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Dynamics of pedogenic carbonate growth in the monsoonal tropical domain
  • +7
  • Alexis Licht,
  • Julia R Kelson,
  • Shelly J. Bergel,
  • Andrew Schauer,
  • Sierra V Petersen,
  • Ashika Capirala,
  • Katharine W Huntington,
  • Guillaume Dupont-Nivet,
  • Zaw Win,
  • Day Wa Aung
Alexis Licht
CEREGE, University of Aix-Marseille, France

Corresponding Author:[email protected]

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Julia R Kelson
Department of Earth and Environmental Sciences, University of Michigan,
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Shelly J. Bergel
University of Texas at Austin
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Andrew Schauer
University of Washington
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Sierra V Petersen
University of Michigan-Ann Arbor
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Ashika Capirala
University of Washington
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Katharine W Huntington
University of Washington, Seattle, WA
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Guillaume Dupont-Nivet
French National Centre for Scientific Research (CNRS)
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Zaw Win
Department of Geology, University of Shwebo
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Day Wa Aung
Department of Geology, University of Yangon
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Abstract

Pedogenic carbonate is widespread at mid latitudes where combined warm and dry conditions favor soil carbonate growth from spring to fall. The mechanisms and tempo of pedogenic carbonate formation are more ambiguous in the tropics, where longer periods of soil water saturation and higher soil respiration enhance calcite dissolution. This paper provides bulk and clumped isotope values from Quaternary and Miocene pedogenic carbonates in the tropical monsoonal domain of Myanmar where annual rainfall reaches up to 1700 mm. We show that carbonate growth in Myanmar is delayed to the coldest months of the year by sustained rainfall from mid spring to late fall. We propose that high soil moisture year-round in the tropical domain makes carbonate growth more episodic than in temperate ecosystems, and particularly sensitive to the seasonal distribution of rainfall. This sensitivity is also enhanced by high winter temperatures, allowing carbonate growth to occur outside the warmest months of the year. This high sensitivity is expected to be more prominent in the geological record during times with higher temperatures and greater expansion of the tropical realm. The winter bias in TD47 values found in Burmese soils, unique for pedogenic carbonates, constitute a potential signature for past tropical monsoonal (warm summer-wet) climates in paleosols, and are also found in our Miocene samples.