Intrusion of basalt into frozen sediments and generation of Coherent-Margined Volcaniclastic Dikes (CMVDs)

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• 作者：A.H. Graettinger^a ; ^{agraettinger@gmail.com} ; I.P. Skilling^a ; D. McGarvie^b ; Á ; . Hö ; skuldsson^c
• 关键词：Askja ; Glaciovolcanic ; Ice-cemented ; Intrusions ; Peperite ; Iceland
• 刊名：Journal of Volcanology and Geothermal Research
• 出版年：2012
• 出版时间：1 March, 2012
• 年：2012
• 卷：217-218
• 期：Complete
• 页码：30-38
• 全文大小：3123 K

文摘

Coherent-Margined Volcaniclastic Dikes (CMVDs) are described for the first time from Askja (Dyngjufj?ll), Iceland. These dikes display continuous, coherent glassy margins 5 cm thick and have a variety of clastic interiors comprising vitric tephra, pillow and pillow-fragment bearing lapilli tuffs. CMVDs are interpreted to form when basaltic dikes interact with subglacial ice-cemented volcaniclastic sediments. Formation requires chilling of dike margins, drainage of the dike interior and flooding of the cavity by meltwater, followed by non-explosive mingling of magma, clastics and water. Evidence for ice-cementation includes minimal interaction with the host (< 3 mm peperite), local pillowed dike margins and the preservation of continuous glassy coherent margins along the edge of a drained dike cavity. CMVDs should be present at other volcanic centers with ice-cemented sediments, including the Martian cryosphere.