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New light on caldera evolution—Askja, Iceland

1991; Geological Society of America; Volume: 19; Issue: 4 Linguagem: Inglês

10.1130/0091-7613(1991)019 2.3.co;2

1943-2682

Geoff Brown, S. P. Everett, Hazel Rymer, Dave McGarvie, Ian Foster,

Polar Research and Ecology

Research Article| April 01, 1991 New light on caldera evolution—Askja, Iceland G. C. Brown; G. C. Brown 1Department of Earth Sciences, The Open University, Milton Keynes MK7 6AA, England Search for other works by this author on: GSW Google Scholar S. P. Everett; S. P. Everett 1Department of Earth Sciences, The Open University, Milton Keynes MK7 6AA, England Search for other works by this author on: GSW Google Scholar H. Rymer; H. Rymer 1Department of Earth Sciences, The Open University, Milton Keynes MK7 6AA, England Search for other works by this author on: GSW Google Scholar D. W. McGarvie; D. W. McGarvie 1Department of Earth Sciences, The Open University, Milton Keynes MK7 6AA, England Search for other works by this author on: GSW Google Scholar I. Foster I. Foster 1Department of Earth Sciences, The Open University, Milton Keynes MK7 6AA, England Search for other works by this author on: GSW Google Scholar Author and Article Information G. C. Brown 1Department of Earth Sciences, The Open University, Milton Keynes MK7 6AA, England S. P. Everett 1Department of Earth Sciences, The Open University, Milton Keynes MK7 6AA, England H. Rymer 1Department of Earth Sciences, The Open University, Milton Keynes MK7 6AA, England D. W. McGarvie 1Department of Earth Sciences, The Open University, Milton Keynes MK7 6AA, England I. Foster 1Department of Earth Sciences, The Open University, Milton Keynes MK7 6AA, England Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1991) 19 (4): 352–355. https://doi.org/10.1130/0091-7613(1991)019 2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation G. C. Brown, S. P. Everett, H. Rymer, D. W. McGarvie, I. Foster; New light on caldera evolution—Askja, Iceland. Geology 1991;; 19 (4): 352–355. doi: https://doi.org/10.1130/0091-7613(1991)019 2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract The large multiple-caldera volcanic system of Askja, central Iceland, is composed principally of subglacial basaltic hyaloclastite-pillow-lava formations and postglacial basaltic scoria and flows. Traditionally, such calderas are believed to be formed by downfaulting and ring-fracture collapse. Whereas this certainly applies to the smaller A.D. 1875 caldera, the older main caldera may have developed positive relief during subglacial construction of laterally confined hyaloclastite ridges above erupting fractures. This is supported by the evidence of a large negative gravity anomaly that reaches minima over the marginal low-density ridges but which is less negative within the caldera, where relatively dense postglacial lavas are believed to cover a more limited hyaloclastite succession beneath the caldera floor. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.