Germán Aguilar

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Verified

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• PhD
• Research Associate at University of Chile

This study investigates the shifts in fan‐river coupling during two major consecutive debris flow events (March 2015 and May 2017) on tributary‐junction alluvial fans situated in the Atacama Desert in the Andes. Studying the geomorphological consequences of debris flow events in these fans provides a unique opportunity to understand the mechanisms...

A large human-induced sediment supply (~ 400 Mt) took place on the Atacama Desert rocky coast (~ 26° S) as a result of the dumping of copper mine tailings between 1938 and 1990. We show that the input of this large sediment load has affected the natural sediment dynamics in this coastal area. The coastal system counterbalanced this abrupt increase...

The Pan de Azúcar National Park (~26◦S, 70.6◦W), located on the southern edge of the Atacama Desert, exhibits for almost 30 km an alongshore morphological segmentation. In this work, we characterized the two contrasting morphological arrangements observed in this area: (1) a wide marine terrace landward backed by a tall coastal cliff, and (2) a seq...

Coastal cliff evolution is modulated by several factors, such as uplift, marine erosion, previous topographical conditions, and changes in global sea level. In this study, a numerical model is used to understand the influence of these processes on the evolution of coastal cliffs. This model is based on erosional and tectonic conditions of the Great...

Landscape evolution models suggest that thalweg morphometry is influenced by a combination of factors, including the rate of rock uplift, the soil erodibility, the channel geometry, the sediment properties and availability, and the climate changes. Approximately 6 Ma ago, the uppermost catchment of the El Transito river (∼29°S, Central Andes) captu...

Denudation is the opposite process of mountain uplift and plays a major role in the Earth system. Despite the research to constrain its environmental control, uncertainties remain about which are the dominant physicochemical processes at play. Here, the 10Be-derived denudation rate, encompassing time windows from 102 to 105 yr, was modelled in over...

During 29-31 January 2021 (austral summer), an extreme storm event triggered catastrophic debris flows in central Chile (33-36°S). At small and precarious rural settlements in the commune of Malloa in central Chile, debris flows where triggered by a hailstorm. Hail-debris flows, with hail volume concentration near 10%-20%, caused 200 injured indivi...

We present a study on the glacial and paraglacial geomorphology of a Patagonian Cordillera Valley that is key to understanding evolution of the great lakes of Patagonia. 10Be cosmogenic nuclide exposure ages of ice-moulded surfaces from the Bayo River Valley confirm that the valley became ice-free before 13.4-14.2 ka. This valley constituted the fi...

The Andes are an emblematic active Cordilleran orogen. Mountain building in the Central Andes (∼20∘ S) started by the Late Cretaceous to early Cenozoic along the subduction margin and propagated eastward. In general, the structures sustaining the uplift of the western flank of the Andes are dismissed, and their contribution to mountain building rem...

This issue, several studies present an analysis of the extreme meteorological events that have occurred over the last 15 years and their relationship to landslides affecting Chile; Addresses environmental pollution, evaluating the impacts of meteorological events on the redistribution of metals and metalloids accumulated by mining activities, with...

In the Western Cordillera of northern Chile, the Proterozoic-Paleozoic Belén Metamorphic Complex is covered by late Oligocene-early Miocene (25-18 Ma) rocks, and both units are involved in west-vergent contractional deformation, which results in exhumation. A Miocene age (18 to 6 Ma) for deformation has been previously constrained by stratigraphy a...

The high mountain segments of the valleys of the southernmost Atacama Desert of Chile present Late Quaternary glacial landforms that developed in already incised valleys. Glacier advances and deglaciation have left a geomorphic imprint in the southernmost Atacama Desert. In this work, the glacial landforms of the Encierro River Valley (29.1°S–69.9°...

In the Western Cordillera of northern Chile, the Proterozoic-Paleozoic Belén Metamorphic Complex is covered by late Oligocene-early Miocene (25-18 Ma) rocks, and both units are involved in west-vergent contractional deformation, which results in exhumation. A Miocene age (18 to 6 Ma) for deformation has been previously constrained by stratigraphy a...

