Refining Hf crust formation ages in Precambrian terranes

Andreas Petersson, Tod E. Waight, Anthony I.S. Kemp, Martin J. Whitehouse

Research output: Contribution to journalArticlepeer-review

Abstract

The mechanisms and timing of long term chemical differentiation of the Earth are fundamental questions in the geosciences. We present detrital zircon U-Pb, O and Hf isotope data from Fennoscandia to assess how crustal growth can be reconciled with its known >1.5 billion year geological history. A broadly linear evolution (176Lu/177Hf = 0.0403), from chondritic mantle at the age of the oldest identified Fennoscandian crust, to present day MORB values (εHf(0 Ma) ≈ þ16), provides a good fit with the most radiogenic zircon and whole rock Hf isotope data from the region. This mantle reference gives crustal growth peaks that correlate with known regional orogenic events. In contrast, a conventional 4.5 Ga strongly depleted mantle generates growth peaks outside of known geologic activity. Applying the same approach to the East Pilbara Terrane and SW Greenland yields model age peaks that also align with known magmatic activity. We propose that more geologically relevant crust formation ages are obtained via referencing a mantle source defined by the most radiogenic zircons/samples in the studied region.

Original languageEnglish
Pages (from-to)7-13
Number of pages7
JournalGeochemical Perspectives Letters
Volume32
Early online date16 Sept 2024
DOIs
Publication statusPublished - 2024

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