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Authigenic and Detrital Carbonate Nd Isotope Records Reflect Pulses of Detrital Material Input to the Labrador Sea During the Heinrich Stadials (2023)

Filippova, Alexandra ; Frank, Martin ; Kienast, Markus ; [et al.]

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Publication Date: 2023-07-19

Description: Limited constraints on the variability of the deep‐water production in the Labrador Sea complicate reconstructions of the strength of the Atlantic Meridional Overturning Circulation (AMOC) during the Late Quaternary. Large volumes of detrital carbonates were repeatedly deposited in the Labrador Sea during the last 32 kyr, potentially affecting radiogenic Nd isotope signatures. To investigate this the Nd isotope compositions of deep and intermediate waters were extracted from the authigenic Fe‐Mn oxyhydroxide fraction, foraminiferal coatings, the residual silicates and leachates of dolostone grains. We provide a first order estimation of Nd release via dissolution of detrital carbonates and its contribution to the authigenic ԑNd signatures in the Labrador Sea. During the Last Glacial Maximum the Nd isotope signatures in the Labrador Sea would allow active water mass mixing with more radiogenic ɛNd values (−12.6 and −14) prevailing in its eastern part whereas less radiogenic values (ɛNd ∼ −18.4) were found on the western Labrador slope. The deposition of detrital carbonates during Heinrich stadials (2,1) was accompanied by negative detrital and authigenic Nd isotope excursions (ɛNd ∼ −31) that were likely controlled by dissolution of dolostone or dolostone associated mineral inclusions. This highly unradiogenic signal dominated the authigenic phases and individual water masses in the Labrador Sea, serving as potential source of highly unradiogenic Nd to the North Atlantic region, while exported southward. The Holocene authigenic ɛNd signatures of the coatings and leachates significantly differed from those of the detrital silicates, approaching modern bottom water mass signatures during the Late Holocene.

Description: Plain Language Summary: The Labrador Sea is an important region for deep water formation and for the ocean circulation in the Atlantic region. Over the last 32 thousand years, numerous discharges from melting glaciers added freshwater to the Labrador Sea which could help understand the future effects of current melting glaciers. This information is necessary to better constrain climate predictions in order to gauge the effects on the Global Ocean Water Circulation. However, past deep water production in the Labrador is still poorly constrained, complicating reconstruction of the Atlantic Meridional Overturning Circulation on different timescales. In this study we investigated changes in deep and intermediate water mass circulation patterns over the last 32 kyr based on the radiogenic Nd isotope compositions that serve as a water mass circulation proxy. Analysis of four marine sediment cores show that the deposition of large volumes of detrital carbonates during studied period had a large effect on the recorded in the sediment column signals. New data suggest active water mass circulation during the maximum extent of glacial ice sheets. The modern day ocean circulation patterns have emerged during the Late Holocene (6 ka).

Description: Key Points: Estimation of Nd release via dissolution of detrital carbonates and its contribution to the authigenic ԑNd signatures in the Labrador Sea. Dissolution of detrital dolostones in the water column during Heinrich stadials at least partially controlled ɛNd signatures. During the LGM generally more radiogenic signatures possibly indicate active water mass advection and mixing in the Labrador Sea.

Description: GEOMAR Helmholtz‐Zentrum für Ozeanforschung Kiel http://dx.doi.org/10.13039/501100003153

Description: Kiel University

Description: https://doi.org/10.1594/PANGAEA.952659

Keywords: ddc:551.9 ; Labrador Sea ; Late Quaternary ; Paleoceanography ; neodymium isotopes ; dolostone ; AMOC ; carbonate dissolution ; Heinrich stadials

Language: English

Type: doc-type:article

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Rare earth element (REE) concentrations of full water column profiles from the Caribbean, the Gulf of Mexico, and the Florida Straits, and surface waters close to the mouth of the Orinoco River during METEOR cruise M78/1 (2016)

Osborne, Anne H ; Haley, Brian A ; Hathorne, Ed C ; [et al.]

PANGAEA

In: Supplement to: Osborne, Anne H; Haley, Brian A; Hathorne, Ed C; Plancherel, Yves; Frank, Martin (2015): Rare earth element distribution in Caribbean seawater: Continental inputs versus lateral transport of distinct REE compositions in subsurface water masses. Marine Chemistry, 177, 172-183, https://doi.org/10.1016/j.marchem.2015.03.013

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Publication Date: 2023-12-01

Description: REE concentrations in filtered seawater collected during research cruise M78/1, February and March 2009 and CTD data (potential temperature, salinity, potential density and oxygen concentration) and water mass assignment for the same samples.

