V020-0031
LIP flows may not have been as thick as they appear
LIP flows may not have been as thick as they appear
Thursday, 10 December 2020
Poster
Abstract:
Large Igneous Provinces (LIPs) are among the greatest magmatic events in Earth history with
volumes in excess of ∼500,000 km3 of predominantly basaltic lavas covering huge
continental and ocean regions (>100,000 km2). Field observations suggest that lava flow
fields in LIPs are made largely of sheet pāhoehoe lava lobes and the 10-100 m thick flows are
formed by inflation. Understanding the emplacement history of these lava lobes can help us
infer the magnitude and temporal dynamics of past events.
We use a phase-field model to describe solidification and re-melting of sequentially emplaced
lava flows. We calibrate model parameters using field measurements at Makaopuhi lava lake
and perform extensive numerical simulations by varying the thickness of individual flow and the
time intervals between eruptions. These results help quantify the complex interplay between
thermal evolution, flow thickness and emplacement frequency. If flows are thick enough and
the interval between emplacement short enough, reheating and re-melting may remove the
textural record of flow contacts – making flows appear thicker than they actually were. Guided
by field observations in Columbia River Basalt and Deccan Traps, we illustrate how the final
morphology of sequentially emplaced lava is controlled by both the time scale of emplacement
intervals and the time scale of cooling. We summarize our results to provide theoretical
constraints on the thickness and emplacement intervals of individual LIP lava flows.
volumes in excess of ∼500,000 km3 of predominantly basaltic lavas covering huge
continental and ocean regions (>100,000 km2). Field observations suggest that lava flow
fields in LIPs are made largely of sheet pāhoehoe lava lobes and the 10-100 m thick flows are
formed by inflation. Understanding the emplacement history of these lava lobes can help us
infer the magnitude and temporal dynamics of past events.
We use a phase-field model to describe solidification and re-melting of sequentially emplaced
lava flows. We calibrate model parameters using field measurements at Makaopuhi lava lake
and perform extensive numerical simulations by varying the thickness of individual flow and the
time intervals between eruptions. These results help quantify the complex interplay between
thermal evolution, flow thickness and emplacement frequency. If flows are thick enough and
the interval between emplacement short enough, reheating and re-melting may remove the
textural record of flow contacts – making flows appear thicker than they actually were. Guided
by field observations in Columbia River Basalt and Deccan Traps, we illustrate how the final
morphology of sequentially emplaced lava is controlled by both the time scale of emplacement
intervals and the time scale of cooling. We summarize our results to provide theoretical
constraints on the thickness and emplacement intervals of individual LIP lava flows.