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Southern Cross GeoScience

Coastal geomorphology

"Chevrons" - Enigmatic littoral deposits. Pilot studies at the coastlines of southern Brazil and central Chile.

Funding / collaborators:

  • German Research Foundation (DFG) - $65,000

Project description:

Chevrons are enigmatic yet understudied lancet-formed sandy sedimentary structures deposited at many coastlines of the world with lengths up to many tens of km and altitudes up to more than 200 m. As their form often resembles parabolic dunes, most coastal scientists attribute their origin to wind-driven (eolian) processes. However, some morphologic characteristics questions this eolian genesis and point to wave driven processes: Their longest axis may diverge from the main wind directions, even in limited coastal sections their direction may differ up to 180, they may show refraction patterns not typical for parabolic dunes, and some of them even content larger clasts. In some cases even impact minerals like shocked quartz, magnetite spherules, partly molten marine micro-organisms etc. have been found in chevron sediments, which may suggest that meteorite impacts in the ocean may play a role in chevron formation.

An overview of worldwide chevron distribution using Google Earth (Scheffers et al., 2008) led us to develop the working hypothesis, that at least those chevrons which contain clasts, differ from the main wind direction and are deposited along rocky shorelines without sand supply may be the result of swash effects during extraordinary (tsunami/storm?) waves. With support from the German Research Foundation we will investigate chevrons in southern Brazil and central Chile based on sedimentologic, geochemical and chronostratigraphic analyses to advance our understanding of the origin of these enigmatic and widely unknown coastal deposits.

Chevron

Team members:

  • A/Prof Anja Scheffers, SCU
  • Prof Helmut Brueckner, University of Colonge
  • Prof Dieter Kelletat, University of Colonge