Abstract
Paleoclimate records from the Atacama Desert are rare and mostly discontinuous, mainly recording runoff from the Precordillera to the east, rather than local precipitation. Until now, paleoclimate records have not been reported from the hyperarid core of the Atacama Desert (<2 mm/yr). Here we report the results from multi-disciplinary investigation of a 6.2 m drill core retrieved from an endorheic basin within the Coastal Cordillera. The record spans the last 215 ka and indicates that the long-term hyperarid climate in the Central Atacama witnessed small but significant changes in precipitation since the penultimate interglacial. Somewhat ‘wetter’ climate with enhanced erosion and transport of material into the investigated basin, commenced during interglacial times (MIS 7, MIS 5), whereas during glacial times (MIS 6, MIS 4–1) sediment transport into the catchment was reduced or even absent. Pelagic diatom assemblages even suggest the existence of ephemeral lakes in the basin. The reconstructed wetter phases are asynchronous with wet phases in the Altiplano but synchronous with increased sea-surface temperatures off the coasts of Chile and Peru, i.e. resembling modern El Niño-like conditions.
Highlights
The Atacama Desert of northern Chile is one of the driest places on Earth; its extreme hyperarid core receives less than 2 mm/yr of precipitation[1]
The study site is situated in the Coastal Cordillera, which forms a 1000–1800 m high and 50–70 km wide structural high that is restricted to the west by a 1000 m coastal cliff and bounded to the east by the Central Depression (Fig. 1A,C)
The results show that the natural signal is above saturation of the corrected dose response curve (DRC), and only minimum ages based on 2D0 of the DRC can be estimated for these samples from deepest within the sediment core, Table 1
Summary
The study site is situated in the Coastal Cordillera, which forms a 1000–1800 m high and 50–70 km wide structural high that is restricted to the west by a 1000 m coastal cliff and bounded to the east by the Central Depression (Fig. 1A,C). The dipping appears to only be flat-angle throughout the basin, and can be extrapolated to a maximum depth of 41 ± 10 m at the centre of the clay pan (Fig. 2A,B). According to the GPR data, the basin morphology is not concentric and symmetric, but exhibits a shallower dipping at the southern part towards the centre and much steeper slopes at the thrusting scarp in the north (Fig. 2A,B). H/V seismic data (Fig. 2A profile red line, for further information see supplementary) were able to resolve soft sediment/bedrock contact, with a maximum depth of approximately 64 +/− 10 m (Fig. 2B). Due to the low soft-sediment density variations, a higher resolution model of the internal structure of the sediment infill could not be obtained from H/V seismic analysis
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