Geochemical fingerprints of glacially eroded bedrock from West Antarctica

Detrital thermochronology, radiogenic isotope systematics and trace element geochemistry in Late Holocene glacial-marine sediments

Patric Simões Pereira, Tina van de Flierdt, Sidney R. Hemming, Samantha J. Hammond, Gerhard Kuhn, Stefanie Brachfeld, Cathleen Doherty, Claus Dieter Hillenbrand

Research output: Contribution to journalReview articleResearchpeer-review

2 Citations (Scopus)

Abstract

Geochemical provenance studies of glacial-marine sediments provide a powerful approach to describe subglacial geology, sediment transport pathways, and past ice sheet dynamics. The marine-based West Antarctic Ice Sheet (WAIS) is considered highly vulnerable to ocean warming and sea level rise that is likely to cause its rapid and irreversible retreat. Studies of its past response to climate change are hence essential for projecting its future behaviour. The application of radiogenic and trace element provenance studies for past ice sheet reconstructions requires surveying the geographic variability of geochemical compositions of glaciomarine sediments. In this study, we characterize the provenance of the detrital fraction of 67 Late Holocene marine sediment samples collected off the Pacific margin of West Antarctica (60°W to 160°W), including 40Ar/39Ar ages of individual hornblende and biotite grains (>150 μm), as well as Sr and Nd isotope and trace element composition of the fine-grained (<63 μm) sediment fraction. Overall, this approach allows differentiating West Antarctica into five source regions: the Antarctic Peninsula, Bellingshausen Sea, Amundsen Sea, Wrigley Gulf-Hobbs Coast and Sulzberger Bay. Minor geochemical variability is found within each individual sector due to local variability in onland geology. 40Ar/39Ar ages of iceberg-rafted hornblende and biotite grains record primarily Carboniferous to Lates Quaternary ages (~0 to 380 Ma), with a notable age peak of ~100 Ma, associated with plutonic intrusions or deformation events during the mid-Cretaceous. Permian-Jurassic 40Ar/39Ar ages are widespread in the Amundsen Sea sector, marking episodes of large-volume magmatism along the long-lived continental margin. Metasedimentary rocks and Late Cenozoic alkali basalts in West Antarctica cannot be detected using detrital hornblende and biotite 40Ar/39Ar ages due to the absence or small grain-size (i.e. <150 μm) of these minerals in such rocks. These sources can however be readily recognized by their fine-grained geochemical composition. In addition, geographic trends in the provenance from proximal to distal sites provide insights into major sediment transport pathways. While the transport of fine-grained detritus follows bathymetric cross-shelf troughs, the distribution of iceberg-rafted grains shows influence by transport in the Antarctic Coastal Current. Our study provides the first systematic geochemical characterisation of sediment provenance off West Antarctica, and highlights the importance of combining multiple provenance approaches in different size fractions of glacial-marine sediments, and paves the way to investigate past WAIS dynamics.

Original languageEnglish
Pages (from-to)204-232
Number of pages29
JournalEarth-Science Reviews
Volume182
DOIs
StatePublished - 1 Jul 2018

Fingerprint

thermochronology
glacial deposit
marine sediment
provenance
bedrock
geochemistry
Holocene
trace element
isotope
ice sheet
hornblende
biotite
iceberg
sediment transport
geology
glaciomarine deposit
coastal current
alkali basalt
metasedimentary rock
sediment

Keywords

  • Geochemical provenance
  • Sediment transport pathways
  • Subglacial geology
  • West Antarctic Ice Sheet

Cite this

Simões Pereira, Patric ; van de Flierdt, Tina ; Hemming, Sidney R. ; Hammond, Samantha J. ; Kuhn, Gerhard ; Brachfeld, Stefanie ; Doherty, Cathleen ; Hillenbrand, Claus Dieter. / Geochemical fingerprints of glacially eroded bedrock from West Antarctica : Detrital thermochronology, radiogenic isotope systematics and trace element geochemistry in Late Holocene glacial-marine sediments. In: Earth-Science Reviews. 2018 ; Vol. 182. pp. 204-232.
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abstract = "Geochemical provenance studies of glacial-marine sediments provide a powerful approach to describe subglacial geology, sediment transport pathways, and past ice sheet dynamics. The marine-based West Antarctic Ice Sheet (WAIS) is considered highly vulnerable to ocean warming and sea level rise that is likely to cause its rapid and irreversible retreat. Studies of its past response to climate change are hence essential for projecting its future behaviour. The application of radiogenic and trace element provenance studies for past ice sheet reconstructions requires surveying the geographic variability of geochemical compositions of glaciomarine sediments. In this study, we characterize the provenance of the detrital fraction of 67 Late Holocene marine sediment samples collected off the Pacific margin of West Antarctica (60°W to 160°W), including 40Ar/39Ar ages of individual hornblende and biotite grains (>150 μm), as well as Sr and Nd isotope and trace element composition of the fine-grained (<63 μm) sediment fraction. Overall, this approach allows differentiating West Antarctica into five source regions: the Antarctic Peninsula, Bellingshausen Sea, Amundsen Sea, Wrigley Gulf-Hobbs Coast and Sulzberger Bay. Minor geochemical variability is found within each individual sector due to local variability in onland geology. 40Ar/39Ar ages of iceberg-rafted hornblende and biotite grains record primarily Carboniferous to Lates Quaternary ages (~0 to 380 Ma), with a notable age peak of ~100 Ma, associated with plutonic intrusions or deformation events during the mid-Cretaceous. Permian-Jurassic 40Ar/39Ar ages are widespread in the Amundsen Sea sector, marking episodes of large-volume magmatism along the long-lived continental margin. Metasedimentary rocks and Late Cenozoic alkali basalts in West Antarctica cannot be detected using detrital hornblende and biotite 40Ar/39Ar ages due to the absence or small grain-size (i.e. <150 μm) of these minerals in such rocks. These sources can however be readily recognized by their fine-grained geochemical composition. In addition, geographic trends in the provenance from proximal to distal sites provide insights into major sediment transport pathways. While the transport of fine-grained detritus follows bathymetric cross-shelf troughs, the distribution of iceberg-rafted grains shows influence by transport in the Antarctic Coastal Current. Our study provides the first systematic geochemical characterisation of sediment provenance off West Antarctica, and highlights the importance of combining multiple provenance approaches in different size fractions of glacial-marine sediments, and paves the way to investigate past WAIS dynamics.",
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Geochemical fingerprints of glacially eroded bedrock from West Antarctica : Detrital thermochronology, radiogenic isotope systematics and trace element geochemistry in Late Holocene glacial-marine sediments. / Simões Pereira, Patric; van de Flierdt, Tina; Hemming, Sidney R.; Hammond, Samantha J.; Kuhn, Gerhard; Brachfeld, Stefanie; Doherty, Cathleen; Hillenbrand, Claus Dieter.

In: Earth-Science Reviews, Vol. 182, 01.07.2018, p. 204-232.

Research output: Contribution to journalReview articleResearchpeer-review

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T2 - Detrital thermochronology, radiogenic isotope systematics and trace element geochemistry in Late Holocene glacial-marine sediments

AU - Simões Pereira, Patric

AU - van de Flierdt, Tina

AU - Hemming, Sidney R.

AU - Hammond, Samantha J.

AU - Kuhn, Gerhard

AU - Brachfeld, Stefanie

AU - Doherty, Cathleen

AU - Hillenbrand, Claus Dieter

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