First amber find on the Antarctic continent provides new insights into Cretaceous forests

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Until recently, a gap existed in the world map of amber discoveries: the Antarctic continent. But that gap has finally been closed, thanks to a team led by Dr. Johann P. Klages from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research and Dr. Henny Gerschel from the TU Bergakademie Freiberg.

In a recently released paper, the experts describe the amber they discovered in a sediment core they had recovered on an expedition with the research icebreaker Polarstern in 2017, using the seafloor drill rig MARUM-MeBo70 at a water depth of 946 meters. They have named the discovery "Pine Island amber" after its locality in the Pine Island Bay of the Amundsen Sea Embayment—at 73.57° South, 107.09° West, to be precise.

The findings are published in the journal Antarctic Science.

"The analyzed amber fragments allow direct insights into environmental conditions that prevailed in West Antarctica 90 million years ago," says first author Klages. "This fascinating find also indicates in more detail how the forest we reconstructed in our Nature study from 2020 could have functioned," the AWI marine geologist adds.

"It was very exciting to realize that at some point in their history, all seven continents had climatic conditions allowing resin-producing trees to survive. Our goal now is to learn more about the forest ecosystem—if it burns down, if we can find traces of life included in the amber. This discovery allows a journey to the past in yet another more direct way."

Those expecting large clumps of amber have to be disappointed: For analyses with reflected-light and fluorescence microscopy, the source material had to be air-dried and carefully sliced up into roughly fragments with 1 mm diameter, from which the amber pieces were picked. But nevertheless, exciting structures were to be found.

"The Antarctic amber likely contains remains of original tree bark as micro-inclusions. Considering its solid, transparent and translucent particles, the amber is of high quality, indicating its burial near the surface, as amber would dissipate under increasing thermal stress and burial depth," explains Henny Gerschel, until recently a member of staff at the TU Bergakademie Freiberg and now a consultant at the Saxon State Office for the Environment, Agriculture and Geology.

The team also found indications for pathological resin flow—a strategy trees use to seal damaged bark induced by parasites or wildfires, hence creating a chemical and physical barrier protecting from insect attacks and infections.

"Our discovery is another piece of the puzzle and will help us gain a better understanding of the swampy, conifer-rich, temperate rainforest environment identified near the South Pole during the mid-Cretaceous," says Gerschel.

More information: Johann P. Klages et al, First discovery of Antarctic amber, Antarctic Science (2024). DOI: 10.1017/S0954102024000208

Journal information: Nature

Provided by Helmholtz Association of German Research Centres