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 ε_Nd(t) values for the Triassic (ε_Nd(251) = +5.1) and Permian (ε_Nd(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.

中文翻译：

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SG-7超深钻孔（西西伯利亚石油和天然气省）从6925.2至8250-m间隔的岩石上最初的147 Sm– 143 Nd数据

摘要

位于西西伯利亚石油北部北部的SG-7超深钻孔（En-Yakha）区间6925.2-8250 m内的14个玄武岩，凝灰岩，硅质岩和白云岩样品的¹⁴⁷ Sm– ¹⁴³ Nd系统。和煤气省，进行了研究。有条件地归因于三叠纪的两个玄武岩的年龄为251 Ma，初始比率（¹⁴³ Nd / ¹⁴⁴ Nd）₀ = 0.51258±0.00028。日期为二叠纪的其他10个样品的¹⁴⁷ Sm– ¹⁴³ Nd数据具有等时性（MSWD = 0.79）依赖性，这决定了276±45 Ma（95％置信限）的年龄和（¹⁴³ Nd / ¹⁴⁴ Nd）₀= 0.512545±0.000046。初始ε_钕（吨），用于三叠纪值（ε_钕（251）= 5.1）和二叠（ε_钕（276）= 5.1）岩研究的间隔的演示对应于适度亏损地幔的值。在^143个Nd模式年龄值表明，新元古代和/或更老的地层进行了研究岩石的原岩。