The Atacama rocky coast in Northern Chile is a tectonically active region that displays a particular morphological assemblage along its extension. There is a major morphostructural element named the Great Coastal Cliff (GCC) that runs parallel to the coastline for almost 1000 km in hyper-arid conditions. This cliff reaches heights between 800 and 2...

Traditionally, interactions between tributary alluvial fans and the main river have been studied in the field and in the laboratory, giving rise to different conceptual models that explain their role in the sediment cascade. On the other hand, numerical modeling of these complex interactions is still limited because the broad debris flow transport...

The Andes are an emblematic active Cordilleran orogen. It is admitted that mountain-building in the Central Andes at ~20°S started by Late Cretaceous to Early Cenozoic along the subduction margin, and propagated eastward. In general, the structures sustaining the uplift of the West Andean flank are dismissed, and their contribution to mountain-buil...

Accepted paper An extreme precipitation event produced catastrophic debris flows in central Chile during 29-31 January 2021 (austral summer). Our study focuses on the triggering factors and dynamic behavior of hail-debris flows affecting the small commune of Malloa (Central Valley), which caused 200 injured and 73 damaged houses. We carried out a...

Solid mine wastes can be dispersed in river systems by fluvial processes contaminating distant areas. This process has been previously reported in rivers of the Atacama Desert impacted by mining. The removal of waste in these rivers is a complex environmental scenario that involves (i) mining operation plans, (ii) the spatio-temporal variability of...

The Central Andes between 18°S and 36°S latitude strike north-south for 2000 km along the Chilean subduction margin, cross several climate zones from hyperarid to humid and exhibit mean elevations in excess of 4000 m.a.s.l. Here, we investigate the relationships between tectonics, climate and exhumation by inverting low-temperature thermochronologi...

The contribution of an individual extreme storm event to long-term erosion rates has been estimated for the first time in the Atacama Desert. A mean erosion of 1.3 mm has been calculated for the March 2015 event that impacted the southernmost part of the Atacama Desert. The estimated erosion is consistent with millennial erosion rates and the previ...

Extreme high magnitude and low frequency storm events in arid zones, provide the necessary runoff to entrain sediments from source areas and therefore dictate the linkages between hillslopes and channels. Nevertheless, the erosive impact of large storms remains difficult to predict. Most of the uncertainty relies the lack of topographic change maps...

Tributary-junction alluvial fans situated at the intersection of confined valleys with <100 km2 tributary catchments are of special interest to evaluate the heterogeneous consequences of extreme rainfall events in arid zones. These fans record the episodic sedimentological behaviour of the hillslope response to rainstorm events within tributary cat...

[English] Small alluvial fans (radius of hundreds of meters and high gradients) exert a fundamental role on the stratigraphic and geomorphic evolution of narrow valleys situated in mountainous regions. We study the sedimentology of three alluvial fans characteristic of El Huasco river valley in the Andes to determine their conditions of formation....

The Copiapó river basin, to the south of the Atacama desert, has a strong anthropic intervention due to mining, agricultural and urban activities. The presence of mining environmental tailings in the basin is relevant, mainly when they are close to watercourses and populated areas. In this work the relationship between the variations of copper, lea...

The Atacama Desert, the driest of its kind on Earth, hosts a number of unique geological and geochemical features that make it unlike any other environment on the planet. Considering its location on the western border of South America, between 17 and 28 °S, its climate has been characterized as arid to hyperarid for at least the past 10 million yea...

Chile is an elongated country, running in a north-south direction for more than 30◦ along a subduction zone. Its climate is progressively wetter and colder from north to south. This particular geography has been used positively by a growing number of studies to better understand the relationships between erosion pro- cesses and climate, land use, s...

In this paper, we discriminate the contribution of the different sediment sources into a river situated in the semiarid region of northern Chile, differentiating the ones driven by the paraglacial response from the ones yielded to the tributary-junction alluvial fans or the ones coming from the hillslopes. The sedimentary infilling is accurately de...

We present new cosmogenic (Be-10) exposure ages obtained on Pleistocene marine abrasion shore terraces of Northern Chile between 24 degrees S and 32 degrees S in order to evaluate the temporal and spatial variability of uplift rates along the coastal forearc. Both the dispersion of cosmogenic concentrations in samples from the same terrace and data...

