Marine microorganisms as amber inclusions: actuo-palaeontological data from the littoral forests of New Caledonia

International audienceMarine microorganisms trapped in amber are extremely rare in the fossil record, but are a very unexpectedoccurrence. Several different scenarios have been proposed to explain how these marine inclusions can becometrapped in a resin of terrestrial origin. The marine inclusions reported to date originate from very few pieces ofCretaceous amber from France, and a coastal setting for the amber source forests is generally proposed.However, there are conflicting suggestions about the conditions required for the marine inclusions to becomeentrapped in amber. These include: through high tides, directly blown in by the wind or from sea spray, orstorms and flooding of the littoral/estuarine forest floor or mangroves where the resin dropped into the seatrapping marine organisms. We tested the wind-blown and sea spray suggestions using a modern highly resinouscoastal forest domnated by Araucaria columnaris in New Caledonia as a model for the Cretaceous amberdeposits from France. We exposed fresh resin surfaces on the seaward side of the trees and collected older in situresins, and then examined them both. Marine microorganisms did become trapped on the freshly exposed resin,along with remnants from terrestrial organisms, and salt crystals. We suggest that for cases where only one ortwo marine inclusions are discovered in a deposit, an aeolian origin is most likely; however, a more energetic butpossibly still aeolian event is likely to be needed to be able to embed the high numbers of marine organismsrecorded from only two pieces of amber