Abstract We report here the evidence of protracted metamorphic evolution of orthopyroxene-sillimanite granulite culminating in UHT metamorphism within the Paleoproterozoic granulite complex of the Angara-Kan block (SW Siberian craton). The Opx-Sil granulites were formed during UHT metamorphism (T=1070-1100°C and P = 9 kbar) at ca. 1.8 Ga which was followed by retrograde isobaric cooling down to the temperature around 900-950°C. At ca. 1.74 Ga Opx-Sil granulites were trapped and partly reworked by a granitic melt with crystallization of perthitic feldspar at about 750°C. The integration of all data on metamorphism and granitoid magmatism of the Angara-Kan block indicates two-staged metamorphic history. The first stage of the granulite metamorphism occurred in the time range of 1.89-1.85 Ga and was terminated by the emplacement of the 1.84 Ga post-collisional granites, the second stage of metamorphism occurred at UHT conditions and culminated in 1.78-1.8 Ga. The UHT metamorphism including the isobaric cooling retrograde stage and granite magmatism is limited by the time interval from 1.78-1.8 to 1.74-1.75 Ga, i.e. its duration was around 30-60 million years.

中文翻译：

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Angara-Kan 地块（西南西伯利亚克拉通）的斜方辉石-硅线石麻粒岩：对 UHT 变质作用时间的限制

摘要 我们在此报告了斜方辉石-硅线石麻粒岩长期变质演化的证据，最终在安加拉-坎地块（西伯利亚西南克拉通）的古元古代麻粒岩复合体中发生 UHT 变质作用。Opx-Sil 麻粒岩是在 UHT 变质作用（T=1070-1100°C 和 P=9 kbar）期间形成的。1.8 Ga，然后逆行等压冷却至 900-950°C 左右的温度。在大约 1.74 Ga Opx-Sil 麻粒岩被花岗岩熔体捕获并部分再加工，在大约 750°C 时结晶长石。Angara-Kan 地块变质作用和花岗岩类岩浆作用的所有数据综合表明，变质历史为两阶段。第一阶段麻粒岩变质作用发生在 1.89-1.85 Ga 的时间范围内，并因 1 的侵位而终止。