ABSTRACT

Zircon xenocrysts from two diamond-barren kimberlite pipes (Leningrad and Ruslovaya) in the West Ukukit kimberlite field opened a ‘window’ to the buried crustal basement in the northern Siberian craton. Zircon U-Pb ages reveal a close affinity of the basement of the Khapchan belt to the Archaean Anabar province and a significant tectonomagmatic reworking in the Paleoproterozoic (~2.1–1.8 Ga) due to collision between the Anabar province and the Olenek province. The West Ukukit kimberlite field experienced multiple tectonomagmatic reactivation from ~670 to 144 Ma, which can be attributed to interaction of the deep crust with mantle-derived melts. Hf isotope composition of zircon xenocrysts reveals significant addition of juvenile material into the crust during the Paleoproterozoic orogeny in diamond-barren kimberlite fields, which is different from the reworking crust in the southern Yakutia diamondiferous kimberlite fields. Eruption of the Leningrad and Ruslovaya pipes were constrained as the Late Jurassic, much later than the well-known Late Silurian-Earth Devonian kimberlites in the West Ukukit kimberlite field. A NE-trending, >2000 km long kimberlite corridor is proposed to account for a prolonged lithospheric channel for episodic eruption of kimberlites in the Siberian craton. The diamond storage in the lithosphere beneath the West Ukukit kimberlite field may have been largely reduced by the Paleoproterozoic orogeny and Phanerozoic reworking.

摘要

来自 West Ukukit 金伯利岩田的两根钻石贫瘠的金伯利岩管（列宁格勒和鲁斯洛瓦亚）的锆石异晶为西伯利亚克拉通北部埋藏的地壳基底打开了一扇“窗户”。锆石 U-Pb 年龄揭示了 Khapchan 带的基底与太古代 Anabar 省密切相关，并且由于 Anabar 省和 Olenek 省之间的碰撞，在古元古代（~2.1-1.8 Ga）发生了显着的构造岩浆改造。West Ukukit 金伯利岩场在 670 至 144 Ma 期间经历了多次构造岩浆活动，这可归因于深部地壳与地幔衍生熔体的相互作用。锆石异种晶的 Hf 同位素组成表明，在金刚石贫瘠的金伯利岩区的古元古代造山运动期间，地壳中显着增加了幼年物质，这与雅库特南部含金刚石金伯利岩田的再加工地壳不同。列宁格勒和 Ruslovaya 管道的喷发被限制为晚侏罗世，比西乌库吉特金伯利岩领域著名的晚志留纪-地球泥盆纪金伯利岩晚得多。提出了一条 NE 向、> 2000 公里长的金伯利岩走廊，以解释西伯利亚克拉通金伯利岩间歇性喷发的延长岩石圈通道。West Ukukit 金伯利岩场下方岩石圈中的钻石储存量可能已因古元古代造山运动和显生宙再加工而大大减少。比西乌库吉特金伯利岩领域著名的晚志留纪-地球泥盆纪金伯利岩晚得多。提出了一条 NE 向、> 2000 公里长的金伯利岩走廊，以解释西伯利亚克拉通金伯利岩间歇性喷发的延长岩石圈通道。West Ukukit 金伯利岩场下方岩石圈中的钻石储存量可能已因古元古代造山运动和显生宙再加工而大大减少。比西乌库吉特金伯利岩领域著名的晚志留纪-地球泥盆纪金伯利岩晚得多。提出了一条 NE 向、> 2000 公里长的金伯利岩走廊，以解释西伯利亚克拉通金伯利岩间歇性喷发的延长岩石圈通道。West Ukukit 金伯利岩场下方岩石圈中的钻石储存量可能已因古元古代造山运动和显生宙再加工而大大减少。