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Item type:Publication, Heinrich events and tectonic uplift as possible drivers for late Quaternary fluvial dynamics in the western Peruvian Andes(Elsevier B.V., 2022-11-01)Late Quaternary fluvial valley development in Peru is considered to be driven by summer insolation maxima in the precession cycle, which coincide with increased precipitation and rising lake levels in the central Andes. Our literature review, however, indicates that fluvial aggradation does not always coincide with summer insolation maxima but may also occur during transitions between insolation maxima and minima or even during summer insolation minima. Tectonic uplift as a driver of fluvial incision has not been considered in the current terrace formation models, despite the Peruvian margin being located above an active subduction zone. We present new chronologic, stratigraphic and geomorphic data of the Cañete River valley over the past 102 ± 6 ka. We mapped its fluvial terraces (11.5°-13° southern latitude) along a 75-km long reach perpendicular to the strike of the Andes. Five fluvial terraces and one floodplain level were identified with relative elevations of up to 181.1 m above the floodplain. Thirty-three (pIR) IRSL ages of eight fluvial terraces and one alluvial fan sediment sample showed that their ages in part correspond to summer insolation maxima of the precession cycle, but that a better match exists with pluvial periods that coincided with Heinrich events of the northern hemisphere and rising lake levels in the Andes. The chronology of terraces of the Cañete River agrees with those of previously studied fluvial systems between 7° and 16° southern latitude in Peru, suggesting a regional-scale fluvial response possibly to the Heinrich events. Reconstructed longitudinal profiles and terrace ages were utilised to calculate vertical incision rates. We calculated a mean rate of 1.8 ± 0.10 mm a−1 over the last 102 ± 6 ka, but incision rates varied considerably within this time period possibly in response to changes in the Qs: Qw ratio as a consequence of increased sediment input during the wet Heinrich events. A set of 1338 GNSS measurements of daily, vertical crustal deformation of the years 2009–2015 showed a continuous and positive trend in interseismic, accumulative vertical crustal movements with a time-averaged, crustal uplift rate of 1.9 ± 3.6 mm a−1. The positive trend in vertical movements, together with data from literature suggest landscape rejuvenation along the forearc and western Cordillera in central Peru. It is proposed that maximally ∼0.5 mm a−1 of the total incision over the past 102 ka may possibly be related to nonrecoverable, interseismic deformation. Climate change-driven variations in the Qs:Qw ratio are superimposed on the long-term tectonic uplift trend, and both are considered the main drivers of fluvial incision. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, A 121-ka record of Western Andean fluvial response to suborbital climate cycles recorded by rhythmic grain size variations of the Lima fluvial fan(John Wiley and Sons Ltd, 2024-06-30)A complete, fluvial stratigraphic record for the last glacial period of the Western Andes in Peru is not available due to preservation issues and spatial variability in sedimentation. Deposits are typically restricted to incomplete records of fluvial terraces or localised occurrences of alluvial fans and landslides. These landforms are thought to have formed under a regime of climate cyclicity controlling increases in precipitation. Because of the fragmented preservation of these deposits, as well as dating uncertainties, it remains unclear if orbital climate cycles, such as the precession cycle, or suborbital cycles, such as the wet Heinrich events, are driving Andean sedimentation. In this paper, we try to answer this question through a sedimentological–stratigraphical analysis of a much more complete sedimentary sequence than usually found in the region. We present the results of a grain size analysis of 5000 clasts and 13 new luminescence ages of a 52-m-long, stratigraphic section of the Lima fluvial fan in Peru. Bayesian age–depth modelling resulted in a robust chronostratigraphic framework and derived sedimentation rates. The stratigraphic record registered sedimentation from 121.7 ± 4 to (Formula presented.) ka. Three major sedimentation periods occurred between 121.7 to (Formula presented.), 87 ± 1 to (Formula presented.), and (Formula presented.) to (Formula presented.) ka. These periods registered various unconformities and coarsening–fining upward sequences which chronologically correlate to suborbital pluvial periods, recognised from speleothems and lake records, that drove fluvial deposition. They also correlate with the timing of other recognised sedimentation events throughout the Western Andes. Marine regression resulted in fan progradation and not in incision. The Lima fan stratigraphy represents therefore the most complete, last glacial fluvial record for the Peruvian Western Andes to date and it highlights the potential of fluvial fans as recorders of suborbital climate variability. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, The first NW European stratigraphic record containing an entire interglacial-glacial cycle of periglacial alluvial fan response to (sub)orbital climate fluctuations(Elsevier BV, 2025-06-01)Periglacial alluvial fans are common in northwestern and central Europe and their pre-Holocene stratigraphic records typically date back to late Middle Pleniglacial and Late Pleniglacial (late MIS3 and 2). Preserved stratigraphic records that include an entire interglacial-glacial cycle have, so far, not been described and it is thus unknown how periglacial alluvial fans responded during a full cycle of interglacial-glacial climate changes. In this paper, we reconstruct the evolution of the Eerbeek periglacial alluvial fan in the Netherlands which was deposited during the late Saalian (MIS 6) to late Weichselian (MIS 2) period, including the entire last interglacial–glacial cycle (MIS 5-2). Our reconstruction is based on 48, up-to 45-m deep borehole and Cone Penetration Test (CPT) logs that allowed the construction of an 8-km long longitudinal and a 7-km long transverse cross section over the Eerbeek periglacial alluvial fan. Age control was provided by means of 17, previously published, Optically Stimulated Luminescence ages of two boreholes on the fan, and 14 14C ages from three boreholes and a nearby, now abandoned, quarry. Overlying a thick, late Saalian (MIS 6) alluvial fan record, is a 4- to 18-m thick alternation of distinct organic (mainly peat and humic clays), siliciclastic alluvial fan (coarse- and medium-grained sands), Rhine (coarse- and medium grained sands), and aeolian (mainly medium-grained sands) stratigraphic units. Organic levels indicate fan stability during the Eemian interglacial (MIS 5e), and Brørup (MIS 5c), Odderade–Ognon interstadial complex (MIS 5a), and Middle Pleniglacial (MIS 3) interstadials 14, 13, 12 and 11 as well as late MIS 2 interstadial 1a. Clastic sediments indicate alluvial fan activity during the Herning (MIS 5d), Rederstall (MIS 5b), Ognon stadial complex (late MIS 5a), Early Pleniglacial (MIS 4) and upper Middle Pleniglacial (upper MIS 3) stadials 13, 12 and 11. Sediments from the coldest and driest period of the Last Glacial (late MIS 3 and MIS 2) are absent and following a phase of aeolian activity, the fan was only reactivated at the MIS 2 to MIS 1 transition (stadial 1). We attribute the absence of fan activity during the coldest period of the last interglacial-glacial cycle to the eastward orientation of the fan making it less sensitive to permafrost melt. The colder MIS substages and stadials in which the Eerbeek fan was active coincided with the presence of permafrost and/or a seasonal, deeply frozen soil, and a relatively humid climate during which vegetation was largely absent. The presence of channels that dissect the underlying organic units suggests that the Eerbeek fan initially responded to the changes from interstadials to stadials by means of erosion. As climate cooled and permafrost/deep frost developed, the fan switched to alluvial aggradation. The consistent presence of coarsening-fining upward sequences suggests a relation with cycles of increased overland flow due to increasingly more frozen subsoil conditions. The fan stratigraphy therefore shows the direct coupling between warmer-colder MIS substages and interstadial-stadial climate cyclicity and alluvial fan response over the entire last interglacial-glacial cycle.3 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, A landslide hazard and impact assessment under varying climate change scenarios in peri-urban catchments of the two largest Peruvian cities(RELX Group (Netherlands), 2026-01-01)2