Argon‐40/argon‐39 age of the El'gygytgyn impact event, Chukotka, Russia
Argon‐40/argon‐39 age of the El'gygytgyn impact event, Chukotka, Russia
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俄罗斯楚科奇半岛 Elgygytgyn 撞击事件的 Argon‐40/argon‐39 年龄
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发表时间：
2000
期刊：
影响因子：
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通讯作者：
P. Layer
中科院分区：
文献类型：
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作者：
P. Layer
摘要：俄罗斯楚科奇的El'gygytgyn湖位于一个大约18公里的陨石坑中，可能是撞击的起源。火山口位于鄂霍次克-楚科奇火山带的白垩纪火山岩中。用激光40Ar/39Ar对El'gygytgyn湖边缘撞击融化的火山岩进行测年，得到10个样本加权的高原年龄为3.58±0.04 Ma。在本研究中，由于白垩纪火山岩在撞击熔融过程中脱气不完全，Ar步进加热方法对于鉴定样品中的遗传Ar至关重要。这个年龄与之前的K - Ar和裂变径迹年龄一致，但比之前的年龄更精确，表明陨石坑是“瞬时”形成的。这种严格的年龄控制，加上撞击物、冲击石英和其他特征的存在，与该结构的撞击起源一致，似乎不符合内部（火山）起源模型。
Abstract— Lake El'gygytgyn, Chukotka, Russia, lies in a ∼18 km crater of presumably impact origin. The crater is sited in Cretaceous volcanic rocks of the Okhotsk‐Chukotka volcanic belt. Laser 40Ar/39Ar dating of impact‐melted volcanic rocks from the rim of Lake El'gygytgyn yields a 10‐sample weighted plateau age of 3.58 ± 0.04 Ma. The Ar step‐heating method was critical in this study in identifying inherited Ar in the samples due to incomplete degassing of the Cretaceous volcanic rocks during impact melting. This age is consistent with, but more precise than, previous K‐Ar and fission‐track ages and indicates an “instantaneous” formation of the crater. This tight age control, in conjunction with the presence of impactites, shocked quartz, and other features, is consistent with an impact origin for the structure and seems to discount internal (volcanogenic) origin models.