Sulfur isotope evidence from peridotite enclaves in southern West Greenland for recycling of surface material into Eoarchean depleted mantle domains
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Sulfur isotope evidence from peridotite enclaves in southern West Greenland for recycling of surface material into Eoarchean depleted mantle domains. / Lewis, J. A.; Hoffmann, J. E.; Schwarzenbach, E. M.; Strauss, H.; Li, C.; Münker, C.; Rosing, M. T.
In: Chemical Geology, Vol. 633, 121568, 2023.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - Sulfur isotope evidence from peridotite enclaves in southern West Greenland for recycling of surface material into Eoarchean depleted mantle domains
AU - Lewis, J. A.
AU - Hoffmann, J. E.
AU - Schwarzenbach, E. M.
AU - Strauss, H.
AU - Li, C.
AU - Münker, C.
AU - Rosing, M. T.
N1 - Publisher Copyright: © 2023 Elsevier B.V.
PY - 2023
Y1 - 2023
N2 - Eoarchean peridotite enclaves found in southern West Greenland's Itsaq Gneiss Complex (IGC) represent an important and valuable record of Earth's early geodynamic history. However, the origins of these rocks and the processes acting on them in the Eoarchean remain a subject of debate. Some researchers have proposed that these peridotites represent the oldest preserved pieces of Earth's mantle, while others have suggested that they represent ultramafic cumulates. Similarly, the geodynamic context in which they formed and were emplaced is subject to multiple interpretations. Some researchers argue that only vertical tectonic processes operated in the Eoarchean and others contend that these peridotites were embedded in the crust by horizontal tectonic processes. We present multiple sulfur isotope data from IGC peridotite enclaves, offering new insights into these rocks' origins and tectonic processes in the early Earth. Generally small but significant nonzero Δ33S values of 0.04 to 0.21‰ were detected in the studied peridotites. Peridotites with almost no petrographic signs of metasomatic alteration have on average slightly higher Δ33S values, whereas peridotites with clear petrographic and geochemical signatures of melt metasomatism were found to have slightly lower Δ33S values. These Δ33S values point to incorporation of surface-derived material of Archean age or older. Correlations between Δ33S values and previously published major and trace element data support the view that these peridotites were subject to hydrous melt depletion of incompatible elements, followed by variable melt re-enrichment. Notably, a distinct correlation also exists between previously published Hf isotope data and Δ33S values, indicating a depleted mantle source for melt percolating through the peridotites in the Eoarchean. The sulfur isotope data demonstrate that these processes included the introduction of surface-derived sulfur, pointing to an early onset of crustal recycling. These findings point to the existence of depleted mantle domains in the Hadean and suggest that crustal recycling processes operated during the Eoarchean or earlier.
AB - Eoarchean peridotite enclaves found in southern West Greenland's Itsaq Gneiss Complex (IGC) represent an important and valuable record of Earth's early geodynamic history. However, the origins of these rocks and the processes acting on them in the Eoarchean remain a subject of debate. Some researchers have proposed that these peridotites represent the oldest preserved pieces of Earth's mantle, while others have suggested that they represent ultramafic cumulates. Similarly, the geodynamic context in which they formed and were emplaced is subject to multiple interpretations. Some researchers argue that only vertical tectonic processes operated in the Eoarchean and others contend that these peridotites were embedded in the crust by horizontal tectonic processes. We present multiple sulfur isotope data from IGC peridotite enclaves, offering new insights into these rocks' origins and tectonic processes in the early Earth. Generally small but significant nonzero Δ33S values of 0.04 to 0.21‰ were detected in the studied peridotites. Peridotites with almost no petrographic signs of metasomatic alteration have on average slightly higher Δ33S values, whereas peridotites with clear petrographic and geochemical signatures of melt metasomatism were found to have slightly lower Δ33S values. These Δ33S values point to incorporation of surface-derived material of Archean age or older. Correlations between Δ33S values and previously published major and trace element data support the view that these peridotites were subject to hydrous melt depletion of incompatible elements, followed by variable melt re-enrichment. Notably, a distinct correlation also exists between previously published Hf isotope data and Δ33S values, indicating a depleted mantle source for melt percolating through the peridotites in the Eoarchean. The sulfur isotope data demonstrate that these processes included the introduction of surface-derived sulfur, pointing to an early onset of crustal recycling. These findings point to the existence of depleted mantle domains in the Hadean and suggest that crustal recycling processes operated during the Eoarchean or earlier.
KW - Eoarchean
KW - Hafnium isotopes
KW - Isua, MIF-S
KW - Mantle peridotites
KW - Sulfur isotopes
U2 - 10.1016/j.chemgeo.2023.121568
DO - 10.1016/j.chemgeo.2023.121568
M3 - Journal article
AN - SCOPUS:85163300651
VL - 633
JO - Chemical Geology
JF - Chemical Geology
SN - 0009-2541
M1 - 121568
ER -
ID: 361546160