Scientists discover 720-foot-wide meteorite crater in French winery

Upon examination, he established that the impact of an iron-nickel meteorite indeed once formed the crater.

A lower magnetic field confirmed the hypothesis

"The microanalysis showed that dark-colored layers in one of the shists, which usually simply comprise a larger percentage of mica, might be shock veins produced by the grinding and fracturing of the rock, which in turn could have been caused by an impact," explained Brenker. He also found evidence of breccia, which is angular rock debris held together by a kind of “cement,” that can also occur during a meteorite impact.

After an initial investigation, Brenker and his colleague Andreas Junge, Professor of Applied Geophysics at Goethe University Frankfurt, and a group of students went with him to Southern France to examine the crater in detail. 

A revelation lay awaiting them. The Earth's magnetic field was slightly weaker in the crater than in the surrounding area. This is not unnatural for impact craters as the impact can shatter or melt the rock, which can "contribute less to Earth’s magnetic field."

The crater depression also contained micro diamonds

The scientists also found tiny iron oxide spherules in the impact crater, thanks to strong magnets attached to a plate. As per laboratory analysis, the spherules also contained nickel-bearing iron and a core of minerals usually found in crater environments. Additionally, numerous shock micro diamonds produced through the high pressure during the meteorite’s impact were also discovered.

Brenker explained: "Such microspheres form either through abrasion of the meteorite in the atmosphere or only upon impact when a large part of the iron meteorite melts and then reacts with the oxygen in the air. On impact, material shattered at the point of impact might then also be encased."

This, along with the lower magnetic field and other finds, led them to arrive at the only conclusion - that a meteorite did strike there.

The finding makes the crater exciting for geological laypeople, too, said Brenker, as "every visitor can experience here the immense energies released upon such an impact."

The study was presented at the 54th Lunar and Planetary Science Conference 2023.

Study Abstract:

Small impact craters (< 300m) are quite rare, and proof of an impact origin is difficult to obtain 1-5, especially if remnants of the impactor material are missing. The Earth Impact Database (EID), hosted in the Planetary and Space Science Centre (PASSC) at the University of New Brunswick, Canada, and recentreviews6-7 lists only three, though much larger, structures in West and Central Europe as a confirmed high-velocity impact craters, namely Rochechouart(France), Nördlinger Ries and Steinheimer Becken(both in Germany). Although smaller impact structures should be much more frequent, no proof for even a single confirmed small crater structure is reported6-7.In this contribution, for the first time, we present compelling mineralogical and geophysical evidence for a small crater structure (about 200m wide) in Southern France, which might be part of a crater field, the Herault impact structure6. The data presented here were collected for the largest structure, the “Domaine du Meteore”-crater formally known as ”le Clot”8.