Abstract
The 147Sm–143Nd systematics of 14 samples of basalts, tuffs, silicites, and dolerites from the interval 6925.2–8250 m of the SG-7 superdeep borehole (En-Yakha), located in the northern part of the West Siberian oil-and-gas province, was studied. The age of two basalts, conditionally attributed to the Triassic, is 251 Ma, the initial ratio (143Nd/144Nd)0 = 0.51258 ± 0.00028. The 147Sm–143Nd data for the other ten samples dated to the Permian yield an isochron (MSWD = 0.79) dependence, which determines the age of 276 ± 45 Ma (95% confidence limit) and (143Nd/144Nd)0 = 0.512545 ± 0.000046. The initial εNd(t) values for the Triassic (εNd(251) = +5.1) and Permian (εNd(276) = +5.1) rocks of the interval studied demonstrate the values corresponding to the moderately depleted mantle. The 143Nd model age values indicate that Neoproterozoic and/or older formations were the protolith of the rocks studied.
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Notes
VC = 100*STDEV/AVERAGE, where AVERAGE = \(\bar {x}\) = \(\frac{1}{n}\sum\nolimits_{i = 1}^n {{{x}_{i}}} \), STDEV = \(\sqrt {\sum\nolimits_{i = 1}^n {({{x}_{i}} - \bar {x})} {\text{/}}(n - 1)} \).
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Funding
This work was conducted within the framework of a State Assignment of the Institute of Geology and Geochemistry, Ural Branch, Russian Academy of Sciences, project no. АААА-А18-118053090044-1.
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Translated by D. Voroshchuk
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Ronkin, Y.L., Karaseva, T.V. & Maslov, A.V. The First 147Sm–143Nd Data on Rocks from the 6925.2- to 8250-m Interval of the SG-7 Superdeep Borehole (West Siberian Oil-and-Gas Province). Dokl. Earth Sc. 496, 130–134 (2021). https://doi.org/10.1134/S1028334X2102015X
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DOI: https://doi.org/10.1134/S1028334X2102015X