Sedimentología y Estructura del Complejo de la Morrena Laterofrontal de la Laguna Palcacocha en la Cordillera Blanca, Perú

Bowman, David; Eyles, Carolyn H.; Narro-Pérez, Rodrigo; Vargas, Roque

doi:10.36580/rgem.i5.27-42

Cited by 2 publications

(4 citation statements)

References 24 publications

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“…2003; Bowman et al . 2018). The internal structure of the lateral moraine fringing Llaca Lake suggests that the moraine may have formed in a similar way, from the alternating accumulation of sediment supplied by supraglacial debrisflows and falls from the lateral ice margins (Kirkbride & Spedding 1996; Benn & Owen 2002; Sigurðardóttir 2013).…”

Section: Geomorphological Characteristics Of Llaca Lakementioning

confidence: 99%

“…Palcacocha; Bowman et al . 2018) suggests that it could contain a combination of clast‐ and matrix‐supported massive diamicts with minor amounts of interbedded finer grained sediment (Fig. 8).…”

Section: Landsystem Zones Within Llaca Lakementioning

confidence: 99%

“…8). Such large lateral and frontal moraines commonly consist of poorly sorted sediments of glacial or glacially transported origin, deposited by a variety of processes including debris falls, slumps, and slides from supraglacial and englacial sources (Owen & Derbyshire 1989;Benn et al 2003;Bowman et al 2018). The internal structure of the lateral moraine fringing Llaca Lake suggests that the moraine may have formed in a similar way, from the alternating accumulation of sediment supplied by supraglacial debrisflows and falls from the lateral ice margins (Kirkbride & Spedding 1996; Benn & Owen 2002; Sigurðard ottir 2013).…”

Section: Latero-frontal Morainementioning

confidence: 99%

“…Avery similar latero-frontal moraine that impounds Palcacocha Lake in an adjacent valley (Fig. 2) contains interbedded massive gravels (Gms) and matrix-supported diamicts deposited by debrisflows and the reworking and bulldozing of debris at the glacier front (Bowman et al 2018). While distinct local factors may have played a role in moraine formation, it is possible similar moraine building processes occurred in the Llaca Valley.…”

Section: Latero-frontal Morainementioning

confidence: 99%

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Landsystem analysis of a tropical moraine‐dammed supraglacial lake, Llaca Lake, Cordillera Blanca, Perú

Pérez

Eyles

Lee

et al. 2023

Boreas

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Tropical glaciers of the Cordillera Blanca, Per u are rapidly thinning and retreating as a result of climate warming. The retreat of these glaciers along narrow linear bedrock valleys has increased the number and size of moraine-dammed glacial lakes formed in the valleys. This study aims to identify the geomorphological and sedimentological characteristics of an enlarging moraine-dammed supraglacial lake (Llaca Lake) in the Cordillera Blanca. Field-based sedimentological observations and geomorphological mapping were combined with remotely sensed data and a photogrammetric model derived from aerial surveys by an uncrewed aerial vehicle to identify landform-sediment assemblages. The geomorphological and sedimentological characteristics of Llaca Lake are synthesized into three landsystem zones: Zone 1: distal portions of Llaca Lake and the latero-frontal moraine; Zone 2: the central zone of icecored hummocks; and Zone 3: the active glacier margin. These zones are differentiated based on the spatial distribution of landforms, sediments, and active geomorphological processes. This is the first study to describe the landform-sediment assemblages in atropical moraine-dammed supraglacial lake system and provides a framework for further landsystem element analysis of these growing supraglacial lakes in rapidly deglaciating high-altitude environments.

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Section: Geomorphological Characteristics Of Llaca Lakementioning

confidence: 99%

Section: Landsystem Zones Within Llaca Lakementioning

confidence: 99%

Section: Latero-frontal Morainementioning

confidence: 99%

Section: Latero-frontal Morainementioning

confidence: 99%

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Landsystem analysis of a tropical moraine‐dammed supraglacial lake, Llaca Lake, Cordillera Blanca, Perú

Pérez

Eyles

Lee

et al. 2023

Boreas

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Modelling the effects of ice transport and sediment sources on the form of detrital thermochronological age probability distributions from glacial settings

et al. 2020

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Abstract. The impact of glaciers on the Quaternary evolution of mountainous landscapes remains controversial. Although in situ or bedrock low-temperature thermochronology offers insights on past rock exhumation and landscape erosion, the method also suffers from potential biases due to the difficulty of sampling bedrock buried under glaciers. Detrital thermochronology attempts to overcome this issue by sampling sediments at e.g. the catchment outlet, a component of which may originate from beneath the ice. However, detrital age distributions not only reflect the catchment exhumation, but also spatially variable patterns and rates of surface erosion and sediment transport. In this study, we use a new version of a glacial landscape evolution model, iSOSIA, to address the effect of erosion and sediment transport by ice on the form of synthetic detrital age distributions. Sediments are tracked as Lagrangian particles formed by bedrock erosion, and their transport is restricted to ice or hillslope processes, neglecting subglacial hydrology, until they are deposited. We base our model on the Tiedemann Glacier (British Columbia, Canada), which has simple morphological characteristics, such as a linear form and no connectivity to large tributary glaciers. Synthetic detrital age distributions are generated by specifying an erosion history, then sampling sediment particles at the frontal moraine of the modelled glacier. Results show that sediment sources, reflecting different processes such as glacier and hillslope erosion, can have distinct bedrock age distribution signatures, and estimating such distributions should help to identify predominant sources in the sampling site. However, discrepancies between the detrital and bedrock age distributions occur due to (i) the selective storage of a large proportion of sediments in small tributary glaciers and in lateral moraines, (ii) the large range of particle transport times due to varying transport lengths and strong variability of glacier ice velocity, (iii) the heterogeneous pattern of erosion, and (iv) the advective nature of glacier sediment transport along ice streamlines. This last factor leads to a poor lateral mixing of particle detrital signatures inside the frontal moraine, and then local sampling of the frontal moraine is likely to reflect local sources upstream. Therefore, sampling randomly across the moraine is preferred for a more representative view of the catchment age distribution. Finally, systematic comparisons between synthetic (U-Th)/He and fission track detrital ages, with different bedrock age-elevation profiles and different relative age uncertainties, show that the nature of the age-elevation relationship and age uncertainties largely control the ability to track sediment sources in the detrital record. However, depending on the erosion pattern spatially, qualitative first-order information may still be extracted from a thermochronological system with high uncertainties (>30 %). Overall, our results demonstrate that detrital age distributions in glaciated catchments are strongly impacted not only by erosion and exhumation but also by sediment transport processes and their spatial variability. However, when combined with bedrock age distributions, detrital thermochronology offers a novel means to constrain the transport pattern and time of sediment particles.

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Sedimentología y Estructura del Complejo de la Morrena Laterofrontal de la Laguna Palcacocha en la Cordillera Blanca, Perú

Cited by 2 publications

References 24 publications

Landsystem analysis of a tropical moraine‐dammed supraglacial lake, Llaca Lake, Cordillera Blanca, Perú

Landsystem analysis of a tropical moraine‐dammed supraglacial lake, Llaca Lake, Cordillera Blanca, Perú

Modelling the effects of ice transport and sediment sources on the form of detrital thermochronological age probability distributions from glacial settings

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