Protogenetic clinopyroxene inclusions in diamond and Nd diffusion modeling—Implications for diamond dating
نویسندگان
چکیده
Abstract Diamonds are witnesses of processes that have operated in Earth's mantle over more than 3 b.y. Essential to our understanding these is the determination diamond crystallization ages. These cannot be directly determined on diamond, but they can calculated using radiogenic isotopic systematics suitable minerals included a diamond. This method relies assumption mineral inclusions were equilibrium with diamond-forming medium. We evaluated validity Sm-Nd ages yielded by clinopyroxene combining crystallographic orientation analyses and Nd diffusion modeling at relevant conditions for cratonic mantle. investigated relationships (CORs) 54 within 18 diamonds from South Africa Siberia. Clinopyroxene some showed specific CORs their hosts, indicating possible syngenesis. Other samples had clusters sharing same no relative older (i.e., protogenetic). Diffusion temperature range typical lithospheric (900–1400 °C) resetting system grains larger 0.05 mm requires geologically long interaction fluid/melt (>3.5 m.y. average ~1150 °C). Depending inclusion size regime, protogenetic may not fully reequilibrate during diamond-formation events. suggest small (<0.2 mm) equilibrated temperatures higher 1050–1080 °C most age determinations.
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ژورنال
عنوان ژورنال: Geology
سال: 2022
ISSN: ['0091-7613', '1943-2682']
DOI: https://doi.org/10.1130/g50273.1