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LIP flows may not have been as thick as they appear
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  • Jonas Katona,
  • Xiaojing Fu,
  • Tushar Mittal,
  • Michael Manga,
  • Stephen Self
Jonas Katona
Yale University

Corresponding Author:[email protected]

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Xiaojing Fu
University of California Berkeley
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Tushar Mittal
University of California Berkeley
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Michael Manga
University of California Berkeley
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Stephen Self
University of California Berkeley
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Abstract

Large Igneous Provinces (LIPs) are among the greatest magmatic events in Earth history withvolumes in excess of ∼500,000 km3 of predominantly basaltic lavas covering hugecontinental and ocean regions (>100,000 km2). Field observations suggest that lava flowfields in LIPs are made largely of sheet pāhoehoe lava lobes and the 10-100 m thick flows areformed by inflation. Understanding the emplacement history of these lava lobes can help usinfer the magnitude and temporal dynamics of past events.We use a phase-field model to describe solidification and re-melting of sequentially emplacedlava flows. We calibrate model parameters using field measurements at Makaopuhi lava lakeand perform extensive numerical simulations by varying the thickness of individual flow and thetime intervals between eruptions. These results help quantify the complex interplay betweenthermal evolution, flow thickness and emplacement frequency. If flows are thick enough andthe interval between emplacement short enough, reheating and re-melting may remove thetextural record of flow contacts – making flows appear thicker than they actually were. Guidedby field observations in Columbia River Basalt and Deccan Traps, we illustrate how the finalmorphology of sequentially emplaced lava is controlled by both the time scale of emplacementintervals and the time scale of cooling. We summarize our results to provide theoreticalconstraints on the thickness and emplacement intervals of individual LIP lava flows.