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Description
Currently, there is little evidence concerning the extent or composition of the Earth’s crust from the time of
formation ca. 4.56 billion years ago (Ga) to the end of the meteoritic Late Heavy Bombardment that affected all
rocky planets at ca. 3.8 Ga on Earth from 4.5 to 4.0 Ga (the Hadean), where no rock record remains, rare
crystals of zircon provide minute time capsules of what our planet’s crust was like. Between 4.0 and 3.6 Ga, a
partial rock record is preserved in just a few terranes on Earth, and geochemical and isotopic relationships
between these rocks and their zircon endowment allow us to extrapolate back to the composition and extent of
the earliest crust. However, the full picture of zircon-host rock relationships in the early Earth is incomplete.
This is because most of these terranes remain under-investigated, especially those in the polar and subpolar
regions of Canada and Antarctica, where there is the greatest potential for discoveries of new areas of
Eoarchean crust. Through a combination of expedition work together with geochemical and geochronological
investigations, the PAAN project will deliver breakthrough science by unlocking significant new information
about Earth’s early history, especially with respect to the formation and evolution of continental crust. To
achieve this goal zircon in samples from polar and sub-polar regions (namely Antarctica, Greenland and
Labrador) will be used in combination with geochemistry and field work. Integration of these avenues of
investigation will be used to compare the geological histories of these regions in order to find ‘missing links’
between them. The overarching goal will be to test the hypothesis that by 3.6 Ga these disparate relics of
Eoarchean crust were part of the same ‘first supercontinent’.
Summary of project results
In the project, through a combination of field expedition work together with geochemical and geochronological investigation, the ‘Poles Together’ project aimed to bring new information about Earth’s earliest history, with the main focus on the formation and evolution of continental crust.
From the time of Earth formation around 4.56 billion years ago (Ga) to the end of the meteoritic Late Heavy Bombardment that affected all rocky planets until ca. 3.8 Ga, there is little evidence concerning the extent or composition of the Earth’s crust. On Earth from 4.5 to 4.0 Ga, no rock record remains, but rare crystals of mineral zircon provide minute time capsules of what our planet’s crust was like. Between 4.0 and 3.6 Ga (Eoarchean), a partial rock record is preserved in just a few terranes on Earth, such as Napier Complex in East Antarctica, Sagle Block in the Labrador Coast and Itsaq Gneiss Complex of SW Greenland. Most of these terranes, being presently in polar and sub-polar regions, remain under-investigate. Field expeditions to remote regions of Labrador and Greenland to obtain unique rock samples were the most challenging part of the project.
The overarching goal of the project, testing the hypothesis that by ca. 3.6 Ga the three disparate relics of Eoarchean crust (namely: Napier Complex, Saglek Block and Itsaq Gneiss Complex) were part of the same ‘first supercontinent’ was achieved.
In the project, through a combination of field expedition work together with geochemical and geochronological investigation, the ‘Poles Together’ project aimed to bring new information about Earth’s earliest history, with the main focus on the formation and evolution of continental crust.
From the time of Earth formation around 4.56 billion years ago (Ga) to the end of the meteoritic Late Heavy Bombardment that affected all rocky planets until ca. 3.8 Ga, there is little evidence concerning the extent or composition of the Earth’s crust. On Earth from 4.5 to 4.0 Ga, no rock record remains, but rare crystals of mineral zircon provide minute time capsules of what our planet’s crust was like. Between 4.0 and 3.6 Ga (Eoarchean), a partial rock record is preserved in just a few terranes on Earth, such as Napier Complex in East Antarctica, Sagle Block in the Labrador Coast and Itsaq Gneiss Complex of SW Greenland. Most of these terranes, being presently in polar and sub-polar regions, remain under-investigate. Field expeditions to remote regions of Labrador and Greenland to obtain unique rock samples were the most challenging part of the project.
The overarching goal of the project, testing the hypothesis that by ca. 3.6 Ga the three disparate relics of Eoarchean crust (namely: Napier Complex, Saglek Block and Itsaq Gneiss Complex) were part of the same ‘first supercontinent’ was achieved.
Most of the work was focussed on Antarctica where our knowledge is extremely limited and where samples were from historical Australian expeditions of 70’s and 80’s (Król et al., 2022, 2023).
Analysed samples have proven existence of crust as early as >3.7 Ga areas as distant as Antarctica, Labrador and Greenland. Additionally, a sequence of magmatic events from Eoarchean to Neoarchean (ca. 3.9-2.57 Ga), similar with the Itsaq Gneiss Complex of SW Greenland, was recorded in the Labrador. These multiple generations of magmatism in Labrador and SW Greenland share strong similarities. Thanks to our study, new tectonic model has been proposed (Keluskar et al. 2024) for the Archean period and our understanding of Labrador – Greenland connection as part of the NAC. Based on the Hf signature, it has been suggested that a change in tectonic environment resulted from the initiation of subduction at ca. 3.2 Ga.
The most surprising result was discovery of emergent land and, consequently, pre-biotic conditions potentially suitable for life as early as in Eoarchean at ca. 3.73 Ga in the Napier Complex of Antarctica (Król et al. 2024). This was done based on the oxygen isotope analysis of zircon grains. This has huge impact for further studies of early Earth, early life and polar regions.
GeoBeLa, built within a frame of the project, has huge impact on scientific community of the Earth science, especially in Poland, where was a shortage of rock-processing laboratory. Already various PhD students and researchers from Poland, Norway, Sweden and India used laboratory.
Another, additional impact of the project is set-up collaboration between Polish and Norwegian scientists together with Canadian researchers in Labrador area. Presently, our institute (the GeoBeLa Laboratory of IGF PAN) is in a possession of the largest collection of rock specimens across the Labrador coast. This will give a frame for future studies.
Last, but not least is the socio-economical impact. Wide dissemination program was offered during the course of the project. Additionally, the Stony Path through Time exhibition was built in the open area of the GeoBeLa Laboratory – the exhibition which will last as an interesting way of learning geology.
Summary of bilateral results
Important aspect of the collaboration was the transfer of knowledge between researchers and institutions, especially applicable to PhD students that were encouraged to work with different methods both in practice and in terms of interpreting complex data. In addition, research in polar regions is of great importance to both countries, and such international collaboration are essential to the advancement of these interests with the production of joint publications and development of research links that have the potential to extend beyond timeframe of the project. Also the project is set-up collaboration between Polish and Norwegian scientists together with Canadian researchers in Labrador area. Presently, our institute (the GeoBeLa Laboratory of IGF PAN) is in a possession of the largest collection of rock specimens across the Labrador coast.