کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
4714622 | 1353978 | 2008 | 9 صفحه PDF | دانلود رایگان |

Six new 40Ar/39Ar and three cosmogenic 36Cl age determinations provide new insight into the late Quaternary eruptive history of Erebus volcano. Anorthoclase from 3 lava flows on the caldera rim have 40Ar/39Ar ages of 23 ± 12, 81 ± 3 and 172 ± 10 ka (all uncertainties 2σ). The ages confirm the presence of a second, younger, superimposed caldera near the southwestern margin of the summit plateau and show that eruptive activity has occurred in the summit region for 77 ± 13 ka longer than previously thought. Trachyte from “Ice Station” on the eastern flank is 159 ± 2 ka, similar in age to those at Bomb Peak and Aurora Cliffs. The widespread occurrences of trachyte on the eastern flank of Erebus suggest a major previously unrecognized episode of trachytic volcanism. The trachyte lavas are chemically and isotopically distinct from alkaline lavas erupted contemporaneously in the summit region < 5 km away.The three 36Cl ages are the first exposure ages reported for rocks from Erebus volcano. At an assumed erosion rate of 1.5 mm/ka 36Cl cosmogenic ages are 6.0 ± 0.5 ka for the Ice Tower Ridge flow, 4.9 ± 0.4 ka for Lower Hut flow, and 6.5 ± 0.6 ka for the Northeast flow. The 36Cl ages overlap within analytical uncertainty or are slightly younger than 40Ar/39Ar ages for these lava flows, and confirm the overall young age (< 25 ka) of the summit lava flows. One interpretation of these uniformly young ages is that older eruptions infilled the topographic depression caused by caldera formation and subsequently was covered by younger lavas.
Journal: Journal of Volcanology and Geothermal Research - Volume 177, Issue 3, 10 November 2008, Pages 569–577