We present new cosmogenic (¹⁰Be) exposure ages obtained on Pleistocene marine abrasion shore terraces of Northern Chile between 24°S and 32°S in order to evaluate the temporal and spatial variability of uplift rates along the coastal forearc. Both the dispersion of cosmogenic concentrations in samples from the same terrace and data obtained in vert...

The Chilean Frontal Cordillera, near 28°45'S, provides a remarkable example to explore the evolution of the Central Andes; this area provides conspicuous pediment surfaces and continental deposits, which allowed us to analyze the timing and propagation of deformation which controlled the Andes building during the Cenozoic using structural, geomorph...

The effect of mean precipitation rate on erosion is debated. Three hypotheses may explain why the current erosion rate and runoff may be spatially uncorrelated: (1) the topography has reached a steady state for which the erosion rate pattern is determined by the uplift rate pattern; (2) the erosion rate only depends weakly on runoff; or (3) the stu...

We combine geomorphological analysis of palaeosurfaces and U–Pb zircon geochronology of overlying tuffs to reconstruct the Neogene landscape evolution in north-central Chile (28–32°S). Prior to the Early Miocene, a pediplain dominated the landscape of the present-day Coastal Cordillera. The pediplain was offset during the Early (Middle?) Miocene, l...

The effect of mean precipitation rate on erosion is debated. Three hypotheses may explain why the current erosion rate and runoff may be spatially uncorrelated: (1) the topography has reached a steady state for which the erosion rate pattern is determined by the uplift rate pattern; (2) the erosion rate only depends weakly on runoff; or (3) the stu...

Climate and topography control millennial-scale mountain erosion, but their relative impacts remain matters of debate. Conflicting results may be explained by the influence of the erosion threshold and daily variability of runoff on long-term erosion. However, there is a lack of data documenting these erosion factors. Here we report suspended-load...

A morphometric analysis that considers hypsometry and topographic slope reveals longitudinal and latitudinal differences in the degree of maturity of the relief of the Andes between 27-32°S. Whereas landscape rejuvenation of the Coastal Cordillera takes place to the south of 29.5°S, in the Main Cordillera it happens south of 28.5°S. The combination...

Terrestrial cosmogenic nuclide concentrations in sediment are used to quantify mean denudation rates in catchments. This article explores the differences between the 10Be concentration in fine (sand) and in coarse (1-3 or 5-10 cm pebbles) river sediment. Sand and pebbles were sampled at four locations in the Huasco Valley, in the arid Chilean Andes...

We quantify erosion rates in the higher sectors of the Huasco Valley, in the Main Cordillera of the semi-arid Andes of Chile, using elevation differences between three successive geomorphic markers (pediments and paleo-valleys) and the present day valley. Available Ar-Ar ages of Neogene pediments are used to estimate mean erosion rates for the thre...

Short-term and long-term erosion rates in Chile

The transitional character of climatic conditions confers great relevance to paleoclimate studies in the semiarid region where glacial and Holocene geomorphologic records are scarce. Here we present the paraglacial and fluvial evolution of the Turbio valley (30°S) using both field observations and 14C AMS chronology. Two key sites at the uppermost...

The Principal Cordillera of the semiarid Andes is a transient relief that developed after the Andean uplift initiated in the Oligocene. Pediment altitudes of the Principal Cordillera in relation with others of the Coastal Cordillera indicate two kilometers of uplift. In response to the uplift depth-incised valleys (~2 km) were excavated in the high...

La Cordillère Principale des Andes semi-arides est un relief transitoire qui se developpe suite au soulèvement des Andes initié à l'Oligocène. L'altitude des pédiments de la Cordillère Principale par rapport à ceux de la Cordillère de la Côte indique que ce soulèvement a atteint deux kilomètres. Ce qui se marque par de profondes vallées incisés (~2...

Abstract Ollagüe is an active stratovolcano located in the Central Andes of Northern Chile, which evolved in three stages from Middle Pleistocene (ca. 1.2 Ma) to Upper Pleistocene (ca. 150 ka), and partially collapsed to the west at ca. 600-400 ? ka. The collapse generated a well-preserved debris avalanche deposit on its western fl ank which partia...