GLORIA

GEOMAR Library Ocean Research Information Access

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Transpolar Drift  (1)
  • ddc:551.302  (1)
  • 2020-2023  (2)
  • 1
    facet.materialart.
    Unknown
    Enhanced Late Miocene Chemical Weathering and Altered Precipitation Patterns in the Watersheds of the Bay of Bengal Recorded by Detrital Clay Radiogenic Isotopes (2021)
    Details
    Publication Date: 2022-03-23
    Description: The late Miocene was a period of declining CO2 levels and extensive environmental changes, which likely had a large impact on monsoon strength as well as on the weathering and erosion intensity in the South Asian Monsoon domain. To improve our understanding of these feedback systems, detrital clays from the southern Bay of Bengal (International Ocean Discovery Program Site U1443) were analyzed for the radiogenic isotope compositions of Sr, Nd, and Pb to reconstruct changes in sediment provenance and weathering regime related to South Asian Monsoon rainfall from 9 to 5 Ma. The 100 kyr resolution late Miocene to earliest Pliocene record suggests overall low variability in the provenance of clays deposited on the Ninetyeast Ridge. However, at 7.3 Ma, Nd and Pb isotope compositions indicate a switch to an increased relative contribution from the Irrawaddy River (by ∼10%). This shift occurred during the global benthic δ13C decline, and we suggest that global cooling and increasing aridity resulted in an eastward shift of precipitation patterns leading to a more focused erosion of the Indo‐Burman Ranges. Sr isotope compositions were decoupled from Nd and Pb isotope signatures and became more radiogenic between 6 and 5 Ma. Grassland expansion generating thick, easily weatherable soils may have led to an environment supporting intense chemical weathering, which is likely responsible for the elevated detrital clay 87Sr/86Sr ratios during this time. This change in Sr isotope signatures may also have contributed to the late Miocene increase of the global seawater Sr isotope composition.
    Description: Plain Language Summary: The South Asian or Indian monsoon affects the lives of billions. Through the erosion and weathering of rocks, the monsoon also has the potential to remove carbon dioxide from the atmosphere through increased weathering in the region including the Himalaya Mountains. The late Miocene, between 9 and 5 million years ago, was a period of global cooling and proliferation of grasslands in different regions including South Asia. Here, we examine the composition of clays formed by rock weathering during the late Miocene to determine their source region around the Bay of Bengal. The results suggest a generally stable mixture of sources with the strongest sources being regions with the highest monsoon rainfall today. We identify slight changes in the mixture of sources, which accompany a global change in carbon cycling, highlighting the role monsoon climate likely played in these changes. Toward the end of the Miocene, we identify a change in the Sr isotopes, which was not caused by source changes but by the strength of the rock weathering. This change has been observed in global records and it seems likely that it was driven by rock weathering in the South Asian Monsoon region.
    Description: Highlights: Radiogenic isotope compositions of detrital clays from the Bay of Bengal indicate a generally stable provenance from 9 to 5 Ma. A step change in Nd and Pb isotope compositions at ∼7.3 Ma reflects a climatically driven eastward shift in precipitation patterns resulting in enhanced erosion of the Indo‐Burman Ranges. Elevated 87Sr/86Sr between 6 and 5 Ma was likely related to increased chemical weathering caused by thicker soils and by C4 plant expansion.
    Description: DFG
    Description: ANR
    Description: IODP
    Keywords: ddc:551.302 ; ddc:551.701
    Language: English
    Type: doc-type:article
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    CITATION GEO-LEO
  • 2
    facet.materialart.
    Unknown
    Neodymium isotopes trace marine provenance of Arctic sea ice (2022)
    European Association of Geochemistry
    Details
    Publication Date: 2022-10-12
    Description: © The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Laukert, G., Peeken, I., Bauch, D., Krumpen, T., Hathorne, E. C., Werner, K., Gutjahr, M., & Frank, M. Neodymium isotopes trace marine provenance of Arctic sea ice. Geochemical Perspectives Letters, 22, (2022): 10–15, https://doi.org/10.7185/geochemlet.2220.
    Description: Radiogenic neodymium (Nd) isotopes (ɛNd) have the potential to serve as a geochemical tracer of the marine origin of Arctic sea ice. This capability results from pronounced ɛNd differences between the distinct marine and riverine sources, which feed the surface waters from which the ice forms. The first dissolved Nd isotope and rare earth element (REE) concentration data obtained from Arctic sea ice collected across the Fram Strait during RV Polarstern cruise PS85 in 2014 confirm the incorporation and preservation of the parental surface seawater ɛNd signatures despite efficient REE rejection. The large ɛNd variability between ice floes and within sea ice cores (−32 to −10) reflects changes in water mass distribution during ice growth and drift from the central Arctic Ocean to Fram Strait. In addition to the parental seawater composition, our new approach facilitates the reconstruction of the transfer of matter between the atmosphere, the sea ice and the ocean. In conjunction with satellite-derived drift trajectories, we enable a more accurate assessment of sea ice origin and spatiotemporal evolution, benefiting studies of sea ice biology, biodiversity, and biogeochemistry.
    Description: We acknowledge financial support by the German Federal Ministry of Education and Research (Grant BMBF 03F0776 and 03G0833) and the Ministry of Education and Science of the Russian Federation. GL also acknowledges financial support from the Ocean Frontier Institute through an award from the Canada First Research Excellence Fund.
    Keywords: Arctic Ocean ; Fram Strait ; Greenland ; Transpolar Drift ; Siberian Shelf ; sea ice ; snow ; seawater ; provenance tracers ; neodymium isotopes ; oxygen isotopes ; rare earth elements ; water masses ; circulation
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    PAPER (OA)
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...