Assessing Sedimentary Detrital Pb Isotopes as a Dust Tracer in the Pacific Ocean

Abstract

Determining source regions and fluxes of aeolian dust deposition to the open ocean can provide insight into atmospheric circulation patterns, climate, and aridity, and may have implications for ocean productivity and carbon sequestration (

Humidification of Central Asia and equatorward shifts of westerly winds since the late Pliocene

“…Hence, we suggest that the circulation changes did not extend to this region or did not exert an important control on the Fe-Mn crust Pb isotope record. In this case, variations in Pb isotope composition in the crust can be used to derive the relative contributions of eolian dust sources based on source mixing 19 . Such changes could be recorded in the composition of crust CM3D18 either directly due to changes in its siliciclastic detrital fraction, or indirectly via changes in the hydrogenetic Fe-Mn oxide framework signature acquired from local seawater 16 .…”

Spatial and Temporal Trends in Mineral Dust Provenance in the South Pacific—Evidence From Mixing Models

“…In dust provenance studies, contributions from different source regions may be highly variable, and the isotopic compositions of individual source regions may also cover wide ranges (Erhardt et al., 2021; Pichat et al., 2014; Struve et al., 2020; Trudgill et al., 2020). As such, an approach which allows for the incorporation of these uncertainties in the modeling of dust mixtures represents a considerable increase in accuracy when compared to typical (often simple binary mixing) source apportionment techniques.…”

“…For example, dust from the New Zealand continental shelf shows highly radiogenic Pb isotope compositions, which fall outside of the mixing envelope (see Supporting Information). Recent work presented Pb isotope compositions for a location at the east coast from New Zealand's South Island (Erhardt et al, 2021) similar to the signal recovered from shelf and margin sediments offshore (Struve et al, 2020;Wengler et al, 2019), but different to any other terrestrial signal in this source region (Koffman et al, 2021). A highly radiogenic Pb isotope signal has been identified for intraplate volcanic rocks in New Zealand (Hoernle et al, 2006), but their Nd and Sr isotope compositions are inconsistent with available terrestrial (Koffman et al, 2021) and shallow-marine fine fraction data in the area (Struve et al, 2020;Wengler et al, 2019).…”

“…Bayesian isotopic mixing models such as MixSIAR were developed in the biological field to apportion prey contributions to the diet of predators using the isotopic composition of both predator and prey tissue (Parnell et al, 2010(Parnell et al, , 2013. MixSIAR has previously been applied to the source apportionment of Pb isotopes in pollution reconstructions (Longman et al, 2018) and to sediment provenance (Blake et al, 2018;Huangfu et al, 2020), but only very recently to dust provenance (Erhardt et al, 2021). This is despite the ability of such models to apportion absolute contributions from many sources.…”

“…The isotope compositions of neodymium (Nd), strontium (Sr), and lead (Pb) are powerful source tracers (Grousset & Biscaye, 2005). The size fraction of far-travelled dust (Delmonte et al, 2017;Kok et al, 2017;Mahowald et al, 2014) is also found in lithogenic marine sediments (Erhardt et al, 2021;van der Does et al, 2021;Wengler et al, 2019), which can be used to investigate dust sources and transport in ocean areas where atmospheric input is the exclusive (or at least predominant) source of lithogenic material in this size fraction. This approach has been applied to reconstruct dust provenance in the South Pacific showing a shift from predominantly Australian sources in Holocene times (Wengler et al, 2019) to a stronger contribution from South American sources during the LGM (Struve et al, 2020).…”