Diamond-inclusion system recording old deep lithosphere conditions at Udachnaya (Siberia)

Fabrizio Nestola, Gabriele Zaffiro, Mattia L. Mazzucchelli, Paolo Nimis, Giovanni B. Andreozzi, Benedetta Periotto, Francesco Princivalle, Davide Lenaz, Luciano Secco, Leonardo Pasqualetto, Alla M. Logvinova, Nikolay V. Sobolev, Alessandra Lorenzetti, Jeffrey W. Harris

Результат исследования: Научные публикации в периодических изданияхстатья

4 Цитирования (Scopus)

Аннотация

Diamonds and their inclusions are unique fragments of deep Earth, which provide rare samples from inaccessible portions of our planet. Inclusion-free diamonds cannot provide information on depth of formation, which could be crucial to understand how the carbon cycle operated in the past. Inclusions in diamonds, which remain uncorrupted over geological times, may instead provide direct records of deep Earth’s evolution. Here, we applied elastic geothermobarometry to a diamond-magnesiochromite (mchr) host-inclusion pair from the Udachnaya kimberlite (Siberia, Russia), one of the most important sources of natural diamonds. By combining X-ray diffraction and Fourier-transform infrared spectroscopy data with a new elastic model, we obtained entrapment conditions, Ptrap = 6.5(2) GPa and Ttrap = 1125(32)–1140(33) °C, for the mchr inclusion. These conditions fall on a ca. 35 mW/m2 geotherm and are colder than the great majority of mantle xenoliths from similar depth in the same kimberlite. Our results indicate that cold cratonic conditions persisted for billions of years to at least 200 km in the local lithosphere. The composition of the mchr also indicates that at this depth the lithosphere was, at least locally, ultra-depleted at the time of diamond formation, as opposed to the melt-metasomatized, enriched composition of most xenoliths.

Язык оригиналаанглийский
Номер статьи12586
Страницы (с-по)12586
Число страниц8
ЖурналScientific Reports
Том9
Номер выпуска1
DOI
СостояниеОпубликовано - 29 авг 2019

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