{"refrec":{"BRefID":404409,"RR":"<b>Hättig, K.; Prokopiou, P.; Schouten, S.; van der Meer, M.T.J.</b> (2024). Large variability and 2H-depletion of Middle Miocene to Pleistocene alkenone hydrogen isotopes in the Equatorial Pacific reflect subsurface, low light haptophyte growth. <i>Org. Geochem. 196</i>: 104840. <a href=\"https://dx.doi.org/10.1016/j.orggeochem.2024.104840\" target=\"_blank\">https://dx.doi.org/10.1016/j.orggeochem.2024.104840</a>","BEntID":402200,"PublicFlag":1,"CheckedFlag":0,"wosflag":1,"vabbflag":0,"RefStringPartII":". <i>Org. Geochem. 196</i>: 104840. <a href=\"https://dx.doi.org/10.1016/j.orggeochem.2024.104840\" target=\"_blank\">https://dx.doi.org/10.1016/j.orggeochem.2024.104840</a>","DocTypID":8,"DocType":"Journal article","MarineFlag":0,"FreshFlag":0,"BrackishFlag":0,"TerrestrialFlag":0,"Authorstring":"Hättig, K.; Prokopiou, P.; Schouten, S.; van der Meer, M.T.J.","OrigTitleTranslFlag":0,"Authorstringtrunc":"Hättig, K. <i>et al.</i>","Englishabstract":"<span style=\"color:rgb(31,31,31);\">Hydrogen isotope ratios of haptophyte derived long-chain alkenones (δ</span><sup>2</sup><span style=\"color:rgb(31,31,31);\">H</span><sub>C37:2</sub><span style=\"color:rgb(31,31,31);\">) have shown to be a useful tool for reconstructing past isotopic compositions of surface seawater (δ</span><sup>2</sup><span style=\"color:rgb(31,31,31);\">H</span><sub>SSW</sub><span style=\"color:rgb(31,31,31);\">). The δ</span><sup>2</sup><span style=\"color:rgb(31,31,31);\">H</span><sub>SSW</sub><span style=\"color:rgb(31,31,31);\"> is related to global ice volume, sea surface salinity and the local hydrological cycle. Here, we present a hydrogen isotope record of alkenones spanning the last 14.5&nbsp;Ma from IODP site U1338 in the east equatorial Pacific. The alkenone-based reconstructed δ</span><sup>2</sup><span style=\"color:rgb(31,31,31);\">H</span><sub>SSW</sub><span style=\"color:rgb(31,31,31);\"> is substantially more negative and variable than reconstructed δ</span><sup>2</sup><span style=\"color:rgb(31,31,31);\">H</span><sub>SSW</sub><span style=\"color:rgb(31,31,31);\"> based on published oxygen isotopes of coccolith carbonates. This suggests that factors other than the isotopic composition of seawater affect the hydrogen isotopic composition of alkenones. The relatively negative and highly variable δ</span><sup>2</sup><span style=\"color:rgb(31,31,31);\">H</span><sub>C37:2</sub><span style=\"color:rgb(31,31,31);\"> values are in line with published modern observations on alkenones from suspended particulate matter in the equatorial and north Pacific, with the highest values at relatively high light conditions at the surface and the lowest values at higher water depth and relatively low light conditions. This suggests that the relatively negative and highly variable δ</span><sup>2</sup><span style=\"color:rgb(31,31,31);\">H</span><sub>C37:2</sub><span style=\"color:rgb(31,31,31);\"> values in these Middle Miocene to Pleistocene sediments are likely derived from haptophytes growing below the sea surface under variable low light conditions. In regions where the contribution of alkenones from subsurface production, due to high subsurface nutrients, at low light intensities to the sediment is relatively high the δ</span><sup>2</sup><span style=\"color:rgb(31,31,31);\">H</span><sub>C37:2</sub><span style=\"color:rgb(31,31,31);\"> has to be interpreted with care as a proxy for δ</span><sup>2</sup><span style=\"color:rgb(31,31,31);\">H</span><sub>SSW</sub><span style=\"color:rgb(31,31,31);\">.</span>","AbstractOtherLang":null,"BibLvlCode":"AS","StandardTitle":"Large variability and 2H-depletion of Middle Miocene to Pleistocene alkenone hydrogen isotopes in the Equatorial Pacific reflect subsurface, low light haptophyte growth","OrigTitleLangCode":"en","OrigTitleLangCodeExtended":"eng","OrigTitleLangID":15,"DateLastModified":{"date":"2026-06-10 01:32:59.511835","timezone_type":1,"timezone":"+02:00"},"UserAccessRight":null,"UserAccID":null,"AuthorKeywords":"<p style=\"margin-left:0px;\">Alkenones; Hydrogen isotopes; Carbon isotopes; Equatorial Pacific","OtherDescriptors":null,"Notes":null,"AnaPub":2024,"MonPub":null,"DateUpdate":"2024-11-26","DateCreate":"2024-11-26","SecASFANote":null,"ConfID":null,"PeerRev":1,"VlizCoreFlag":1,"WoScode":null,"VABBcode":null,"OpenAcc":1,"DOI":"10.1016/j.orggeochem.2024.104840"},"refs":null,"anarec":{"AnaID":404409,"PubliDate":2024,"Pagination":"104840","XtraPublOfAnaID":null,"ISBN":null,"Volume":"196","Issue":null,"BRefMon":null,"BRefMonRR":null,"BRefXtra":null,"BRefXtraRR":null,"SerBRefID":111331,"SerRR":"Organic Geochemistry. 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