the settling pond, are strong enough to be encoded in the sediments. Meso-scale studies of depositional systems such as these quarry deltas provide a bridge between small-scale analogue models and natural source to sink systems that we are in the process of sampling to further test our approach.