Projects per year
Abstract
Generation of continental crust during early Earth was a vital step towards stabilizing the cratonic lithosphere. How and when this happened is, however, still poorly understood. Radiogenic isotope data from the oldest crust, and minerals therein, provide a unique insight into the timing and processes that operated during Earth's earliest evolution. Using combined zircon U-Pb, O and Lu-Hf isotope data from a glacial stream-sediment within the Isukasia (Isua) terrane of southern West Greenland, we argue for an isolated mantle source for the ca. 1.3 Ga of initial stages of crustal growth in the North Atlantic Craton. Zircon Hf isotope data between 3939 and 2950 Ma yield strikingly homogeneous, near chondritic signatures, with the few analyses that deviate slightly being indicative of ancient Pb-loss. Combined with published data from carefully selected and well-characterized ca. 3.9–2.6 Ga magmatic rocks of the NAC, almost no indications of reworking of older crust can be detected, but all strongly sub-chondritic data rather fall on Pb-loss trends tracing back to chondritic sources. This long-lived and near-chondritic signature with negligible influence from a strongly depleted mantle, or from un-radiogenic sources, argues for protracted crust separation from an isolated mantle source. We suggest a scenario whereby primary melting to produce basaltic and komatiitic crust leaves an infertile harzburgitic residue, unlikely to re-melt, that becomes sequestered as mantle lithosphere. Hence, domains of primordial fertile mantle are continuously sourced from an undepleted mantle reservoir. Combined with small wavelength mantle convection, a near-chondritic to mildly depleted regional mantle is retained into at least the Mesoarchean.
Original language | English |
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Article number | 107399 |
Journal | Precambrian Research |
Volume | 407 |
DOIs | |
Publication status | Published - 1 Jul 2024 |
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Dive into the research topics of 'An isolated mildly depleted mantle source for the north atlantic craton'. Together they form a unique fingerprint.Projects
- 3 Finished
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Testing continental growth models with calcium and strontium isotopes
Kemp, T. (Investigator 01), Wilde, S. (Investigator 02), Van Kranendonk, M. (Investigator 03) & Elliott, T. (Investigator 04)
ARC Australian Research Council
1/01/20 → 3/12/24
Project: Research
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Expanding the frontiers of mass spectrometry: a laser ablation multiple split streaming (LAMSS) facility for Australia
Kemp, A. (Chief Investigator), McCulloch, M. (Chief Investigator), Fiorentini, M. (Chief Investigator), McCuaig, C. (Chief Investigator), Rate, A. (Chief Investigator), Rasmussen, B. (Chief Investigator), Evans, N. (Chief Investigator) & Clark, C. (Chief Investigator)
ARC Australian Research Council
1/01/15 → 31/12/15
Project: Research
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Advanced Facility for Climate & Environmental Change Research in Australias Indian Ocean Region
McCulloch, M. (Chief Investigator), Cawood, P. (Chief Investigator), Waite, A. (Chief Investigator), Lowe, R. (Chief Investigator), Kilburn, M. (Chief Investigator), Clode, P. (Chief Investigator), Falter, J. (Chief Investigator), Wyrwoll, K.-H. (Chief Investigator), Lynch, M. (Chief Investigator), Wasson, R. (Chief Investigator), Lavery, P. (Chief Investigator), Trotter, J. (Chief Investigator), McNaughton, N. (Chief Investigator) & Loneragan, N. (Chief Investigator)
ARC Australian Research Council
1/01/10 → 31/12/10
Project: Research