Some Lava Flows May Not Have Been as Thick as They Appear

Jonas Katona,Tushar Mittal,Michael Manga,Xiaojing Fu,Stephen Self

doi:10.1029/2021gl095202

Jonas Katona, Tushar Mittal + Show 3 more

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https://doi.org/10.1029/2021gl095202

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Abstract

AbstractIndividual lava flows in flood basalt provinces are composed of sheet pāhoehoe lobes and the 10–100 m thick lobes are thought to form by inflation. Quantifying the emplacement history of these lobes can help infer the magnitude and temporal dynamics of prehistoric eruptions. Here we use a phase‐field model to describe solidification and remelting of sequentially emplaced lava lobes to explore additional processes that may lead to thick flows and lobes. We calibrate parameters using field measurements at Makaopuhi lava lake. We vary the lobe thicknesses and the time interval between eruptions to study the interplay between these factors and their impact on the thermal evolution of flows. Our analysis shows that if the time between emplacements is sufficiently short, remelting may merge sequentially emplaced lobes—making lava flows appear thicker than they actually were—which suggests that fused lobes could be another mechanism that creates apparently thick lava flows.

Highlights

Continental flood basalt (CFB) province eruptions contain the largest (>1,000 km3, Bryan and Ernst (2008); Self et al (2014)) and longest (∼1000 km; Self et al (2008))lava flows
Given the general lack of large lava tubes in CFBs (Kale et al, 2020; Self et al, 1998), the primary process hypothesized for creating thick flows is the formation of pāhoehoe lobes by inflation (Hon et al, 1994)
There is a body of literature that commonly assumes that even the thickest (>40 m) CFB flows were formed by flow inflation (e.g., Anderson et al, 1999; Rader et al, 2017; Self et al, 1996, 1998), inspired by observations of Hawaiian lava flows (Hon et al, 1994)

Summary

Introduction

Continental flood basalt (CFB) province eruptions contain the largest (>1,000 km3 , Bryan and Ernst (2008); Self et al (2014)) and longest (∼1000 km; Self et al (2008))lava flows. If the lateral magma pressure is large enough, the lobe can propagate laterally by sporadic breakouts (Hamilton et al, 2020; Hon et al, 1994; Kauahikaua et al, 1998). This process has been observed in modern meter-scale Icelandic and Hawaiian lobes (Self et al, 1998). The maximal final inflated lobe thickness in Hawaiian flows, is only 10-15 m (Kauahikaua et al, 1998), which is smaller than many

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