Effects of Miocene–Pliocene global climate changes on continental sedimentation: A case study from the southern Central Andes


Stevens Goddard, A
and Carrapa, B

Sedimentation rates are valuable proxies for changes in tectonics, climate, and sediment routing systems. We use sedimentation rates from the Bermejo foreland basin of the southern Central Andes to evaluate the role of global Miocene–Pliocene climate changes on continental erosion and sedimentation in non-glaciated landscapes. Our compilation identifies a tripling of sedimentation rates between ca. 10 and 8.5 Ma coinciding with a period of short-lived global warming and increased seasonality, and a decrease by half in sedimentation rates between ca. 6 and 5 Ma coinciding with increased global cooling and aridity. Both the increase and decrease in sedimentation rates occured during periods of heightened tectonic activity. Our results suggest that periods of aridity can reduce erosion and mask contemporaneous tectonic signals, and that more humid, variable climate conditions amplify the signal of tectonic forcing in the sedimentary record. This work shows that changes in sedimentation rates can accurately filter climatic variabilities out of the overprinting tectonic signal.

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Figure 1. A: South American mean annual precipitation from NASA Tropical Rainfall Measuring Mission (TRMM) data (1998–2013) (Huffman et al., 2014) and ERA-Interim (https://www.ecmwf.int /en /forecasts /datasets /archive -datasets /reanalysis -datasets /era-interim) and annual mean 850 hPa winds (Dee et al., 2011). Black box indicates study area shown in B. B:Geologic map of study area, modified from Stevens Goddard and Carrapa (2017). White circles depict locations of stratigraphic sections with geochronologic constraints used to calculate the sedimentation rates for this study.

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GEOLOGY, July 2018; v. 46; no. 7; p. 647–650 | https://doi.org/10.1130/G40280.1 © 2018 Geological Society of America.