Keywords: 162-1; 164-1; 166-1; 182-1; 194-13; 200-2; 220-1; 222-1; 226-3; 236-1; 246-1; 247-1; 249-1; Analytical method; Boca Grande Orinoco; BUCKET; Bucket water sampling; Cerium; Cerium anomaly; Comment; CTD/Rosette; CTD-RO; Date/Time of event; Density, sigma-theta (0); DEPTH, water; Description; Dysprosium; Dysprosium/Erbium ratio; E. Tobago, Prospector Slope; Elevation of event; Erbium; Europium; Event label; Florida Straits; Gadolinium; Heavy rare-earth elements/light rare-earth elements ratio; Holmium; Isla de Blanquilla; Lanthanum; Latitude of event; Longitude of event; Lutetium; M78/1; M78/1_162-1; M78/1_164-1; M78/1_166-1; M78/1_182-1; M78/1_194-13; M78/1_200-2; M78/1_220-1; M78/1_222-1; M78/1_226-3; M78/1_236-1; M78/1_246-1; M78/1_247-1; M78/1_249-1; Meteor (1986); Middle rare-earth elements anomaly; Mississippi Profile Station 2; Neodymium; Oxygen; Plankton station 1; Plankton station 2; Plankton station 4; Plankton station 7; Praseodymium; Salinity; Samarium; Temperature, water, potential; Terbium; Thulium; W. Yucatan Channel; W-Florida Slope; Ytterbium; Yttrium

Type: Dataset

Format: text/tab-separated-values, 2158 data points

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Persistent Provenance of South Asian Monsoon‐Induced Silicate Weathering Over the Past 27 Million Years (2021)

Ali, Sajid ; Hathorne, Ed C. ; Frank, Martin

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Publication Date: 2021-07-21

Description: The development of the South Asian monsoon (SAM) and Himalaya‐Tibetan Plateau uplift were closely intertwined with some studies suggesting that uplift initiated the monsoon whereas others link tectonics with monsoon‐controlled exhumation. Silicate weathering controls atmospheric CO2 on geological timescales resulting in a large potential for monsoon strength and the Himalayan orogeny to influence global climate but detailed records of SAM‐induced weathering on million year (Myr) timescales are lacking. Here, we present radiogenic Sr, Nd, and Pb isotope compositions of clay minerals produced by silicate weathering and transported to the central Bay of Bengal. The radiogenic isotope data exhibit a relatively small range and demonstrate a remarkably consistent mixture of sources dominated by Himalayan rocks and the Indo‐Burman ranges, which consist of sediments derived from the Himalayas. This suggests that the spatial pattern of regional weathering, which today is highest in the regions of strongest monsoon rains, has persisted in a similar form for the last 27 Myrs. A pronounced increase in primary clay mineral abundance (from 9% to 22%) coincident with global cooling 13.9 Myrs ago points to a shift in the weathering regime given that the clay provenance did not change dramatically. Relatively weaker chemical weathering intensity during the mid and late Miocene cooling suggests increased aridity and changes in the large scale atmospheric circulation in the SAM domain. The establishment of the dry winter monsoon season during the mid and late Miocene may have caused this shift in the weathering regime and can reconcile much of the contrasting evidence for SAM initiation.

Description: Key Points: Relatively stable mixture of source rocks weathered to clays over the past 27 Myrs Pronounced increase in primary clay minerals occurred 13.9 Myrs ago Shift in weathering regime possibly result of winter monsoon dry season development

Keywords: 551.3 ; Bay of Bengal ; clay minerals ; radiogenic Sr, Nd, Pb isotopes ; Silicate silicate weathering ; South Asian monsoon

Type: article

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Neodymium isotopes trace marine provenance of Arctic sea ice (2022)

Laukert, Georgi ; Peeken, Ilka ; Bauch, Dorothea ; [et al.]

European Association of Geochemistry

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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

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South Asian monsoon history over the past 60 kyr recorded by radiogenic isotopes and clay mineral assemblages in the Andaman Sea (2015)

Ali, Sajid ; Hathorne, Ed C. ; Frank, Martin ; [et al.]

John Wiley & Sons

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Publication Date: 2022-05-26

Description: Author Posting. © American Geophysical Union, 2015. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry, Geophysics, Geosystems 16 (2015): 505–521, doi:10.1002/2014GC005586.

Description: The Late Quaternary variability of the South Asian (or Indian) monsoon has been linked with glacial-interglacial and millennial scale climatic changes but past rainfall intensity in the river catchments draining into the Andaman Sea remains poorly constrained. Here we use radiogenic Sr, Nd, and Pb isotope compositions of the detrital clay-size fraction and clay mineral assemblages obtained from sediment core NGHP Site 17 in the Andaman Sea to reconstruct the variability of the South Asian monsoon during the past 60 kyr. Over this time interval εNd values changed little, generally oscillating between −7.3 and −5.3 and the Pb isotope signatures are essentially invariable, which is in contrast to a record located further northeast in the Andaman Sea. This indicates that the source of the detrital clays did not change significantly during the last glacial and deglaciation suggesting the monsoon was spatially stable. The most likely source region is the Irrawaddy river catchment including the Indo-Burman Ranges with a possible minor contribution from the Andaman Islands. High smectite/(illite + chlorite) ratios (up to 14), as well as low 87Sr/86Sr ratios (0.711) for the Holocene period indicate enhanced chemical weathering and a stronger South Asian monsoon compared to marine oxygen isotope stages 2 and 3. Short, smectite-poor intervals exhibit markedly radiogenic Sr isotope compositions and document weakening of the South Asian monsoon, which may have been linked to short-term northern Atlantic climate variability on millennial time scales.

Description: Part of this work was funded by German Science Foundation (DFG), grant HA5751/3-1.

Description: 2015-08-24

Keywords: Marine sediments ; Clay minerals ; Radiogenic isotopes ; Andaman Sea ; South Asian monsoon

Repository Name: Woods Hole Open Access Server

Type: Article

Format: application/msword

Format: application/pdf

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