Volcanic controls on smectite authigenesis and paleoclimate signals across the Paleocene-Eocene Thermal Maximum (PETM) sedimentary record from the Norwegian-Greenland Sea
Abstract
Clay mineral records provide archives of continental weathering and paleohydrology, but these paleoclimate signals can be obscured by authigenic or diagenetic overprinting. International Ocean Discovery Program Expedition 396 drilled an expanded Paleocene–Eocene Thermal Maximum (PETM) succession from the Modgunn Hydrothermal Vent Complex on the Norwegian Continental Margin, a setting characterised by volcanic ash input from the North Atlantic Igneous Province. Three lithological units record distinct clay mineral assemblages reflecting shifts in the relative contributions of detrital and authigenic material across the Late Paleocene to Early Eocene. Smectite is the dominant clay mineral throughout, with subordinate illite, kaolinite, and chlorite. Potential post-deposition transformation of volcanic ash into authigenic smectite complicates the use of clay mineralogy as a paleoclimate and continental weathering proxy at this site. Using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and rare earth element analysis, we discriminate detrital smectite reflecting continental weathering from authigenic smectite formed through in situ alteration of pyroclastic material. In the Late Paleocene and earliest Eocene, the clay-sized fraction is dominated by Al-rich, pedogenic montmorillonite-beidellite smectite, alongside other detrital clay minerals, consistent with warm, seasonally humid weathering conditions. Conversely, in the upper PETM, pervasive in situ alteration of volcanic ash produced Mg-rich authigenic smectite, driving a two- to three-fold enrichment in bulk smectite content and overprinting paleoclimate signals despite terrigenous input. This PETM record demonstrates the importance of establishing clay mineral provenance and authigenic processes before paleoenvironmental interpretation, with implications for clay-based paleoclimate records across volcanically influenced settings during the Early Paleogene.
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BibTeX
@article{turton2026volcanic,
title = {{Volcanic controls on smectite authigenesis and paleoclimate signals across the Paleocene-Eocene Thermal Maximum (PETM) sedimentary record from the Norwegian-Greenland Sea}},
author = {Nikita A. Turton and Pierre Pellenard and Weimu Xu},
journal = {Palaeogeography, Palaeoclimatology, Palaeoecology},
year = {2026},
month = sep,
doi = {10.1016/j.palaeo.2026.114231},
url = {https://ube.hal.science/hal-05757256v1},
note = {CC BY},
}
RIS
TY - JOUR
TI - Volcanic controls on smectite authigenesis and paleoclimate signals across the Paleocene-Eocene Thermal Maximum (PETM) sedimentary record from the Norwegian-Greenland Sea
AU - Nikita A. Turton
AU - Pierre Pellenard
AU - Weimu Xu
PY - 2026
DA - 2026/09/21
JO - Palaeogeography, Palaeoclimatology, Palaeoecology
DO - 10.1016/j.palaeo.2026.114231
UR - https://ube.hal.science/hal-05757256v1
AB - Clay mineral records provide archives of continental weathering and paleohydrology, but these paleoclimate signals can be obscured by authigenic or diagenetic overprinting. International Ocean Discovery Program Expedition 396 drilled an expanded Paleocene–Eocene Thermal Maximum (PETM) succession from the Modgunn Hydrothermal Vent Complex on the Norwegian Continental Margin, a setting characterised by volcanic ash input from the North Atlantic Igneous Province. Three lithological units record distinct clay mineral assemblages reflecting shifts in the relative contributions of detrital and authigenic material across the Late Paleocene to Early Eocene. Smectite is the dominant clay mineral throughout, with subordinate illite, kaolinite, and chlorite. Potential post-deposition transformation of volcanic ash into authigenic smectite complicates the use of clay mineralogy as a paleoclimate and continental weathering proxy at this site. Using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and rare earth element analysis, we discriminate detrital smectite reflecting continental weathering from authigenic smectite formed through in situ alteration of pyroclastic material. In the Late Paleocene and earliest Eocene, the clay-sized fraction is dominated by Al-rich, pedogenic montmorillonite-beidellite smectite, alongside other detrital clay minerals, consistent with warm, seasonally humid weathering conditions. Conversely, in the upper PETM, pervasive in situ alteration of volcanic ash produced Mg-rich authigenic smectite, driving a two- to three-fold enrichment in bulk smectite content and overprinting paleoclimate signals despite terrigenous input. This PETM record demonstrates the importance of establishing clay mineral provenance and authigenic processes before paleoenvironmental interpretation, with implications for clay-based paleoclimate records across volcanically influenced settings during the Early Paleogene.
SN - 0031-0182
SN - 1872-616X
ER -