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dc.contributor.authorDhuime, Bruno
dc.contributor.authorHawkesworth, Chris J.
dc.contributor.authorDelavault, Hélène
dc.contributor.authorCawood, Peter A.
dc.date.accessioned2018-06-06T23:33:31Z
dc.date.available2018-06-06T23:33:31Z
dc.date.issued2017-07-15
dc.identifier.citationDhuime , B , Hawkesworth , C J , Delavault , H & Cawood , P A 2017 , ' Continental growth seen through the sedimentary record ' , Sedimentary Geology , vol. 357 , pp. 16-32 . https://doi.org/10.1016/j.sedgeo.2017.06.001en
dc.identifier.issn0037-0738
dc.identifier.otherPURE: 250198215
dc.identifier.otherPURE UUID: 313a3f1f-caf6-4662-93ca-975298fa7f96
dc.identifier.otherRIS: urn:957F72AAAA81B928961AC41E87A04672
dc.identifier.otherScopus: 85020479937
dc.identifier.otherWOS: 000406730500002
dc.identifier.urihttp://hdl.handle.net/10023/13787
dc.descriptionThis work was supported by the Natural Environment Research Council [NERC grant NE/K008862/1], the Leverhulme Trust [grant RPG-2015–422], and the Australian Research Council [grant FL160100168].en
dc.description.abstractSedimentary rocks and detrital minerals sample large areas of the continental crust, and they are increasingly seen as a reliable archive for its global evolution. This study presents two approaches to model the growth of the continental crust through the sedimentary archive. The first builds on the variations in U-Pb, Hf and O isotopes in global databases of detrital zircons. We show that uncertainty in the Hf isotope composition of the mantle reservoir from which new crust separated, in the 176Lu/177Hf ratio of that new crust, and in the contribution in the databases of zircons that experienced ancient Pb loss(es), adds some uncertainty to the individual Hf model ages, but not to the overall shape of the calculated continental growth curves. The second approach is based on the variation of Nd isotopes in 645 worldwide fine-grained continental sedimentary rocks with different deposition ages, which requires a correction of the bias induced by preferential erosion of younger rocks through an erosion parameter referred to as K. This dimensionless parameter relates the proportions of younger to older source rocks in the sediment, to the proportions of younger to older source rocks present in the crust from which the sediment was derived. We suggest that a Hadean/Archaean value of K = 1 (i.e., no preferential erosion), and that post-Archaean values of K = 4–6, may be reasonable for the global Earth system. Models built on the detrital zircon and the fine-grained sediment records independently suggest that at least 65% of the present volume of continental crust was established by 3 Ga. The continental crust has been generated continuously, but with a marked decrease in the growth rate at ~ 3 Ga. The period from > 4 Ga to ~ 3 Ga is characterised by relatively high net rates of continental growth (2.9–3.4 km3 yr−1 on average), which are similar to the rates at which new crust is generated (and destroyed) at the present time. Net growth rates are much lower since 3 Ga (0.6–0.9 km3 yr−1 on average), which can be attributed to higher rates of destruction of continental crust. The change in slope in the continental growth curve at ~ 3 Ga is taken to indicate a global change in the way bulk crust was generated and preserved, and this change has been linked to the onset of subduction-driven plate tectonics. At least 100% of the present volume of the continental crust has been destroyed and recycled back into the mantle since ~ 3 Ga, and this time marks a transition in the average composition of new continental crust. Continental crust generated before 3 Ga was on average mafic, dense, relatively thin (< 20 km) and therefore different from the calc-alkaline andesitic crust that dominates the continental record today. Continental crust that formed after 3 Ga gradually became more intermediate in composition, buoyant and thicker. The increase in crustal thickness is accompanied by increasing rates of crustal reworking and increasing input of sediment to the ocean. These changes may have been accommodated by a change in lithospheric strength at around 3 Ga, as it became strong enough to support high-relief crust. This time period therefore indicates when significant volumes of continental crust started to become emergent and were available for erosion and weathering, thus impacting on the composition of the atmosphere and the oceans.
dc.format.extent17
dc.language.isoeng
dc.relation.ispartofSedimentary Geologyen
dc.rights© 2017 Elsevier Ltd. All rights reserved. This work has been made available online in accordance with the publisher’s policies. This is the author created, accepted version manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at https://doi.org/10.1016/j.sedgeo.2017.06.001en
dc.subjectContinental growthen
dc.subjectHadean/Archaeanen
dc.subjectPlate tectonicsen
dc.subjectZirconen
dc.subjectShaleen
dc.subjectU-Pb/Hf/Nd/O isotopesen
dc.subjectGE Environmental Sciencesen
dc.subjectQE Geologyen
dc.subjectNDASen
dc.subjectBDCen
dc.subject.lccGEen
dc.subject.lccQEen
dc.titleContinental growth seen through the sedimentary recorden
dc.typeJournal articleen
dc.description.versionPostprinten
dc.contributor.institutionUniversity of St Andrews.School of Earth & Environmental Sciencesen
dc.contributor.institutionUniversity of St Andrews.School of Geography and Geosciencesen
dc.contributor.institutionUniversity of St Andrews.Scottish Oceans Instituteen
dc.contributor.institutionUniversity of St Andrews.St Andrews Isotope Geochemistryen
dc.identifier.doihttps://doi.org/10.1016/j.sedgeo.2017.06.001
dc.description.statusPeer revieweden
dc.date.embargoedUntil2018-06-06


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