An international team led by the Alfred Wegener Institute for Marine and Polar Research (Awi) and the TU Bergakademie Freiberg University in Germany has discovered traces of amberi.e. fossil resin of conifers, dating back to around 90 million years agothus demonstrating that the Antarctic continent was home to forests at that time. Amber was found in one sediment core taken in 2017 from the seabed near theWest Antarctica. Its presence testifies to the diffusion on the Antarctic continent, in the Cretaceous period, of Swampy temperate rainforestsrich in conifers.
Although it is difficult to imagine, up until about 34 million years ago theAntarctica it was not covered by ice, but had a temperate climate and was home to forests and waterways. Over time, numerous pieces of evidence have been identified that confirm this.
The discovery of amber in the marine sediments of Antarctica
In 2017, during an expedition aboard the Polarstern research vessel, a core was taken from the seabed near Pine Islandin the’West Antarctica. The carrot was subjected to long analyzes which led to the identification of a network of fossilized roots dating back to the Middle Cretaceous, but also pollen And spores. Now in these same sediments one has been discovered layer of carbonaceous mud 3 m long which hosts numerous fragments of amber measuring between 0.5 and 1 mm, with colors ranging from yellow to orange.
Antarctica is the only continent where amber has never been found (the southernmost place where its presence has been detected is in New Zealand). The conservation up to now of the resin produced by Cretaceous conifers has been possible thanks to its chemical characteristics suitable for fossilization and the presence of a marshy environment. Here the remains of plants (including the resin associated with wood) were deposited in oxygen-poor stagnant waters after their death. There oxygen deficiency hindered the decomposition of the remains, which over time were buried by sediments and became compacted until they became lignitei.e. fossil coal. In fact, Antarctic amber was found right inside a 5 cm thick layer of lignite present in the carbonaceous mud.
The analysis of Antarctic core amber
The lignite found in the layer of carbonaceous mud was dried and then reduced into small fragments. These were analyzed by microscopy with reflected light and fluorescence, which revealed the presence of numerous pieces of amber. Amber, in particular, shows signs that reveal that the resin from which it was formed leaked from the plants to repair bark lesions typical of forest fires. Evidence of fires in the forests of the Cretaceous, one of the hottest periods in Earth’s history, has also been found elsewhere at lower latitudes. Pine Island amber appears to be associated with small fragments of barkbut further analysis is needed to confirm this. Another goal is to look for any traces of life within the fossilized resin.
This discovery is very important because it allows us to reconstruct the landscape and climate of West Antarctica before the polar climate took over. 34 million years agoin fact, the decrease in carbon dioxide (carbon dioxide) in the atmosphere led to a global climate cooling and therefore the formation of Antarctic ice sheet.
