Abstract:
Earth’s history has been punctuated by
vast magmatic episodes. These events
are preserved in the geological record
as large igneous provinces — areas of
Earth’s surface flooded by millions of cubic
kilometres of lava that erupted in short
periods of time1. Thought to be triggered by
upwelling plumes of hot mantle2, the size
and frequency of these volcanic episodes
may have been greater in the past, fuelled
by the hotter mantle of Earth’s Archaean
eon3. During this time, a distinctive type of
igneous rock — komatiite — formed from
magmas with high eruption temperatures
that cooled to grow long needle-like olivine
crystals4,5 (Fig. 1). The rarity of komatiite
eruptions more recently in Earth’s history4
is taken as evidence of the mantle’s slow
cooling3,6. However, komatiitic lavas
that formed 89 million years ago from
the volcanic outpourings of the nascent
Galápagos plume have been found in the
Tortugal suite of the Caribbean large igneous
province7. Writing in Nature Geoscience,
Trela et al.8 demonstrate that these lavas
formed from anomalously hot mantle with a
temperature similar to that which produced
the ancient Archaean komatiites, challenging
our view of Earth’s thermal structure
and history.
