Bernhardt, Anne; Schwanghart, Wolfgang; Hebbeln, Dierk; Stuut, Jan-Berend W; Strecker, Manfred R (2017): Age models of turbidite cores and a humidity index of sediment cores from the Chilean continental margin. PANGAEA, https://doi.org/10.1594/PANGAEA.876590, Supplement to: Bernhardt, A et al. (2017): Immediate propagation of deglacial environmental change to deep-marine turbidite systems along the Chile convergent margin. Earth and Planetary Science Letters, 473, 190-204, https://doi.org/10.1016/j.epsl.2017.05.017
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Understanding how Earth-surface processes respond to past climatic perturbations is crucial for making informed predictions about future impacts of climate change on sediment fluxes. Sedimentary records provide the archives for inferring these processes, but their interpretation is compromised by our incomplete understanding of how sediment-routing systems respond to millennial-scale climate cycles.
We analyzed seven sediment cores recovered from marine turbidite depositional sites along the Chile continental margin. The sites span a pronounced arid-to-humid gradient with variable relief and related sediment connectivity of terrestrial and marine environments. These sites allowed us to study event-related depositional processes in different climatic and geomorphic settings from the Last Glacial Maximum to the present day. The three sites reveal a steep decline of turbidite deposition during deglaciation. High rates of sea-level rise postdate the decline in turbidite deposition. Comparison with paleoclimate proxies documents that the spatio-temporal sedimentary pattern rather mirrors the deglacial humidity decrease and concomitant warming with no resolvable lag times.
Our results let us infer that declining deglacial humidity decreased fluvial sediment supply. This signal propagated rapidly through the highly connected systems into the marine sink in north-central Chile. In contrast, in south-central Chile, connectivity between the Andean erosional zone and the fluvial transfer zone probably decreased abruptly by sediment trapping in piedmont lakes related to deglaciation, resulting in a sudden decrease of sediment supply to the ocean. Additionally, reduced moisture supply may have contributed to the rapid decline of turbidite deposition. These different causes result in similar depositional patterns in the marine sinks. We conclude that turbiditic strata may constitute reliable recorders of climate change across a wide range of climatic zones and geomorphic conditions. However, the underlying causes for similar signal manifestations in the sinks may differ, ranging from maintained high system connectivity to abrupt connectivity loss.
Median Latitude: -32.732924 * Median Longitude: -72.835480 * South-bound Latitude: -39.890900 * West-bound Longitude: -75.901350 * North-bound Latitude: -29.716660 * East-bound Longitude: -71.868660
Date/Time Start: 1995-04-27T00:00:00 * Date/Time End: 2002-04-07T00:00:00
BACON min: denotes the lower bound of the age model's 95% probability interval.
BACON max: denotes the upper bound of the age model's 95% probability interval.
BACON median: denotes the meadian of the age model's 95% probability interval.
BACON wmean: denotes the weighted mean of the ag emodel's 95% probability interval.
Age models of turbidite cores are based on previously published radiocarbon (14C) ages by Blumberg et al., (2008) and Bernhardt et al. (2015) and derived with the Bayesian age-depth modeling software program BACON (Blaauw and Christen, 2011) and the Marine 13 calibration curve (Reimer et al., 2013).
At sites A and SA, ages were corrected for a reservoir age deviation of DR 400 ± 100 yrs (0-6 kyrs) and DR 31 ± 156 yrs (> 6 kyrs) following Carré et al. (2016). Late Pleistocene estimates of DR lack in this region. At site H, we applied an increase in DR from 400 ± 100 yr at ages < 11 kyrs , 600 ± 200 yr between 11 and 23 kyrs, and 800 ± 300 at ages >23 kyrs, acknowledging the reconstruction of DR variations in the region (Siani et al., 2013). The supplementary material contains the age models and their parameters for each core.
Thickness measurements of turbidite layers were conducted during core description and verified using magnetic susceptibility measurements in cores from Sites A and SA and taken from the literature for Site H (Blumberg et al., 2008). The timing of turbidite deposition is not modelled directly since turbidite layers are excluded from the age-depth modelling. We thus consistently assigned to each turbidite layer the age of the directly overlying 5mm-core slice, repeatedly for all Markov Chain Monte Carlo (MCMC) iterations returned by BACON.
Datasets listed in this publication series
- Bernhardt, A; Schwanghart, W; Hebbeln, D et al. (2017): Age model of ODP site 202-1232 (Site H). https://doi.org/10.1594/PANGAEA.876602
- Bernhardt, A; Schwanghart, W; Hebbeln, D et al. (2017): Age model of sediment core GeoB3304-5 (Site SA). https://doi.org/10.1594/PANGAEA.876597
- Bernhardt, A; Schwanghart, W; Hebbeln, D et al. (2017): Age model of sediment core GeoB3368-2 (Site A). https://doi.org/10.1594/PANGAEA.876598
- Bernhardt, A; Schwanghart, W; Hebbeln, D et al. (2017): Age model of sediment core GeoB3369-1 (site A). https://doi.org/10.1594/PANGAEA.876599
- Bernhardt, A; Schwanghart, W; Hebbeln, D et al. (2017): Age model of sediment core GeoB7136-2 (Site A). https://doi.org/10.1594/PANGAEA.876600
- Bernhardt, A; Schwanghart, W; Hebbeln, D et al. (2017): Age model of sediment core GeoB7138-2 (Site A). https://doi.org/10.1594/PANGAEA.876601
- Bernhardt, A; Schwanghart, W; Hebbeln, D et al. (2017): Age model of sediment core SO161/5_50SL (Site H). https://doi.org/10.1594/PANGAEA.876603
- Bernhardt, A; Schwanghart, W; Hebbeln, D et al. (2017): Humidity index of sediment core GeoB7139-2. https://doi.org/10.1594/PANGAEA.876589