Spatial correlation bias in late-Cenozoic erosion histories derived from thermochronology

Abstract

The potential link between erosion rates at the Earth's surface and changes in global climate has intrigued geoscientists for decades because such a coupling has implications for the influence of silicate weathering and organic-carbon burial on climate and for the role of Quaternary glaciations in landscape evolution. A global increase in late-Cenozoic erosion rates in response to a cooling, more variable climate has been proposed on the basis of worldwide sedimentation rates. Other studies have indicated, however, that global erosion rates may have remained steady, suggesting that the reported increases in sediment-accumulation rates are due to preservation biases, depositional hiatuses and varying measurement intervals. More recently, a global compilation of thermochronology data has been used to infer a nearly twofold increase in the erosion rate in mountainous landscapes over late-Cenozoic times. It has been contended that this result is free of the biases that affect sedimentary records, although others have argued that it contains biases related to how thermochronological data are averaged and to erosion hiatuses in glaciated landscapes. Here we investigate the 30 locations with reported accelerated erosion during the late Cenozoic. Our analysis shows that in 23 of these locations, the reported increases are a result of a spatial correlation bias-that is, combining data with disparate exhumation histories, thereby converting spatial erosion-rate variations into temporal increases. In four locations, the increases can be explained by changes in tectonic boundary conditions. In three cases, climatically induced accelerations are recorded, driven by localized glacial valley incision. Our findings suggest that thermochronology data currently have insufficient resolution to assess whether late-Cenozoic climate change affected erosion rates on a global scale. We suggest that a synthesis of local findings that include location-specific information may help to further investigate drivers of global erosion rates.

Miocene basement exhumation in the Central Alps recorded by detrital garnet geochemistry in foreland basin deposits

“…This is thought to represent the transition to Molasse-type sedimentation in an overfilled basin and is discussed to be potentially related to a break-off of the European slab around the time of the Eocene-Oligocene boundary (e.g. Sinclair et al, 1991;Sinclair, 1997;Schlunegger and Kissling, 2015). Since this time, the northern foreland basin has become a major sink of orogenic detritus and an important sedimentary archive.…”

“…Sedimentary rocks preserved in the northern peripheral foreland basin of the Central Alps, the Swiss part of the Molasse basin, are a well-studied archive recording tectonic and climatic adjustments in the central orogen between ca. 32 and 14 Myr ago (Schlunegger et al, 1993(Schlunegger et al, , 1996Kempf et al, 1999;Spiegel et al, 2000;Kuhlemann and Kempf, 2002;von Eynatten, 2003;Schlunegger and Kissling, 2015). So far, the provenance of the Molasse deposits has been investigated using optical heavy mineral analysis, framework petrography, and both bulk and single-grain geochemical techniques, including epidote geochemistry and cooling ages derived from zircon fission track analysis and Ar-Ar dating of white mica (Spiegel et al, 2000(Spiegel et al, , 2002von Eynatten, 2003;von Eynatten and Wijbrans, 2003).…”

Glacial limitation of tropical mountain height

“…No wpELA estimate was provided. Modern glaciers are presently less than 2 km 2 in the Mérida Range (Stansell et al, 2007) and have been steadily shrinking throughout the 20th century (Schubert, 1992). Stansell et al (2007) used the elevation of the 0 • isotherm to broadly constrain the wpELA in the Mérida Range to 4470-5040 m.…”

Late Quaternary Tectonics, Incision, and Landscape Evolution of the Calchaquí River Catchment, Eastern Cordillera, NW Argentina

“…The attempt to unravel tectonics, climate, and erosion is partly complicated because of temporal climate variability. For example, some studies suggest coupling between erosion rates and a long-term shift toward cool conditions in the Quaternary (e.g., Herman et al, 2013;Molnar & England, 1990;Willenbring & von Blanckenburg, 2010), although these studies may suffer from spatial or temporal correlation bias (Schildgen et al, 2018;Schumer & Jerolmack, 2009). Cyclic changes in climate (Zachos et al, 2001) may complicate unraveling links between climate, tectonics, and landscape evolution as well (e.g., Braun et al, 2015).…”