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Brown, Richard J.; Blake, S.; Bondre, N. R.; Phadnis, V. M. and Self, S.
(2011).
DOI: https://doi.org/10.1007/s00445-011-0450-7
Abstract
Newly identified ´a´ā lava flows outcrop intermittently over an area of ~110 km2 in the western Deccan Volcanic Province (DVP), India. They occur in the upper Thakurvadi Formation in the region south of Sangamner. The flows, one of which is compound, are 15–25 m thick, and exhibit well-developed basal and flow-top breccias. The lavas have microcrystalline groundmasses and are porphyritic or glomerocrystic and contain phenocrysts of olivine, clinopyroxene or plagioclase feldspar. They are chemically similar to compound pāhoehoe flows at a similar stratigraphic horizon along the Western Ghats. Petrographic and geochemical differences between ´a´ā flows at widely spaced outcrops at the same stratigraphic horizon suggest that they are the product of several eruptions, potentially from different sources. Their presence in the DVP could suggest relative proximity to vents. This discovery is significant because ´a´ā lavas are generally scarce in large continental flood basalt provinces, which typically consist of numerous inflated compound pāhoehoe lobes and sheet lobes. Their scarcity is intriguing, and may relate to either their occurrence only in poorly preserved or exposed proximal areas or to the flat plateau-like topography of flood basalt provinces that may inhibit channelization and ´a´ā formation, or both. In this context, the ´a´ā flow fields described here are inferred to be the products of eruptions that produced unusually high-effusion-rate lavas compared to typical flood basalt eruptions. Whether these phases were transitional to lower intensity, sustained eruptions that fed extensive low effusion rate pāhoehoe flow fields remains unclear.
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About
- Item ORO ID
- 30876
- Item Type
- Journal Item
- ISSN
- 1432-0819
- Project Funding Details
-
Funded Project Name Project ID Funding Body On the trail of flood-basalt vent systems from the western Deccan Volcanic Province, India NE/E019021/1 NERC (Natural Environment Research Council) - Keywords
- ´A´ā lava; flood basalt; Deccan Volcanic Province; Pāhoehoe
- Academic Unit or School
-
Faculty of Science, Technology, Engineering and Mathematics (STEM)
Faculty of Science, Technology, Engineering and Mathematics (STEM) > Environment, Earth and Ecosystem Sciences - Copyright Holders
- © 2011 Springer-Verlag
- Depositing User
- Stephen Blake